Background\n\nAging of the adrenal cortex selectively erodes the zona reticularis, causing a steep decline in DHEAS while cortisol output is maintained or increased, elevating the cortisol-to-DHEAS ratio and linking to frailty, cognitive decline, and dementia, especially in males {1,2}. Mechanistic drivers include proteostatic stress, cholesterol import limitation, and vascular injury, but the initiating trigger remains unclear. Recent work highlights sex‑dimorphic WNT/FRZB signaling and extracellular matrix remodeling that pre‑pattern zona reticularis susceptibility {1}.\n\n## Hypothesis\n\nWe propose that age‑dependent mitochondrial ROS production in zona reticularis cells activates the NLRP3 inflammasome, leading to caspase‑1–mediated cleavage of steroidogenic acute regulatory (StAR) protein and cytochrome P450c17 (CYP17A1), thereby suppressing DHEAS synthesis. This inflammasome activation is amplified by declining adiponectin signaling, which normally suppresses NLRP3 via AdipoR1/AMPK pathways. Importantly, corticotropin‑driven cortisol synthesis in the zona fasciculata is less dependent on StAR and CYP17A1 under basal conditions, preserving cortisol output despite inflammasome activity.\n\n## Predictions\n\n1. In adrenal tissue from aged male mice and humans, NLRP3 protein, ASC speck formation, and caspase‑1 activity will be elevated specifically in the zona reticularis, correlating with DHEAS loss but not with cortisol levels.\n2. Genetic or pharmacologic inhibition of NLRP3 (e.g., MCC950) or adrenal‑specific knockout of Nlrp3 will prevent age‑related zona reticularis thinning and maintain DHEAS secretion, while leaving basal and ACTH‑stimulated cortisol unchanged.\n3. Exogenous adiponectin or AMPK activation will reduce NLRP3 activation in cultured human zona reticularis‑like cells exposed to oxidative stress, rescuing StAR and CYP17A1 expression and DHEAS output.\n4. The cortisol-to-DHEAS awakening ratio will improve (decrease) following NLRP3 inhibition in aged male subjects, without altering the cortisol awakening response (CAR) magnitude {3}.\n\n## Experimental Approach\n\n- Use immunohistochemistry and immunofluorescent co‑staining for NLRP3, ASC, and cleaved caspase‑1 on adrenal sections from young (3 mo) and aged (24 mo) male C57BL/6 mice, quantifying zona reticularis‑specific signal {4}.\n- Generate Adrp‑Cre;Nlrp3^fl/fl mice to delete NLRP3 selectively in steroidogenic cells; measure serum DHEAS, cortisol, CAR, and perform zona reticularis morphometry at 24 mo.\n- Treat aged wild‑type mice with the NLRP3 inhibitor MCC950 (10 mg/kg i.p., three times weekly) for 8 weeks; assess hormone ratios, frailty index, and cognitive performance in maze tests.\n- In vitro, differentiate human induced pluripotent stem cells into adrenal‑like cells, expose to H2O2 to mimic oxidative stress, with/without adiponectin (10 µg/mL) or AMPK activator AICAR, then quantify NLRP3 inflammasome activation (Western blot for cleaved caspase‑1) and DHEAS secretion (ELISA).\n- Conduct a small pilot clinical trial in older men (65‑80 yr) with elevated cortisol/DHEAS ratio, randomizing to MCC950 or placebo for 12 weeks; primary outcome: change in morning cortisol-to-DHEAS ratio; secondary: CAR, frailty, and cognitive scores {5}.\n\n## Potential Implications\n\nIf NLRP3 drives zona reticularis senescence, targeting this inflammasome could uncouple DHEAS loss from cortisol preservation, offering a mechanism‑based strategy to lower the cortisol/DHEAS ratio and mitigate age‑related frailty and cognitive decline. This hypothesis is falsifiable: failure to observe zona reticularis‑specific NLRP3 activation, or lack of DHEAS rescue despite inflammasome inhibition, would refute the model.