Immunohistochemical Changes in The Thyroid and Adrenal Glands Under the Influence of Mycobacteria: An Age-Dependent Experimental Study (CASPASE-3, CD68, P53 AND INHIBIN)

Abstract

Background and objective. Chronic inflammation induced by mycobacteria-containing Freund's adjuvant may alter apoptosis, macrophage activity and the functional state of endocrine cells. This study evaluated the age-dependent immunohistochemical (IHC) changes of the thyroid and adrenal glands in rats exposed to mycobacteria, using Caspase-3 and CD68 (thyroid) and p53 and inhibin (adrenal).

Methods. Outbred white male rats aged 4 and 9 months were studied; experimental animals received a single subcutaneous injection of Freund's adjuvant containing killed mycobacteria, and intact animals served as controls. IHC was performed with DAB chromogen; slides were scanned and the positive-expression level (%) was quantified with QuPath-0.5.1 at ×200 magnification.

Results. In the thyroid, mycobacterial exposure markedly increased Caspase-3 expression (from 10.57% to 51.11% at 4 months and from 9.23% to 75.00% at 9 months) and CD68 expression (from 15.43% to 30.37% and from 16.98% to 31.71%, respectively). In the adrenal cortex, p53 expression decreased (from 48.51% to 29.96% and from 45.77% to 21.75%) and inhibin expression decreased (from 42.08% to 25.31% and from 39.05% to 29.50%). Conclusion. Mycobacteria induce a reproducible, age-modified IHC signature — enhanced thyroid apoptosis (Caspase-3) and macrophage infiltration (CD68) together with reduced adrenal p53 and inhibin expression — reflecting parallel immune-inflammatory injury of the thyroid and functional impairment of adrenocortical cells

Conclusion. Pulmonary morphology in these poisonings is corroborative rather than diagnostic. A defensible medico-legal conclusion integrates scene investigation, autopsy, histology and—decisively—toxicology (ethanol concentration and COHb). Awareness of the combined-exposure scenario and of analytical pitfalls is critical to avoid misclassification.

Keywords:

Immunohistochemistry, Caspase-3, CD68, p53, inhibin

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