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Butyrate is a short-chain fatty acid (SCFA) created within the intestinal lumen by bacterial fermentation of largely undigested dietary carbohydrates. Its beneficial effects on cellular energy metabolism and intestinal homeostasis have garnered significant attention among SCFAs. Butyrate also has systemic effects and is known to regulate the immune system. Most of the butyrate and other SCFAs are produced in the human colon, through the fermentation of dietary fiber or resistant starch. However, the modern diet often lacks sufficient intake of fermentable dietary fiber, which can lead to low butyrate levels in the colon. To increase butyrate levels, it is helpful to incorporate fiber sources into meals and drinks that rely on slow bacterial fermentation. Butyrate is well known for its anti-inflammatory properties and has a range of immune system-related properties. As an agonist for GPR41, GPR43, or GPR109A, butyrate may have anti-inflammatory effects through these receptors’ signaling pathways. Butyrate also serves as an epigenetic regulator, responding to environmental or pharmacological changes by inhibiting HDAC, up-regulating miR-7a-5p, and promoting histone butyrylation and autophagy processes. This review discusses the importance of butyrate in regulating immunological homeostasis and the inflammatory response. It also addresses experimental models and human studies investigating the therapeutic potential of butyrate supplementation in immune-related conditions linked to butyrate depletion. Specifically, it covers the role of butyrate in some immune-related diseases such as systemic lupus erythematosus, atopic dermatitis, psoriasis, human immunodeficiency virus, cancer, and several other special conditions.

Invasive Staphylococcus aureus infections are frequently associated with bacteraemia. To support clinical decisions on antibiotic therapy, there is an urgent need for reliable markers as predictors of infection outcome. In the present study in mice, bacteraemia was established by intravenous inoculation of a clinical S. aureus isolate at the LD50 inoculum. As potential biomarkers for fatal outcome, blood culture (qualitative and quantitative), serum levels of C-reactive protein (CRP), as well as 31 selected cytokines and chemokines were assessed during the first three days of infection. A positive S. aureus blood culture, the quantitative blood culture, CRP levels, and levels of eight cytokines were indicative for the presence of S. aureus bacteraemia. However, only tumor necrosis factor (TNF) α, interleukin (IL) 1α, and keratinocyte chemoattractant (KC; a functional homologue of human IL-8) were each significantly elevated in eventually non-surviving infected mice versus eventually surviving infected mice. In severe S. aureus bacteraemia in mice, TNF-α, IL-1α, and KC are biomarkers predicting fatal outcome of infection. KC was a biomarker elevated irrespective the progression of infection, which is very interesting regarding clinical application in view of the heterogeneity of patients experiencing bacteraemia in this respect.

BACKGROUND: Pre-exposure prophylaxis (PrEP) with tenofovir and emtricitabine effectively prevents new HIV infections. The optimal scenario for implementing PrEP where most infections are averted at the lowest cost is unknown. We determined the impact of different PrEP strategies on averting new infections, prevalence, drug resistance and cost-effectiveness in Macha, a rural setting in Zambia. METHODS: A deterministic mathematical model of HIV transmission was constructed using data from the Macha epidemic (antenatal prevalence 7.7%). Antiretroviral therapy is started at CD4