Chemokine release is associated with the protective action of PACAP-38 against HIV envelope protein neurotoxicity.
The envelope protein (gp120) of the human immunodeficiency virus produces neuronal cell death in cultures that can be prevented by co-treatment with pituitary adenylate activating peptide-38 (PACAP-38) or chemokines. To investigate the hypothesis that a functional relationship exists between these two protectants, the release of chemokines was measured in rat astrocyte cultures after PACAP-38 treatment. Chemokine analyses were performed by immunoaffinity capillary electrophoresis. Bell-shaped dose-responses for PACAP-mediated release of chemokines into the culture medium were observed with EC(50)'s of 3 x 10(15) M (RANTES: regulated upon activation normal T cell expressed and secreted), 3 x 10(-11) M (MIP-1 beta) and 10(-7)M (MIP-1 alpha). In addition, PACAP-mediated depletion of chemokines from cultured astrocytes exhibited inverted bell-shaped curves, with similar EC(50)'s to those observed for chemokine measurements of the medium. Comparative studies with structurally related peptides (vasoactive intestinal peptide [VIP] and secretin) revealed that PACAP was the most potent secretagogue for RANTES on astrocyte cultures. Gp120-mediated neuronal cell death was prevented by co-treatment with PACAP-38, although the efficacy of protection varied significantly among the gp120 isolates. A bi-model dose-response was observed with EC(50)'s of 3 x 10(-15) and 3 x 10(-11) M. Co-treatment with neutralizing antiserum to RANTES attenuated PACAP-mediated protection from toxicity associated with gp120. In contrast to previous studies with VIP and gp120 toxicity, co-treatment with anti-MIP-1 alpha did not affect PACAP-induced protection. These studies support the hypothesis that PACAP produces neuroprotection from gp120 toxicity, in part, through the release of RANTES and this mechanism is distinct from that observed with VIP.
Brenneman
Douglas E
DE
Section on Developmental and Molecular Pharmacology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Building 49, Room 5A38, Bethesda, MD 20892, USA. dbrenn@codon.nih.gov
Hauser
Janet M
JM
Spong
CatherineY
C
Phillips
Terry M
TM
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D054407:Chemokine CCL4; D018946:Chemokine CCL5 / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015699:HIV Envelope Protein gp120 / Q000633:toxicity*; D007202:Indicators and Reagents; D019402:Macrophage Inflammatory Proteins / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
C495403:Adcyap1 protein, rat; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D018925:Chemokines; D015699:HIV Envelope Protein gp120; D007202:Indicators and Reagents; D019402:Macrophage Inflammatory Proteins; D009479:Neuropeptides; D018696:Neuroprotective Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014660:Vasoactive Intestinal Peptide