Evidence for tmTNF reverse signaling in vivo: Implications for an arginase-1-mediated therapeutic effect of TNF inhibitors during inflammation.

In order to ascertain the significance of transmembrane tumor necrosis factor (tmTNF) reverse signaling in vivo, we generated a triple transgenic mouse model (3TG, TNFR1-/-, TNFR2-/-, and tmTNFKI/KI) in which all canonical tumor necrosis factor (TNF) signaling was abolished. In bone-marrow-derived macrophages harvested from these mice, various anti-TNF biologics induced the expression of genes characteristic of alternative macrophages and also inhibited the expression of pro-inflammatory cytokines mainly through the upregulation of arginase-1. Injections of TNF inhibitors during arthritis increased pro-resolutive markers in bone marrow precursors and joint cells leading to a decrease in arthritis score. These results demonstrate that the binding of anti-TNF biologics to tmTNF results in decreased arthritis severity. Collectively, our data provide evidence for the significance of tmTNF reverse signaling in the modulation of arthritis. They suggest a complementary interpretation of anti-TNF biologics effects in the treatment of inflammatory diseases and pave the way to studies focused on new arginase-1-dependent therapeutic targets.

Biological DMARD efficacy in psoriatic arthritis: a systematic literature review and meta-analysis on articular, enthesitis, dactylitis, skin and functional outcomes.

OBJECTIVES: There is no hierarchy in the use of biotherapies (bDMARDs) in psoriatic arthritis (PsA) and no published head-to-head comparative studies. Our purpose is to evaluate the respective efficacy of TNF inhibitors, IL12/23 inhibitors (ustekinumab), IL17 inhibitors (secukinumab, ixekizumab) and CTLA4Ig (abatacept) on articular, enthesitis, dactylitis, skin and functional outcomes in PsA. METHODS: Randomised controlled trials assessing bDMARDs in PsA were selected through the MedLine, Cochrane and Embase databases. ACR20/50/70 and PASI75/90 response rates, enthesitis and dactylitis reduction rates and HAQ-DI mean reductions were collected. Pooled meta-analyses were performed to assess relative risks (RR) with their 95% confidence interval (95%CI) for each class of bDMARDs in comparison with placebo. RESULTS: 17 RCTs were analysed. Compared to placebo, all bDMARDs showed higher ACR20 response rates, with RRs ranging from 1.77 (1.31, 2.39) to 3.21 (2.52, 4.08), and a greater HAQ-DI mean reduction. TNF inhibitors, secukinumab and IL17 inhibitors showed higher ACR50/70 and PASI75/90 response rates. TNF inhibitors, secukinumab and IL17 inhibitors showed higher enthesitis resolution rates and only TNF inhibitors and IL17 inhibitors showed higher dactylitis resolution rates, with RRs ranging from 1.41 (1.02, 1.95) to 2.31 (1.60, 3.34) and from 2.07 (1.38, 3.12) to 2.65 (1.79, 3.94), respectively. CONCLUSIONS: All bDMARDs showed higher ACR20 response rates and better HAQ-DI mean reduction compared to placebo. This meta-analysis highlights the variability of bDMARD efficacy on ACR50/70, PASI75/90 and enthesitis or dactylitis response rates. Head-to-head studies are needed to draw definitive conclusions on potential efficacy-related differences between bDMARDs in PsA.