engleski

Gene expression of collagen VI alpha 3 (COL6A3) as indicator of adipose tissue inflammation in early childhood

OBJECTIVES: The extracellular matrix (ECM) is a key component of adipose tissue (AT) architecture and is necessary to maintain the balance and integrity of the tissue structure itself. In people with overweight/obesity, there is an increased deposition of connective tissue (collagen) in the ECM and disturbances in the morphology and architecture of AT. Collagens are the largest group of ECM proteins and their structure and integrity is strictly controlled at the molecular level. Among several types of collagen, collagen IV alpha 3 (COL6α3) is strongly associated with weight gain and acts as cemotaxis for adipose tissue macrophages. The aim of this study was to examine correlation between COL6α3 expression and number of adipose tissue macrophages in adipose tissue of male children and adolescents depending on their weight status. MATERIALS-METHODS: Tissue samples from subcutaneous (SAT) and visceral (VAT) fat depots were collected during surgery from 28 healthy male children who underwent elective abdominal surgery having hernia repairs or orchidopexies at the Department for Pediatric Surgery of the University Hospital Osijek. Subjects were divided in two groups depending on their BMI Z-score, there were 16 normal weight and 12 subjects with overweight/obesity. On samples of SAT and VAT which were gained during surgical procedure immunohistochemistry (IHC) for CD163+ cells was performed with BenchMark ULTRA fully automated workflow system and number of positive cells was counted per mm2 of adipose tissue by three independent researchers. AT gene expression of COL6α3 and TNFα was measured by quantitative RT- PCR (BioRad rtPCR CFX96) and reference genes were used for data normalisation. RESULTS: There was no statistical difference in age between groups, children with normal weight were 3, 28[2, 30-6, 60] years old, and children with overweight/obesity 4, 83[3, 35-8, 98] (Mann-Whitney U test, p=0, 347). A higher number of CD163+ cells was counted in VAT of children with overweigt/obesity (Mann-Whitney U test, p=0, 003). COL6α3 mRNA was higher in children with overweight/obesity in both adipose tissues (Mann- Whitney U test, p=0, 010 and p=0, 001). It correlated positively with BMI Z-score in both SAT and VAT (p=0, 016 and p<0, 001), number of CD163+ cells in VAT (p=0, 017) and TNFα mRNA in SAT (p=0, 004 ; Spearman's correlation). CONCLUSION: Increased mRNA COL6α3 expression in visceral and subcutaneous adipose tissue of male children and adolescents positively correlates with their weight status, number of CD163+ cells in visceral adipose tissue and mRNA TNFα expression in subcutaneous adipose tissue which indicates that COL6α3 contributes to inflammation and remodeling processes of adipose tissue in male children with overweight/obesity in early childhood.

pretilost, djetinjstvo, col6a3, upala, ekspresija gena, masno tkivo

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