Interferons (IFN) have been shown to alter lipid metabolism in immune and some non-hematopoietic cells and this affects host cell response to pathogens. In type 1 diabetes, IFN gamma acts as a proinflammatory cytokine that, along with other cytokines, is released during pancreatic beta cell autoinflammation and contributes to immune response and beta cell dysfunction. The hypothesis tested herein is that IFN modifies beta cell lipid metabolism and this is associated with enhanced anti-viral response and beta cell stress. Treatment of INS-1 cells with IFN gamma for 6 to 24 h led to a dynamic change in TAG and lipid droplet (LD) levels, with a decrease at 6 h and an increase at 24 h. The later accumulation of TAG was associated with increased de novo lipogenesis (DNL), and impaired mitochondrial fatty acid oxidation (FAO). Gene expression results suggested that IFN gamma regulates lipolytic, lipogenic, LD and FAO genes in a temporal manner. The changes in lipid gene expression are dependent on the classical Janus kinase (JAK) pathway. Pretreatment with IFN gamma robustly enhanced anti-viral gene expression induced by the viral mimetic polyinosinic: polycytidylic acid (PIC), and this potentiating effect of IFN gamma was markedly attenuated by inhibitors of DNL. The IFN gamma-induced accumulation of lipid, however, was insufficient to cause endoplasmic reticulum (ER) stress. These studies demonstrated a non-canonical effect of IFN gamma in regulation of pancreatic beta cell lipid metabolism that is intimately linked with host cell defense and might alter cellular function early in the progression to type 1 diabetes.

High-Frequency and -Field EPR (HFEPR) studies of Fe(TPP)X (X = F, Cl, Br; I, TPP2-= meso-tetraphenylporphyrinate dianion) and far-IR magnetic spectroscopic (FIRMS) studies of Fe(TPP)Br and Fe(TPP)I have been conducted to probe magnetic intra- and inter-Kramers doublet transitions in theseS = 5/2 metalloporphyrin complexes, yielding zero-field splitting (ZFS) andgparameters for the complexes: Fe(TPP)F,D = +4.67(1) cm(-1),E = 0.00(1) cm(-1),g(perpendicular to) = 1.97(1),g(||) = 2.000(5) by HFEPR; Fe(TPP)Cl,D = +6.458(2) cm(-1),E = +0.015(5) cm(-1),E/D = 0.002,g(perpendicular to) = 2.004(3),g(||) = 2.02(1) by HFEPR; Fe(TPP)Br,D = +9.03(5) cm(-1),E = +0.047(5) cm(-1),E/D = 0.005,g(iso) = 1.99(1) by HFEPR andD = +9.05 cm(-1),g(iso) = 2.0 by FIRMS; Fe(TPP)I,D = +13.84 cm(-1),E = +0.07 cm(-1),E/D = 0.005,g(iso) = 2.0 by HFEPR andD = +13.95 cm(-1),g(iso) = 2.0 by FIRMS (the sign ofEwas in each case arbitrarily assigned as that ofD). These results demonstrate the complementary nature of field- and frequency-domain magnetic resonance experiments in extracting with high accuracy and precision spin Hamiltonian parameters of metal complexes withS > 1/2. The spin Hamiltonian parameters obtained from these experiments have been compared with those obtained from other physical methods such as magnetic susceptibility, magnetic Mossbauer spectroscopy, inelastic neutron scattering (INS), and variable-temperature and -field magnetic circular dichroism (VT-VH MCD) experiments. INS, Mossbauer and MCD give good agreement with the results of HFEPR/FIRMS; the others not as much. The electronic structure of Fe(TPP)X (X = F, Cl, Br, I) was studied earlier by multi-referenceab initiomethods to explore the origin of the large and positiveD-values, reproducing the trends ofDfrom the experiments. In the current work, a simpler model based on Ligand Field Theory (LFT) is used to explain qualitatively the trend of increasing ZFS from X = F to Cl to Br and to I as the axial ligand. Tetragonally elongated high-spin d(5)systems such as Fe(TPP)X exhibitD > 0, but X plays a key role. Spin delocalization onto X means that there is a spin-orbit coupling (SOC) contribution toDfrom X-center dot, as opposed to none from closed-shell X-. Over the range X = F, Cl, Br, I, X(center dot)character increases as does the intrinsic SOC of X(center dot)so thatDincreases correspondingly over this range.