Anti-IFNG monoclonal antibody, clone YNH2.3 [PerCP/Cy5.5®]

Murine/LPS models of Gram negative sepsis indicate that vasoactive intestinal peptide (VIP) has therapeutic potential. We investigated the unknown effect of VIP on JAK/STAT proteins and genes in human monocytes infected with Salmonella Typhimurium 14028. S. Typhimurium 14028 increased expression of both IL-6 receptor (IL-6R) and interferon gamma receptor 1 (IFN gamma R1) on monocytes but co-culture of infected monocytes with VIP (10(-7) M) only decreased expression of IFN gamma R1 (P < 0.05). In contrast, S. Typhimurium 14028 infection or co-culture with VIP had no effect on IL-10 receptor expression on the monocyte surface. However, S. Typhimurium 14028 down regulated IFNGR1 gene expression and this was not altered by co-culture with VIP, suggesting that changes in IFN gamma R1 protein may be due to an effect on cytoplasmic transport. 15 JAK/STAT genes, out of 84 studied, were up-regulated by S. Typhimurium 14028 infection and five were down-regulated. Co-culture with VIP significantly decreased expression of two genes (IFNG and IL-20) and increased expression of three genes (SOCS1, SOCS3 and STAT4) (P < 0.05). S. Typhimurium 14028 also increased expression of PTPN1, which dephosphorylates JAK2 and TYK2. This was unaltered by co-culture with VIP but S. Typhimurium 14028-induced expression of ISG15, associated with susceptibility to Gram negative infection, was further increased by VIP. We conclude that the effect of VIP on JAK/STAT genes may preclude its therapeutic use in human Gram negative sepsis.

Acute graft-versus-host disease (aGVHD) hinders the efficacy of allogeneic hematopoietic cell transplantation (HCT). Plasma levels of soluble membrane-bound ST2 (ST2) are elevated in human and murine aGVHD and correlated to type 1 T cells response. ST2 signals through the adapter protein MyD88. The role of MyD88 in T cells during aGVHD has yet to be elucidated. We found that knocking out MyD88 in the donor T cells protected against aGVHD independent of IL-1R and TLR4 signaling in two murine HCT models. This protection was entirely driven by MyD88(-/- )CD4 T cells. Transplanting donor MyD88(-/-) conventional T cells (Tcons) with wild-type (WT) or MyD88(-/-) regulatory T cells (Tregs) lowered aGVHD severity and mortality. Transcriptome analysis of sorted MyD88(-/-) CD4 T cells from the intestine 10 d post-HCT showed lower levels of Il1rl1 (gene of ST2), Ifng, Csf2, Stat5, Batf, and Jak2. Transplanting donor ST2(-/-) Tcons with WT or ST2(-/-) Tregs showed a similar phenotype with what we observed when using donor MyD88(-/-) Tcons. Decreased ST2 was confirmed at the protein level with less secretion of soluble ST2 and more expression of ST2 compared with WT T cells. Our data suggest that Treg suppression from lack of MyD88 signaling in donor Tcons during alloreactivity uses the ST2 but not the IL-1R or TLR4 pathways, and ST2 represents a potential aGVHD therapeutic target sparing Tregs.