Identification of Cartilage Microbial DNA Signatures and Associations With Knee and Hip Osteoarthritis.

OBJECTIVE: Alterations of the gut microbiota have been implicated in many forms of arthritis, but an examination of cartilage microbial patterns has not been performed. This study was undertaken to characterize the microbial DNA profile of articular cartilage and determine changes associated with osteoarthritis (OA). METHODS: We performed 16S ribosomal RNA gene deep sequencing on eroded and intact cartilage samples from knee OA patients (n = 21 eroded and 21 intact samples) and hip OA patients (n = 34 eroded and 33 intact samples) and cadaver controls (n = 10 knee samples and 10 hip samples). Microbial DNA diversity was assessed, groups were compared, and metagenomic profiles were reconstructed. Confirmation was performed in an independent cohort by clade-specific quantitative polymerase chain reaction. Findings in human cartilage were compared to those in cartilage from OA-susceptible C57BL/6 (B6) mice and OA-resistant MRL/MpJ (MRL) mice. Germ-free B6 mouse cartilage was analyzed as a methodologic control. RESULTS: Alpha diversity was reduced in human OA versus control samples (P < 0.0001), and in hip versus knee samples (P < 0.0001). Numerous clades were different in human OA versus control samples, and similar findings were noted in comparisons of murine B6 versus MRL mice. Hip samples were microbiologically distinct from knee samples. OA microbial DNA demonstrated increased gram-negative constituents (P = 0.02). Functional analysis demonstrated increases in lipopolysaccharide production (P = 9.9 × 10-3 ), phosphatidylinositol signaling (P = 4.2 × 10-4 ), and nitrogen metabolism (P = 8 × 10-3 ) and decreases in sphingolipid metabolism (P = 7.7 × 10-4 ) associated with OA. CONCLUSION: Our study reveals a microbial DNA signature in human and mouse cartilage. Alterations in this signature, including increases in gram-negative constituents, occur during the development and progression of human OA. Furthermore, our findings indicate that strain-specific signatures exist within mouse cartilage that mirror human patterns. Further study of the establishment and potential pathogenic role of these DNA signatures is needed.

Cartilage-gut-microbiome axis: a new paradigm for novel therapeutic opportunities in osteoarthritis.

DNA of gut microbiota can be found in synovium of osteoarthritis and rheumatoid arthritis. This finding could result from the translocation of still alive bacteria from gut to joints through blood, since the diversified dormant microbiota of healthy human blood can be transiently resuscitated in vitro. The recent finding of gut microbiome in human cartilage, which differed between osteoarthritis and controls, suggests that a similar trafficking of dead or alive bacteria from gut microbiota physiologically occurs between gut and epiphysial bone marrow. Subchondral microbiota could enhance cartilage healing and transform components of deep cartilage matrix in metabolites with immunosuppressive properties. The differences of microbiome observed between hip and knee cartilage, either in osteoarthritis or controls, might be the counterpart of subtle differences in chondrocyte metabolism, themselves in line with differences in DNA methylation according to joints. Although bacteria theoretically cannot reach chondrocytes from the surface of intact cartilage, some bacteria enter the vascular channels of the epiphysial growth cartilage in young animals, whereas others can infect chondrocytes in vitro. In osteoarthritis, the early osteochondral plate angiogenesis may further enhance the ability of microbiota to locate close to the deeper layers of cartilage, and this might lead to focal dysbiosis, low-grade inflammation, cartilage degradation, epigenetic changes in chondrocytes and worsening of osteoarthritis. More studies on cartilage across different ethnic groups, weights, and according to age, are needed, to confirm the silent presence of gut microbiota close to human cartilage and better understand its physiologic and pathogenic significance.

Successful treatment of a Candida auris intra-articular infection.

A 78-year-old woman with a long-term ankle spacer with antibacterials developed an intra-articular Candida auris infection. Treatment with systemic antifungal therapy plus an amphotericin B moulded cement spacer was successful.

Cutibacterium acnes and the shoulder microbiome.

BACKGROUND: Advances in DNA sequencing technologies have made it possible to detect microbial genome sequences (microbiomes) within tissues once thought to be sterile. We used this approach to gain insights into the likely sources of Cutibacterium acnes (formerly Propionibacterium acnes) infections within the shoulder. METHODS: Tissue samples were collected from the skin, subcutaneous fat, anterior supraspinatus tendon, middle glenohumeral ligament, and humeral head cartilage of 23 patients (14 male and 9 female patients) during primary arthroplasty surgery. Total DNA was extracted and microbial 16S ribosomal RNA sequencing was performed using an Illumina MiSeq system. Data analysis software was used to generate operational taxonomic units for quantitative and statistical analyses. RESULTS: After stringent removal of contamination, genomic DNA from various Acinetobacter species and from the Oxalobacteraceae family was identified in 74% of rotator cuff tendon tissue samples. C acnes DNA was detected in the skin of 1 male patient but not in any other shoulder tissues. CONCLUSION: Our findings indicate the presence of a low-abundance microbiome in the rotator cuff and, potentially, in other shoulder tissues. The absence of C acnes DNA in all shoulder tissues assessed other than the skin is consistent with the hypothesis that C acnes infections are derived from skin contamination during surgery and not from opportunistic expansion of a resident C acnes population in the shoulder joint.

Septic Arthritis/Osteomyelitis May Lead to Osteochondrosis-Like Lesions in Foals.

Failure of the cartilage canal blood supply leads to ischemic chondronecrosis which causes osteochondrosis, and osteochondral lesions. Osteochondrosis is a disease with a heritable component and usually occurs under aseptic conditions. Because bacteria can bind to growth cartilage and disrupt the blood supply in pigs and chickens, we considered whether this might play a role in development of equine osteochondrosis. The aim of this study was to examine whether bacteria are present in canals in the growth cartilage of foals with septic arthritis/osteomyelitis, and whether this is associated with osteochondrosis. The material consisted of 7 foals aged 9-117 days euthanized because of septic arthritis/osteomyelitis. The 7 cases had 16 lesions in growth cartilage that were evaluated histologically. Bacteria were present in cartilage canals in foals with septic arthritis/osteomyelitis. Portions of necrotic canals adjacent to bacteria frequently contained neutrophils, termed acute septic canals; or granulation tissue with neutrophils, termed chronic septic canals. Acute and chronic septic canals were associated with ischemic chondronecrosis in the articular-epiphyseal cartilage complex (AECC) of 5 cases and in the physis of 2 cases, and ossification was focally delayed in 5 of those 7 cases. Lesions occurred with and without adjacent osteomyelitis. Bacteria were present in cartilage canals and were associated with focal chondronecrosis in both the AECC and the physis. This establishes sepsis as a plausible cause of some osteochondral lesions in horses. It is recommended that horses with sepsis-related osteochondral lesions may be used for breeding without increasing the prevalence of OCD-predisposing genes in the population.

Chondrocyte Viability After a Simulated Blast Exposure.

OBJECTIVES: The effects of blast exposure have gained increasing interest in the military medical community with their continued occurrence on the battlefield. The impact of the direct and indirect energy imparted from blasts to hollow viscera, as well as closed head injuries, have been well studied. However, the injury to articular cartilage has not been investigated, despite previous correlations regarding the development of osteoarthritis. The purpose of this study was to assess the degree of injury to articular chondrocytes after exposure to a simulated blast overpressure wave. METHODS: Fresh juvenile porcine stifle joints were subjected to a simulated blast overpressure wave utilizing a custom fabricated blast simulator with compressed gases, within the reported range of observed battlefield blasts. Chondrocyte viability was assessed with live/dead staining using ethidium homodimer-2 and calcien acetoxymethylester stain and confocal laser scanning microscopy, calculated as a ratio of dead chondrocytes to live chondrocytes. Testing was performed at time points of 2, 4, and 8 hours after blast exposure and was compared with unblasted control samples. RESULTS: Chondrocyte viability decreased after exposure to a blast overpressure wave when compared with control samples. The amount of death was greater closer to the articular surface and dissipated with increasing tissue depth. Chondrocyte death increased with time after exposure. CONCLUSIONS: Chondrocyte death is present after exposure to a simulated blast wave. There is an inverse relationship between chondrocyte viability and the depth from the articular surface. Additional studies are needed to further characterize dose and time effects of blast exposure.

Is overcorrection preferable for repair of degenerated articular cartilage after open-wedge high tibial osteotomy?

PURPOSE: This study was performed to determine whether the overcorrected knee could obtain a higher ratio of articular cartilage repair in the medial compartment of the femorotibial joint after open-wedge high tibial osteotomy (HTO). The hypothesis of the study was that overcorrected knees had a higher ratio of articular cartilage repair than moderately corrected knees. METHODS: A total of 71 knees that underwent arthroscopy to evaluate the articular cartilage during open-wedge HTO and second-look arthroscopy were reviewed. The articular cartilage was classified as no repair or repair according to Koshino et al. Overcorrection was defined as knees with femorotibial angle ≤166°. RESULTS: Second-look arthroscopy was performed 410 ± 64 days after HTO. Based on arthroscopic observations, 45 knees (63.4 %) showed no repair and 26 knees (36.6 %) showed repair. In terms of the ratio of cartilage repair, there was no difference between overcorrected knees with mean femorotibial angle of 165° ± 1° and moderately corrected knees with mean femorotibial angle of 170° ± 2° (n.s.). CONCLUSIONS: No significant differences were found in the ratio of cartilage repair between overcorrected and moderately corrected knees. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Diet-Intestinal Microbiota Axis in Osteoarthritis: A Possible Role.

Intestinal microbiota is highly involved in host physiology and pathology through activity of the microbiome and its metabolic products. Osteoarthritis (OA) is a common form of arthritis characterized by articular cartilage destruction and osteophyte formation. Although various person-level risk factors, such as age, sex, and obesity, have been proposed for the pathogenesis of OA, the underlying links between these person-level factors and OA are still enigmatic. Based on the current understanding in the crosstalk between intestinal microbiota and these risk factors, intestinal microbiota could be considered as a major hidden risk factor that provides a unifying mechanism to explain the involvement of these person-level risk factors in OA.

Unsolved matters in leprosy: a descriptive review and call for further research.

Leprosy, a chronic mycobacterial infection caused by Mycobacterium leprae, is an infectious disease that has ravaged human societies throughout millennia. This ancestral pathogen causes disfiguring cutaneous lesions, peripheral nerve injury, ostearticular deformity, limb loss and dysfunction, blindness and stigma. Despite ongoing efforts in interrupting leprosy transmission, large numbers of new cases are persistently identified in many endemic areas. Moreover, at the time of diagnosis, most newly identified cases have considerable neurologic disability. Many challenges remain in our understanding of the epidemiology of leprosy including: (a) the precise mode and route of transmission; (b) the socioeconomic, environmental, and behavioral factors that promote its transmission; and

Detection of Kingella kingae osteoarticular infections in children by oropharyngeal swab PCR.

OBJECTIVE: The purpose of this study was to investigate if oropharyngeal swab polymerase chain reaction (PCR) could predict osteoarticular infection (OAI) due to Kingella kingae in young children. METHODS: One hundred twenty-three consecutive children aged 6 to 48 months presenting with atraumatic osteoarticular complaints were prospectively studied. All had a clinical evaluation, imaging, and blood samples. Blood and oropharyngeal specimens were tested with a PCR assay specific for K kingae. OAI was defined as bone, joint, or blood detection of pathogenic bacteria, or MRI consistent with infection in the absence of positive microbiology. K kingae OAI was defined by blood, bone, or synovial fluid positivity for the organism by culture or PCR. RESULTS: Forty children met the OAI case definition; 30 had K kingae OAI, 1 had another organism, and 9 had no microbiologic diagnosis. All 30 oropharyngeal swabs from the K kingae case patients and 8 swabs from the 84 patients without OAI or with OAI caused by another organism were positive. The sensitivity and specificity of the oropharyngeal swab PCR assay for K kingae were 100% and 90.5%, respectively. CONCLUSIONS: Detection of K kingae DNA in oropharyngeal swabs of children with clinical findings of OAI is predictive of K kingae OAI. If these findings are replicated in other settings, detection of K kingae by oropharyngeal swab PCR could improve the recognition of OAI.

Expression profile analysis of mycotoxin-related genes in cartilage with endemic osteochondropathy Kashin-Beck Disease.

BACKGROUND: Kashin-Beck Disease (KBD) is an endemic osteochondropathy. Mycotoxins are believed to play an important role in the pathogenesis of KBD. Because the molecular mechanism of mycotoxin-induced cartilage lesions remains unclear, there is not effective treatment for KBD now. To identify key genes involved in the mycotoxin-induced cartilage lesions, we compared the expression profiles of mycotoxin-related genes (MRG) between KBD cartilage and healthy cartilage. METHODS: Total RNA was isolated from cartilage samples, following by being amplified, labeled and hybridized to Agilent human whole genome microarray chip. qRT-PCR was conducted to validate the microarray data. 1,167 MRG were derived from the environmentally related genomic database Toxicogenomics. The microarray data of MRG was subjected to single gene and gene ontology (GO) expression analysis for identifying differently expressed genes and GO. RESULTS: We identified 7 up-regulated MRG and 2 down-regulated MRG in KBD cartilage, involved in collagen, apoptosis, metabolism and growth & development. GO expression analysis found that 4 apoptosis-related GO and 5 growth & development-related GO were significantly up-regulated in KBD cartilage. CONCLUSIONS: Based on the results of previous and our studies, we suggest that mycotoxins might contribute to the development of KBD through dysfunction of MRG involved in collagen, apoptosis and growth & development in cartilage.

S100A4 deficiency is associated with efficient bacterial clearance and protects against joint destruction during Staphylococcal infection.

BACKGROUND: Efficient host defense mechanisms are crucial for survival in sepsis and septic arthritis. S100 proteins are reported to have proinflammatory and bactericidal properties. The aim of this study was to investigate the role of S100A4 in staphylococcal arthritis. METHODS: S100A4 knockout mice (S100A4KO) and wild-type counterparts (WT) were intravenously and intra-articularly challenged with Staphylococcus aureus strain LS-1. Clinical and morphological signs of arthritis and sepsis, phagocytosis, bone mineral density (BMD), and bone metabolism were then monitored in S100A4 and WT mice. RESULTS: S100A4KO mice had a lower bacterial load in the kidneys than WT mice (P < .05) but developed more severe clinical signs of arthritis (P < .001) and had higher levels of interleukin 6 and L-selectin (P = .002). S100A4KO mice had fewer morphological signs of synovitis and cartilage/bone destruction following intra-articular instillation of bacteria. S100A4KO mice were protected from loss of BMD and had lower levels of RANKL, MMP3, and MMP9 (P < .05). S100A4 was not bactericidal in vitro. CONCLUSIONS: In staphylococcal infection, S100A4 regulates bacterial clearance as well as systemic and local inflammatory responses.

Induced apoptosis of chondrocytes by Porphyromonas gingivalis as a possible pathway for cartilage loss in rheumatoid arthritis.

The role of bacterial infections in the pathogenesis of rheumatoid arthritis (RA) has gained increasing interest. Patients with RA often exhibit periodontal disease, which is associated with pathogens like Porphyromonas gingivalis. The present study examines the direct effects of P. gingivalis on apoptosis of human chondrocytes (a feature of inflammatory joint diseases) as one can assume an interrelation of pathogenesis of RA and P. gingivalis infections. Primary chondrocytes were infected with P. gingivalis. Early apoptotic and dead cell analysis was performed using Annexin-V, 7AAD, and propidium iodide and examined by flow cytometry and fluorescence microscopy. Caspase activation and DNA fragmentation were determined by western blot analysis and TUNEL reaction. Flow cytometry and fluorescence microscopy demonstrated an increase of Annexin-V-positive early apoptotic chondrocytes after infection. Western blot showed upregulation of activated caspase-3 expression, and TUNEL reaction revealed considerable DNA fragmentation following infection. The data show that P. gingivalis promotes early and later stages of apoptosis of primary human chondrocytes, which might contribute to the joint damage seen in the pathogenesis of RA.

Articular aspergillosis: case report and review of the literature.

The incidence of invasive aspergillosis is increasing due to more frequent use of immunosuppressant agents in patients with autoimmune diseases, hematological malignancies, and solid organ and hematopoietic stem cell transplants. Invasive aspergillosis most commonly affects the lungs, sinuses, and brain. Aspergillosis affecting the musculoskeletal system is rare. We describe here a case of articular aspergillosis in a febrile neutropenic patient successfully treated with voriconazole and caspofungin, and briefly review the 10 cases of articular aspergillosis that have previously been described in the literature.

Tibiotalocalcaneal arthrodesis using a supracondylar femoral nail for advanced tuberculous arthritis of the ankle.

PURPOSE: To review 7 patients with advanced osteoarticular tuberculous arthritis of the ankle who underwent arthrodesis using a supracondylar femoral nail. METHODS: All patients showed gross destruction of the articular cartilage of the tibiotalar joint with severe periarticular rarefaction on radiographs. Their pre- and one-year post-operative Foot and Ankle Outcome Scores (FAOS) were compared. All patients underwent joint debridement, complete synovial excision, and arthrodesis using a supracondylar femoral nail, followed by multidrug chemotherapy for 12 months (isoniazid, rifampicin, pyrazinamide, and ethambutol for 3 months, and isoniazid and rifampicin for 9 months). RESULTS: All patients achieved fusion in a mean of 13 weeks and regained their preoperative level of independence. No patient had a relapse, major complications, or hardware failure. At postoperative year one, the mean FAOS for pain improved to 85 from 26, whereas the mean FAOS for quality of life improved to 60 from 5. CONCLUSION: Tibiotalocalcaneal arthrodesis using a supracondylar femoral nail, combined with debridement and multidrug therapy, enabled a reliable one-stage solution for advanced osteoarticular tuberculosis and early return to function.

Effects of Porphyromonas gingivalis on cell cycle progression and apoptosis of primary human chondrocytes.

BACKGROUND: It has been suggested that bacterial infections have a role in the pathogenesis of rheumatoid arthritis (RA). P gingivalis, a Gram-negative, anaerobic rod, is one of the major pathogens associated with periodontal disease. OBJECTIVE: To examine P gingivalis infection and its effects on cell cycle progression and apoptosis of human articular chondrocytes. METHODS: Primary human chondrocytes cultured in monolayers were challenged with P gingivalis. Infection and invasion of P gingivalis into chondrocytes was analysed by scanning electron microscopy, double immunofluorescence and by antibiotic protection and invasion assay. Cell cycle progression of infected chondrocytes was evaluated by flow cytometry. Also, cell apoptosis was visualised by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) of DNA strand breaks and by western blot analysis. RESULTS: Data showed that P gingivalis could adhere and infect primary human chondrocytes. After chondrocyte infection, intracellular localisation of P gingivalis was noted. Flow cytometry analyses demonstrated affected cell cycle progression, with an increase of the G(1) phase and a significant decrease of the G(2) phase after infection. In addition, increased apoptosis of P gingivalis-infected chondrocytes was visualised by TUNEL assay and by upregulation of caspase-3 protein expression. CONCLUSION: These data demonstrate that P gingivalis infects primary human chondrocytes and affects cellular responses, which might contribute to the tissue damage seen in the pathogenesis of rheumatoid arthritis.

Septic arthritis in Western and sub-Saharan African children - a review.

This article reviews what is known about the incidence, aetiology, presentation, bacteriology and management of septic arthritis in children. It compares where possible the different presentations and characteristics of this condition in the Western and sub-Saharan African regions.

Role of aggrecanase 1 in Lyme arthritis.

OBJECTIVE: Arthritis is one of the hallmarks of late-stage Lyme disease. Previous studies have shown that infection with Borrelia burgdorferi, the causative agent of Lyme disease, results in degradation of proteoglycans and collagen in cartilage. B burgdorferi do not appear to produce any exported proteases capable of digesting proteoglycans and collagen, but instead, induce and activate host proteases, such as matrix metalloproteinases (MMPs), which results in cartilage degradation. The role of aggrecanases in Lyme arthritis has not yet been determined. We therefore sought to delineate the contribution of aggrecanases to joint destruction in Lyme arthritis. METHODS: We examined the expression patterns of aggrecanases 1 and 2 (ADAMTS 4 and 5, respectively) in B burgdorferi-infected primary human chondrocyte cell cultures, in synovial fluid samples from patients with active Lyme arthritis, and in the joints of mice by real-time quantitative reverse transcription-polymerase chain reaction and immunoblotting techniques. Bovine cartilage explants were used to determine the role of aggrecanases in B burgdorferi-induced cartilage degradation. RESULTS: ADAMTS-4, but not ADAMTS-5, was induced in human chondrocytes infected with B burgdorferi. The active forms of ADAMTS-4 were increased in synovial fluid samples from patients with active Lyme arthritis and were elevated in the joints of mice infected with B burgdorferi. Using cartilage explant models of Lyme arthritis, it appeared that the cleavage of aggrecan was predominantly mediated by "aggrecanases" rather than MMPs. CONCLUSION: The induction of ADAMTS-4 by B burgdorferi results in the cleavage of aggrecan, which may be an important first step that leads to permanent degradation of cartilage.

Effect of selected wound antiseptics on adult articular cartilage (bovine sesamoid bone) in the presence of Escherichia coli and Staphylococcus aureus.

After removing an inoculum of 10(8)-10(9) cfu of Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) effectively within 2 h from bovine sesamoid bones (bsb) using the iodophore Betaisodona [0.5 and 1.0% (v/v) PVP-I], the biguanide polihexanide (PHMB) [0.005 and 0.01% (v/v)], and the bispyridinamine Octenidine (Oct) [0.005 and 0.01% (v/v)] the metabolic effect on proteoglycans (PG) in bsb was investigated by subsequent culture of bsb for 7 d and biosynthetically labeling with (35)S-sulfate for a period of 24 h. The treatment with the iodophore stimulates the incorporation of (35)S-sulfate into PG, whereas that of Oct was toxic. The PHMB treatment was both tolerated and effective only when it was used at low concentrations (0.005%). The antiseptic treatment did not result in an increase of catabolism of PG. This in vitro study clearly demonstrates that irrigation of cartilage with an antiseptic should be limited to an effective concentration and treatment time compatible with antiseptic function. Iodophores have no negative feedback on cartilage metabolism, moreover, they stimulate chondrocytes in vitro. Cationic antiseptics are not suited as irrigating solutions.

Production of endogenous antibiotics in articular cartilage.

OBJECTIVE: Defensins are broad-spectrum antimicrobial peptides that are components of innate immunity. To date, only epithelial surfaces and blood cells have been shown to produce these cationic peptides in bactericidal concentrations when challenged with microorganisms or inflammatory cytokines. Infections caused by gram-negative pathogens occur only infrequently in association with joint surgery. The present study was undertaken to investigate whether this may be explained by intraarticular production of gram-negative-specialized antimicrobial peptides. METHODS: Healthy articular cartilage and cultured T/C-28a2 chondrocytes were assessed, by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry, for expression of various antimicrobial peptides. The expression of human beta-defensin 2 (HBD-2) was studied in cultured chondrocytes after exposure to bacterial supernatants and proinflammatory cytokines and was assayed by real-time RT-PCR and immunoblot analysis. A septic arthritis mouse model was used to investigate the regulation of the murine homolog of HBD-2 in articular cartilage after bacterial inoculation. RESULTS: Healthy articular cartilage and T/C-28a2 chondrocytes were able to produce different antimicrobial peptides. After exposure to gram-negative bacteria and proinflammatory cytokines, expression of cartilage-derived HBD-2 strongly increased. Immunoblot analysis revealed up-regulation of the gram-negative-specialized HBD-2 in microbicidal doses. Immunohistochemistry analysis revealed induction of the murine homolog of HBD-2 in vivo after intraarticular injection of bacteria. CONCLUSION: This study demonstrated a previously unrecognized function of human chondrocytes. In addition to its biomechanical properties, articular cartilage has the ability to produce antimicrobial substances when challenged with microorganisms. The expression of HBD-2 in microbicidal doses suggests that antimicrobial peptides may contribute to host defense mechanisms in articular joints.