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Protein kinase C regulates NO-cGMP pathway in muscarinic receptor activation by HIV+-IgA
M E Sales1, A J Español, L Sterin-Borda
1Instituto de Oncologia Angel H. Roffo, Buenos Aires, Argentina.
Abstract:
In this work we demostrate that IgA purified from HIV infected patients recognizes a band with a molecular weight corresponding to radiolabelled ileal muscarinic acethylcholine receptors (mAChR) by immunoblotting. HIV+-IgA triggers the signals that are the consequence of mAChR stimulation in the intestine, regulating protein kinase C (PKC) and nitric oxide synthase (NOS) activity as well as 3',5'-cyclic guanosine monophosphate (cGMP) formation. On the one hand PKC activation by HIV+-IgA induces NOS inhibition and as a consequence, low amounts of NO that could improve local immunosuppression in the intestine; on the other hand HIV+-IgA stimulates cGMP production which could potentiate ileal motility and loss of water/electrolytes involved in intestinal damage in AIDS.
Insights
Immunoglobulin A (IgA) from HIV patients binds to intestinal muscarinic acetylcholine receptors (mAChR). This binding influences signaling pathways, potentially impacting intestinal immunity and function in HIV infection.
Area of Science:
- Gastroenterology
- Immunology
- Neurogastroenterology
Background:
- HIV infection is associated with gastrointestinal complications.
- The role of immunoglobulin A (IgA) in HIV-related intestinal pathology is not fully understood.
- Muscarinic acetylcholine receptors (mAChR) play a role in regulating intestinal function.
Purpose of the Study:
- To investigate the interaction between IgA from HIV-infected patients and intestinal mAChR.
- To elucidate the signaling pathways triggered by this interaction.
- To understand the potential implications for intestinal dysfunction in HIV/AIDS.
Main Methods:
- Purification of IgA from HIV-infected patients.
- Immunoblotting with radiolabeled ileal mAChR.
- Analysis of signaling molecules including protein kinase C (PKC), nitric oxide synthase (NOS), and cyclic guanosine monophosphate (cGMP).
Main Results:
- HIV-patient-derived IgA (HIV+-IgA) recognized a specific band corresponding to mAChR.
- HIV+-IgA initiated mAChR-mediated signaling in the intestine.
- HIV+-IgA modulated PKC, NOS activity, and cGMP production.
- PKC activation by HIV+-IgA led to NOS inhibition and reduced nitric oxide (NO) levels.
- HIV+-IgA stimulated cGMP production, potentially increasing ileal motility and fluid secretion.
Conclusions:
- IgA from HIV-infected individuals directly interacts with intestinal mAChR.
- This interaction triggers signaling cascades with dual effects: potential local immunosuppression via NO inhibition and enhanced intestinal motility/secretion via cGMP.
- These findings offer insights into the mechanisms underlying intestinal damage in AIDS.