Arctic soil methane sink increases with drier conditions and higher ecosystem respiration.

Arctic wetlands are known methane (CH) emitters but recent studies suggest that the Arctic CH sink strength may be underestimated. Here we explore the capacity of well-drained Arctic soils to consume atmospheric CH using >40,000 hourly flux observations and spatially distributed flux measurements from 4 sites and 14 surface types. While consumption of atmospheric CH occurred at all sites at rates of 0.

Tryptophan hydroxylase-1 regulates immune tolerance and inflammation.

Nutrient deprivation based on the loss of essential amino acids by catabolic enzymes in the microenvironment is a critical means to control inflammatory responses and immune tolerance. Here we report the novel finding that Tph-1 (tryptophan hydroxylase-1), a synthase which catalyses the conversion of tryptophan to serotonin and exhausts tryptophan, is a potent regulator of immunity. In models of skin allograft tolerance, tumor growth, and experimental autoimmune encephalomyelitis, Tph-1 deficiency breaks allograft tolerance, induces tumor remission, and intensifies neuroinflammation, respectively.

A retinoic acid-dependent checkpoint in the development of CD4+ T cell-mediated immunity.

It is known that vitamin A and its metabolite, retinoic acid (RA), are essential for host defense. However, the mechanisms for how RA controls inflammation are incompletely understood. The findings presented in this study show that RA signaling occurs concurrent with the development of inflammation.

Transplantation survival is maintained by granzyme B+ regulatory cells and adaptive regulatory T cells.

Granzyme B (GZB) has been implicated as an effector mechanism in regulatory T cells (T(reg)) suppression. In a model of T(reg)-dependent graft tolerance, it is shown that GZB- deficient mice are unable to establish long-term tolerance. Moreover, mice overexpressing the inhibitor of GZB, serine protease inhibitor 6, are also resistant to tolerization to alloantigen.