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The cytokine Tumor Necrosis Factor Superfamily member 14, TNFSF14 (or LIGHT), is a controversial player in numerous diseases. We investigated the role of endogenously expressed TNFSF14 in diet-induced obesity in vivo. Firstly, we studied the effects of Tnfsf14 ablation on the development of obesity, glucose intolerance, insulin resistance, steatosis, tissue inflammation, and mitochondrial respiration in the liver. Secondly, we examined the role of TNFSF14 expression in hematopoietic cells on obesity and insulin sensitivity. Male Tnfsf14 knockout (KO) and wild type mice were fed chow or high fat diet (HFD) for 12 weeks and were assessed for weight gain, glucose intolerance, insulin resistance, hepatosteatosis, mitochondrial dysfunction, and cytokine expression. Wild-type mice were also reconstituted with bone marrow cells from Tnfsf14 knockout mice and were fed chow or HFD for 12 weeks. These mice were examined for weight gain and insulin resistance. HFD fed mice had elevated circulating levels of serum TNFSF14. Liver and white adipose tissue are potential sources of this elevated TNFSF14. Tnfsf14 deficient mice displayed increased obesity, glucose intolerance, insulin resistance, hepatosteatosis, and mitochondrial dysfunction compared to control mice on a HFD. Hepatic cytokine profiling pointed to a potential novel role of decreased IL-6 in the metabolic disturbances in obesogenic Tnfsf14 knockout mice. Bone marrow cells from Tnfsf14 deficient mice appeared to promote diet-induced obesity, insulin resistance and reduced FGF21 levels in white adipose tissue and liver. Our novel data suggest that Tnfsf14 ablation exacerbates parameters of the metabolic syndrome under high fat feeding conditions and provides evidence to support the development of TNFSF14 agonists as potential therapeutics in diet-induced obesity., (© 2017 Australasian Society for Immunology Inc.)

Mycobacterium avium strain 104 was chosen as the M. avium isolate to sequence, as it is virulent to humans, stable and readily transfectable. As this strain has not been widely studied we sought to investigate the pattern of 104 infection in mice. Bacterial growth and the immune response generated were compared with infection with the low virulence M. avium strain 100, and the high virulence common laboratory strain, 101. Mycobacterium avium strains 104 and 101 grew progressively within mice, while strain 100 was gradually cleared. Strains 104 and 101 induced strong T cell activation and spleen cell cultures produced similar levels of IFN-gamma. In mice infected with strain 100 no significant T cell activation or IFN-gamma production was measured. Further, mice infected with strain 104 or 101 also displayed comparable inflammatory responses and similar granuloma formation, while only minimal inflammation was seen in mice infected with strain 100. Strains 101 and 104 also grew in a similar fashion in bone-marrow-derived macrophages and induced significant levels of TNF and nitric oxide. Thus infection with M. avium strain 104 induced an immunological response comparable to M. avium strain 101 and, with the availability of its sequence, should be a useful tool for designing new vaccines or drugs therapies to treat the increasing incidence of M. avium infection in humans.