Morphine exacerbates HIV-1 Tat-induced cytokine production in astrocytes through convergent effects on [Ca(2+)](i), NF-kappaB trafficking and transcription.
Astroglia are key cellular sites where opiate drug signals converge with the proinflammatory effects of HIV-1 Tat signals to exacerbate HIV encephalitis. Despite this understanding, the molecular sites of convergence driving opiate-accelerated neuropathogenesis have not been deciphered. We therefore explored potential points of interaction between the signaling pathways initiated by HIV-1 Tat and opioids in striatal astrocytes. Profiling studies screening 152 transcription factors indicated that the nuclear factor-kappa B (NF-kappaB) subunit, c-Rel, was a likely candidate for Tat or Tat plus opiate-induced increases in cytokine and chemokine production by astrocytes. Pretreatment with the NF-kappaB inhibitor parthenolide provided evidence that Tat+/-morphine-induced release of MCP-1, IL-6 and TNF-alpha by astrocytes is NF-kappaB dependent. The nuclear export inhibitor, leptomycin B, blocked the nucleocytoplasmic shuttling of NF-kappaB; causing p65 (RelA) accumulation in the nucleus, and significantly attenuated cytokine production in Tat+/-morphine exposed astrocytes. Similarly, chelating intracellular calcium ([Ca(2+)](i)) blocked Tat+/-morphine-evoked MCP-1 and IL-6 release, while artificially increasing the concentration of extracellular Ca(2+) reversed this effect. Taken together, these results demonstrate that: 1) exposure to Tat+/-morphine is sufficient to activate NF-kappaB and cytokine production, 2) the release of MCP-1 and IL-6 by Tat+/-morphine are highly Ca(2+)-dependent, while TNF-alpha appears to be less affected by the changes in [Ca(2+)](i), and 3) in the presence of Tat, exposure to opiates augments Tat-induced NF-kappaB activation and cytokine release through a Ca(2+)-dependent pathway.
El-Hage
Nazira
N
Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA. nelhage@vcu.edu
Bruce-Keller
Annadora J
AJ
Yakovleva
Tatiana
T
Bazov
Igor
I
Bakalkin
Georgy
G
Knapp
Pamela E
PE
Hauser
Kurt F
KF
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000276:immunology*; D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis*; D003593:Cytoplasm / Q000378:metabolism; D020573:Genes, rel; D015497:HIV-1; D051379:Mice; D008813:Mice, Inbred ICR; D008954:Models, Biological; D009020:Morphine / Q000494:pharmacology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
D000701:Analgesics, Opioid; D016207:Cytokines; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D054322:tat Gene Products, Human Immunodeficiency Virus; D009020:Morphine; D002118:Calcium