IL6 and chronic kidney disease: Ameliorated chronic kidney disease (CKD) via multiple mechanisms: reduced kidney pathological damage and kidney index; modulated neuroendocrine–immune regulation (lowered ACTH/cGMP, elevated cAMP); suppressed systemic inflammation (reduced IL-1β, IL-6, TNF-α); improved intestinal pathology, with fecal transplantation confirming gut–kidney axis mediation