ER
Stress Regulates
HIV
Tat and Alcohol‐Induced
NLRP6
Activation in Astrocytes
Seema Singh, Elias Horanieh, Shilpa Buch, Palsamy Periyasamy ABSTRACT
Introduction
Chronic alcohol consumption is common among people living with HIV (PLWH) and exacerbates HIV‐associated neurocognitive disorders (HAND). HIV‐1 transactivator of transcription (Tat) and ethanol synergistically promote neuroinflammation, but the underlying molecular mechanisms remain unclear. This study aimed to determine whether endoplasmic reticulum (ER) stress regulates astrocytic NLRP6 inflammasome activation in response to HIV Tat and ethanol coexposure.
Methods
Mouse primary astrocytes were exposed to HIV Tat (50 ng/mL) and ethanol (50 mM), individually or in combination. Astrocyte activation, NLRP6 inflammasome signaling, proinflammatory cytokine production, and ER stress responses were assessed using western blotting, immunocytochemistry, qPCR, and ELISA. ER stress was inhibited using 4‐phenylbutyric acid (4‐PBA), and NLRP6 was silenced using siRNA to define pathway hierarchy.
Results
Combined HIV Tat and ethanol exposure markedly increased astrocytic activation, NLRP6 expression, caspase‐1 cleavage, and IL‐1β and IL‐18 production compared with individual treatments. Coexposure also significantly induced ER stress markers BiP, ATF6, and phosphorylated eIF2α. Pharmacological inhibition of ER stress suppressed NLRP6 inflammasome activation and astrocytic reactivity, whereas NLRP6 knockdown attenuated inflammatory signaling without affecting ER stress markers, indicating ER stress acts upstream of NLRP6.
Conclusion
These findings identify an ER stress–NLRP6 inflammasome axis as a potential mechanism underlying HIV Tat and ethanol‐induced astrocytic neuroinflammation, providing mechanistic insight into alcohol‐associated neuroinflammatory processes relevant to HAND.