Alteration of Polymeric Immunoglobulin Receptor and Neonatal Fc Receptor Expression in the Gut Mucosa of Immunodeficiency Virus‐Infected Rhesus Macaques

Polymeric immunoglobulin receptors (pIgR) and neonatal Fc receptors (FcRn) are crucial immunoglobulin (Ig) receptors for the transcytosis of immunoglobulins, that is IgA, IgM and IgG, the levels of which in mucosal secretions were altered in both HIV‐ and SIV‐infected individuals. To gain an insight into the changes of pIgR and FcRn expression after immunodeficiency virus (SHIV/SIV) infection, real‐time RT‐PCR methods were established and the mRNA levels of pIgR and FcRn in normal and SHIV/SIV‐infected rhesus macaques were quantitatively examined. It was found that the levels of pIgR mRNA were within a range of 10⁷ copies per million copies of GAPDH mRNA in the gut mucosa of rhesus macaques, which were up to 55 times higher than that in the oral mucosa, the highest among the non‐gut tissues examined. Levels of FcRn mRNA were generally lower than that of pIgR, and the levels of FcRn mRNA in the gut mucosa were also lower than that in most non‐gut tissues examined. Notably, the levels of pIgR mRNA in the duodenal mucosa were positively correlated with that of IL‐17A in normal rhesus macaques. Both pIgR and FcRn mRNA levels were significantly reduced in the duodenal mucosa during acute SHIV infection and in the jejunum and caecum during chronic SHIV/SIV infection. These data expanded our knowledge on the expression of pIgR and FcRn in the gastrointestinal tract of rhesus macaques and demonstrated altered expression of pIgR and FcRn in SHIV/SIV, and by extension HIV infections, which might have contributed to HIV/AIDS pathogenesis.