title: BTLA expression contributes to septic morbidity and mortality by inducing innate inflammatory cell dysfunction.
abstract: A proper innate inflammatory response is essential for prevention of the systemic inflammation associated with sepsis. BTLA is an immune-regulatory receptor demonstrated to be expressed not only on adaptive immune populations and have potent inhibitory effects on CD4(+) T cells but is also expressed on innate cell populations (CD11c(+) and CD11b(+) cells) and has been shown to diminish pathogen clearance following bacterial and parasite infection. The role of BTLA in sepsis and the mechanisms by which BTLA alters pathogen clearance, however, have not been addressed clearly. Here, we show that following acute experimental sepsis induction in mice (CLP), the number of infiltrating BTLA- and HVEM (the ligand for BTLA)-expressing macrophages, inflammatory monocytes, mature and immature DCs, and neutrophils increased in the peritoneum compared with sham surgery, suggesting that a high level of HVEM:BTLA interactions occurs between these cells at the site of septic insult. Given this, we evaluated BTLA(-/-) mice, 24 h post-CLP, and observed a marked increase in the degree of activation on these cell populations, as well as a reduction in peritoneal bacterial burden and IL-10 induction, and most importantly, BTLA(-/-) mice exhibited a higher rate of survival and protection from organ injury when compared with WT mice. Such changes were not restricted to experimental mice, as circulating BTLA+ and HVEM+ monocytes and HVEM+ granulocytes were increased in septic ICU patients, supporting a role for BTLA and/or HVEM as potential, novel diagnostic markers of innate immune response/status and as therapeutic targets of sepsis.
authors.affiliation: Division of Surgical Research, Department of Surgery at Rhode Island Hospital, Warren Alpert School of Medicine, Providence, RI, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Shubin
authors.forename: Chun S
authors.initials: CS
authors.lastname: Chung
authors.forename: Daithi S
authors.initials: DS
authors.lastname: Heffernan
authors.forename: Lydea R
authors.initials: LR
authors.lastname: Irwin
authors.forename: Sean F
authors.initials: SF
authors.lastname: Monaghan
authors.forename: Alfred
authors.initials: A
authors.lastname: Ayala
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005434:Flow Cytometry; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology*; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D022423:Myeloid Cells / Q000276:immunology / Q000378:metabolism; D010641:Phenotype; D011971:Receptors, Immunologic / Q000276:immunology* / Q000378:metabolism; D053240:Receptors, Tumor Necrosis Factor, Member 14 / Q000276:immunology* / Q000378:metabolism; D018805:Sepsis / Q000276:immunology* / Q000378:metabolism
chemical_list: C482586:BTLA protein, human; C488868:BTLA protein, mouse; D011971:Receptors, Immunologic; D053240:Receptors, Tumor Necrosis Factor, Member 14; C506028:TNFRSF14 protein, human; C506029:Tnfrsf14 protein, mouse