Leucocyte integrins, but neither caspases nor NLR inflammasome are associated with lipopolysaccharide recognition and response in barramundi (Lates calcarifer). Issue 91 (August 2019)

• Record Type: Journal Article
• Authors: Zoccola, Emmanuelle; Kellie, Stuart; Barnes, Andrew C.
• Is Part Of: Fish & shellfish immunology. Issue 91(2019)
• Page Start: 172
• Page End: 179
• Publication Date: 2019-08
• Subjects: Caspase -- Integrin -- Leucocyte -- Lipopolysaccharide -- NLR -- Inflammasome; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2019.05.015
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: The inflammatory response of fish to LPS is subdued, attributed to absence of TLR4, a key pro-inflammatory receptor for LPS in mammals. Nevertheless, LPS is processed in fish in a T-independent manner and is a protective antigen in fish vaccines, yet pathways for processing LPS in fish remain to be elucidated. Here, we report that caspases and NOD-like receptor inflammasomes typically responsible for LPS recognition and processing in mammals lack critical domains or are absent in barramundi ( Lates calcarifer ). On the other hand, leucocyte integrins MAC-1 and LFA-1 were detected on the surface of neutrophil- and lymphocyte-like cells respectively in the barramundi spleen by immunocytochemistry, and leucocytes displaying MAC-1 or LFA-1 bound to Factor X and ESM-1 respectively. Exposure to MAC-1 and LFA-1 induced significant IL-1β expression post-stimulation with LPS compared to unstimulated and isotype controls, but the differences observed in TNF-α expression were inconclusive. Our findings implicate MAC-1 and LFA-1 involvement in immune processing of LPS in barramundi and in antigen processing in fish. Highlights: Caspase 4 is absent from barramundi transcriptome and Caspase 5 lacks a CARD domain so is unlikely to process LPS. Absence of NLRPs in barramundi implies that inflammasome formation is unlikely. Leucocyte integrins MAC-1 and LFA-1 are present on granulocytes and lymphocytes respectively in barramundi splenocytes. MAC-1 and LFA-1 mediate binding of splenocytes to ESM-1 and Factor X in vitro. Splenocyte response to LPS is changed by anti-integrin antibodies implicating MAC-1 and LFA-1 in LPS processing in fish.