Macrophage‐inducible C‐type lectin (MINCLE): In silico characterization and its in vitro effects on head–kidney leukocytes from the fishLutjanus peru

Abstract

MINCLE is a C-lectin receptor mainly expressed in macrophages to recognize carbohydrates enhanced by the innate immune response in mammals and fish. Toxin A (ToxA) from Vibrio parahaemolyticus N16 was evaluated as an antigenic protein; it was observed to induce IgM production, increase cytokine gene expression, and offer immunoprotection against bacterial challenges in fish. This study was aimed at analysing the MINCLE receptor from the Pacific red snapper (Lutjanus peru) through bioinformatics tools, and the stimulating effects of β-glucans from Sterygmatomyces halophilus 4 N16 (β-Glu/Sh) combined with an antigenic protein on head-kidney leukocytes (HKLs) before and on challenge with Vibrio parahaemolyticus N16. LpMincle was mainly expressed in the intestine, eyes and head-kidney tissues. Before and after V. parahaemolyticus challenge, an up-regulation of the receptors (Mincle, Marco and tlr2) and pro-inflammatory cytokines (il-1β and il-6) gene expression was observed in HKLs incubated with β-Glu/Sh. Respiratory burst activity was mainly enhanced in cells incubated with ToxA before and after V. parahaemolyticus infection. Nitric oxide (NO) production increased in leukocytes incubated with β-Glu/Sh or ToxA, whereas myeloperoxidase (MPO) activity augmented only after ToxA stimulation before the bacterial challenge. In conclusion, MINCLE from L. peru was characterized in silico and its effects on HKLs was identified. Receptors and pro-inflammatory cytokine genes up-regulated by β-Glu/Sh alone or in combination with ToxA can be elicitors of innate immune parameters. These findings evidence the function and recognition of novel βglucans from yeast either alone or in combination with antigenic proteins by β-glucan receptors and their cytokines response.