Staphylococcal
septic arthritis remains a serious medical concern due to rapid and sustained production of inflammatory
cytokines that leads to progressive and irreversible joint destruction with high mortality rate in patients despite adequate
antibiotics treatment. TNF-α signalling via TNFR-1 contributes to arthritic destruction by aggravating
inflammation. Impact of TNFR-2 signalling is not well established in this aspect. Hence the objective of our study was to evaluate the role of dual neutralization TNFR-1 and TNFR-2 in the pathogenesis of S. aureus
infection induced
septic arthritis. Mice were infected with live S. aureus (5 × 106 cells/ml) followed by administration of TNFR-1and TNFR-2
neutralizing antibody. To measure
arthritis index and osteoclastogenesis, histology result in joint tissue and TRAP staining images of
arthritis joints have been performed respectively. Maximum reduction in the joint and paw swelling was observed in infected mice treated with both TNFR-1 and TNFR-2 antibody. NF-κB signalling was found to be mainly regulated by TNFR-1 whereas TNFR-2 significantly modulated JNK pathway. Lowest levels of inflammatory
cytokines like TNF-α, IL-1β,
IL-6, and IFN-γ were observed in both serum and synovial tissues signifying maximum protection in S. aureus
arthritis during combination treatment. However IFN-γ and
IL-10 levels were significantly altered by TNFR-2 neutralization that indicates both pro and anti inflammatory role of TNFR-2 respectively. Highest decrement in ROS concentration, iNOS expression with least MPO and
lysozyme activity was detected in case of combined neutralization. During the early phase of
infection all the aforesaid inflammatory parameters remained elevated due to lack of
IL-10 as a result of TNFR-2 neutralization as
IL-10 negatively modulates pro inflammatory
cytokines. Increase in inflammatory
cytokines during early phase might also be responsible for decreased bacterial count in TNFR-2 neutralized groups. Thus it can be suggested that combined administration of TNFR-1 and TNFR-2 antibody has a beneficial effect against the severity of S. aureus induced
arthritis.