Study of hydrogen sulfide biosynthesis in synovial tissue from diabetes-associated osteoarthritis and its influence on macrophage phenotype and abundance

Type 2 diabetes (DB) is an independent risk factor for osteoarthritis (OA). However, the mechanisms underlying the connection between both diseases remain unclear. Synovial macrophages from OA patients with DB present a marked pro-inflammatory phenotype. Since hydrogen sulphide (H2S) has been previously described to be involved in macrophage polarization, in this study we examined H2S biosynthesis in synovial tissue from OA patients with DB, observing a reduction of H2S-synthetizing enzymes in this subset of individuals. To elucidate these findings, we detected that differentiated TPH-1 cells to macrophages exposed to high levels of glucose presented a lower expression of H2S-synthetizing enzymes and an increased inflammatory response to LPS, showing upregulated expression of markers associated with M1 phenotype (i.e., CD11c, CD86, iNOS, and IL-6) and reduced levels of those related to M2 fate (CD206 and CD163). The co-treatment of the cells with a slow-releasing H2S donor, GYY-4137, attenuated the expression of M1 markers, but failed to modulate the levels of M2 indicators. GYY-4137 also reduced HIF-1α expression and upregulated the protein levels of HO-1, suggesting their involvement in the anti-inflammatory effects of H2S induction. In addition, we observed that intraarticular administration of H2S donor attenuated synovial abundance of CD68+ cells, mainly macrophages, in an in vivo model of OA. Taken together, the findings of this study seem to reinforce the key role of H2S in the M1-like polarization of synovial macrophages associated to OA and specifically its metabolic phenotype, opening new therapeutic perspectives in the management of this pathology. (AU)

Study of hydrogen sulfide biosynthesis in synovial tissue from diabetes-associated osteoarthritis and its influence on macrophage phenotype and abundance.

Type 2 diabetes (DB) is an independent risk factor for osteoarthritis (OA). However, the mechanisms underlying the connection between both diseases remain unclear. Synovial macrophages from OA patients with DB present a marked pro-inflammatory phenotype. Since hydrogen sulphide (H2S) has been previously described to be involved in macrophage polarization, in this study we examined H2S biosynthesis in synovial tissue from OA patients with DB, observing a reduction of H2S-synthetizing enzymes in this subset of individuals. To elucidate these findings, we detected that differentiated TPH-1 cells to macrophages exposed to high levels of glucose presented a lower expression of H2S-synthetizing enzymes and an increased inflammatory response to LPS, showing upregulated expression of markers associated with M1 phenotype (i.e., CD11c, CD86, iNOS, and IL-6) and reduced levels of those related to M2 fate (CD206 and CD163). The co-treatment of the cells with a slow-releasing H2S donor, GYY-4137, attenuated the expression of M1 markers, but failed to modulate the levels of M2 indicators. GYY-4137 also reduced HIF-1α expression and upregulated the protein levels of HO-1, suggesting their involvement in the anti-inflammatory effects of H2S induction. In addition, we observed that intraarticular administration of H2S donor attenuated synovial abundance of CD68+ cells, mainly macrophages, in an in vivo model of OA. Taken together, the findings of this study seem to reinforce the key role of H2S in the M1-like polarization of synovial macrophages associated to OA and specifically its metabolic phenotype, opening new therapeutic perspectives in the management of this pathology.

Clinical outcome and microbiological findings using antibiotic-loaded spacers in two-stage revision of prosthetic joint infections.

OBJECTIVES: Antibiotic-loaded spacers may improve antimicrobial efficacy in two-stage revision of prosthetic joint infections, but they may also interfere in the course of infection. This prospective study of prosthetic joint infections managed with two-stage revision and antibiotic-loaded spacers (2004-09) analyzes case outcomes and proposes a second-stage culture interpretation scheme. METHODS: Second-stage infection was diagnosed upon second-stage cultures (synovial membranes, joint fluid, spacers), as either superinfection (≥2 samples, new organism) or persistence (≥1 samples, previously isolated organism). Isolated positive antibiotic-loaded spacers cultures were considered as colonizations. RESULTS: Of 42 patients, two had two prosthetic infections (n = 44): 25 knees, 19 hips. Spacers contained gentamicin (33), vancomycin (10) and aztreonam (1). Three patients (7%) with wound healing impairment required debridement and spacer exchange. The remainder underwent second-stage surgery as planned: 34 (77%) new arthroplasties, five arthrodeses, one resection arthroplasty and one permanent spacer. Of 18 cases (44%) with ≥1 positive sample, only four (10%) were second-stage infections. Fourteen antibiotic-loaded spacers cultures (34%) were positive. Four new prostheses (9%) supervened further infections: one by the organism isolated in the spacer, three by new bacteria. CONCLUSIONS: The findings of second-stage cultures show that the surgical site is frequently non-sterile at reimplantation. Isolated positive antibiotic-loaded spacer cultures usually have no clinical consequences, but together with tissue cultures they help to diagnose second-stage infections when clinical signs are absent.