👤 Sam Santhosh

Gastrointestinal (GI) motility is controlled by the coordinated activity of enteric neurons, glial cells, and resident muscularis macrophages (mMφs). Apolipoprotein E (ApoE) is highly expressed in mMφs, but its functional role in the gut remains unclear. We hypothesized that mMφ-derived ApoE regulates intestinal motility under physiological and stress conditions. Global ApoE knockout mice, bone marrow chimeras, and macrophage-specific ApoE-deficient mice were used to assess the impact of ApoE loss on gut transit, immune response, and neuromuscular integrity in both homeostatic and postoperative ileus (POI) settings. (1) Single-cell RNA sequencing revealed that muscularis macrophages highly express ApoE, with further upregulation after intestinal manipulation. (2) Bone marrow chimera experiments showed that hematopoietic-derived ApoE only partially contribute to the maintenance of gut motility. (3) Global ApoE deficiency led to mild impairment of intestinal transit and increased glial activation, accompanied by an expansion of the macrophage population and elevated gene expression of inflammatory cytokines. (4) Macrophage-specific deletion of ApoE did not affect gastrointestinal transit or tissue morphology under normal conditions. Although highly expressed and dynamically regulated in muscularis macrophages, ApoE is largely dispensable for intestinal neuromuscular function at baseline and during postoperative ileus. Show less

This study reports the prevalence of five clinically significant variants associated with increased risk of cardiovascular disorders, and variable responses of individuals to commonly prescribed cardiovascular drugs in a South Indian population from the state of Kerala. Genomic DNA isolated from 100 out-patient samples from Kerala were sequenced to examine the frequency of clinically relevant polymorphisms in the genes MYBPC3 (cardiomyopathy), SLCO1B1 (statin-induced myopathy), CYP2C9, VKORC1 (response to warfarin) and CYP2C19 (response to clopidogrel). Our analyses revealed the frequency of a 25 bp deletion variant of MYBPC3 associated with risk of cardiomyopathy was 7%, and the SLCO1B1 "C" allele associated with risk for statin-induced myopathy was 15% in this sample group. Among the other variants associated with dose-induced toxicity of warfarin, VKORC1 (c.1639G>A), was detected at 22%, while CYP2C9*3 and CYP2C9*2 alleles were present at a frequency of 15% and 3% respectively. Significantly, the tested sample population showed high prevalence (66%) of CYP2C19*2 variant, which determines response to clopidogrel therapy. We have identified that certain variants associated with cardiovascular disease and related drug response in the five genes, especially those in VKORC1, CYP2C19 and MYBPC3, are highly prevalent in the Kerala population, with almost 2 times higher prevalence of CYP2C19*2 variant compared with other regions in the country. Since the variants chosen in this study have relevance in disease phenotype and/or drug response, and are detected at a higher frequency, this study is likely to encourage clinicians to perform genetic testing before prescribing therapy. Show less