New antisera specific for human C1Q-TNF-related protein 8 (CTRP8): characterization and tissue distribution
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Date
2020
Authors
Krishnan, Sai Nivedita
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Abstract
Introduction: Adiponectin and the structurally related C1Q-Tumor Necrosis Factor-related proteins (CTRP) have important roles in innate immunity and metabolism. CTRP8 is the most recently discovered and least characterized member of this family. Our lab had identified human CTRP8 as a novel ligand of the relaxin/insulin-like family peptide receptor 1 (RXFP1) in glioblastoma. We have generated high-affinity rabbit antisera to CTRP8 and identified a selective mast cell population in human prostate normal and neoplastic tissues. Mast cells are innate immune cells that are best known for their role in mediating allergic responses. Mast cell have been shown to accumulate in prostate cancer tissues and serve as potential prognostic marker in prostate cancer.
Methods: Affinity-purified rabbit polyclonal antisera directed against an epitope unique to human CTRP8 were characterized by Western blot, immunofluorescence and immunohistochemistry in clinically validated patient prostate tissues and tissue microarrays (TMAs).
Results: Of several Flag-tagged human and mouse CTRP family members transiently expressed in HEK293 cells, both rabbit antisera exclusively detected human CTRP8 in Western blots. The two antisera (1438 and 1439) were also successfully used for the detection of CTRP8+ cells in human tissues. Immunoreactive CTRP8 co-localized with toludiene blue positive cells in human tissues. Immunofluorescence studies in normal and neoplastic human prostate tissues revealed a subpopulation of mast cells immunoreactive for CTRP8 and Tryptase, the latter being a marker for mature mast cells. Analysis of prostate cancer tissue microarrays (TMAs) revealed a significant increase in the proportion of Tryptase+/ CTRP8+ cells versus total number of mast cells (Tryptase+/ CTRP8+ and Tryptase+/ CTRP8- cells) in the peritumoral compartment as compared to the intratumoral regions of prostate cancer samples with Gleason grades 6 and 7.
Conclusions: This is the first report on CTRP8 expression in cells of the innate immune system. We identified CTRP8 as a novel marker for a subpopulation of Tryptase+ mast cells in the neoplastic human prostate gland. We observed an increase in Tryptase+/ CTRP8+ mast cells adjacent to tumor tissues compared to intratumoral regions in prostate cancer cases with Gleason 6 and 7.
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Cell biology
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APA