Oleic acid enhances proliferation and calcium mobilization of CD3/CD28 activated CD4+ T cells through incorporation into membrane lipids.

Unsaturated fatty acids (UFA) are crucial for T-cell effector functions, as they can affect the growth, differentiation, survival, and function of T cells. Nonetheless, the mechanisms by which UFA affects T-cell behavior are ill-defined. Therefore, we analyzed the processing of oleic acid, a prominent UFA abundantly present in blood, adipocytes, and the fat pads surrounding lymph nodes, in CD4+ T cells. We found that exogenous oleic acid increases proliferation and enhances the calcium flux response upon CD3/CD28 activation. By using a variety of techniques, we found that the incorporation of oleic acid into membrane lipids, rather than regulation of cellular metabolism or TCR expression, is essential for its effects on CD4+ T cells. These results provide novel insights into the mechanism through which exogenous oleic acid enhances CD4+ T-cell function.

Glucocorticoid receptor antagonist CORT113176 attenuates motor and neuropathological symptoms of Huntington's disease in R6/2 mice.

Huntington's Disease (HD) is a progressive neurodegenerative disease caused by a mutation in the huntingtin gene. The mutation leads to a toxic gain of function of the mutant huntingtin (mHtt) protein resulting in cellular malfunction, aberrant huntingtin aggregation and eventually neuronal cell death. Patients with HD show impaired motor functions and cognitive decline. Elevated levels of glucocorticoids have been found in HD patients and in HD mouse models, and there is a positive correlation between increased glucocorticoid levels and the progression of HD. Therefore, antagonism of the glucocorticoid receptor (GR) may be an interesting strategy for the treatment of HD. In this study, we evaluated the efficacy of the selective GR antagonist CORT113176 in the commonly used R6/2 mouse model. In male mice, CORT113176 treatment significantly delayed the loss of grip strength, the development of hindlimb clasping, gait abnormalities, and the occurrence of epileptic seizures. CORT113176 treatment delayed loss of DARPP-32 immunoreactivity in the dorsolateral striatum. It also restored HD-related parameters including astrocyte markers in both the dorsolateral striatum and the hippocampus, and microglia markers in the hippocampus. This suggests that CORT113176 has both cell-type and brain region-specific effects. CORT113176 delayed the formation of mHtt aggregates in the striatum and the hippocampus. In female mice, we did not observe major effects of CORT113176 treatment on HD-related symptoms, with the exception of the anti-epileptic effects. We conclude that CORT113176 effectively delays several key symptoms related to the HD phenotype in male R6/2 mice and believe that GR antagonism may be a possible treatment option.

Fatty acid metabolism in aggressive B-cell lymphoma is inhibited by tetraspanin CD37.

The importance of fatty acid (FA) metabolism in cancer is well-established, yet the mechanisms underlying metabolic reprogramming remain elusive. Here, we identify tetraspanin CD37, a prognostic marker for aggressive B-cell lymphoma, as essential membrane-localized inhibitor of FA metabolism. Deletion of CD37 on lymphoma cells results in increased FA oxidation shown by functional assays and metabolomics. Furthermore, CD37-negative lymphomas selectively deplete palmitate from serum in mouse studies. Mechanistically, CD37 inhibits the FA transporter FATP1 through molecular interaction. Consequently, deletion of CD37 induces uptake and processing of exogenous palmitate into energy and essential building blocks for proliferation, and inhibition of FATP1 reverses this phenotype. Large lipid deposits and intracellular lipid droplets are observed in CD37-negative lymphoma tissues of patients. Moreover, inhibition of carnitine palmitoyl transferase 1 A significantly compromises viability and proliferation of CD37-deficient lymphomas. Collectively, our results identify CD37 as a direct gatekeeper of the FA metabolic switch in aggressive B-cell lymphoma.

Innate Immune Training of Human Macrophages by Cathelicidin Analogs.

Trained innate immunity can be induced in human macrophages by microbial ligands, but it is unknown if exposure to endogenous alarmins such as cathelicidins can have similar effects. Previously, we demonstrated sustained protection against infection by the chicken cathelicidin-2 analog DCATH-2. Thus, we assessed the capacity of cathelicidins to induce trained immunity. PMA-differentiated THP-1 (dTHP1) cells were trained with cathelicidin analogs for 24 hours and restimulated after a 3-day rest period. DCATH-2 training of dTHP-1 cells amplified their proinflammatory cytokine response when restimulated with TLR2/4 agonists. Trained cells displayed a biased cellular metabolism towards mTOR-dependent aerobic glycolysis and long-chain fatty acid accumulation and augmented microbicidal activity. DCATH-2-induced trained immunity was inhibited by histone acetylase inhibitors, suggesting epigenetic regulation, and depended on caveolae/lipid raft-mediated uptake, MAPK p38 and purinergic signaling. To our knowledge, this is the first report of trained immunity by host defense peptides.

Stable human regulatory T cells switch to glycolysis following TNF receptor 2 costimulation.

Following activation, conventional T (Tconv) cells undergo an mTOR-driven glycolytic switch. Regulatory T (Treg) cells reportedly repress the mTOR pathway and avoid glycolysis. However, here we demonstrate that human thymus-derived Treg (tTreg) cells can become glycolytic in response to tumour necrosis factor receptor 2 (TNFR2) costimulation. This costimulus increases proliferation and induces a glycolytic switch in CD3-activated tTreg cells, but not in Tconv cells. Glycolysis in CD3-TNFR2-activated tTreg cells is driven by PI3-kinase-mTOR signalling and supports tTreg cell identity and suppressive function. In contrast to glycolytic Tconv cells, glycolytic tTreg cells do not show net lactate secretion and shuttle glucose-derived carbon into the tricarboxylic acid cycle. Ex vivo characterization of blood-derived TNFR2hiCD4+CD25hiCD127lo effector T cells, which were FOXP3+IKZF2+, revealed an increase in glucose consumption and intracellular lactate levels, thus identifying them as glycolytic tTreg cells. Our study links TNFR2 costimulation in human tTreg cells to metabolic remodelling, providing an additional avenue for drug targeting.

Metabolic response of porcine colon explants to in vitro infection by Brachyspira hyodysenteriae: a leap into disease pathophysiology.

INTRODUCTION: Swine dysentery caused by Brachyspira hyodysenteriae is a production limiting disease in pig farming. Currently antimicrobial therapy is the only treatment and control method available. OBJECTIVE: The aim of this study was to characterize the metabolic response of porcine colon explants to infection by B. hyodysenteriae. METHODS: Porcine colon explants exposed to B. hyodysenteriae were analyzed for histopathological, metabolic and pro-inflammatory gene expression changes. RESULTS: Significant epithelial necrosis, increased levels of l-citrulline and IL-1α were observed on explants infected with B. hyodysenteriae. CONCLUSIONS: The spirochete induces necrosis in vitro likely through an inflammatory process mediated by IL-1α and NO.