Preparation and applications of monoclonal antibodies to different collagen types

Differentiation of deer tendons from cattle tendons by a loop-mediated isothermal amplification (LAMP) test and bone remodeling bioassays

BACKGROUND

Deer tendons are believed more effective than cattle tendons in tonifying kidney yang (shen yang) and enhancing bone and tendons. This study aims to differentiate the two types of tendons by a loop-mediated isothermal amplification (LAMP) test and bone remodeling bioassays.

METHODS

Internal control primers to detect both types of tendons and specific primers for deer tendons were designed according to a sequence analysis. The LAMP test was set up and the results were analyzed by conventional gel electrophoresis, real-time fluorescence observation, and colorimetric detection. Crude tendon extracts were prepared by water extraction to compare their effects on bone. The anti-osteoclastic effects were investigated on mouse pre-osteoclast Raw264.7 cells by cell viability determination and tartrate-resistant acid phosphatase staining. The osteogenic effects were examined using rat osteoblast-like UMR106 cells by evaluation of cell proliferation, alkaline phosphatase activity, and calcium deposition. The relative gene expressions of bone remodeling-related markers, including nuclear factor of activated T-cells cytoplasmic 1, tartrate-resistant acid phosphatase, cathepsin K, and osteoprotegerin/receptor activator of NF-κB ligand, were determined by real-time PCR.

RESULTS

In the LAMP test, both deer and cattle tendons were detected in the control reactions, while only deer tendons were amplified by the specific LAMP test. In the bioassays, both tendons inhibited the viability and differentiation of pre-osteoclast Raw264.7 cells, and promoted the proliferation and mineralization of osteoblast-like UMR106 cells. The mRNA expressions of bone remodeling-related markers were consistent with the results of the bioassays.

CONCLUSION

This study demonstrated that the isothermal LAMP test can distinguish between deer tendons and cattle tendons. Both types of tendons exhibited similar beneficial effects on bone remodeling according to the bioassay findings.

The molecular composition of the extracellular matrix of the human iliolumbar ligament

BACKGROUND CONTEXT

The human iliolumbar ligament connects the transverse process of L5 to the iliac crest and contributes to lumbosacral stability and has been associated with low back pain. However, different opinions exist regarding the functional relevance of the ligament.

PURPOSE

In the present study, we analyze the regional molecular composition of the ligament extracellular matrix.

STUDY DESIGN

Special attention is given to the attachment sites, to determine whether the ligament is subjected to a certain mechanical environment.

METHODS

Iliolumbar ligament samples, extending from one enthesis to the other, were removed from 11 cadavers and fixed in methanol. Cryosections were immunolabeled with a panel of antibodies directed against collagens, glycosaminoglycans, proteoglycans, matrix proteins, and neurofilament.

RESULTS

The mid-substance of the ligament labeled for all the molecules normally found in dense fibrous connective tissue including types I, III, and VI collagen, versican, dermatan -, chondroitin 4 -, and keratan sulfate. However, both entheses were fibrocartilaginous and labeled for type II collagen, aggrecan, and chondroitin 6- sulfate. A common feature was fat between the fiber bundles near the entheses. Occasionally this fat contained nerve fibers.

CONCLUSIONS

The existence of fibrocartilaginous entheses suggests that the insertion sites of the ligament are subject to both tensile and compressive loading-probably because of insertional angle changes between ligament and bone during loading. Our findings support the suggestion that the iliolumbar ligament might play an important role in the stabilization of the lumbosacral junction.

Assaying the efficacy of dual-antiplatelet therapy: use of a controlled-shear-rate microfluidic device with a well-defined collagen surface to track dynamic platelet adhesion

We report the development and demonstration of an assay that distinguishes the pharmacological effects of two widely used antiplatelet therapies, aspirin (COX-1 inhibitor) and clopidogrel (P2Y12 inhibitor). Whole blood is perfused through a low-volume microfluidic device in contact with a well-characterized (ellipsometry, atomic force microscopy) acid-soluble type I collagen surface. Whole human blood treated in vitro with a P2Y12 inhibitor 2-methylthioadenosine 5'-monophosphate triethylammonium salt (2-MeSAMP) extended the time to the start of platelet recruitment, i.e., platelet binding to the collagen surface. Treatment with 2-MeSAMP also slowed the rate of aggregate buildup, with an overall reduced average platelet aggregate area after 8 min of constant blood flow. A far smaller effect was observed for in vitro treatment with aspirin, for which the rate of change of surface coverage is indistinguishable from controls. In whole blood obtained from patients under treatment with dual-antiplatelet therapy (aspirin and clopidogrel), a significant extension of time to platelet recruitment was observed along with a slowed rate of aggregate buildup and an average aggregate size approximately half that of control measurements. Differentiation of the pharmacological effects of these two well-targeted antiplatelet pathways suggests a role for this assay in determining the antiplatelet effects of these and related new therapeutics in clinical settings.

Immunohistochemical composition of the human lunotriquetral interosseous ligament

PURPOSE

The human lunotriquetral ligament (LTL) is a functionally important intrinsic hand ligament, which is assumedly subjected to insertion angle changes at the entheses during movement. To clarify whether the current model of the ligament's mechanical environment is reflected in its structural composition, we determined the regional distribution of extracellular matrix-related antigens.

METHODS

The extracellular matrix was immunohistochemically investigated in 12 LTLs from both wrists of 6 human donors (Mean age: 60 y).

RESULTS

The dorsal, proximal, and volar portions of the ligament immunolabeled for type I, III collagen and versican. Both entheses labeled strongly for type II collagen, aggrecan, and link protein and were distinctly cartilaginous. The ligament midsubstance was positive for collagen II in 30%, for aggrecan in 40%, and for keratocan and lumican in 100% of specimens. In contrast, keratocan and lumican were absent from the fibrocartilaginous entheses and the articular cartilage. Ligament insertion at a carpal bone occurs either directly through fibrocartilage or indirectly through a bilayered configuration of fibrocartilage and hyaline-like cartilage. The hyaline-like cartilage is continuous with the neighboring articular cartilage.

CONCLUSIONS

The LTL has an extracellular matrix comparable with that of ligaments experiencing a combination of tensile and shear/compressive load at the attachment sites. All regions of the LTL exhibit fibrocartilaginous entheses; purely fibrous attachment sites are rare. The ligament midsubstance shows a more fibrous phenotype than the entheses and expresses keratocan and lumican, which previously have not been recorded in any human hand ligament.

Adipose tissue at entheses: the innervation and cell composition of the retromalleolar fat pad associated with the rat Achilles tendon

This study set out to determine whether the fat pad at the attachment of the Achilles tendon has features enabling it to function as an immune organ and a mechanosensory device, and to be a source of pain in insertional tendon injuries. Sections for histology and immunohistochemistry were cut from the Achilles tendon enthesis organ of 1 day old, 1 month, 4 month and 24 month old rats. For fluorescence and peroxidase immunohistochemistry, cryosections were labelled with primary antibodies directed against PGP9.5, substance P, neurofilament 200, calcitonin gene related peptide, CD68, CD36, myeloid related protein 14, actin and vinculin. The fat pad contained not only adipocytes, but also fibrous tissue, mast cells, macrophages, fibroblasts and occasional fibrocartilage cells. It was richly innervated with nerve fibres, some of which were likely to be nociceptive, and others mechanoreceptive (myelinated fibres, immunoreactive for neurofilament 200). The fibres lay between individual fat cells and in association with blood vessels. In marked contrast, the enthesis itself and all other components of the enthesis organ were aneural at all ages. The presence of putative mechanoreceptive and nociceptive nerve endings between individual fat cells supports the hypothesis that the fat pad has a proprioceptive role monitoring changes in the insertional angle of the Achilles tendon and that it may be a source of pain in tendon injuries. The abundance of macrophages suggests that the adipose tissue could have a role in combating infection and/or removing debris from the retrocalcaneal bursa.

Immunodetection of collagen types I, II, III, and IV for differentiation of liver fibrosis stages in patients with chronic HCV

The current study is aimed at evaluating serum collagens and other serum biochemical markers as useful, non-invasive markers of hepatic fibrosis associated with chronic hepatitis C virus (HCV). Collagen types I, II, III, and IV were detected in serum using ELISA and Western blot techniques. The ELISA levels of collagen I, II, III, and IV increased significantly with the progression of fibrosis staging. Based on receiver-operating characteristic (ROC) curve analysis, the collagen type III (70 kDa) and type IV (200 kDa) were more useful than other serum bio-markers for differentiating severe fibrosis from mild fibrosis. Multivariate discriminant analysis (MDA) selected a fibrosis discriminant score (FDS) = [2.345 + Collagen III (microg/mL) x 1.923 + Collagen IV (microg/mL) x 1.544 + ALT (U/mL) x 0.005] - [albumin(g/L) x 0.046]. The FDS correctly classified 87% of the severe fibrosis patients at a cut-off score = 2.2 (i.e., more than 2.2 indicated severe fibrotic liver and less than 2.2 indicated mild fibrotic liver) with specificity of 97%. In a validation study, the FDS was applied to the second cohort of patients and the results were reproduced without significant difference. In conclusion, the developed four-parameter based FDS is useful for identifying severe liver fibrosis in patients with chronic HCV infection.

Expression and role of type I collagen in a rat spinal cord contusion injury model

To verify the expression of type I collagen after SCI and discuss its role and cellular origin, a standardized animal model of contusive spinal cord injury (SCI) was analyzed. Male Sprague-Dawley rats were injured at T11/12 and sacrificed at 1, 4 and 8 weeks after injury. The spinal cord was removed en block for both Western blotting and RT-PCR in order to verify expression of type I collagen. For immunohistological examination, those sections were stained with anti-type I collagen, RECA-1 and anti-rat prolyl-4-hydroxylase. Double-labeling immunohistochemistry was performed using anti-type I collagen and RECA-1. Those sections were examined with an electron microscope. Western blots for type I collagen were positive, as was the gene expression of type I collagen mRNA. Type I collagen after SCI was observed around blood vessels in the ventral white matter of the spinal cord 4 weeks after injury in double-labeling immunohistological examination and electron microscopic images. Immunohistochemical expression of fibroblast was increased 4 weeks after injury. This study revealed the post-SCI expression of type I collagen around blood vessels. Type I collagen may play a role in angiogenesis after SCI. Fibroblasts may produce type I collagen in rat spinal cord.

Expression of extracellular matrix molecules typical of articular cartilage in the human scapholunate interosseous ligament

The scapholunate interosseous ligament (SLIL) connects the scaphoid and lunate bones and plays a crucial role in carpal kinematics. Its rupture leads to carpal instability and impairment of radiocarpal joint function. As the ligament is one of the first structures affected in rheumatoid arthritis, we conducted an immunohistochemical study of cadaveric tissue to determine whether it contains known autoantigens for rheumatoid arthritis. We immunolabelled the ligament from one hand in 12 cadavers with monoclonal antibodies directed against a wide range of extracellular matrix (ECM) molecules associated with both fibrous and cartilaginous tissues. The labelling profile has also enabled us to comment on how the molecular composition of the ligament relates to its mechanical function. All regions of the ligament labelled for types I, III and VI collagens, chondroitin 4 and 6 sulphates, keratan sulphate, dermatan sulphate, versican, tenascin and cartilage oligomeric matrix protein (COMP). However, both entheses labelled strongly for type II collagen, aggrecan and link protein and were distinctly fibrocartilaginous. In some regions, the ligament attached to bone via a region of hyaline cartilage that was continuous with articular cartilage. Labelling for cartilage molecules in the midsubstance was most evident dorsally. We conclude that the SLIL has an ECM which is typical of other highly fibrocartilaginous ligaments that experience both tensile load and shear. The presence of aggrecan, link protein, COMP and type II collagen could explain why the ligament may be a target for autoantigenic destruction in some forms of rheumatoid arthritis.

An immunohistochemical study of the extracellular matrix of the tarsal plate in the upper eyelid in human beings

The superior tarsus is a plate of tissue that stiffens the upper eyelid, gives it support and determines its form. The purpose of the present study was to relate the composition of its extracellular matrix to its function and to report regional differences that may influence the activity of its Meibomian glands. Fourteen methanol-fixed specimens were cryosectioned for immunohistochemistry and labelled with a panel of monoclonal antibodies against a wide range of collagens, glycosaminoglycans and proteoglycans. Labelling was detected with avidin-biotin-peroxidase. A further six specimens were formalin-fixed for routine histology. The tarsal plate immunolabelled strongly for types I, III and VI collagen and for aggrecan, versican, tenascin, cartilage oligomeric matrix protein (COMP) together with a variety of glycosaminoglycans (notably chondroitin 6 sulphate). A region of strong labelling for aggrecan, dermatan sulphate and chondroitin 6 sulphate immediately surrounded the Meibomian glands. The site of labelling corresponded to a layer of acellular and amorphous matrix seen histologically that we have termed the 'territorial matrix'. The results suggested that the tarsal plate is a specialized connective tissue that is neither purely fibrous nor cartilaginous, yet has an aggrecan content that probably contributes to its stiffness. Its unique character highlights the challenge in choosing an ideal mechanical substitute. As patients with rheumatoid arthritis often have problems relating to tear film deficiency, the ability of aggrecan or COMP to act as autoantigens may be significant. An immune reaction directed against these molecules could alter tarsal gland function by interfering with the interaction between the glands and their territorial matrix.

Monoclonal antibodies that distinguish avian type I and type III collagens: isolation, characterization and immunolocalization in various tissues

Monoclonal antibodies were prepared that were specific for chicken type I and type III collagens. The specificity of these antibodies was determined by ELISA, inhibition ELISA, and immunoblot assays. The results showed that the monoclonal antibodies were specific for their respective antigens without significant cross reactivity to other types of collagen. An analysis of the location of the epitopes by rotary shadowing that a monoclonal antibody for type I collagen (called DD4) recognized type I procollagen close to the large globular domain at the carboxyl terminus of the molecule. A monoclonal antibody for type III collagen (called 3B2) recognized both the intact type III molecule and also the TCA fragment of type III collagen after mammalian collagenase digestion. The epitope was located approximately one-fifth of the distance from the amino-terminus of the intact molecule. The monoclonal antibodies were used for immunolocalization of type I and type III collagens in cryosections of heart, aorta, kidney, liver, thymus, skin, gizzard and myotendinous junction. In heart, aorta, kidney, liver, thymus and skin, type I and III collagens were colocalized in the connective tissue of each organ. In contrast, gizzard and myotendinous junction showed distinctly different staining patterns for the distribution of type I and type III collagen. The two monoclonal antibodies reported here are potentially useful reagents to study fibril formation involving type I and type III collagens.

Multiple antigenic determinants on type III collagen

Eight monoclonal antibodies have been produced against human pepsin-soluble type III collagen. All antibodies were shown to be highly specific for type III collagen and did not cross-react with a range of other collagen types or connective-tissue proteins. Examination of type III collagen from other species showed that these antibodies had a wide range of species specificities, indicating that several distinct epitopes were being recognized. The location of the epitopes was investigated by using reactivity of the antibodies to CNBr fragments and to sequential fragments formed by tryptic digestion of renaturing type III collagen. These data also indicated that several distinct epitopes were recognized and that they were located over the length of the type III collagen.

Characterisation of a monoclonal antibody against native human type I collagen

A monoclonal antibody against a pepsin-soluble mammalian type I collagen has been produced. This antibody, subclass IgG1, kappa, was specific for type I collagen and did not cross-react with a range of other collagen types or connective tissue proteins. The epitope recognized by the antibody was dependent upon an intact triple-helical structure for the collagen, and was shown by rotary shadowing and by immunoblotting of collagenase-derived fragments to be near the C-terminal of the pepsin-soluble collagen. Although the antibody had a low affinity, with Kd = 4 x 10(-7) M, it could be used for immunohistology of tissue sections and for studies of collagen produced by cells in culture. The antibody, which was raised against human collagen, also recognized type I collagens from certain other species, including calf, pig, sheep, goat and dog.