Desert hedgehog knockout mice show a reduced ratio of CD4+:CD8+ in thymic developing T cells
Keywords:Desert hedgehog, Thymocytes, CD4 cells, CD8 cells, CD4, 8 ratios, Desert hedgehog knockout mice
Background: Thymic differentiation is important and determines the strength of adaptive immunity in mammals in their later days in life. There are many factors that have been found to influence the development of T lymphocytes in the thymus and these include the effect of hedgehog signalling family of proteins. Immunologists and other basic science researchers have established the role of Indian hedgehog and sonic hedgehog in thymocytes development in the recent past, but the role of hedgehog is not well known. The aim of this study was to determine the influence of Desert hedgehog in CD4:CD8 ratio in developing thymocytes of mice.
Methods: Smashed thymocytes from mice deficient of Desert hedgehog and those with an intact gene coding for this protein were prepared in a cell suspension using standard procedurs. The cell suspensions were stained using fluorochrome-labelled monoclonal anti: CD4-PE, CD8-TRI, CD3-FITC, CD5-FITC, CD44-PE and CD25-FITC (e-Bioscience). Samples were analyzed using a three-color flow cytometry. The flow cytometry-generated data was analyzed using flowjo (Treestar, USA). Statistical significance of the findings was determined using paired t-test and reported at p<0.05.
Results: There was a general upward trend on CD4+CD8+ double positive thymocytes in Desert hedgehog mice relative to WT controls. An analysis of CD4:8 ratio revealed a reduced ratio in Dhh KO mice compared to that of WT controls attributable to the finding that there might have been a preferential differentiation of DP CD4+CD8+ to SP CD4+ in Dhh knockout mice as demonstrated by percentage of thymic subsets. The results of this study were not statistically significant and this was blamed on the fewer number of animals used in the study.
Conclusions: Dhh might have a role arresting the DP cell subjects from differentiating preferentially to CD4+ T cells. To get statistically significant findings, these experiments could be repeated with a larger animal sample.
Salda I, Crompton T, Furmanski AL, Ono M, Holl G. Sonic Hedgehog regulates thymic epithelial cell differentiation. J Autoimmun. 2016;68:86-97.
Azzi S, Treps L, Leclair HM, Ngo HM, Harford-Wright E, Gavard J. Desert Hedgehog/Patch2 Axis Contributes to Vascular Permeability and Angiogenesis in Glioblastoma. Front Pharmacol. 2015;6:1-11.
Furmanski AL, Saldana JI, Ono M, Sahni H, Paschalidis N, D'Acquisto F, et al. Tissue-Derived Hedgehog Proteins Modulate Th Differentiation and Disease. J Immunol. 2013;190(6):2641-9..
Barbarulo A, Lau C, Mengrelis K, Ross S, Solanki A, Saldaña JI, et al. Hedgehog Signalling in the Embryonic Mouse Thymus. J Dev Biol. 2016;4(3):22.
Outram S, Varas A, Pepicelli C, Crompton T. Hedgehog signalling regulates Differentiation from double negative to double positive thymocytes. J Immun. 2000;13(4):584.
Umehara F, Mishima K, Egashira N, Ogata A, Iwasaki K, Fujiwara M. Elevated anxiety-like and depressive behaviour in Desert hedgehog knockout male mice. J Behav Bra Res. 2006;174:167-73.
Varjosalo M, Taipale J. Hedgehog : functions and mechanisms. 2008: 2454-22.
Katoh Y, Katoh M. Hedgehog signalling pathway and gastric cancer. Cancer Biol Ther. 2005;4(10):1050-4.
Lehmann H, Felderer L, Frew IJ, Matsushita S, Levesque MP, Dummer R. Hedgehog Pathway Inhibitors Promote Adaptive Immune Responses in Basal Cell Carcinoma. 2015: 1-10.
Sacedón R, Varas A, Frías MCG. Hedgehog proteins : 2003;22(1):17-26.
Rimkus TK, Carpenter RL, Qasem S, Chan M, Lo H. Targeting the Sonic Hedgehog Signaling Pathway : Review of Smoothened and GLI Inhibitors. Cancers (Basel). 2016;8(2):22.
Kuby J, Osborne B., Goldsby R., Kindt T. Kuby Immunology. 6th ed. U.S.A: Sara Tenney; 2007.
Shah D., Hager-Theodorides A. OS., Ross S., Varas A, Crompton T. Reduced thymocyte development in sonic hedgehog knockout embryos. J Immunol. 2004;142(4):2296-306.
Outram S., Hager-Theodorides, A.L Shah D., Rowbotham, N.J Drakopoulou E, et al. Indian hedgehog (Ihh) both promotes and restricts thymocyte differentiation. Blood. 2009;113(10):2217-28.
Naramura M, Kole H., Ren-Juhu, Gu H. Altered Thymic Positive Selection and Intracellular Signals In Cbl-deficient Mice’. Immunol. 1998;95:15547-52.
Moore T., Zlonik A. T-cell lineage Commitment and Cytokine Responses of Thymic Progenitors. Blood. 1995;86(5):1885-60.
Azzam H, DeJarnette J, Huang K, Emmons R, Park CS, Sommers CL, et al. Fine Tuning of TCR Signalling by CD5. J Immun. 2001;166:5464-72.