Cytokine gene expression in HIV-infected intestinal mucosa

Cytokine dysregulation has been implicated in AIDS pathogenesis and the gastrointestinal tract, containing approximately 40% of the body's lymphoid tissue, is likely to act both as a reservoir of viral infection and a site for immune dysregulation. In this study evidence of cytokine dysregulation in intestinal mucosa has been sought using the reverse transcriptase polymerase chain reaction (RT-PCR) to amplify cytokine mRNA.

RT-PCR was performed on intestinal biopsies obtained from 50 HIV-infected patients and 31 controls. Tissue was obtained at diagnostic endoscopy and total RNA extracted using an RNAzol technique. Following RT, cDNA was amplified using primers specific for beta-actin, interleukin (IL)-1 beta, tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma, IL-2, IL-4, IL-10 and IL-13.

There was a significant increase in the expression of the proinflammatory cytokines IL-1 beta and IFN-gamma in the HIV-infected compared with the control small intestinal samples (P < 0.01). IL-10 was significantly reduced in the respective groups' large intestine (P < 0.02). The expression of IL-2 was also reduced in both the small and large intestinal HIV samples although this was not significant. IL-13 mRNA was only detected in one control patient.

Dysregulation of cytokine gene expression occurs in the intestinal mucosa of patients with HIV infection and is characterized by increased expression of proinflammatory cytokine mRNA. Further studies are needed to localize the cellular origin of such dysregulation and to quantify the degree of abnormality.