👤 Dániel Kuti

Fasting triggers complex physiological and neuroimmune adaptations, yet its impact on hypothalamic microglia and the underlying regulatory role of glucocorticoids remains incompletely understood. The present study focused on fasting-induced systemic changes and cellular adaptations seen in the hypothalamus where components of metabolic- hormonal- and immune regulations are integrated. Adult male microglia reporter (CX3CR1 Overnight fasting resulted in a decrease in energy expenditure and respiratory exchange ratio (RER) indicating conservation of energy and a metabolic shift towards utilization of fatty acids as alternative energy source. Fasting increased hypothalamic expression of orexigenic neuropeptides and mRNA levels of Pdk4, Glut1, and Mct2 genes, in line with metabolic compensation. Upregulation of hypothalamic Crh and increased plasma concentration of corticosterone indicated sustained activation of the HPA axis. Importantly, fasting promoted an anti-inflammatory milieu in the hypothalamus characterized by elevated Il-4, Il-10 and IkBα genes without significant activation of pro-inflammatory cytokines (e.g., Il-1β, Il-6, Tnfα). Morphological analysis revealed region-specific changes in microglia number and branching complexity, particularly in hypothalamic regions directly exposed to blood-borne signals. Functional profiling showed increased microglial expression of IkBα and decreased pIkBα, indicating suppressed NFkB signaling. Adrenalectomy (1 week) and acute pharmacological inhibition of corticosterone synthesis (methyrapone) revealed that fasting-induced anti-inflammatory and metabolic gene expression, as well as microglial plasticity were largely glucocorticoid dependent. Hypothalamic expression of fasting-related neuropeptides (Npy, Agrp) and genes, related to the metabolic shift (Pdk4, Glut-1, Mct2, Angptl4) as well as some immune-related genes (Il10, Iba1) was dependent on presence of the adrenal gland or fasting-induced elevation of corticosterone. These findings highlight short term fasting as a potent modulator of hypothalamic immune-metabolic crosstalk and reveal critical role of adrenal glucocorticoids in orchestrating microglial responses to energetic challenges. The results have potential implications for therapeutic interventions targeting metabolic and inflammatory disorders. Show less

A major modifiable risk factor for atherosclerotic cardiovascular disease is abnormalities in lipid and lipoprotein metabolism which are frequently seen in HIV as well as its treatment. Apo-E is a protein that is important in plasma lipid homeostasis and its genetic alleles have been shown to contribute to lipid abnormalities. We examined for the effect of Apo-E gene polymorphisms on plasma lipid levels in PLHIV on protease inhibitor therapy. This was a cross-sectional study conducted among adult persons living with HIV. Lipid profile, Apo-B and Apo-A were measured in fasting plasma. Amplification and analysis of Apo-E genotypes were determined using the Seeplex Apo-E ACE genotyping kit. Differences in quantitative values were compared with non-parametric analysis methods. Eighty-four persons were recruited into the study, 75% of whom were virally suppressed. The 3 homozygous genotypes had significantly different levels of low-density lipoprotein cholesterol (LDL-C), Apolipoprotein B (Apo-B) and Apolipoprotein A1 (Apo-A1). Persons with apo ε2/ε2 had higher LDL-C compared to those with apo ε3/ε3 (3.26 (3.61) mmol/L vs. 2.76 (1.28) mmol/L, p = 0.010). Those with apo ε4/ε4 had lower Apo-A1 compared to those with apo ε3/ε3 (0.84 (0.48) g/dL vs. 1.27 (0.70) g/dL, p =0.009). Compared with the same group, the heterozygous genotype, apo ε2/ε3 had lower triglyceride levels :1.33 (0.65) mmol/ L vs. 1.86 (1.11) mmol/L, p = 0.045. Polymorphisms in the Apo-E gene may have significant influences on plasma lipid and apolipoprotein levels in PLHIV on PI therapy. This may have implications for the assessment of risk for cardiovascular disease. Show less