Toll-like receptors (TLRs) sense pathogen-associated molecular patterns to activate the production of inflammatory mediators. TLR4 recognizes lipopolysaccharide (LPS) and drives the secretion of inflammatory cytokines, often contributing to sepsis. We report that transient receptor potential melastatin-like 7 (TRPM7), a non-selective but Ca-conducting ion channel, mediates the cytosolic Ca elevations essential for LPS-induced macrophage activation. LPS triggered TRPM7-dependent Ca elevations essential for TLR4 endocytosis and the subsequent activation of the transcription factor IRF3. In a parallel pathway, the Ca signaling initiated by TRPM7 was also essential for the nuclear translocation of NFκB. Consequently, TRPM7-deficient macrophages exhibited major deficits in the LPS-induced transcriptional programs in that they failed to produce IL-1β and other key pro-inflammatory cytokines. In accord with these defects, mice with myeloid-specific deletion of Trpm7 are protected from LPS-induced peritonitis. Our study highlights the importance of Ca signaling in macrophage activation and identifies the ion channel TRPM7 as a central component of TLR4 signaling.

CD4Foxp3 regulatory T cells (Tregs) protect the kidney during AKI. We previously found that IL-2, which is critical for Treg homeostasis, upregulates the IL-33 receptor (ST2) on CD4 T cells, thus we hypothesized that IL-2 and IL-33 cooperate to enhance Treg function. We found that a major subset of Tregs in mice express ST2, and coinjection of IL-2 and IL-33 increased the number of Tregs in lymphoid organs and protected mice from ischemia-reperfusion injury (IRI) more efficiently than either cytokine alone. Accordingly, we generated a novel hybrid cytokine (IL233) bearing the activities of IL-2 and IL-33 for efficient targeting to Tregs. IL233 treatment increased the number of Tregs in blood and spleen and prevented IRI more efficiently than a mixture of IL-2 and IL-33. Injection of IL233 also increased the numbers of Tregs in renal compartments. Moreover, IL233-treated mice had fewer splenic Tregs and more Tregs in kidneys after IRI. , splenic Tregs from IL233-treated mice suppressed CD4 T cell proliferation better than Tregs from saline-treated controls. IL233 treatment also improved the ability of isolated Tregs to inhibit IRI in adoptive transfer experiments and protected mice from cisplatin- and doxorubicin-induced nephrotoxic injury. Finally, treatment with IL233 increased the proportion of ST2-bearing innate lymphoid cells (ILC2) in blood and kidneys, and adoptive transfer of ILC2 also protected mice from IRI. Thus, the novel IL233 hybrid cytokine, which utilizes the cooperation of IL-2 and IL-33 to enhance Treg- and ILC2-mediated protection from AKI, bears strong therapeutic potential.

Highlights d The ATP release channel, Panx1, limits the severity of allergic airway inflammation d Panx1 on CD4 + T cells is necessary and sufficient for limiting inflammation d Treg-Teff crosstalk via Panx1 extracellular nucleotides controls effector response d Panx1 activation is dependent on phosphorylation and Saltinducible kinase (SIK)

Highlights d Identification of MCU as a major regulator of phagosomal killing by macrophages d Mice lacking Mcu in myeloid cells are highly susceptible to in vivo candidiasis d Fungal pathogens elicit mCa 2+ elevations using a fast twophase Ca 2+ relay d mCa 2+ signaling activates pyruvate dehydrogenase during phagocytosis