Gastrointestinal manifestations of HIV infection

Prevalence of enteric viruses in human immunodeficiency virus seropositive patients in Venezuela

The prevalence of enteric viruses associated with gastroenteritis was determined in 125 stool samples from patients infected with the human immunodeficiency virus (HIV), with or without diarrhea. Diagnostic assays included enzyme immunoassays for the identification of rotavirus, adenovirus, and Norwalk virus; polyacrylamide gel electrophoresis for atypical rotaviruses and picobirnaviruses and polymerase chain reaction for astrovirus. Enteric viruses were detected in 6.4% (8 of 125) of the stools collected: five (4.0%) samples positive for adenoviruses, and three (2.3%) samples positive for picobirnaviruses were detected. No rotavirus, astrovirus, or Norwalk virus were observed. Only one of the viruses identified (adenovirus) was found in a sample from a patient with diarrhea. Viruses were detected in 10% of the patients with AIDS, 14% of the symptomatic patients, and none of the asymptomatic persons. These results do not support a major role for enteric viruses in the diarrhea suffered by HIV-infected patients.

Oesophageal narrowing in chronic granulomatous disease

A 14 year-old boy with X-linked chronic granulomatous disease (CGD) developed a long smooth narrowing at the mid oesophagus with severe dysphagia. Endoscopy revealed a normal mucosa and biopsy showed non-specific acute inflammatory changes. Bacterial cultures of the biopsy specimens were sterile. Combined treatment with antibiotics and steroids resulted in a transitory remission, but symptoms recurred after 2.5 months. One second course of steroids and antibiotics lead to a long-term remission. Oesophagogram was more useful than endoscopy to evaluate the severity of the stricture.

HIV-1 p24 but not proviral load is increased in the intestinal mucosa compared with the peripheral blood in HIV-infected patients

OBJECTIVE

To investigate differences in viral and proviral load between the peripheral blood and the intestinal mucosal immune system in HIV-infected patients.

DESIGN

HIV-1 p24 and HIV DNA content were compared in blood samples and intestinal biopsies from HIV-infected patients.

METHODS

Intestinal biopsies and peripheral blood were simultaneously obtained from 27 HIV-infected patients undergoing diagnostic endoscopy. The p24 concentrations were measured in serum and homogenized intestinal biopsies by enzyme-linked immunosorbent assay after acid-dissociation of immune complexes. Proviral load was determined in blood and intestinal biopsies by a quantitative competitive polymerase chain reaction amplifying the HIV-1 nef gene from genomic DNA.

RESULTS

No significant differences were found in proviral load comparing HIV copies per 1.5 x 10(5) cell equivalents in blood [2650 (600-44000)] and intestinal biopsies [4200 (1325-19 625)]. Paired analysis revealed a strong positive correlation between serum and mucosal proviral load. In contrast, HIV core protein p24 was detected in intestinal biopsies from 18 patients in much higher concentrations than in serum [858 (262-4111) pg/g versus 34 (9-242) pg/g; P < 0.005]. The p24 concentrations in serum and intestinal biopsies did not correlate and no significant correlation was observed in serum or intestinal biopsies between proviral load and p24 concentrations. No clear correlations were observed between clinical parameters and HIV DNA or HIV p24 levels in blood or biopsies.

CONCLUSIONS

Our findings demonstrate a homogenous distribution of HIV proviral load in the peripheral blood and the intestinal mucosal immune system. The high viral antigen load in the intestine therefore indicates that mucosal HIV production is upregulated at the transcriptional and/or translational level. The intestinal mucosa is a major reservoir for HIV in HIV-infected patients.

Endoscopic evaluation of chronic human immunodeficiency virus-related diarrhea: is colonoscopy superior to flexible sigmoidoscopy?

OBJECTIVES

In patients with chronic human immunodeficiency virus (HIV)-related diarrhea undergoing lower endoscopy, the decision to perform flexible sigmoidoscopy or colonoscopy is controversial. The purpose of this study is twofold: 1) to evaluate the diagnostic yield of colonoscopy in a large group of patients with chronic HIV-related diarrhea and negative stool studies, and 2) to determine whether colonoscopy is superior to flexible sigmoidoscopy in this setting.

METHODS

All HIV-infected patients with chronic diarrhea who were referred for diagnostic colonoscopy at Bellevue Hospital Center between January 1992 and December 1996 were identified. Patient charts, pathology reports, and endoscopy records were reviewed.

RESULTS

During the 5-yr study period, 317 consecutive patients with chronic unexplained diarrhea undergoing colonoscopy were identified. A potential cause of diarrhea was found in 116 patients (36.6%). Cytomegalovirus was the most common pathogen detected (24%). The yield of colonoscopy was significantly higher in patients with a CD4 count of <100 cells/mm3 than in those with higher CD4 counts (44.8% vs 6.4%, p < 0.0001). Thirty percent of pathogens and 75% of lymphomas were identified only on biopsies taken from the proximal colon, well beyond the reach of the flexible sigmoidoscope. Importantly, 94% of the pathogens that were found only in the proximal colon were organisms for which effective therapy is currently available.

CONCLUSIONS

Colonoscopy is superior to flexible sigmoidoscopy in HIV-infected patients with chronic unexplained diarrhea. If flexible sigmoidoscopy had been performed instead of colonoscopy, 30% of pathogens would have been missed and 75% of lymphomas would have escaped detection.

Characteristics of IgA anti-HIV antibodies in plasma from patients with HIV infection

The concentration of total IgA and the specificity and molecular size of IgA anti-human immunodeficiency virus (HIV) type-1 antibodies in plasma obtained from individuals at different stages of HIV infection were analyzed. The concentration of total IgA in the plasma was not decreased even in the late stage of HIV infection, in contrast with those of total IgG and IgM. The IgA anti-HIV antibodies differed to the IgG anti-HIV antibodies in their specificity as determined by Western blotting. The IgA antibodies mainly bind to Env glycoproteins. The IgA anti-HIV antibodies in plasma were detected between IgG and IgM by gel filtration, suggesting the presence of polymeric IgA anti-HIV antibodies. These results indicate that the production of non-specific IgA in plasma is enhanced by unknown mechanisms in every stages of HIV infection, and suggest that IgA anti-HIV antibodies in plasma which are possibly polymeric and have unique specificity may play an important role in HIV infection.

Direct effect of type 1 human immunodeficiency virus (HIV-1) on intestinal epithelial cell differentiation: relationship to HIV-1 enteropathy

Human immunodeficiency virus (HIV)-infected patients display severe impairments of gastrointestinal functions, including diarrhea and malabsorption, even in the absence of opportunistic infections. Since HIV-1 proteins and nucleic acids have been detected in several cell types of the intestinal mucosa, it has been postulated that HIV-1 itself could alter enterocytic functions. In the present study, we analyzed the effect of HIV-1 on the differentiation process of the epithelial intestinal cell clone HT-29-D4, which mimics the maturation of enterocytes along the crypt-villus axis of the small intestine. We found that HIV-1 infection impairs cellular differentiation (i) by affecting the barrier function of the epithelium, as evidenced by a decrease in the transepithelial electrical resistance, and (ii) by inhibiting the activity of one major glucose absorption function, i.e., sodium/glucose cotransport. At the morphological level, HIV-1 infection of HT-29-D4 cells was associated with the formation of lumina, which are representative of a defect in cellular organization. These morphofunctional perturbations induced by HIV-1 could be mimicked by nocodazole, a microtubule-disrupting agent. Correspondingly, HIV-1 exposure of HT-29-D4 cells evoked a massive disruption of microtubules, as revealed by alpha-tubulin indirect immunofluorescence staining. A similar effect was observed after incubation of the cells with either recombinant gp120 or a monoclonal antibody against galactosylceramide (GalCer), the intestinal receptor for HIV-1 gp120, suggesting that the effect of HIV-1 was mediated by the binding of gp120 to GalCer. Based on these data, we propose that HIV-1 may selectively alter enterocytic functions through a direct effect on the intracellular architecture of the cells. In contrast with previous theories for HIV-1 enteropathy, our data support the concept that HIV-1 may perturb intestinal functions without necessarily infecting intestinal epithelial cells.