Mycoplasma infections as models of chronic joint inflammation

The Relationship between Mycoplasmas and Cancer: Is It Fact or Fiction ? Narrative Review and Update on the Situation

More than one million new cancer cases occur worldwide every year. Although many clinical trials are applied and recent diagnostic tools are employed, curing cancer disease is still a great challenge for mankind. Heredity and epigenetics are the main risk factors often related to cancer. Although, the infectious etiological role in carcinogenesis was also theorized. By establishing chronic infection and inflammation in their hosts, several microorganisms were suggested to cause cell transformation. Of these suspicious microorganisms, mycoplasmas were well regarded because of their intimate parasitism with host cells, as well as their silent and insidious role during infections. This assumption has opened many questions about the real role played by mycoplasmas in oncogenesis. Herein, we presented a sum up of many studies among the hundreds which had addressed the Mycoplasma-cancer topic over the past 50 years. Research studies in this field have first started by approving the mycoplasmas malignancy potential. Indeed, using animal models and in vitro experiments in various cell lines from human and other mammalians, many mycoplasmas were proven to cause varied modifications leading to cell transformation. Moreover, many studies have looked upon the Mycoplasma-cancer subject from an epidemiological point of view. Diverse techniques were used to assess the mycoplasmas prevalence in patients with cancer from different countries. Not less than 10 Mycoplasma species were detected in the context of at least 15 cancer types affecting the brain, the breast, the lymphatic system, and different organs in the genitourinary, respiratory, gastrointestinal, and urinary tracts. Based on these revelations, one should concede that detection of mycoplasmas often linked to ‘‘wolf in sheep's clothing” is not a coincidence and might have a role in cancer. Thorough investigations are needed to better elucidate this role. This would have a substantial impact on the improvement of cancer diagnosis and its prevention.

Identification of an isoschizomer of the HhaI DNA methyltransferase in Mycoplasma arthritidis

The genome of Mycoplasma arthritidis strain 158 has modified cytosine residues at AGCT sequences that render the DNA resistant to digestion with the AluI restriction endonuclease. The DNA methyltransferase responsible for the base modification has previously been designated MarI. From the complete genome sequence of M. arthritidis, we identify Marth_orf138 as a candidate marI gene. Marth_orf138 was cloned in Escherichia coli and its TGA codons converted to TGG. DNA isolated from E. coli cells expressing the modified Marth_orf138 gene was degraded by the AluI nuclease, indicating that Marth_orf138 does not code for MarI. However, the DNA from E. coli was found to have acquired resistance to the restriction endonuclease HhaI. Genomic DNA from M. arthritidis was also found to be resistant to HhaI (recognizes GCGC). The M. arthritidis isoschizomer of the HhaI DNA methyltransferase, coded by Marth_orf138, is designated MarII. Transformation of M. arthritidis was not significantly affected by modification of plasmid at HhaI sites, indicating that the mycoplasma lacks a restriction endonuclease that recognizes GCGC sites.

Association of Mycoplasma arthritidis mitogen with lethal toxicity but not with arthritis in mice

Mycoplasma arthritidis induces an acute to chronic arthritis in rodents. Arthritis induced in mice histologically resembles human rheumatoid arthritis and can be associated with lethal toxicity following systemic injection. The M. arthritidis mitogen (MAM) superantigen has long been implicated as having a role in pathogenesis, but its significance with respect to toxicity and arthritogenicity in mycoplasma-induced disease is unclear. To study the pathogenic significance of MAM, M. arthritidis mutants that overproduced or failed to produce MAM were developed. MAM overproduction and knockout mutants were more and less mitogenic, respectively, than the wild-type strain. The degree of mitogenic activity correlated with lethal toxicity in DBA/2J mice. In contrast, histopathological studies detected no correlation between MAM production and the severity of arthritis induced in DBA/2J and CBA/J mice.

The cancer stem cell: evidence for its origin as an injured autoreactive T cell

This review explores similarities between lymphocytes and cancer cells, and proposes a new model for the genesis of human cancer. We suggest that the development of cancer requires infection(s) during which antigenic determinants from pathogens mimicking self-antigens are co-presented to the immune system, leading to breaking T cell tolerance. Some level of autoimmunity is normal and necessary for effective pathogen eradication. However, autoreactive T cells must be eliminated by apoptosis when the immune response is terminated. Apoptosis can be deficient in the event of a weakened immune system, the causes of which are multifactorial. Some autoreactive T cells suffer genomic damage in this process, but manage to survive. The resulting cancer stem cell still retains some functions of an inflammatory T cell, so it seeks out sites of inflammation inside the body. Due to its defective constitutive production of inflammatory cytokines and other growth factors, a stroma is built at the site of inflammation similar to the temporary stroma built during wound healing. The cancer cells grow inside this stroma, forming a tumor that provides their vascular supply and protects them from cellular immune response.

As cancer stem cells have plasticity comparable to normal stem cells, interactions with surrounding normal tissues cause them to give rise to all the various types of cancers, resembling differentiated tissue types. Metastases form at an advanced stage of the disease, with the proliferation of sites of inflammation inside the body following a similar mechanism. Immunosuppressive cancer therapies inadvertently re-invigorate pathogenic microorganisms and parasitic infections common to cancer, leading to a vicious circle of infection, autoimmunity and malignancy that ultimately dooms cancer patients. Based on this new understanding, we recommend a systemic approach to the development of cancer therapies that supports rather than antagonizes the immune system.

Sensory properties of articular afferents following Mycoplasma arthritis in the chicken

The physiological properties of joint capsule mechanical nociceptors of monoarthritic chickens (Gallus domesticus) were studied by recording the electrical activity from single C (Group IV) and A-delta (Group III) fibres dissected from the parafibular nerve. By injecting live Mycoplasma gallisepticum cultures into the ankle joint a typical mycoplasma arthritis was induced which was restricted to a single joint. During the early stage of the disease (7-21 days after infection) there was histopathological evidence of an acute synovitis and the fibres showed evidence of sensitisation. Sensitisation was observed in the significantly increased receptive field size, decreased response thresholds, increased response to joint movement both noxious and innocuous, but only in the C-fibres was there an increase in spontaneous activity. During the more chronic stage of the disease (49-56 days after infection) there was pathological evidence of prolonged synovitis but the sensory fibres responded normally to mechanical stimulation and joint movement. These changes in sensitivity of the joint capsule mechanical nociceptors provides peripheral neural evidence of possible pain experienced during the acute stage of the disease but not at the chronic stage when the disease might be in period of remission. The absence of any clear correlation between pathology and receptor activity demonstrates the difficulty of trying to predict nociceptive consequences in animals on the basis of histopathology.

Experimental arthritis induced by a clinical Mycoplasma fermentans isolate

BACKGROUND

Mycoplasma fermentans has been associated with rheumatoid arthritis. Recently, it was detected in the joints and blood of patients with rheumatoid arthritis, but it is not clear yet how the bacteria enter the body and reach the joints. The purpose of this study was to determine the ability of M. fermentans to induce experimental arthritis in rabbits following inoculation of the bacteria in the trachea and knee joints.

METHODS

P-140 and PG-18 strains were each injected in the knee joints of 14 rabbits in order to evaluate and compare their arthritogenicity. P-140 was also injected in the trachea of 14 rabbits in order to test the ability of the bacteria to reach the joints and induce arthritis.

RESULTS

M. fermentans produced an acute arthritis in rabbits. Joint swelling appeared first in rabbits injected with P-140, which caused a more severe arthritis than PG-18. Both strains were able to migrate to the uninoculated knee joints and they were detected viable in the joints all along the duration of the experiment. Changes in the synovial tissue were more severe by the end of the experiment and characterized by the infiltration of neutrophils and substitution of adipose tissue by connective tissue. Rabbits intracheally injected with P-140 showed induced arthritis and the bacteria could be isolated from lungs, blood, heart, kidney, spleen, brain and joints.

CONCLUSION

M. fermentans induced arthritis regardless of the inoculation route. These findings may help explain why mycoplasmas are commonly isolated from the joints of rheumatic patients.

Mycoplasma infections and different human carcinomas

AIM: To explore relationships between human carcinomas and mycoplasma infection.

METHODS: Monoclonal antibody PD4, which specifically recognizes a distinct protein from mycoplasma hyorhinis, was used to detect mycoplasma infection in different paraffin embedded carcinoma tissues with immunohistochemistry. PCR was applied to amplify the mycoplasma DNA from the positive samples for confirming immunohistochemistry.

RESULTS: Fifty of 90 cases (56%) of gastric carcinoma were positive for mycoplasma hyorhinis. In other gastric diseases, the mycoplasma infection ratio was 28% (18/49) in chronic superficial gastritis, 30% (14/46) in gastric ulcer and 37% (18/49) in intestinal metaplasia. The difference is significant with gastric cancer (χ² = 12.06, P < 0.05). In colon carcinoma, the mycoplasma infection ratio was 55.1% (32/58),but it was 20.9% (10/ 49) in adenomarous polyp (χ² = 13.46, P < 0.005). Gastric and colon cancers with high differentiation had a higher mycoplasma infection ratio than those with low differentiation (P < 0.05). Mycoplasma infection in esophageal cancer, lung cancer, breast cancer and glioma was 50.9% (27/53), 52.6% (31/ 59), 39.7% (25/63)and 41% (38/91), respectively. The mycoplasma DNA was successfully amplified with the DNA extracted from the cancer tissues that were positive for mycoplasma infection (detected with antibody PD4).

CONCLUSION: There was high correlation between mycoplasma infection and different cancers, which suggests the possibility of an association between the two. The mechanism involved in oncogenesis by mycoplasma remains unknown.

Mycoplasma-mediated uptake of the exogenous human BRCA1 gene by hatching blastocysts

PURPOSE

Biological vectors for cell transfection are mainly viral in origin, with inherent shortcomings. Mycoplasmas are ubiquitous organisms that traverse cells easily. The objective was to determine if Ureaplasma urealyticum (T-mycoplasma) would vector exogenous BRCA1 DNA into blastocysts.

METHODS

Hatching mouse blastocysts (N = 70) were incubated in the presence of either viable or dead Ureaplasma urealyticum at 37 degrees C for 1 hr. The blastocysts were exposed to human BRCA1 DNA lacking homology in the mouse genome for 2 hr, followed by DNase-1 treatment and wash. Polymerase chain reaction and agarose gel electrophoresis analysis of amplified products were performed.

RESULTS

The BRCA1 gene was detected in the blastocysts only when viable Ureaplasma was present. PCR analyses of control Ureaplasma and untreated blastocysts were negative.

CONCLUSION

Viable Ureaplasma organisms were shown to mediate the uptake of DNA fragments into blastocysts, resulting in transgenic mouse blastocysts with a normal human BRCA1 exon 11 gene.

Histopathological studies of the acute inflammation in synovial tissue of rat knee joint following intra-articular injection of PLA2 from Chinese Cobra (Naja naja atra) venom

A phospholipase A2 was purified from Chinese Cobra Naja naja atra by a two-step procedure: gel filtration on Superdex 75 and reverse-phase high-performance liquid chromatography (HPLC) on a NUCLEOSIL 5 C18 column. Purified phospholipase A2 was homogeneous, as indicated by capillary electrophoresis and electrospray mass spectrometry. It was a basic protein (pI = 8.2 +/- 0.03) with a molecular mass of 13,258 Da. Amino acid sequence analysis of the N-terminal demonstrated a high degree of homology with other related PLA2 from elapid venoms. The histopathological effects of the purified PLA2 on synovial tissue of knee joint were studied in Wistar rats. Rats were injected intra-articularly with 100 microl solution of PLA2 of different concentrations. Synovial tissue samples with patella were taken for light microscope study. Histopathological evaluation revealed a significant induction of acute inflammation in synovial tissue after injection, as indicated by synovial lining-cell hyperplasia, subsynovial cellular infiltration, and peri-articular soft-tissue cellular infiltration. Marked inflammatory and proliferative changes in synovial tissue were evident after repeated intra-articular injections of 100 microg PLA2. This study failed to show any significant histological changes in cartilage of patella as well as in the surrounding muscle tissue of the knee joints. These results suggest that PLA2 purified from Chinese Cobra venom induce time- and dose-dependent inflammatory changes in the synovial tissue of rat knee joint.

Assessment of archived paraffin-embedded cervical condyloma tissues for mycoplasma-conserved DNA using sensitive PCR-ELISA

Clinically, it is important to detect mycoplasmas because these organisms have been implicated in gastric and ovarian cancer, pneumonia, postabortal fever, pelvic inflammatory disease, pyelonephritis, endometritis, urethritis, perinatal mortality, arthritis, spontaneous abortion, infertility and interference with sperm development and they act as cofactors catalyzing the HIV disease state. Recently, the combined polymerase chain reaction and enzyme-linked immunosorbent assay method targeting the consensus DNA of over 15 species of mycoplasmas was shown to be superior for the detection of mycoplasmas. The objective was to determine if there was an association between mycoplasmas and cervical neoplasia. Cervical tissues, histopathologically categorized by cervical intraepithelial neoplasia (CIN) grade, flat or exophytic, and acanthosis or koilocytotic, were used. The results showed that mycoplasmas DNA were present in 21.4% of the condyloma tissues and in 33.3% of condyloma tissues with CIN. In contrast, mycoplasmas DNA were not detected when there were no CIN. The presence or absence of human papillomavirus (HPV) did not make a difference. Mycoplasmas DNA were present in 40.0 and 12.5% of the exophytic and flat condylomas, respectively. A higher percentage of cervical tissues graded with slight koilocytosis had (P = 0.05) mycoplasmas DNA compared with tissues graded with moderate koilocytosis. The detection of mycoplasmas DNA in archived cervical condyloma tissues with CIN corroborated previous reports of an association between mycoplasmas and CIN. However, the association between mycoplasmas and the presence of HPV could not be made in this study.

Lumbar pain caused by Mycoplasma infection

A 45-year-old woman was admitted to hospital following acute onset of lower back pain. Clinical and laboratory investigations established a lumbar paraspinal soft tissue infection with Mycoplasma hominis associated with severe spondylarthrosis at L5/S1. A relationship to a recently performed hysterectomy must be considered.

Induction of inflammatory arthropathy resembling rheumatoid arthritis in mice transgenic for HTLV-I

Human T cell leukemia virus type-I (HTLV-I) is the etiologic agent of adult T cell leukemia and has also been suggested to be involved in other diseases such as chronic arthritis or myelopathy. To elucidate pathological roles of the virus in disease, transgenic mice were produced that carry the HTLV-I genome. At 2 to 3 months of age, many of the mice developed chronic arthritis resembling rheumatoid arthritis. Synovial and periarticular inflammation with articular erosion caused by invasion of granulation tissues were marked. These observations suggest a possibility that HTLV-I is one of the etiologic agents of chronic arthritis in humans.

The effect of Mycoplasma arthritidis infection on the phagocytic activity of macrophages in rats and mice

The phagocytic activity of mononuclear phagocytes of A/J mice and Wistar rats was estimated by the carbon clearance test following injection of Mycoplasma arthritidis. In mice, the overall phagocytic activity was significantly increased at the end of the first week (P less than 0.0001), but the increase was marginal by the third and fourth weeks after injection. A significant increase in the relative weight of liver and spleen was observed even when phagocytic activity had returned to levels similar to those of controls (P less than 0.001). In rats, the overall phagocytic activity was significantly increased until the fourth week (P less than 0.00001). There was not, however, an increase in the relative weight of liver and spleen as observed for the mice. The results are discussed in the context of factors contributing to the pathogenic mechanisms responsible for differences in the patterns of arthritis due to mycoplasma observed in mice and rats.

Mycoplasma fermentans-derived high-molecular-weight material induces interleukin-6 release in cultures of murine macrophages and human monocytes

A Mycoplasma fermentans-derived high-molecular-weight material (MDHM) is described which causes differentiation of concanavalin A-stimulated CBA/J or C57BL/6 mouse thymocytes to cytolytic effector T cells (CTLs). The effect of MDHM was inhibited by addition of monoclonal anti-interleukin-6 (IL-6) antibody. It could also be abolished after removal of adherent cells. However, adherent cell-depleted thymocytes could still form CTLs after addition of IL-6. The action of MDHM could thus be explained by the capacity of MDHM to stimulate IL-6 release from adherent cells. MDHM was active on macrophages from CBA/J and C3H/HeJ endotoxin nonresponder mice and was also capable of stimulating IL-6 release from human monocytes. On gel chromatography, MDHM had an apparent molecular size of 1.5 x 10(6) daltons. Treatment with RNase and DNase had no effect on either size or biological activity. Proteinase K did not abolish activity but reduced the apparent molecular size of MDHM. MDHM production by M. fermentans required either coculture with eucaryotic cell lines in RPMI 1640 medium with fetal calf serum or addition of eucaryotic cell sonic extracts to this medium. The biological activity of MDHM is not identical to that of a mitogen for murine spleen cells derived from M. arthritidis; MDHM caused only slight proliferation in this system compared with the mitogen from M. arthritidis, and the latter did not elicit IL-6 release from macrophages. The results are discussed in relation to mycoplasmas as putative etiological agents for rheumatoid arthritis, since high IL-6 titers were reported for synovial fluid from patients with this disease.

Enhanced interferon-gamma production by lymphocytes induced by a mitogen from mycoplasma arthritidis in patients with ankylosing spondylitis

We have examined proliferation of and interferon-gamma (IFN-gamma) production by peripheral blood lymphocytes induced by a purified mitogen derived from mycoplasma arthritidis (MAS) in patients with seronegative spondylo-arthropathies and healthy individuals. In all patients and healthy controls MAS exerted a potent nonspecific lymphoproliferation. In contrast, only patients with ankylosing spondylitis (ASp) showed a strong IFN-gamma production after stimulation with MAS. The maximal IFN-gamma response was observed in HLA-B27+/HLA-DQw3+ patients. However, healthy controls with the HLA-DQw3 haplotype with or without the presence of HLA-B27 exhibited also a slight but statistically not significant increase of IFN-gamma production. Moreover, in this study we have found an enhanced frequency of HLA-DQw3 in patients with ASp and reactive arthritis. This immunogenetic association explains the enhanced lymphocyte reactivity in these inflammatory rheumatic disorders to mycoplasmal antigens.

Detection of Mycoplasma pulmonis in arthritic joints of rats by indirect immunoperoxidase staining

Neonatal and 8-week-old rats were inoculated with Mycoplasma pulmonis. A portion of the animals developed polyarthritis. Indirect immunoperoxidase staining was used to identify the localization of M. pulmonis within arthritic joints. M. pulmonis antigen was most often observed within cartilage in the neonatal group and in synovial tissue in the 8-week-old group.

Increased susceptibility to Mycoplasma infection in patients with hypogammaglobulinemia

The incidence and morbidity of Mycoplasma infections were examined in a group of 23 patients with hypogammaglobulinemia. Among this group of patients, 18 had one or more episodes of acute respiratory illness during which Ureaplasma urealyticum, Mycoplasma orale, or Mycoplasma pneumoniae were isolated from sputum. Resolution only followed institution of specific antibiotic therapy and elimination of the Mycoplasma. In addition to respiratory illness, U. urealyticum was isolated from the urine of two patients with urinary tract infection and from an area of cellulitis in another patient. M. pneumoniae was isolated from the joint of a patient with arthritis. In six patients with chronic lung disease, Mycoplasma was frequently isolated and clinical improvement, albeit transient, coincided with negative Mycoplasma culture results. These findings emphasize the unique susceptibility to Mycoplasma infection in patients with hypogammaglobulinemia.

Suppressive effect of Escherichia coli on adjuvant-induced arthritis in germ-free rats

Our previous finding, that germ-free F344 rats develop severe adjuvant-induced arthritis, whereas specific pathogen-free rats develop mild disease, prompted us to investigate the role of bacterial flora in promoting the development of this disease. Germ-free rats given Escherichia coli experienced disease suppression. Germ-free rats treated with 3 strains of Lactobacillus experienced an enhancement of the disease, although it was not significant. Germ-free rats treated with a combination of E coli and lactobacilli had disease suppression similar to that of E coli monoassociated rats. Thus, these findings suggest that E coli may play a dominant role in modulating the development of the disease in this particular strain of F344 rats, possibly through its lipopolysaccharide (as evidenced by positive results on limulus tests). These findings also suggest that microflora play an important role in modifying the development of joint disease.

Reverse effect of gram-positive bacteria vs. gram-negative bacteria on adjuvant-induced arthritis in germfree rats

Germfree (GF) F344 rats developed severe adjuvant-induced arthritis with a 100% incidence after a single intradermal injection of heat-killed Mycobacterium bovis (BCG). Specific pathogene-free (SPF) rats developed less severe arthritis with a lower incidence. The rats colonized with Escherichia coli or Bacteroides developed mild disease comparable to that in SPF rats. The rats colonized with Bifidobacterium, Propionibacterium acnes, Lactobacillus casei, L. fermentum, L. murini, and L. acidophilus developed more severe disease than that in GF rats. Furthermore, the rats colonized with a mixture of E. coli and the above lactobacilli developed very mild disease similar to that in SPF rats. These results suggest that gram-negative bacteria, such as E. coli and Bacteroides, may suppress the disease, possibly through their lipopolysaccharides, and may be responsible for the lower susceptibility of SPF rats; gram-positive bacteria, such as Bifidobacterium, P. acnes, and lactobacilli, may enhance the disease, possibly through their peptidoglycans; and E. coli may play a dominant role in modulating the development of adjuvant-induced arthritis.

Etiology of rheumatoid arthritis

Definite genetic associations with immunological cooperative HLA-D(R) antigens have been demonstrated for rheumatoid arthritis (RA). Microbial etiology has not been proven, but some hope for the supporters of this view is still given by small viruses, plasmids of enteric bacteria or perhaps oncogen-like DNA-sequences. Yet, electrophoretical analysis of membrane proteins or surface glycoproteins of RA synovial cells does not show any differences compared to reference cells. Autoimmunity to several tissue elements has been demonstrated, but most of it is of secondary nature. Antigenicities of type II and III collagens are probably only contributory factors for HLA-DR4 positive individuals. Proteoglycans or minor cartilage collagens have not been extensively studied, so far. Endocrine, dietary or psychological influences might be triggering events for otherwise 'preloaded' individuals.

Lymphoproliferation induced in mouse spleen cells by Mycoplasma arthritidis mitogen. Reversal of the defect of nonresponder mice

Spleen cells of various mouse strains (e.g. BALB/c, C311, and CBA) reacted towards MAS (a mitogen derived from supernatants of cultured Mycoplasma arthritidis) with a marked lymphoproliferative response. This reactivity was T-cell-dependent. It was reduced by 90% after removal of macrophages by passage of the spleen cells through Sephadex G-10 columns. Addition of 2-mercaptoethanol (2-ME) to macrophage-depleted CBA spleen cells completely restored the response to MAS. Spleen cells of C57BL/6 and C57BL/10 mice were unreactive to MAS, even in the presence of macrophages, and this non-reactivity was controlled by the I-region of H-2. Other mouse strains that, similarly to C57BL/6, lack the expression of I-E on the cell surface (that is, mice of the haplotype H-2f, H-2q, and H-2s) were also non-responsive to MAS. However, the addition of 2-ME to spleen cells of non-responder mice resulted in high lymphoproliferative responses to MAS, which were as high as those of CBA spleen cells. The reaction of C57BL/6 spleen cells to MAS in the presence of 2-ME again was T-cell-dependent, as shown by data with spleen cells of homozygous nude mice and spleen cells treated by anti-thy-1 and C. A macrophage dependency of this response was also evident. When C57BL/6 spleen cells were vigorously freed of accessory cells by the use of nylon wool columns, the MAS response could no longer be restored by 2-ME.

Morphologic changes following intraarticular inoculation of Mycoplasma bovis in calves

Intraarticular inoculation of Mycoplasma bovis into the joints of six-week-old calves caused severe arthritis in five inoculates and mild arthritis in a sixth. Intraarticular inoculation of killed M. bovis did not cause arthritis. Arthritic calves had fever, joint swelling, lameness, neutrophilia, and intercurrent pneumonia from which M. bovis could not be recovered. Gross lesions were massive fibrinosuppurative synovitis and tenosynovitis, erosion of cartilage, and its replacement by polypoid granulation tissue. Histologic lesions were extensive ulceration of synovial membranes, leukocytic infiltration of the subsynovium, congestion, hyperemia, and thrombosis of the subsynovial vessels. Cartilage erosion was accompanied by chronic osteomyelitis and formation of pannus tissue. The presence of thrombi and platelet aggregates suggests that the inflammatory process in the synovium may arise from the interaction of M. bovis with the vasculature and the coagulation process of the host.

Localization of Mycoplasma pulmonis in cartilage

Transmission electron microscopy of articular cartilage in Mycoplasma pulmonis-infected neonatal rats revealed the presence of mycoplasmas within the matrix and lacunae. The mycoplasmas appeared to have a tropism for the chondrocytes and induced lysis of both the chondrocytes and matrix of the cartilage.