Dose-dependent Immunomodulatory Effects of Edible Chalk (Nzu) in Phenylhydrazine- induced Immune Dysfunction in Female Wistar Rats

Abstract

Background: Edible chalk (Nzu), a geophagic kaolin widely consumed in several African communities, particularly among women, has been associated with both perceived health benefits and potential toxicological risks. This study investigated the immunomodulatory effects of edible chalk in a phenylhydrazine (PHZ)-induced model of oxidative stress and immune disruption in female Wistar rats. Methods: This study adopted a randomized controlled experimental design. Thirty adults female Wistar rats were randomly assigned into six groups (n = 5): normal control; PHZ-only group (0.5 ml intraperitoneally); PHZ plus Fesolate (65 mg/kg, positive control); and three treatment groups receiving PHZ followed by edible chalk at doses of 400, 600, or 800 mg/kg body weight, administered orally once daily for 22 days. Immunological assessment included serum quantification of immunoglobulins (IgA, IgM, and IgG) and pro-inflammatory cytokines (IL-1 and IL-6) using enzyme-linked immunosorbent assay (ELISA) and automated immunoturbidimetric techniques. Splenic histoarchitecture was examined using hematoxylin and eosin staining to assess structural and cellular integrity. Results: PHZ administration induced marked immune dysregulation, evidenced by significantly elevated IL-6 levels and pronounced reductions in immunoglobulin concentrations, indicating concurrent inflammation and humoral immunosuppression. Treatment with edible chalk at 400 and 600 mg/kg significantly ameliorated these alterations. The 600 mg/kg dose demonstrated the most effective immunorestorative activity, normalizing immunoglobulin levels, suppressing inflammatory cytokine expression, and promoting recovery of splenic white and red pulp architecture. Conversely, the 800 mg/kg dose exacerbated immune dysfunction, resulting in further immunoglobulin depletion, heightened IL-6 expression, and severe splenic histopathological damage characterized by lymphoid depletion and architectural distortion. Conclusion: Edible chalk exhibits a biphasic, dose-dependent immunological effect, with moderate doses conferring immunoprotective and anti-inflammatory benefits, while excessive intake induces significant immunotoxicity, underscoring important public health concerns regarding its unregulated consumption, especially among pregnant women.