Ahmad Rasheed, Kochumon Shihab, Thomas Reeby, Atizado Valerie, Sindhu Sardar
Immunology & Innovative Cell Therapy Unit, Dasman Diabetes Institute (DDI), Al-Soor Street, P.O. Box 1180, Dasman, 15462 Kuwait.
Tissue Bank Core Facility, Dasman Diabetes Institute (DDI), Al-Soor Street, P.O. Box 1180, Dasman, 15462 Kuwait.
J Inflamm (Lond). 2016 Dec 8;13:38. doi: 10.1186/s12950-016-0147-y. eCollection 2016.
The innate immune Toll-like receptors (TLRs) 2/4 are important players in chronic low-grade inflammation called metabolic inflammation in obesity and type-2 diabetes (T2D). While TLR2/4 expression changes associated with metabolic inflammation are known, the adipose tissue expression of endocytic TLR8, which is expressed by all major macrophage subsets, remain unclear. We, therefore, determined the TLR8 mRNA/protein expression in the adipose tissue samples from lean, overweight, and obese individuals with or without T2D.
Subcutaneous fat biopsy samples were collected from 49 non-diabetic (23 obese, 17 overweight, and nine lean) and 45 T2D (32 obese, ten overweight, and three lean) individuals. TLR8 gene expression was determined using real-time RT-PCR and TLR8 protein expression was assessed by both immunohistochemistry and confocal microscopy. The changes in TLR8 expression were compared with those of macrophage markers, proinflammatory cytokines/chemokines, and surface TLRs/adapter proteins. The data were analyzed using -test/Mann-Whitney -test, Pearson's correlation, and multiple regression test.
The data show that in obese non-diabetic/T2D individuals, TLR8 gene expression was significantly upregulated as compared with lean individuals which correlated with body mass index (BMI) and body fat percentage in non-diabetic population ( < 0.05). As expected, TLR8 adipose tissue protein expression in non-diabetic/T2D obese individuals was also higher than that of overweight/lean counterparts. In non-diabetic/T2D individuals, TLR8 gene expression associated ( < 0.05) with the expression of CD68, CD11c, CD86, and CD163 macrophage markers. Also, in these individuals, TLR8 gene expression correlated positively ( < 0.05) with adipose tissue expression of TNF-α, IL-18, and IL-8 as well as with systemic CRP levels (in non-diabetics). TLR8 expression was also associated with TLR4/TLR2 and MyD88 expression in the adipose tissue.
The elevated adipose tissue expression of TLR8 in obesity/T2D has consensus with inflammatory signatures and may thus represent an immune marker of metabolic inflammation.
天然免疫Toll样受体（TLR）2/4是肥胖和2型糖尿病（T2D）中称为代谢性炎症的慢性低度炎症的重要参与者。虽然已知与代谢性炎症相关的TLR2/4表达变化，但由所有主要巨噬细胞亚群表达的内吞性TLR8在脂肪组织中的表达仍不清楚。因此，我们测定了有或无T2D的瘦、超重和肥胖个体脂肪组织样本中TLR8的mRNA/蛋白表达。
从49名非糖尿病患者（23名肥胖、17名超重和9名瘦者）和45名T2D患者（32名肥胖、10名超重和3名瘦者）中采集皮下脂肪活检样本。使用实时逆转录聚合酶链反应（RT-PCR）测定TLR8基因表达，并通过免疫组织化学和共聚焦显微镜评估TLR8蛋白表达。将TLR8表达的变化与巨噬细胞标志物、促炎细胞因子/趋化因子以及表面TLR/衔接蛋白的变化进行比较。使用t检验/曼-惠特尼U检验、皮尔逊相关性检验和多元回归检验分析数据。
数据显示，在肥胖非糖尿病/T2D个体中，与瘦个体相比，TLR8基因表达显著上调，这与非糖尿病人群的体重指数（BMI）和体脂百分比相关（P<0.05）。正如预期的那样，非糖尿病/T2D肥胖个体的TLR8脂肪组织蛋白表达也高于超重/瘦个体。在非糖尿病/T2D个体中，TLR8基因表达与CD68、CD11c、CD86和CD163巨噬细胞标志物的表达相关（P<0.05）。此外，在这些个体中，TLR8基因表达与脂肪组织中肿瘤坏死因子-α（TNF-α）、白细胞介素-18（IL-18）和白细胞介素-8（IL-8）的表达以及全身C反应蛋白（CRP）水平（在非糖尿病患者中）呈正相关（P<0.05）。TLR8表达还与脂肪组织中TLR4/TLR2和髓样分化因子88（MyD88）的表达相关。
肥胖/T2D中脂肪组织TLR8表达升高与炎症特征一致，因此可能代表代谢性炎症的免疫标志物。
