CA2110263A1 - Detection of collagen degradation in vivo - Google Patents

Abstract

Methods of determining collagen degradation in vivo, by quantitating concentration of the following peptides (I) in a body fluid, wherein (II) is hydroxylysyl pyridinoline or lysyl pyridinoline, J is pyroglutamic acid or glutamine, and the parentheses designate optional amino acids. Also, compositions useful in quantitating collagen peptides to determine the rate of bone resorption are prepared by treating bone with a protease, such as collagenase, and purifying the compositions so as to enrich them with peptides capable of binding to the monoclonal antibody MAb-1H11.

Description

WO 92/21698 PCr/US92t04104 21~0263 D~T~:CTION OF COLLAG3E~ DEGRADA.TlC3N lN ~lVO :
This is a continuation-in-part of U.S. Serial No. 614,719, which is a continuation-in-part of U.S~ Serial No. 444,881, flled December 1, 1989, which is a:
continustion-in-part o~ U.S. Serial No. `118,234, filed ~November 6, 1987, now issued as U.S. Patent 4,973,6~6.
This invention was made with government support under grants ~AR37318 and AR36794 awarded by the National lnstitutes of;~Health. ~The~go~errament~has ~ertain rights ~n the anvention. ~
F~eld o~ thé Invention The ~present inventiotl re~ ~- to ~et'odc for ~detect~ng~ and~monito~ing ~:
:~ collagen: degradation u~l ViYo. ~ ~ More ~p~cificalIy,~it ~relates to methods ~or:::
uantitating; certain cross-linked telop~ptides produ~ed :ir~ vivo upon degradation ~: . of collagen and to reagents ;useful ~in:sucb~:methods.
Back~und o~:~th~.~Invention:
~ ~e:~own~il~sesof~lla~ë~Ye~éen~dèscribèdto~date.~:The~Cl~
collagens, su~l i~ed~ lnto~ t ~ I' 'IIl; V, and~ ~l, are; ~ownl to ~ rm~ f These~ ~ :~2~ ~i e~ proco~agen~ mol~cules,~ `~m~de~:up~o~
N-term~nal and C-termin~l pro~e~tides,~which aFe atta~hed to~the aoFe~colla~en :: : molecule~ ~f~er removal o~ the:~propeptîdes, which occurs~n~turally~ut viw during ~a collagen ~thesi, the remalnlng core o~ the collagen molecule ¢onsists largeb oâ
a triple helical domain haviag termin~l :telopeptide sequences whi:ch are nontriple-he1ical. These telopeptide~ sequences ~hàve ~an important function~ as ~sites~of~
intermo1ecular~ross-linkillg:o~ collag~n ~ibrils extracellulaPly.
:The~present invention~-elates~to methods~of detecting co11agen~degradstion~
based on ~saying for particular~ ~ro~-linked telopeptides produced~ ivo upon : collagen degradation. ~: In the past,; assays~have~ been :developed or :monitoring~
degrad~tion of ~collagen in ~Jivo: by mçasuring various :biochemical markers, som~
of which have beerl degradation produ¢ts o~ collagen. For e~tample, ~one turnover :: : :
:: :

W(;) 92/216~8 PCI`/US92/04104 ~llo2 63 -2- ~

associated with Ps~et's disease has been monitored by measuring small peptides cont~ining hydroxyproline, which are excreted in the urine following degradationof bone collagenl, Russell et aL, Metab. Bone Dis. ~nd ReL Res. 4 and 5, 255-262(1981); and Singer, F.R., et al., Metabolie Bone Di~sase, Vol. II (eds. Avioli, L.V.
and Xane, S.M.), 489-575 (lg78), A~!ademic Press, New York.
Other researchers ha~e measured the cro~s-linking con~pound pyridinoline in urine as an index of collagen degradation in joint disease. ~ee, for background and for example, Wu and Eyre, Biochemu~try, 23:1850 (l984); Black et al., Annal3 of the Rheumatic Di~ea3es, 48:641-644 (1989); Robins et alO; Annal~ of the Rheumatic Di3ea~es, 45:969-973 (1985); and Seibel et al., l'he Journa~ of Rheumatolo~y, 16:964 (1989). In contrast to the present invention, some prior researchers have hydrolyzed peptides from body fluids and then looked for the pre~ence o~ individual hydro~cypyri~dinium residue~. None o~ these researcl~ rs has reported mePsuring a telopeptide containing a cross-link that is naturally produced Ul YiVo upon collagen degradation, aS in the present inven1:ion.
U.K. Patent application GB 2~205,643 reports that the degradation of type III
collagen in the body is quantitatively determined by measuring the ~oncentrationof an N-terminal telopeptide from type III collagen in a body fluid. In this reference, it i~ reported that cross-linked telopeptide regions are not desirable. In ~act, this referenee reports that it is necessary to use a non-cross-linked source of collagen to obtain the telopeptide, The peptides of the present invention sre all cross-linked. Collagen cross-links are diseussed in greater detail below, under the heading "Collagen Cross-Linking."
There are a number of report~ lndicating ~that collagen degradation ean be .~ i measured ;by guanti~ating certain procoUagen peptides. ~;The~ prese!nt in~rehtion involve~ te~opeptides rather than propept~des, the two being distinguished by their loeation in the collagen molecule and the timing o~ their clesvage in vivo. See U.S. Patent 4,5û4,587; U.S. Patent 4,312,853; Pierard et al., Analytical Biochemistry 141:127-136 (1984~; Niemela, Clut. Chem., 31/8:1301-13û4 (19B5);
and Rohde et al., Europ~m Jownal of Clinical Im~e~tigation, 9:451-459 (197~).
U.S. Patent 4~7789768 relates to a method of determining changes occurring in articular cartilage involving quantifying proteoglyeul monomer or antigenic fragments thereof in a~synovial fluid sample. This patent does not relate to detecting cross-linked telopeptides derived from degraded collagen.
Dodge, J. Clin. Invest., 83:B47-661 (1981~ diseloses methods for analyzing type II collagen degradation utilizing a polyclonal antiserum that specii~icallyreacts with unwound alpha~hains and cyanogen bromide-derived peptides of WO 92/21698 PCI~/US92/04104 -3- ;

2~1026~
human and bovine type II collagens. The peptides involved are not cross-linked telopeptides as in the present invention.
Amino acid sequences of humals type III collagen, human proc~1(1I) collsg~n, and the entire preproc~1~III) chain o~ human type III collagen and corresponding5 cDNA clones h~ve been investi6~ated and determined by several groups of researchers. See Loidl et al., Nucl~ic Acids Re~earch 12:9383-9394 (1984);
Sangiorgi et al., Nuoleio Acid~ Re$earch, 13:2207-2225 (1985); Baldwin et al., Biochem. J., 262:521-528 ~1989); and Ala-Kokko et al., Biochem. J., ~60:509-516 (1989). None of these re~eren~es spe~ifies the structures of particular telopeptide 10 degradation produets that eould be messured to determine the amount of degr~lded fibrillar eollagen ~n vivo.
In spite of the above-described background information, there remains a need for effe~tive and simple assays for determining collagen degradation in vivo. Such assays could be used to detect and monitor disease st~tes in humans, l5 such as osteoarthritis (type Il collagen degradation)9 and various inflammatory disorders, such as vas~ulitis syndrome (type III csllagen degradation).
Assays ~or type I collagen degradation, described in a parent application, U.S. æerial No. 118,234, can be utilized to dete~t and assess the rate of bone resorption ln VtV5. Detection of th~ rate of bone ress)rption may be a ~actor of20 interest in monitoring and detecting disea~es such as osteoporosis. Osteoporosis is the most ~olJlmon bone disease in msn. Primary osteoporosis, with increased susceptibility to fra~!tures~ results from a progressive net loss of skeletal bone m8~s. It is estimated to aPfect 15-20 million individuals in the IJnited States. Its b8si~ i8 an age~ependellt ~mbalance in bone remodeling, i.e.,-in the rates of ' '~2~ s~thèsis and degradation~of bone tis~ue.~i . "~ r ~ '` ;
About 1.2 milliorl o~teoporo~is-related fractures occur in the elderly ~ach year including about 538,000 compre5sion fractures of the spine, about 227~000 hip ~ra~tures and a sul)3tantiaI number of early fractured peripheral bones. Twelve to 20% o~ the hip fractures are fatal because they cause severe trauma and bleeding, 30 and hal~ of the surviving patients require nursing home care~ Total costs from o~teoporosis-related 1njuries now amount to at least $7 billion annu~lly (Barnes, O.P~., Science, 236:914 (1~87)~.
Osteoporosis is most common in postmenopausal women who, on average, lose 15% of thelr bone mass in the 10 years after menopause. This disease also 35 occurs in men as they get older ~nd in young amenorrheie women sthletes.
I)espite the major, and growing, social and economic consequences of o~teoporosis9 no method is available for measuring bone resorption rates in WO 9~/21698 PCr/US92/~4104 -2 1t 0 2 63 ~4~
patients or normal subjects. A msjor difficulty in monitoring the disease is the la~k o~ a speciIic assay for measuring bone resorption rates.
Methods for assessing bone mass often rely on measuring whole-body calcillm by neutron activation analysis or mineral msss in a given bone by photon 5 absorption techni~ues. These measurements can giV2 only long-term impressions of whether bone mass is decreasing. Measuring caleium balances by comparing intake with output is tedious, unreliable ~nd c8n only indirectly appraise whether bone mineral is being lost over the long term~ Other methods currently availablefor assessing decreased bone mass and altered bone metabolism include 10 quantitative scanning radiometry at seleeted bone locations (wrist, calcan~us, etc.) and histomorphometry of iliac orest biopsies. The former provides a crude measure of the bone mineral content at a specific site in a single bone~
Histomorphometry ~i-.re~ a 3emi-quantitative a~essment of the balance between newly deposited bone seams and resorbing surfaces.
A urinary assay for the whole-body output of degraded bone in 24 hours would be much more t~eful. Mineral studies (e.g., calcium balance) cannot do this reliably or easily. Sirlce bone resorption involves degradation of the mineral and the organi~ matrix, a specific bioehemi~al m0rker for newly degraded bone product~ in body ~luid~i would be the ideal irldex. Several potenti~ organic indices 20 have been te~ted. For e~ample, hydroxyproline, an amin~s acid lsrgely restricted to collagen, and the pril;cipal structural proteill in bone and all other connective tissues9 is excreted in urinec Its excretion rate is known to be increased in certain conditions, notably Paget's disease, a metabolic bone disorder in which bone turnover is greatly i~ressed, as pointed out above. . ~For this reason, urin~y 25 hydrosr~proline hs~ ~en ~ed e~tensively a~;an.amislo.,acid,mark:er.~for collagen degradation. $inger9 F.,R., et al. (1978), cjted hereinabove. ~
U.S. Patent No. 3~600,132 discloses a 2roee~s for determination of hydro~yproline in body fluids ~uch as serum, ur;ne, lumbar fiuid and other intercellular fluids in order to monitor deviations in collagen metabolism~ In 30 p~rtîcular~ this inventor notes that in pathologic conditions su~h as Paget'sdisesse, M~rfQn's syndrome~ osteogenesis imperfeeta, neoplastic growth in collagen tis~ue~ and in various forms of dwarfism, increased collagen anabolism or cataboli~m as measured by hydroxyproline content in biological fluids can be determined. This invlentQr measures hydroxyproline by oxidizing it to a pyrrole 35 compound with hydroeen peroxide and ~-chloro-e-toluenesulphonamide followed by colorimetri~ determination in p dimethy}-amino-benzaldehyde~

WO ~2/21698 PCI/US92~4104 , . . ~

0 2 6 3 ~' In the case OI Paget's dise~se, the increased urinary hydroxyproline probably comes largely from bone degradation; hydroxyproline, however~ g~nerally cannot be u~ed as a specifi~ in~lcx. Much o~ the hydroxyproline in urine may come from new collagen synthe~is (considerable amounts of the newly made protein are 5 degraded and excreted without ever becoming incorporated into tissue fabric), and from turnover of ~ertain blood proteins as well as other proteins that contain hydroxyproline. Furthermore, about 80% of the free hydroxyproline derived from protein degradation ls metabolized in the liver and never appears in the urine.
Ki-viriko, E~.l. Int. Re~. Conneet. TL~ue Re~. 5:93 (197~)9 snd Weiss, P.H. and Klein, L., J. C~ v~3t. ~8:1(1969).
Hydroxylysine and its glycoside derivatives, both peculiar to collagenous proteins, have been considered to be more accurate than hydroxyproline as markers of collagen degradation. However, for the same reasons described above for hydroxyproline, hydroxyly~ine and its glycosides are probably equally non-spe~ific markers of bone resorption. Krane, S~Mo and Simon, L.S. De~elop.
Biochem., 22:185 (l98?).
In addition to amino acids lmique to collagen, various non-collagenous proteins of bone matrix such as osteocalcin, or their breakdown products, have formed the ba~is o~ immunoa~say~ aimed at measuring bone metabolism. Price, P.A. et al. J. Clin. ~n~e~t., 66: 878 (1980), and Gundberg, C.M. et al., Meth E:nzymol., 107:516 ~1984~. However, it is now clear that bone-derived non-collagenous proteins, though poten~ially a useful index of bone metabolic activity are unlikely, on their own, to provide quantitative measures of bone resorption.The con~en~ration irl ~erum of o~teocal~in, for e%ample,~fluctuates quite widelyboth normally asld ln metabolic bone di~ease. i lts concentration is elevated instates of high ~kelelhl turnover but it is un~lear whether this . results from increased synthe~is or ~degradation of bone. Krane, S.M., et aL, Develop.
Bio~hemO~ 22:185 (19B1~, Price~ P.A. et al., J. Clul. Invest.~ 66:878 ~1980); and Gundberg, C.M. et alO~ A~eth. Enzymol., 107:516 (1984).
Colla~en Cross-Linking The polymers of most genetic types o~ vertebrate collagen require the formation of aldehyde-mediated cross-links for norm~Ll function. Collagen alde-hydes are derived from a few specific lysine or hydro~ylysine s;de-chains by theaction of lysyl oxidase. Various di-, tri- and tetrafunction~l cross-linking amino acids are formed by the spontaneous intra- and intermolecular reaetions of thesealdehydes within the newly formed collagen polymers; the type of cross-linking residue varies specifically with tis~ue type ~see Eyre, D.R. et al., Arul. Rev.
Biochem., 53:717-748 (1984)).

WO 92/2~698 P~/U~92~04104 21io263 ",, Two basie pathYI~ays of cross-linking can be differentiated for the banded (67nm repeat) ~ibrillar ~ollagenfi, one based on lysine aldehydes, the other on hydroxylysine aldehydes. The lysine ald~hyde p~hway dorninates in adult ~kin~
cornea, s~lera, and r at ta;l tendon and also frequently occurs in other soft 5 connective tissues. The hydroxylysine sldehyde pathway dominates in bone, cartilage, ligament, nnost tendons and most internal can~ective tissues of the body, Eyre, D.R. et al. ~1984) vida s~pra. The operating pathway is governed by whether lysine residues are hydroxylated in the telopeptid~ sites where aldehyderesidues will later be formed by lysyl oxidase ~Barnes, M.J. et al., Biochem. J~, 13~:461 (197~
The ~hemical structure(s) of the mature cross-linking amino acids on the lysine aldehyde pathw~y are unknown, but hydroxypyridinium residues have been identified as mature products on the hydroxyly~ine aldehyde route. C)n both pathways and in most 1:issues the intermediate, borohydride-reducible cross-linking 1~ residues disappear as the n~wly formed ~ollagen matures9 suggesting that they are relatively short-lived intermediates (Bailey, A.J. et al., FEBS L~tt.9 16:86 (1971)3. E~cceptions are bone and dentin, where the redueible residue~ persist in appreciable con~entration throughout life, in part apparently because the rapid mineralization of the newly made collagen fibrils inhibits further spontaneous 20 cross-linking interactions (lEyre, ~.R., In: The ~hemi~try ~md Biolo~y of ~klineralized Connective TL~Iles, (Veis, A. ed.) pp. 51-55 (1981)9 Elsevier, NewYork, and Walter~ C. ¢t al.~ CalcO r~O l~tl.~ 35:401-405 (1983)).
Two chemi~l folrms o~ 3-hydro2~ypyridinium cros3-link have been identified (Formula I and II~. -Both coml?ounds sre naturally: ~luores~ent, with the same - 25 characteristic e~citation ~and em~s~ion 9pe~tra (Fuiimoto~: D.~ et:al. Biochem.
Biophy~ Re~. Communb, 7~:1124 ~19?7), and Eyre, D~R.~ ~ewlop.-B~ochem., 22:53 1981)~. The~e amino a~ids c an be resolved and assayed directly in tissue hydrolysates with good ~ensitivity ~ing reverse phase HPLC and fluorescence detection. Eyre, I:~.R. et al.9 Analyte. Biochem., 13~:380-388 (19~4). It should be 30 noted that the presen't invention involves quantitating particular pept;des rather than amino a~ids.

WO 9Z/21698 PCI`~US92/04104 _7_ 2110263 NH~ NH~
Ca'l~ 0J~ 8 5800C~

C~--o~ ~

IJ2N C~08 4h~ ~08 ~OR~IULA l ~ORMIlILA 1 :
In growing animals~ it has been reported that these m~ture cross-links may be ~oncentrated more in an unmineralized fraction of ~one collagen than in the mineraljæed ¢ollagen (Banes, ~A.J., ~et ~1.,: :Biochem. Blophys, Res. Commun., 113:1975 (1S83). Howe~er, other studies on young boYIne or adult human: bone do ~ :
not:~upport thi~ con~ept, Eyr~, D.R4, In::~The ~hæmi~try~and Biolo~y of Mineralized~
~25 ~ Tl~ue~ ~3utler, W.T.~ ed.~ p. 105 (l985~,` Eb~o ~qé~ia Inc., ~Birmingham,~Alabà~a.
.The presence o~ collagen hyd~oxyp~ridiDium oross-links in human::urine:~as;
~t reported by~Gunja-~mith a~ld Boucek tGun3a-s~mith~ z :and Bou~ek,;~R.J., :: Biochem J., lg7:75g-762 (I981)) using lengthy i~olation procedures for~p~ptides and conventional ~mino ac1d analy~is. At that time,, they were aware only of theHP form ol~ the ~ross-link. Roblns ~Robins, ~S.P., Biochem ~J., 207:6l7-1~2~ (1982) has reported an enzyme-linked immunoassay to measure HP in urine, having rsised poly~lonal antibodies to the free amino aeid ~onjugated to boYine serum albumin.This assay is intended to provide an inde~ for monitorin~ increased joint de~truc-tion that occurs w;th arthritic d;seases and is based, according to:Robin~, on the ~inding that pyridinoline is much more prevalent in cartila~e than in bone colla-gen.

WO 9ZI21b98 P~JUS92/04104 211q263 -8-In more recent work involving enzyme-linked immunosssay, Robins reports that lysyl pyridinoline is unreactive toward antiserum to pyridinoline covalently linked to ~vine serum albumin (Robins et 81., Ann. Rheum. Di~ea~es, 45:969-973 (1986)). Robins' urinary index for cartilage destruction is based on the discovery 5 that hydroxylysyl pyridinoline, deri-/ed primarily from cartilage, is found in urine a~ concentrations proportional to the rate of joint cartilage resorption (i.e., degradation). In principle, this index could be used to measure whole body cartilage los~; however, no information on bone resorption would be available.
A need therefore exist~ for a method that allows the measllrement of whole-10 body bone resorption rates in humans. The most useful such method would be pne that could be applied to body fluids, especially urine~ The method should be sensitive, i.e., quantifiable down to 1 picomole and rapidly measure 24-hour bone resorption rates so that the progre~s of various therapies (e.g~, estrogen) can be asses~ed.
Prior U.S. Serial Nos. 614,719, 444,881 and 118~234, which are hereby incorporated by referen~e herein, dis~losed parti~ular peptides, methods of asssying for collag~n degradation based on detecting the~e peptides, and kit~
u~eful for practic;ng the methods. Additionally, U.S. Serial No. 614~719 disclosed a particular monoclon~ antibody MA~1H11 that is capable o~ bindiflg to a peptide20 having the following structure:

FORNVLA m . Asp-~lu-K-Ser-Thr-Gly-Gly ~1 (I) 25 . ~ , Gln-Tyr-Asp-Gly-K-Gly Val-Gly ~ 2 (I) , ~ K -where K
K

is hydroxylysyl pyridinoline (HP) or lysyl pyridinoline (LP), and Gln is glutamine or 3~ pyrrolidone ~arboxyli~ acid, and other peptides that ~ontain the same bindingepitop~. The present invention is based on these prior discoveries, but providesadditional previously undisclo~ed elements thereof.

_g_ . ~ .

Summary of the Invention In a first embodiment, the present invention pro~ides certain novel peptides derived from type I collagen that are produced Ul ViYo and that may be found in body fluids. These peptides are recognized and bound by the 5 antibody MAb-lHll. Structures of the peptides have been determined and/or veri~ied by electrospray mass spe~trometry (using a gCIEX instrument). The structures of the peptides isolated from urine using MAb-lHll are reported hereinbelow in the description oî FIGURI: 1, and include the type I collagen peptide having the formula reported previously in U.S. Patent 4,973,666, as well as 10 some relatively minor variants thereof. Additionally, a previously unknown peptide was discovered in urine using this affinit~r chromatography technique~
This p~ptide, correspondi~g to peak D in FIGURE 1, and having the stru¢ture provided in the description o~ FIGURE 1 below, i~ a peptide eomposed of two segments of c.(2) chains o~ collagen. Thc first aspect of the present invention 15 relates to this dimeric peptide, methods of analyzing collagen degradation, which is correlated to the rate of bone resorption, based on quantitating the peptide? and kits for such quantitation.
A second embodiment of the present invention relates to compositions for use in quantitating cross-linked ~ollagen telopeptides derived from :type I
20 collagen. It has been discovered that protease treatment of collagen from bone, followed by purification of the collagen fragments to enrich the mixture in an epitope that is spe~ifi~ally recogr1ized by the antibody MA~lHll, results in a compo~ition that can be u~ed in~an assay for type I collagen telopeptides that oecur in ~v~ in body fluids9 Thu~,~ this~ aspect o~ the invention i9 :directed to a 25 compos~iion o~ collagen ~peptldle~ derived from protease treatment of bone, to~
, . method~ employing the ~omEto~ition in quantitation of t~pe I collagen: telopeptides,~
and to kits that ;nclude such compositions in solution~ lyophilized, or ooated on B
~olid support.
These and other aspects of the present inven~ion will be described in greater~
30 detail hereinbelow.
rief D~on of the Drawin~s FI(~URE 1 depicts an elution profile of peptides; isolated by affinity chromatography from human urine. The structures of the peptides, as determined by mass spec~rometry, are as follows:

W~ g2/~16~8 P~T/US92/ 104 '2Illlz63 -10~

Asp-Glu-K-Ser-Thr-Gly-(Gly) A: - ¦ FORMULA IV
J-Tyr-Asp-Gly-K-Gly-Val-G1y ..
Tyr Asp-Glu-K-Ser-Thr-Gly-(Gly) ¦ FORMULA V
J~-Tyr-Asp-Gly-K~Gly-Val-Gly B: +
Asp-Glu~-Ser-Thr-61y-(Gly3 I FORMULA VI
J Tyr-Asp-Gly-K-Gly-Val-Gly-Leu ,, i Tyr-Asp-Glu-K-Ser-Thr-61y-(Gly) C: ¦ : FORMULA VlI
J-Tyr-Asp-&ly-K Gly-llal~Gly-Leu ; K
: :
J-Tyr-Asp-Gly-~-Gly-Val-Gly-(Leu~ :
- D~ F~RMULA V~II
J-Tyr-Asp-Gly-K-~ly-Val-61y-(Leu) wherein J reprèsents pyroglutsmio aci~ or ~lutamine~and t}~e parenthe~es indi~ate~
that an ~mino acidl may or may not be pres~nt.:
Detailed Description o~ the Preferred Embodiments ~ :
Cross-Linked Peptides A f~r8t embodiment o~ the present invention relates to cross-linked peptides isolatable from urine thst are derived from ~ype I collagen~and are released~when bone is resorbed ~n vivo. These peptldes o~cur natura~:ly in body fluids, su~h as urine, and may be~isolated by standard purification~ proto~ols. The~purified peptides may ~be u~ed, Ior~ example, as antigens: to produce immunologioal binding~
partners thereto. A preferred purification proto~ol employs the antibody MAb-lH11. The hybridoma (lH11) that prod~aces this preferred monoclonal .

WO 92/2169X P~/US92/04104 antibody has been deE~osited at the American l`ype Culture Colleetion (ATCC), 12301 Parklawn Drive9 Rockville, Maryland 20852? under a~cession No. HB 10~11. Purificstion of these peptides by affinity chromatography using monoclonal antibodies produced by lH1ï results in highly purified bone-type I
5 ~ollagen cross-linked N-telop~ptides, as shown in FIGURE 1.
A particularly imteresting peptide isolated in this fnanner corresponds to peak D in FIGLJRE 1, whieh has the ~ollowing strueture:

FORMULA VIII
~-Tyr-Asp~Gly-K-Gly-Val-Gly-(Leu) ~-Tyr-Asp Gly-K-Gly-Val-Gly-(Leu) K
wherein J is pyroglutamic acid or glutamine, (Leu3 mealls optional leucines (i.e., 15 either leueine may be present, both leucines may be present3 or neither leucine may be present), and the cross-linking amino acad HP or LP is represented by theconnected E~ residues. Although the above stru~ture covers several peptides, Iorconvenience, the following discussion refers to a~ single peptide.
This structure is surprising in that it implies that it is derived from three 2û entirely separate collagen molecules that are ~ross-linked together. There has been some controversy in the scientific literature as to whether cross-linking of eollaten moleeules occurs ~intramole~ularly or intermolecularly. The structure of the above dimeric pept~de supports the latter view.
- In more pra~ti~l terms, the-a~ove-de~cribed peptide may~be used in an 25 assay Isr the rate o~ bone resorption. Under these ~ir~utnstan~es, the procedures, te~hniques, kits, etc., dis~losed in the prior related applicat}ons, whi~h~ have been incorporated by referer~ce a~ove, may~be employed analogously with this peptide.A pre~erred method o~ quantitating this peptide (and its eguivalents) employs an immunol~ical binding partner thereto. The peptide is utilized as an antigen, 30 either alone or conjugated to a carrier molecule to produce antibodies, which may be polyclonal or monoclonal, or binding fragments thereof. Binding fragments may also be produced recombinantly, if ~esired. Monoclonal antibodies are preferred. An especi~lly preferred monoclonal antibody is that produced by lHl1,described herein. The amount of this peptide in a body fluid may be correlated 35 dire~tly to the absolute rate of bone resorption, or the level o~ this pept;de may be correlated to other type I collagen peptides that occur in greater quantities, which in turn may be correlated to the ab~olute rate of bone resorption. A kit W~O 92/~l698 P~/US92~MlO4 - 2110263 -~2- ~

containing reagents, etc., for quantitating this peptide is al90 contemplated inaccordance with the present invention. These kits would typi~ally include containers of appropriate reagents, such ss imm~mological binding partners to the above-described peptid~e, suitable corltrols, competitive binding reagents, and the like. Any other ~tandard method of peptide quantitation may also be employed forthese purposes. E~it~ Ior c~rrying out such methods are alsb contemplated.
By an~lo~y to the disclosure incorporated herein from prior U.S. Serial No. 614,719, the p~rridinoline ring ~ontained in the above-described peptide may be open or closed. An assay based on quantitating either form or both forms of the peptide, and kits for carrying out the assay, are also contemplated.
In addition to tllle dimeric peptide described above, addltional peptides corresponding to Formula III in U.S. Serial No. 118,234, now issued as U.S.
Patent 4,,973,666, are ~Llso isolatable from urine. The~e peptides illustrate the fact that a small number of amino acids (e.g.9 1-3) may be attached to the N or C
termini of the peptides in body fluids. For e~ample, the peptides of Formula IIImay have a Tyr residue attached to the N-terminsl ol^ the nl (I) chain. Also, the the peptide corresponding to peak A in FIGIJRE 1 is an eguivalent of the peptides corltained }n peaks B snd C. Analogously, the peptide falltng within peak D is also expected to have equi~alent peptides in which one or a small number of amino acids are combined wi'th the N or C termini thereof. These amino acids will typically correspond to the amino acids normally ~ound in type I collagen molecules in vivo. The language "~onsisting essentially o~" includes such peptide eguiva~ents. ~ :
~ ~ preferred m'ethod o~ i~olating the peptides descr~bed above, and `25 ` ~chematieally-~hown: in ]FIGlJRE 1, will now be described~

~finity-column Purification of Cross-linked N-telopeptides frorn Human Bone Collagen 1. Preparation of Column ~onoclonal antibody (MAb) lH11 was coupled to CNBr-acti-,rated ;~Seph~rose~' ~Pharmacia~ by conventional methods (manufacturer's protocol~
Mouse a~¢ites fluid (3 ml) containing ~Ab lH11 was adsorbed on a Protein G-SepharoseGI' af~ ity column diluted (1:1 v/v) in 0.15~q NaCl, 0.025M Tris-HCl ~TBS1, pH 7.5~ A~ter washing in the s me buffer, I~G was eluted by 0.1M
glycine-HCl, pH 2.5, dialysed a~ainst the coupling buffer and coupled to activated Sephsrose~.

WO ~2/2169~ PCI/US92/04104 . ~
-13- ` 21102~3 --2. Binding and Elution OI Urinary Peptides Urine (17-year adolescent, male) was diluted with TBS~ pEI ~.5 (1:1 v/v3 and eluted dropwise at 25C through the lH11 affinity ~olumn t5 ml bed volume)~
After washing with TBS, bound peptides were eluted with 50% saturated ammonium sulfate eontaining 1% (v/v) trifluoroacetic acid (TFA). The eluted peptides were passed through a pre-conditioned C18-Se~Pak (Waters), bound peptides were eluted with 50% (v~v) acetonitrile and clried. Individual peptideswere resolved by reverse-pha~e HPLC (C8, RP-300 E~rownlee~ using an aeetonitrile:n-propanol (3:1 v/v) gradient in aqueous 0.1% (v/v~ TFA. Highly 10 purified bone type I collagen cross-linked N-telopeptides were recovered ~see FIÇ:URE 1).
Protease-Generated Compositions A second embodiment of the present invention relstes to compositions comprising peptides derived from bone collagen by treatment thereof with a l 5 protease ul vitro. One preferred protease is collagenase. Such compositions should contain peptide fragments that include the epitope recognized by the monoclonal antibody produced by lH11. It is preferred th~t the ~ompo~itions be enriched in su~h epitopes by purifi~ation (dis~ussed below). The reslllting compositions are usefuil in ~arrying out assays to quantitate collagen-derived 20 peptides that are produ~ed in viw as described above. For example, a eomposition containing epitope-enriched collagenase-produ~ed peptide fragments may be eoated on a solid substrate ~e.g., a mi~rotiter assay plate) to be used in a heterogeneous competit;ve immunoasssy. Since these peptides are expected to be relatiYely hydrophilics coat1ng th~m on a relati~eb hydrophobi~ solid surface may 2~ ` reguire ~onjugation of the-peptides in thë composition to a~ carrier mole~ule, su~h as bovinê serùm albumin, which will enhance adsorption onto a solid substrate.
The peptides of these compositions may also be u3eful in a~homogeneous ~ompetitive immunoassay in ~olution by labeling the: peptides with a detectable marker. ~xamples of ~uitable detectable markers include, but are not lirnited to:
30 enzyme~, co-enzymes~ enzyme inhibitors, chromophores, fluorophores, phosphorescent materials, chemiluminescent materials, paramagneti~ metals, spin labels, avidin~biotin; and radionu~lides. The peptide mixtures produced ~y protease digestion (labeled or unlabeled) ~an be provided in solution ~preferably havirlg a concentration of 1 to 1ID0 picomoles of peptide ~tru~tures containing 35 lH11 epitope per milliliter) and included in a kit. The3e labeled peptides compete with naturally o-~curring peptide fragments in a body fluid for binding to a suitable binding partner. Such compositions may al~o be used as a control solution in an WC~ 92/~t698 PCI/US92/04104 2~102 63 -14-assay, enabling calibration in terms of units of bone collagen. The solutions may eontain salts and other standard ingredients to stabili~e or preserve them.
Preferably, phosph~te or Tris buff2red saline will be used. It is also possib!e ~o provide the protease-generated compositions in solid (e.g., lyophilized) form.
Any of various standard types of immunoassays can be utilized to measure the concentration of the collagen-derived peptides cont~ined in a body fluid.
Many of these assays will be compatible with the protease~enerated compositiorlsdescribed herein. One specific assay involves coating lH11 antibody on a solid substrate and employing this coated antibody to bind to a target peptide in a body fluid, in the presence of a standard amount of B protease~enerated pept,ide composition. A labeled seeond antibody specific to an epitope only present on the protease~enerated peptides could then be used to deteet bound non-target peptide(s). A grealter amount of dete~ted labeled antibody would mean less target peptide in the body fluid.
By "enriched'9 is meant that the protease~enerated composition is partially purified to increase the amount of epitopes recognized by lH11 contained an the composition. It is known that bone collagen consists of approximately 0.1% by weight of the peptides of FORMULAS IV-VIII, which contain the lH11 epitopes.
Theoretically, therefore, it can be calculated tlut the maximum possible enrichm2nt (corresponding to completely purified lH11 epitope) is 1û00-fold. This degree of puri~ication could be achieved by affinity chromatography using bound 1~11 antibody. Lesser degrees of enrichment, e.g., 10-fold to 50-fold, may be achieYed by HPLC or other standard purification protocols. Preferably, the en~ichment o~- lH11 ~epitopes will be at least about 10-fold. ~ Particularly 25 prefe~ably7 the enricbment~ ~will be at: le~t ~-about 50-fold.,~, .The~ ~degree of - enri~hment may be verified by testing a sample of the prep~ration with an affinity column contsining lHll monoclonal antibodies and determining the amount of material retained on the eolumn as a percentage of the amount of material introdueed into the column.
To produce the above-described compositions o~ this invention, it is necessary to contact protea~e, preferably bacterial collagenase, with bone collagen for a period of time sufficient to produce peptide fragments from the bone collagen. Pre~erably, bone will be finely powdered and demineralized beforecontacting it with collagenase. See, for example, Wu, J-J. and Eyre, D.R., "Fin~e Powdering Expo~es the Mineral-Protected Collagen of Bone to Protease Digestion,", Calcif. Ti~sue Int., 42:243-247 (1988).

WO 92/216g8 PCI/US92/04104 Other proteases that can produce peptide fragments capable of being bound by 1Hll could also be u~ed. A given protease may be screened by allowing it to contact bone collagen and then determiflir.g sf the fragment~ that are generatedbind to lH1l.
Collagenase may be obtained from commercial sources such as Sigma, ICN
Biochemicsls, Boehringer Mannheim, etcO Collagenase ~hat is com mercially available generally contains a small a m ount of elastase andlor other enzymes as impurities. ~uch impurities are actually beneficial in producing the compositions described herein, since they produce additional cleavages of the collagen molecule that may enhance the yield of lH11 epitopes contained therein. Such prepara~tions ~re believed to cleave the collagen molecules at several locations around the pyridinoline cross-links in the N-terminal end of type I collagen.
In a typical procedure for producing these co m positions, before contacting the powdered bone with collagenase, it should first be decalcified by standard procedures, washed, heated7 cooled to around 37C in a water bath, and then contact~d with ba~terial collagenase. The amount of collagenase will typicPlly be about 1:25-1:1û0 by weight based on the dry weight of decalcified bone. Digestion is allowed to proceed for at least about 24 hours up to four days or more at room temperature to 40C. Preferably, the contacting period will be 24 hours to 48 hours at about 37C. After dige~tion is complete, the digest is then purified toremove small peptides (preferably tripeptides), which have a molecular weight ofless than abQut 1000 daltons~ For example, purification could be achieved by gelfiltration. The composition is next enriehed in lHl1 epitopes, as described~above, by further puri~i~ation.
` 2~ A particular pro~edure for preparing a collagenase-generated cross-linked peptide ~omposition of the present invention is described as follows: :
Preparation of Bacteri Collagenase Generated Cross-linked Peptides Human cortical bone (femur) was powdered in a Spex mill (SPEX:lndustries) cooled by liquid Nz. Powdered bone was decalcified in 0.5M EDTA, pH 7.5, for 5-l0 days at 4C. The washed collsgenous matrix was suspended in 0.lM CaC12, 0.û5M Tris-HCl, pH 7.5, heated at 70C for 15 min, cooled to 37C in a water bath and ba~terial collagenase was added (l:50 per dry weight of dec~lcified bone). Digestion was continued for a minimum of 24 hours at 37C. The digest was centrifuged and the supernatant (adjusted to 1% v/v TFA) was passed tlFIrough a (: lB-Sep-Pak cartridge (Waters). After washing with 5% (v/v) acetonitrile to remove small collagenous peptides, the enriched cross-linked peptide fragments were eluted with 20% acetonitrile and dried. Further purification could be W O 9~/21~98 PC~r/US92/04104 effected by m olecular sieve chro m atography (Bio-Gel P10 in 10 % (v/v) acetic acid),ion-exchange H PLC ~DEA E-5-P W Bio-Rad) and reverse-phase HPLC.
Alternatively, the cro~s-linked N-telopeptides of the ~one collagen generated by bacterial collagenase eould be highly purified directly by adsorption on the M Ab lH11 ~ffinity colu ~ n using esszntially the above procedure.
The co m positions described above may be included as aqueous solutions in containers in a kit or may be included coated on a solid substrate for use in animmunoassay, and th~ like. Such assays may be carried out as described in the prior related cases that have been incorporat~d herein by reference above.
While the invention has been described in con~unction with preferred embodi-ments, one of ordinary skill sfter reading the foregoing specifi~ation will be able to effect various changes, substitutions of equivalents, and alterations to the subject matter set forth herein. Hen~e, the invention can be practiced in ways other than those specifically described herein. It is therefore intended that the proteetion granted by Letters Patent hereon be limited only by the appended claims and equivalerlts thereof,, :

Claims (16)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of determining the rate of bone resorption, comprising the step of quantitating in a body fluid one or more peptides selected from the group consisting essentially of:
, , , , and wherein is hydroxylysyl pyridinoline or lysyl pyridinoline, J is pyroglutamic acid or glutamine, and the parentheses designate optional amino acids.

2. A method according to claim 1, wherein said quantitating comprises contacting said body fluid with an immunological binding partner to one or more of said peptides and detecting any bound immunological binding partner.

3. A method according to claim 1, wherein said body fluid is urine, blood, serum, or synovial fluid.

4. A peptide selected from the group consisting essentially of:
, , , , and wherein is hydroxylysyl pyridinoline or lysyl pyridinoline, J is pyroglutamic acid or glutamine, and the parentheses designate optional amino acids.

5. A kit for determining the rate of bone resorption, comprising a container of an immunological binding partner to a peptide consisting essentially of:
wherein is hydroxylysyl pyridinoline or lysyl pyridinoline, J is pyroglutamic acid or glutamine, and (Leu) are optional leucines.

6. A composition comprising peptides produced by digesting bone collagen with a protease capable of generating peptides that bind to the monoclonal antibody IH11, and then purifying the digested bone collagen to enrich the concentration of :
peptides that contain the epitope recognized by IH11 by at least 10-fold.

7. A composition according to claim 6, in an aqueous solution.

8. A composition according to claim 7, wherein the concentration of said peptides is about 1 to about 100 picomoles per milliliter of said aqueous solution.

9. A composition according to claim 69 coated on a substrate.

10. A composition according to claim 9, wherein said substrate is a microtiter assay plate.

11. A composition according to claim 6, wherein said peptides are labeled with a detectable marker.

12. A kit for determining the rate of bone resorption, comprising a container of a composition according to claim 7.

13. A kit for determining the rate of bone resorption, comprising a coated microtiter assay plate according to claim 10.

14. A kit for determining the rate of bone resorption comprising a container of a composition according to claim 11.

15. A method of determining the rate of bone resorption, comprising contacting a body fluid with an immunological binding partner to a cross-linkedN-telopeptide derived from bone collagen and detecting any bound immunological binding partner, wherein a composition according to claim 6 is used as a control.

16. A method of determining the rate of bone resorption comprising contacting a body fluid with an immunological binding partner to a cross-linked N-telopeptide derived from bone collagen and detecting any bound immunological binding partner, wherein a composition according to claim 11 is used as a competitive ligand.