Aquaporin-9-expressing neutrophils are required for the establishment of contact hypersensitivity

Abstract

1Aquaporin-9 (AQP9), a water/glycerol channel protein, is expressed in several immune cells including neutrophils; however, its role in immune response remains unknown. Here we show the involvement of AQP9 in hapten-induced contact hypersensitivity (CHS), as a murine model of skin allergic contact dermatitis, using AQP9 knockout (AQP9 −/− ) mice. First, the CHS response to hapten dinitrofluorobenzene (DNFB) was impaired in AQP9 −/− mice compared with wild-type (WT) mice. Adoptive transfer of sensitized AQP9 −/− draining lymph node (dLN) cells into WT recipients resulted in a reduced CHS response, indicating impaired sensitization in AQP9 −/− mice. Second, administration of WT neutrophils into AQP9 −/− mice during sensitization rescued the impaired CHS response. Neutrophil recruitment to dLNs upon hapten application was attenuated by AQP9 deficiency. Coincidentally, AQP9 −/− neutrophils showed a reduced CC-chemokine receptor 7 (CCR7) ligand-induced migration efficacy, which was attributed to the attenuated recruitment of neutrophils to dLNs. Furthermore, we found that neutrophil deficiency, observed in AQP9 −/− or neutrophildepleted mice, decreased IL-17A production by dLN cells, which might be responsible for T cell activation during a subsequent CHS response. Taken together, these findings suggest that AQP9 is required for the development of sensitization during cutaneous acquired immune responses via regulating neutrophil function.Allergic contact dermatitis (ACD) is one of the most prevalent skin diseases consisting of sensitization and elicitation phases 1,2 . Advanced studies of hapten-induced contact hypersensitivity (CHS) as a murine model of ACD have expanded our understanding of the mechanism of allergic reactions occurring in the skin, especially the specific roles of a variety of immune cells. During the sensitization phase, hapten-bearing cutaneous dendritic cells (DCs) migrate into skin draining lymph nodes (dLNs), where the presentation of antigens to naïve T cells and subsequent T cell priming occur. During the elicitation phase, re-exposure to cognate hapten results in the recruitment of antigen-specific T cells to the site of allergen challenge and T cell-mediated tissue damage 2 . Increasing evidence shows that several subsets of immune cells, including various types of T cells (Th1, Th17, regulatory, and natural killer), DCs (dermal DCs and Langerhans cells), and mast cells, work synergistically in the skin and its dLNs to exert antigen presentation and T cell activation during the development of sensitization in CHS [3][4][5][6][7] . Neutrophils have long been considered as the final effector cells of an acute inflammatory response. On the other hand, accumulating evidence has extended the function of neutrophils to include activation and regulation during innate and adaptive immune responses 8,9 . Several studies have focused on the

A Systematic Characterization of Aquaporin-9 Expression in Human Normal and Pathological Tissues

“…In one study, TNFα-dependent AQP9 upregulation in synovial lining cells as well as mesenchymal cells of osteoid and rheumatoid arthritis patients was observed (Nagahara et al 2010). These findings are supported by a mechanistic study, identifying an AQP9-dependent role of neutrophils in a murine model of psoriasis (Moniaga et al 2015). We have thus studied AQP9 expression and a potential modulation thereof by the TNFα inhibitor Humira.…”

IL-36 receptor antagonist deficiency resulted in delayed wound healing due to excessive recruitment of immune cells

“…According to the Human Genetic Variation Database, two IL36RN founder mutations (c.28C > T (p.Arg10X) and c.115 + 6T > C (p.ArgfsX1)) are seen in about 2% of Japanese population 14 . The pathogenic roles of IL-36 in skin inflammatory diseases including atopic dermatitis, blistering disease, and allergic dermatitis have studied [15][16][17] . We found that deficiency of IL-36Ra increased the contact hypersensitivity response by eliciting excessive infiltration of neutrophils into the skin, a result of the activation of IL-36R-mediated sustained inflammatory signaling 13 .…”

ω3 fatty acid metabolite, 12‐hydroxyeicosapentaenoic acid, alleviates contact hypersensitivity by downregulation of CXCL1 and CXCL2 gene expression in keratinocytes via retinoid X receptor α

“…We next examined the impact of 12‐HEPE on neutrophils as the inflammatory cells implicated in the development of CHS 16,19,20 . Flow cytometric analyses revealed that topical application of 12‐HEPE inhibited DNFB‐induced neutrophil infiltration into the skin (Figure 3A,B).…”

“…We next examined the impact of 12-HEPE on neutrophils as the inflammatory cells implicated in the development of CHS. 16,19,20 Flow cytometric analyses revealed that topical application of 12-HEPE inhibited DNFB-induced neutrophil infiltration into the skin (Figure 3A,B). Immunohistological analysis also revealed that inflammation-associated infiltration of neutrophils into the dermis was inhibited by topical application of 12-HEPE (Figure 3C).…”

“…Once in the skin, the infiltrated neutrophils release reactive oxygen species, granule‐derived mediators (eg, leukotriene B 4 , defensins, and elastase), and pro‐inflammatory cytokines that induce skin edema and injury 12‐18 . Depletion of neutrophils by administration of a cell‐specific antibody has been shown to decrease ear swelling, indicating that neutrophils play major roles in the development of CHS 16,19,20 . The activated keratinocytes also produce CXCL9 and CXCL10, which guide the migration of memory CD8 + T cells to the inflamed skin 5 .…”