Submitted on August 22, 2003
Accepted on December 24, 2003
Diarrhea-associated HIV-1 aspartyl protease-inhibitors potentiate muscarinic Cl- secretion by T84 cells via prolongation of cytosolic Ca2+ signaling
Paul A Rufo1, Patricia W Lin2, Adriana Andrade3, Lianwei Jiang4, Lucia Rameh5, Charles W Flexner6, Seth L Alper7, and Wayne I Lencer8*
1 GI Cell Biology, Combined Program in Pediatric Gastroenterology and Nutrition, Children's Hospital, Boston, MA, USA; Contributed equally to these studies, USA; Department of Pediatrics, Harvard Medical School, Boston, MA, USA
2 GI Cell Biology, Combined Program in Pediatric Gastroenterology and Nutrition, Children's Hospital, Boston, MA, USA; Contributed equally to these studies, USA; Division of Newborn Medicine, Children's Hospital, Boston, MA, USA
3 Lead Investigator for Clinical Study, USA; Division of Infectious Diseases, Johns Hopkins University, Baltimore, MD, USA
4 Molecular and Vascular Medcine and Renal Units, Beth Israel Deaconess Medical Center, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA
5 Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA, USA
6 Division of Clinical Pharmacology, Johns Hopkins University, Baltimore, MD, USA
7 Molecular and Vascular Medcine and Renal Units, Beth Israel Deaconess Medical Center, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA; Harvard Digestive Diseases Center, Boston, MA, USA
8 GI Cell Biology, Combined Program in Pediatric Gastroenterology and Nutrition, Children's Hospital, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, Boston, MA, USA; Harvard Digestive Diseases Center, Boston, MA, USA
* To whom correspondence should be addressed. E-mail: wayne.lencer{at}tch.harvard.edu.
Aspartyl-protease inhibitors (API) effectively extend the length and quality of life in HIV-infected patients, but dose-limiting side effects such as lipodystrophy, insulin-resistance, and diarrhea have limited their clinical utility. Here, we show that the API nelfinavir induces a secretory form of diarrhea in HIV-infected patients. In vitro studies demonstrate that nelfinavir potentiates muscarinic stimulation of Cl- secretion by T84 human intestinal cell monolayers through amplification and prolongation of an apical membrane Ca2+-dependent Cl- conductance (CaCC). This stimulated ion secretion is associated with increased duration of muscarinic-induced intracellular [Ca2+]i transients via activation of a long-lived, Ba2+-sensitive, store-operated Ca2+ entry pathway. The enhanced intracellular Ca2+ signal is associated with uncoupling of CaCC from down-regulatory intracellular mediators generated normally by muscarinic activation. These data show that APIs modulate Ca2+ signaling in secretory epithelial cells and identify a novel target for treatment of clinically important API side effects.
