Basal polarization of the mucosal compartment in Flavobacterium columnare susceptible and resistant channel catfish (Ictalurus punctatus)

Physiology and immunology of mucosal barriers in catfish (Ictalurus spp.)

“…Yazawa et al 55 established a transgenic zebrafish strain expressing a chicken lysozyme gene under the control of a keratin promoter which resulted in a 65% survival rate against F.columnare compared to 0% survival in wild-type fish. 25 We have also observed suppression of skin/gill lysozyme C levels following short-term feed deprivation 30 and elevated lysozyme levels in gills following feeding a diet supplemented with mannan-oligosaccharides (unpublished results).…”

“…3 A series of RNA-seq expression studies in catfish gill exposed to F. columnare or following feed deprivation have cataloged a diverse innate repertoire likely secreted into the mucus. 25,30,47 These include complement factor D, C1, C7, C1q, NK-lysin, bacterial permeability-increasing protein (BPI) and several fish toxin proteins including natterin and toxin-1 precursor, lysozyme C, and lysozyme G. In the intestine, we have additionally detected H2 antimicrobial peptides, serine proteases, granzyme and abundant metalloproteinases. 44 Of these, lysozyme C appears to be a particularly good marker of immune readiness, particularly in the skin and gill of catfish.…”

“…1) and mucin expression, a pattern maintained after infection. 25 Interestingly, F. columnare shows a strong chemotactic attraction to catfish mucus, where it appears to associate with goblet cells. [26][27][28] Mucin levels are also altered by short-term fasting, a nutritional state previously associated with higher F. columnare mortality.…”

“…32 Similarly, we have observed changes in AGR2 due to diet and immune status. 25,30 Quantity and composition (e.g. sialomucin vs. sulfomucin) of mucus is likely critical for dynamics of pathogen invasion, successful attachment to host receptors, and persistence, and, therefore, is a target of immuno-sculpting by fish pathogens.…”

“…Lysozyme C also displayed consistently higher expression in resistant catfish gill than that observed in susceptible fish. 25 Plasma lysozyme levels have been studied for several decades in the context of fish immunity, but relatively little attention has been given to the level and roles of lysozyme in mucosal surfaces. 48,49 In mammals, lysozymes are among the most abundant secreted mucosal enzymes from the epithelium as well as a major component of granules of professional phagocytes.…”