Type 1 diabetes (T1D) is a T-cell mediated autoimmune disease characterized by the destruction of insulin-producing pancreatic islet β-cells. An understudied area is the role lipid signaling plays in this process. We find that the Ca2+-independent phospholipase A2β (iPLA2β) is induced under a diabetic milieu and mitigation of iPLA2β activity attenuates β-cell death.iPLA2β, a member of the PLA2 family, hydrolyzes the sn-2 substituent from glycerophospholipid substrates to yield a free fatty acid. When the fatty acid is arachidonic acid, it can be metabolized to eicosanoids, many of which are pro-inflammatory. To address our overarching hypothesis that iPLA2β-derived lipids (iDLs) contribute to T1D development, we investigated the role of immune cell-iDLs by utilizing a T-cell adoptive transfer. We isolated CD4+/8+ T-cells from splenocytes prepared from 11-week-old donor female NOD and NOD.iPLA2 β +/- (HET) . These were transferred i.p. to 4-week-old NOD.scid recipient mice. We find that NOD4/8-recipient mice develop T1D between 14-16 weeks of age. In contrast, T1D onset in HET4/8-recipient mice is delayed by 12 weeks and this was associated with better glucose tolerance, compared to NOD4/8 T-cell recipients. This finding is also supported by histology analysis of the pancreatic islet, which revealed less islet infiltration, more islet abundance, and the frequency of CD4 T cells were increased in the pancreas of HET4/8-recipient mice compared to NOD4/8 recipients. Further, lipidomics analyses revealed that HET donor T-cell production of proinflammatory lipids (i.e., PGE2 and DHETs) is decreased, relative to NOD T-cells. These findings suggest that pro-inflammatory iDLs generated by CD4 T-cells are critical contributors T1D development and can be targeted to counter T1D onset.
T.White: None. C.Chalfant: None. T.P.Dilorenzo: None. S.Ramanadham: None. D.Stephenson: None.
Training Program in Cell, Molecular, and Developmental Biology (5T32GM008111-34) NIH/NIDDK (R01DK110292) NIH/NIAID R21 (AI 146743) Cell, Developmental, & Integrative Biology (CDIB) , the University of Alabama at Birmingham