Peri-islet glial cells (PIGCs) are positioned to control neuronal-endocrine-vascular cell communication within the islet, but their role in islet cell function is not known. Hypothalamic glial cells become reactive in response to high fat diet (HFD) feeding and are implicated in the pathogenesis of obesity and type 2 diabetes. We hypothesize that metabolic stress such as diet-induced obesity and hyperglycemia promote the expansion of PIGCs, similar to what has been observed in the central nervous system. To test this hypothesis, we used the glial cell marker, glial fibrillary acidic protein (GFAP) , to identify PIGCs and compared GFAP immunoreactivity in pancreas from the following groups. First, pancreas was harvested from HFD- or chow fed control C57BL/6J male mice after 2 days, 2 weeks or 8 weeks on diet (n=6-8/group) . Second, pancreas was taken from 12-wk old db/db male mice and their control littermates with or without empagliflozin (EMPA) treatment (20mg/kg/d for 6 weeks; n=4-7/group) . Islet PIGC area was quantified as GFAP-positive area/total islet area x100%. Mann-Whitney test and one-way ANOVA were used for data analysis. We found that HFD feeding increased mouse pancreatic peri-islet GFAP expression relative to chow controls at 2 days (HFD 1.4±0.2%, chow 0.8±0.1%; p=0.02) , 2 weeks (HFD 3.5±0.4%, chow 1.2±0.1%; p<0.001) and 8 weeks (HFD 5.4±0.3%, chow 1.8±0.2%; p=0.002) in association with body weight gain and impaired glucose tolerance. Similar results were observed in obese and hyperglycemic db/db mouse vs. control littermates (db/db 5.0±1.4%, control 1.2±0.4%; p=0.004) . There was a trend for EMPA treatment to reduce islet PIGC area in the db/db mice (EMPA 2.0±0.5, VEH 5.0±1.4%, p=0.08) .
In conclusion, these findings indicate that islet gliosis is observed in two obese and hyperglycemic mouse models and raise the possibility that pancreatic ‘gliosis’ may have a relevant role in islet-cell function regulation under metabolic challenge.
J.Niu: None. J.B.Moss: None. W.Rosario: Employee; Merck & Co., Inc. R.Arumugam: None. D.J.Hackney: None. R.L.Hull-meichle: Research Support; Casma Therapeutics. J.Tong: None.
National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (R01DK097550) ;Department of Veterans Affairs (IBX004063)