Dectin-1 is a pathogen recognition receptor as well as an innate immune response modulator; its function in metabolic disorders is yet unclear. Previously, we identified dectin-1 as a biomarker of metabolic inflammation in obesity. In this study, we sought to identify potential signaling pathways that could modify the expression of the dectin-1 gene and assess the expression of dectin-1 in the adipose tissue (AT) of obese patients based on their diabetic status. The study cohort included 95 obese individuals split into two groups: prediabetics with moderate glycemia (Hb1Ac 6.5%, n = 49) and diabetics with hyperglycemia (Hb1Ac 6.5%, n = 46). Dectin-1 expression was assessed using immunohistochemistry. Gene expression and inflammatory markers were determined via qRT-PCR. We found a significant positive correlation between dectin-1 expression and HbA1C levels in AT isolated from obese individuals with HbA1C levels of 6.5% or higher. Dectin-1 gene expression was significantly correlated with several inflammatory markers; however, glycemic-dependent associations were also observed. Dectin-1 and TNF-α were found to be significantly correlated in AT from individuals with Hb1Ac 6.5%, indicating a possible mechanism of gene regulation between these two factors. As a result, we investigated the observed dectin-1/TNF-α crosstalk using in vitro cell culture and animal studies. Unlike wild-type animals, mice lacking TNF-α exhibited reduced levels of dectin-1 gene and protein expression in their AT, which were restored by injecting exogenous TNF-α. ChIP studies showed that TNF-α induced dectin-1 gene transcription by mediating NF-kB binding to newly identified regulatory elements located in the dectin-1 proximal regulatory region. The interplay between dectin-1 and TNF-α signaling pathways is intriguing and has the potential to be a therapeutic target in obesity and diabetes. Furthermore, dectin-1 could be a potential marker for the onset of hyperglycemia and diabetes. Disclosure A.Al madhoun: None. D.Haddad: None. S.P.Kochumon: None. F.Alrashed: None. R.S.Thomas: None. L.P.Miranda: None. S.T.K.Sindhu: None. R.Ahmad: None. F.Almulla: None.

We Have previously established that caveolin-1 (CAV1) rs1997623 C/A variant is associated with metabolic syndrome in obese children (PMID: 30622557) and adults (ADA 82) . Here, we evaluated the functional role of the identified variant in association with obesity. Sequence analysis revealed that the variant is located at CAV1 regulatory region and creates a site for EBF Transcription Factor 1 (EBF1) . DNA fragment (240pb) flanking the variant was cloned upstream luciferase reporter gene. Wildtype, CAV1-C-Luc, and the generated mutant, CAV1-A-Luc, were individually transfected into pre-adipocytes. CAV1-A-luc significantly upregulated Luciferase activity indicating a prospective functional role of CAV1-A allele in CAV1 regulation. The reporter gene activity was differential regulated in lean versus obese pre-adipocytes. Co-transfections with EBF1 construct resulted in a significant upregulation in CAV1-A Luc activity, particularly in pre-adipocytes from obese individuals. The role of EBF1 was further evaluated in vivo using ChIP assays. PCR analysis using specific primers flanking the CAV1 variant and anti-bodies against EBF1 showed a significant elevated enrichment of chromatins from obese individuals, which was also associated with an enrichment for H3K27ac at the same locus, indicating active transcription. Moreover, CAV1 expression was differentially regulated in response to EBF1 siRNA/overexpression in pre-adipocytes harboring CAV1 A/A or A/C alleles relative to that with C/C allele. Furthermore, a significant reduction of DNA methylation at the variant locus was observed particularly in preadipocytes with A/A alleles. Finally, RNA isolated from adipose tissue of lean and obese individuals showed a significant correlation between CAV1 and cytokines transcripts in healthy obese individuals, at least in part, is due to CAV1 rs1997623 variant as verified by sequence analysis. Taken together, our study delineates the role of CAV1 rs1997623 variant in the context of obesity and MetS. Disclosure A.Al madhoun: None. D.Haddad: None. S.P.Kochumon: None. R.Nizam: None. S.Jacob: None. S.T.Sindhu: None. R.Ahmad: None. F.Almulla: None. Funding Kuwait Foundation for the Advancement of Sciences (KFAS) and Dasman Diabetes Institute, Project RA CB-2021-007

Studies have implicated CAV1 in the pathophysiology of diabetes and obesity. Previously, we demonstrated a potential association between the CAV1 rs1997623 C/A variant and metabolic syndrome (MetS) in Kuwaiti children. In the present study, we substantiate the association of CAV1 with MetS in adult Arab individuals. Method: The CAV1 rs1997623 was genotyped in three cohorts of Arabs (n=479) , South Asians (n=660) and South East Asians (n=362) . MetS status of the individuals was diagnosed using the IDF criteria (i.e., presence of central obesity and of at least two abnormalities of high TG, low HDL, hypertension, or type 2 diabetes) . The quantitative measure of MetS was calculated as siMS=2*WC/Height + FBG/5.6 + TG/1.7 + SBP/130 - HDL/1.02 for males or HDL/1.28 for females. Allelic associations with quantitative and dichotomous traits were assessed using linear and logistic regression, respectively, with and adjustment for age and sex. CAV1 transcripts were quantified in adipose tissues from a cohort of 50 Arab individuals differing in siMS score. Results: The CAV1 variant was significantly associated with MetS status (OR=1.8[1.25-2.61]; P-value=0.0015; Pemp=0.0013) and with siMS (Effect size = 0.206; P-value=0.0035; Pemp=0.0028) in the cohort of Arab individuals. The variant was weakly and insignificantly associated in the cohorts of South Asian and South East Asian individuals (OR= 1.and 1.11; P-values= 0.25 and 0.67, respectively) . siMS scores correlated positively with mRNA levels of CAV1 in adipose tissue. Conclusion: The association of CAV1 rs1997623 C/A with MetS in Arab pediatric is now demonstrated in adults as well. Higher expression levels were seen in individuals poses increasing MetS rates further validates the implication of CAV1 rs1997623 C/A variant in MetS phenotype. Only a weak association signal was seen in the South Asian and South East Asian populations leading us to propose that the CAV1 rs1997623 association with MetS is probably specific to Arab ethnicity. Disclosure A.Al madhoun: None. P.Hebbar: None. R.Nizam: None. D.Haddad: None. M.H.Dashti: None. M.Abu-farha: None. R.Ahmad: None. A.T.Thangavel: None. F.Almulla: None. Funding Kuwait Foundation for the Advancement of Sciences (KFAS) and Dasman Diabetes Institute, Project RA CB-2021-007