Characterization of splenic lymphocyte populations to assess the effect of the microalga Chlorella vulgaris in healthy and prediabetic rats

Abstract

This Final Degree Project evaluated the immunomodulatory effects of the microalga Chlorella

vulgaris (CV), along with the omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA)

and docosahexaenoic acid (DHA), both under healthy conditions and in a rat model of

prediabetes induced by a high-fat high-sugar (HFHS) diet. The main objective was to assess the

modulation exerted by CV in combination with EPA and DHA (collectively referred to as CV) on

splenic lymphocyte populations in healthy rats and in a prediabetic model in rats.

After six months of dietary intervention with HFHS and/or CV, splenic lymphocytes were

isolated. The use of immunofluorescence and flow cytometry analysis to detect various

lymphocyte populations showed that the HFHS and/or CV diets did not alter the main

proportions of B lymphocytes, T lymphocytes (TCRαβ, TCRγδ), or the CD4+ and CD8+ T cell

subpopulations. However, an increase in the proportions of NK and NKT cell populations was

observed in animals receiving the HFHS diet supplemented with CV compared to those on the

HFHS diet alone. This increase affected both CD4+ and CD8+ cells within the NK and NKT

subpopulations.

In addition, cells positive for the activation marker CD25 were also modulated by CV treatment

in both B lymphocytes and CD8+ T lymphocytes. Specifically, an increase in the proportion of

CD25+ cells was observed with CV supplementation in both healthy animals and those on the

HFHS diet. Furthermore, among CD8+ cells, changes were noted in the expression of tissue

residency and homing markers (CD62L and CD103). In animals fed the HFHS diet, CV

supplementation led to an increased proportion of CD8+ CD62L−CD103− cells, accompanied by

a decrease in CD8+ CD62L+CD103+ cells.

In conclusion, supplementation with CV together with EPA and DHA exerts immunomodulatory

effects on splenic lymphocyte populations, notably increasing NK and NKT cells, as well as

modulating the activation of B and CD8+ T lymphocytes, particularly under prediabetic

conditions induced by an HFHS diet

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