Objectives Dysregulation of innate and adaptive immune responses contributes to the pathogenesis of systemic lupus erythematosus (SLE) and its associated premature vascular damage. To date, no drug targets both systemic inflammatory disease and the cardiovascular complications of SLE. Tofacitinib is a Janus kinase (JAK) inhibitor that blocks signaling downstream of multiple cytokines implicated in lupus pathogenesis. While clinical trials have shown that tofacitinib exhibits significant clinical efficacy in various autoimmune diseases, its role in SLE and on its associated vascular pathology remains to be characterized. Methods MRL/lpr lupus-prone mice received tofacitinib or vehicle by gavage for 6 weeks (therapeutic arm) or 8 weeks (preventive arm). Nephritis, skin inflammation, serum autoantibody levels and cytokines, mononuclear cell phenotype and gene expression, neutrophil extracellular trap (NET) release, endothelium-dependent vasorelaxation and endothelial differentiation were compared in treated and untreated mice. Results Treatment with tofacitinib led to significant improvement in measures of disease activity including nephritis, skin inflammation, and autoantibody production. In addition, tofacitinib treatment reduced serum levels of pro-inflammatory cytokines and interferon responses in splenocytes and kidney tissue. Tofacitinib also modulated NET formation and significantly increased endothelium-dependent vasorelaxation and endothelial differentiation. The drug was effective as both preventive and therapeutic strategies. Conclusions Tofacitinib modulates the innate and adaptive immune responses, ameliorates murine lupus and improves vascular function. These results indicate that JAK inhibitors have the potential to be beneficial in SLE and its associated vascular damage.

Interleukin-1β (IL-1β), a potent pro-inflammatory cytokine, has been implicated in many diseases, including atherosclerosis. Activation of IL-1β is controlled by a multi-protein complex, the inflammasome. The exact initiating event in atherosclerosis is unknown, but recent work has demonstrated that cholesterol crystals (CC) may promote atherosclerosis development by activation of the inflammasome. High-density lipoprotein (HDL) has consistently been shown to be anti-atherogenic and to have anti-inflammatory effects, but its mechanism of action is unclear. We demonstrate here that HDL is able to suppress IL-1β secretion in response to cholesterol crystals in THP-1 cells and in human-monocyte-derived macrophages. HDL is able to blunt inflammatory monocyte cell recruitment in vivo following intraperitoneal CC injection in mice. HDL appears to modulate inflammasome activation in several ways. It reduces the loss of lysosomal membrane integrity following the phagocytosis of CC, but the major mechanism for the suppression of inflammasome activation by HDL is decreased expression of pro-IL-1β and NLRP3, and reducing caspase-1 activation. In summary, we have described a novel anti-inflammatory effect of HDL, namely its ability to suppress inflammasome activation by CC by modulating the expression of several key components of the inflammasome.

BACKGROUND Low high-density lipoprotein-cholesterol (HDL-C) is a risk factor for coronary artery disease. Investigating mechanisms underlying acquired severe HDL deficiency in noncritically ill patients (“Disappearing HDL Syndrome”) could provide new insights into HDL metabolism. OBJECTIVE To determine the cause of low HDL-C in patients with severe acquired HDL deficiency. METHODS AND RESULTS Patients with intravascular large B-cell lymphoma (IVLBCL, n=2), diffuse large B-cell lymphoma (DLBCL, n=1), and autoimmune lymphoproliferative syndrome (ALPS, n=1) presenting with markedly decreased HDL-C, low LDL-C and elevated triglycerides were identified. The abnormal lipoprotein profile returned to normal following therapy in all four cases. All cases were found to have markedly elevated serum interleukin-10 (IL-10) levels that also normalized following therapy. In a cohort of ALPS patients (n=93), IL-10 showed a strong inverse correlation with HDL-C (R2=0·3720, P<0·0001). A direct causal role for increased serum IL-10 in inducing the observed changes in lipoproteins was established in a randomized, placebo-controlled clinical trial of recombinant human IL-10 (rhIL-10) in psoriatic arthritis patients (n=18). Within a week of initiating subcutaneous rhIL-10 injections, HDL-C precipitously decreased to near-undetectable levels. LDL-C also decreased by over 50% (P<0·0001) and triglycerides increased by approximately 2-fold (P<0·005). All values returned to baseline after discontinuing IL-10 therapy. CONCLUSION Increased IL-10 causes severe HDL-C deficiency, low LDL-C and elevated triglycerides. IL-10 is thus a potent modulator of lipoprotein levels, a potential new biomarker for B-cell disorders, and a novel cause of Disappearing HDL syndrome.