Fibroblasts Express Immune Relevant Genes and Are Important Sentinel Cells during Tissue Damage in Rainbow Trout (Oncorhynchus mykiss)

Abstract

Fibroblasts have shown to be an immune competent cell type in mammals. However, little is known about the immunological functions of this cell-type in lower vertebrates. A rainbow trout hypodermal fibroblast cell-line (RTHDF) was shown to be responsive to PAMPs and DAMPs after stimulation with LPS from E. coli, supernatant and debris from sonicated RTHDF cells. LPS was overall the strongest inducer of IL-1β, IL-8, IL-10, TLR-3 and TLR-9. IL-1β and IL-8 were already highly up regulated after 1 hour of LPS stimulation. Supernatant stimuli significantly increased the expression of IL-1β, TLR-3 and TLR-9, whereas the debris stimuli only increased expression of IL-1β. Consequently, an in vivo experiment was further set up. By mechanically damaging the muscle tissue of rainbow trout, it was shown that fibroblasts in the muscle tissue of rainbow trout contribute to electing a highly local inflammatory response following tissue injury. The damaged muscle tissue showed a strong increase in the expression of the immune genes IL-1β, IL-8 and TGF-β already 4 hours post injury at the site of injury while the expression in non-damaged muscle tissue was not influenced. A weaker, but significant response was also seen for TLR-9 and TLR-22. Rainbow trout fibroblasts were found to be highly immune competent with a significant ability to express cytokines and immune receptors. Thus fish fibroblasts are believed to contribute significantly to local inflammatory reactions in concert with the traditional immune cells.

The Transcription Factor GLI1 Modulates the Inflammatory Response during Pancreatic Tissue Remodeling

“…However, these cells not only contribute to tissue homeostasis but also respond to epithelial damage. In addition to promoting epithelial recovery, fibroblasts secrete a range of immunomodulatory proteins, such as IL-6, MCP-1, and IL-8, which regulate immune cell function during both tissue damage and recovery (49,50). This function is critical, as improper immune cell recruitment has adverse effects on various aspects of tissue healing.…”

The development of the gut microbiota in rainbow trout (Oncorhynchus mykiss) is affected by first feeding and diet type

“…However, it should also be considered that the increased amount of bacteria present in the intestine after first feeding directly could have led to a higher transcription of the immune apparatus, potentially mediated via interaction of the intestinal bacteria with e.g. toll-like receptors (Ingerslev et al, 2010). To support this, it is known from zebrafish that the transcription of innate immune genes like C3, C4 and SAA1 in germ-free fish are down-regulated in comparison to conventionally raised fish, thus showing that the immune system and gut microbiota are interrelated and cross-talking (Rawls et al, 2004).…”

Acoustic Telemetry Evaluation of Juvenile Salmonid Passage and Survival at John Day Dam, 2010

“…Spleen IL1-β was elevated in the TGD treatment compared to the ROR and PRT treatments for CH1, STH, and CH0. Similarly, Ingerslev et al (2010) demonstrated that rainbow trout have elevated muscle tissue IL1-β expression in response to physical injury.…”

“…IL1-β is a cytokine involved in the innate immune response and is indicative of a generalized inflammation response to injury or pathogens. Up-regulated IL1-β gene expression has been demonstrated in response to physical injury (Ingerslev et al 2010). Both RAG-1 and IgM are involved in adaptive immune responses against specific antigens (viral, bacterial, etc.…”