The past few years of research on leptin have provided important information on the link between metabolism and immune homeostasis. Adipocytes influence not only the endocrine system but also the immune response through several cytokine-like mediators known as adipokines, which include leptin. It is widely accepted that leptin can directly link nutritional status and pro-inflammatory T helper 1 immune responses, and that a decrease of leptin plasma concentration during food deprivation can lead to an impaired immune function. Additionally, several studies have implicated leptin in the pathogenesis of chronic inflammation, and the elevated circulating leptin levels in obesity appear to contribute to the low-grade inflammatory background which makes obese individuals more susceptible to increased risk of developing cardiovascular diseases, type II diabetes, or degenerative disease including autoimmunity and cancer. Conversely, reduced levels of leptin such as those found in malnourished individuals have been linked to increased risk of infection and reduced cell-mediated immune responses. We discuss here the functional influences of leptin in the physiopathology of inflammation, and the effects of leptin in the modulation of such responses.

In systemic lupus erythematosus (SLE), adaptive CD4+CD25+Foxp3+ regulatory T cells (Tregs) suppress Th cells that help autoantibody (autoAb)-producing B cells. It is not known whether naturally occurring Tregs can directly suppress B cells in SLE without an intermediate suppression of Th cells. This aspect is important for its implications in the natural course of SLE, because most if not all of the clinical and pathologic effects in SLE are associated with a dysregulated production of autoAbs. In this study, we show that natural Tregs can inhibit B cell activity in vitro and in vivo in SLE through cell contact-mediated mechanisms that directly suppress autoAb-producing B cells, including those B cells that increase numerically during active disease. These results indicate that one way by which natural Tregs attempt to limit humoral autoimmunity in SLE is by directly targeting autoreactive B cells.

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ObjectivesThe impact of corticosteroids on the risk of organ damage in the context of clinical end points endorsed in some systemic lupus erythematosus (SLE) clinical trials is underexplored.MethodsWe analysed data from the Hopkins Lupus Cohort using Cox proportional hazards models to understand the impact of exposure to different corticosteroid doses on the risk of developing any new organ damage or any new organ damage at the individual organ systems over time.ResultsMean prior prednisone dose, recent disease activity and immunosuppressant use during follow-up, as well as organ damage score at cohort entry, were significant independent predictors of the risk of developing any new organ damage. Even after adjustment for recent disease activity, there was a dose-response relationship across the different levels of exposure to prednisone during follow-up and the risk of developing any new organ damage. The risk more than doubled in patients exposed to a mean prior prednisone dose of ≥20 mg/day versus <7.5 mg/day (HR=2.514, p<0.001). It was estimated that a 1 mg/day increase in prior prednisone dose during follow-up was associated with a 2.8% increase in the risk of developing new organ damage. For individual organ systems, exposure to a mean prior prednisone dose of ≥7.5 mg/day versus <7.5 mg/day significantly increased the risk of developing cataracts (HR=2.41, p<0.001), osteoporotic fractures (HR=2.16, p<0.001) and cardiovascular damage (HR=1.54, p=0.041), but showed no significant difference for renal damage (HR=1.44, p=0.163) or for other individual organ systems.ConclusionsOrgan damage in SLE is multifactorial; corticosteroid treatment and disease activity play a role.

We found definite seasonal differences in RA patients, both subjectively and objectively. RA disease activity was higher in spring and lower during fall. Seasonal changes may play an important role in evaluating disease activity of RA patients and should be taken into account when examining these patients.