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.

Nonalcoholic fatty liver disease (NAFLD) is a risk factor of type-2 diabetes and cardiovascular disease. Obesity induced by various high-fat diets from different sources results in different types of meta-inflammatory derangements, including NAFLD. Fats are a central part of healthy diets, however, the impact of various dietary fats, lacking in sucrose, on liver fat accumulation and expression of lipogenic and inflammatory markers remains unclear. To study this, C57BL/6J mice were fed sucrose-free HFDs comprising fat from diverse sources, including cocoa butter (c-HFD), sunflower oil (s-HFD), soybean oil (so-HFD), and fish oil (f-HFD). Mice fed c-HFD or so-HFD developed more severe liver steatosis, compared with those fed s-HFD or f-HFD. Liver histopathology displayed high levels of lobular inflammation in mice fed c-HFD, so-HFD, and s-HFD. Kupffer cell counts were higher in mice fed c-HFD and s-HFD. Hepatic fibrosis was seen in mice fed s-HFD or so-HFD. Of note, there was no hepatic fibrosis in mice fed f-HFD. None of the diet had a significant impact on total body weight. However, liver weight was slightly increased in mice fed c-HFD or s-HFD. Mice fed c-HFD, s-HFD, and so-HFD displayed insulin resistance. Expression of the key genes of glycolysis (Pklr), de novo lipogenesis (Acaca, Fasn, Scd1), fatty acid oxidation (Cpt1a, Ppar-α), inflammation (Tnf-α) was upregulated in mice fed c-HFD or s-HFD. No significant difference was seen regarding genes of fatty acid uptake (Cd36, Fabp2), and chemokine-associated inflammation (Ccl2). Interestingly, hepatic IL-1β and IL-6 were elevated only in mice fed c-HFD. Taken together, these findings indicate that mice fed the sucrose-free HFDs comprising lipids from various dietary sources may have differential effects on hepatic steatosis at levels of de novo lipogenesis, hepatic inflammation, and whole-body insulin resistance. Disclosure R. Ahmad: None. T.K. Jacob: None. S.P. Kochumon: None. R.S. Thomas: None. S. Shenouda: None. N. Akhter: None. A. Wilson: None. F. Bahman: None. A. Hasan: None. F. Alrashed: None. H. Arefanian: None. A. Al Madhoun: None. F. Almulla: None. S.T.K. Sindhu: None. Funding Kuwait Foundation for the Advancement of Sciences (RAAM-2016-007)

Purpose: Childhood obesity is a major risk factor for chronic diseases such as type 2 diabetes (T2D) and cardiovascular disease. Elevated soluble suppression of tumorigenicity 2 (sST2) is associated with obesity, diabetes, and cardiovascular disease in adults, and is used as a biomarker of cardiometabolic disease. Such biomarkers play an important role in the management of obesity and cardiometabolic disease. In this cross-sectional study, we examined the levels of circulating sST2 in children and adolescents, as well as its association with inflammatory and metabolic markers. Methods: A total of 85 children and adolescents (aged 5-16 years) were included. Participants' characteristics included being of normal weight (body mass index, BMI <85th percentile; n=13), overweight (BMI 85-94th percentile; n=2), or obese (BMI ≥95th percentile; n=70; a total of 8 with confirmed T2D). Clinical and biochemical markers (including plasma glucose, glycated hemoglobin (HbA1c), insulin, vitamin D, and lipid, liver, and renal profiles) were assessed using established procedures on peripheral blood samples. The levels of sST2, interleukin (IL)-33, IL-6, C-reactive protein (CRP), leptin, and adiponectin, were quantified using commercially available ELISA kits. Results: sST2 level was directly correlated with body fat % (r=0.3, P=0.016, n=64) and fat to muscle ratio (r=0.37, P=0.01, n=45), but inversely correlated with muscle mass % (r=-0.34, P=0.02, n=45). sST2 level was directly correlated with insulin (r=0.29, P=0.04, n=50), HbA1c (r=0.29, P=0.04, n=51), and urea (r=-0.34, P=0.01, n=54). sST2 level was directly correlated with the inflammatory markers CRP (r=0.34, P=0.008, n=59) and IL-6 (r=0.32, P=0.0045, n=77). The data were consistent after adjustment for age and sex. Conclusion: Increased circulating levels of sST2 is associated with increased body fat, metabolic dysfunction, and inflammation in children and adolescents. Disclosure A.Hasan: None. S.P.Kochumon: None. I.D.Albasiri: None. F.Almulla: None. R.Ahmad: None. Funding The Kuwait Foundation for the Advancement of Sciences (RA2011-018)

Obesity is marked by metabolic inflammation and by metabolic impairment caused by increased endotoxin, free fatty acids, and vascular endothelial growth factor (VEGF) levels; and involves the endoplasmic reticulum (ER) stress as well. However, it remains unclear whether the ER stress can induce/amplify VEGF expression in metabolically-stressed monocytic cells; and if so, by which mechanism(s). To test this, metabolic stress was induced in THP-1 monocytic cells by treating cells separately with lipopolysaccharide (LPS), palmitic acid (PA), and oleic acid (OA), in presence/absence of ER stressor thapsigargin (TG). Gene expression of VEGF/ER stress markers was assessed by qRT-PCR, protein expression by ELISA, ROS by DCFH-DA assay, phosphorylation of HIF-1α, NF-κB, ERK1/2, and p38 MAPK by immunoblotting, and the insulin response in stressed cells by glucose-uptake assay. Regarding clinical analyses, adipose VEGF gene and protein expression was detected using qRT-PCR and IHC, respectively, while plasma hs-CRP, TNF-α, MDA, and OX-LDL levels were measured by ELISA. The experimental data show that a cooperative interaction between the metabolic and ER stresses led to the expression of VEGF, ROS, CHOP, ATF6, SOD2, and NRF2 (P˂0.05), as well as stimulated the CHOP and NRF2 promoter activities in reporter cells (P˂0.05). However, the glucose uptake was not impaired. The VEGF expression was dependent on phosphorylation of HIF-1α, NF-κB, and p38 MAPK; and the inhibitors of NF-κB/MAPK pathways as well as antioxidants or ROS scavengers suppressed the VEGF production. Further, individuals with obesity showed increased VEGF expression which associated positively with plasma levels of hs-CRP, TNF-α, MDA, and OX-LDL (P≤0.05). Overall, our findings support a cooperativity model in which the ER and metabolic stresses interact to augment VEGF expression in monocytic cells via the mechanisms involving CHOP/ROS/HIF-1α/NRF2 and NF-κB/p38 MAPK pathways. Disclosure S.A.K.Sindhu: None. F.Alzaid: None. F.Almulla: None. R.Ahmad: None. N.Akhter: None. A.Wilson: None. H.Arefanian: None. A.Al madhoun: None. R.S.Thomas: None. S.P.Kochumon: None. F.Alrashed: None. F.Bahman: None. Funding Kuwait Foundation for the Advancement of Sciences (RA2015-027, RA2010-003, RAHM-2019-022)

Obesity induced chronic low-grade inflammation is a central risk factor for the development of metabolic syndrome. It has been well documented that high LDL-c induces inflammation. The proinflammatory cytokine Il-23 plays a pivotal role in the pathogenesis of inflammatory diseases. IL-23 and its relationship with LDL- c has not been reported yet. In this cross-sectional study we investigated whether adipose tissue expression of IL-23 associated with the other inflammatory mediators in individuals with high serum levels of low-density lipoprotein cholesterol (LDL-c) . Subcutaneous adipose samples were collected from 67 individuals and divided into two groups based on their serum LDL-c levels (LDL-c: < 2.9 or ≥2.9 mmol/L) . Expression of IL-23 and inflammatory markers was determined using real-time RT-PCR. Plasma lipid measurements included total cholesterol (TC) , triglyceride (TG) , high-density lipoprotein cholesterol (HDL-c) and LDL-c by standard methods, and serum adiponectin was measured by enzyme-linked immunosorbent assay (ELISA) . Individuals with increased serum levels of LDL-c showed high IL-23 expression levels in adipose tissue (p < 0.011) . AT IL-23 expression was correlated positively with LDL-c (r= 0.39, p < 0.0001) . IL-23 expression levels were positively correlated with macrophage markers (CD11c, CD68, CD86, CD127; (r ≥0.37, p≤ 0.02) , TLRs (TLR8, TLR10; (r ≥ 0.39, p ≤ 0.022) , IRF3 (r= 0.46, p< 0.01) , cytokines (TNF-α, IL-12, IL-18; (r ≥ 0.35, p ≤ 0.04) , chemokines (CXCL8, CCL3, CCL5, CCL15, CCL20; (r ≥0.43, p ≤ 0.01) . Notably, IL-23 is negatively correlated with adiponectin (r=-0.44, p < 0.03) in the individuals with high LDL-c. However, such association of IL-23 with inflammatory markers was not found in the individuals with low LDL-c. In conclusion, adipose tissue IL-23 may be a biomarker for inflammation progression in the individuals with high LDL-c and could be used as a therapeutic target for the treatment of metabolic syndrome. Disclosure R.Ahmad: None. S.P.Kochumon: None. A.Hasan: None. S.T.Sindhu: None. H.Arefanian: None. F.Alrashed: None. F.Almulla: None. Funding Kuwait Foundation for Advancement of Sciences (RA-2010-003)