Modulation of the orodigestive tract microbiome in HIV-infected patients.

More than 37 million people are living with human immunodeficiency virus 1 (HIV), and more people than ever received lifesaving antiretroviral therapy worldwide. HIV-1 infection disrupts the intestinal immune system, leading to microbial translocation and systemic immune activation. We investigated the impact of HIV-1 infection on the GI microbiome and its association with host immune activation. The data indicated that the microbiome was different in HIV-positive and HIV-negative individuals. The initial sequence analysis of saliva indicated that there were major differences in the phyla of Bacteroidetes, Firmicutes, Proteobacteria, and TM7. Phylum Tenericutes was only seen in HIV-positive saliva. At the family level, we identified differences in Streptococcacea, Prevotellaceae, Porphyromonadaceae, and Neisseriaceae, whereas data from various sites in GI tract indicated that Prevotella melaninigencia, Fusobacterium necrophorum, Burkholderia, Bradyrhizobium, Ralstonia, and Eubacterium biforme were predominant but differentially present at various sites. Furthermore, there was a decrease in seven proteins associated with the alternative complement pathway and an increase in 6 proteins associated with the lectin and classical complement pathways. The correlation with a shift in complement pathways suggests that compromised immunity could be responsible for the observed dysbiosis in the GI microbiome.

IL-22-producing CD4+ cells are depleted in actively inflamed colitis tissue.

T helper type (Th17) cytokines such as interleukin (IL)-17A and IL-22 are important in maintaining mucosal barrier function and may be important in the pathogenesis of inflammatory bowel diseases (IBDs). Here, we analyzed cells from the colon of IBD patients and show that Crohn's disease (CD) patients had significantly elevated numbers of IL-17+, CD4+ cells compared with healthy controls and ulcerative colitis (UC) patients, but these numbers did not vary based on the inflammatory status of the mucosa. By contrast, UC patients had significantly reduced numbers of IL-22+ cells in actively inflamed tissues compared with both normal tissue and healthy controls. There was a selective increase in mono-IL-17-producing cells from the mucosa of UC patients with active inflammation together with increased expression of transforming growth factor (TGF)-ß and c-Maf. Increasing concentrations of TGF-ß in lamina propria mononuclear cell cultures significantly depleted Th22 cells, whereas anti-TGF-ß antibodies increased IL-22 production. When mucosal microbiota was examined, depletion of Th22 cells in actively inflamed tissue was associated with reduced populations of Clostridiales and increased populations of Proteobacteria. These results suggest that increased TGF-ß during active inflammation in UC may lead to the loss of Th22 cells in the human intestinal mucosa.

Use of immobilized HLA-A2:Ig dimeric proteins to determine the level of epitope-specific, HLA-restricted CD8(+) T-cell response.

A novel assay to assess antigen-specific cytokine release from stimulated CD8(+) T cells derived from the mucosal and peripheral blood compartments has been developed and standardized using the influenza A virus matrix protein (MP) peptide, GILGFVFTL. This technology is based on the capacity for the human leucocyte antigen (HLA)-A2:Ig dimeric protein to stimulate CD8(+) T cells in a major histocompatibility complex (MHC) class I-restricted fashion without the necessity for antigen presenting cells (APC). This assay has been optimized utilizing a 9-amino acid residue (9mer) peptide, the optimal peptide length for presenting an epitope to CD8(+) T cells. Compared to existing assays, this more sensitive and specific methodology requires fewer cells, enabling easier and more accurate monitoring of the CD8(+) T-cell response in biological compartments, such as the mucosa during the course of viral infection and may be utilized to assess epitope-specific CD8(+) T-cell responses in vaccine trials.

Screening colonoscopy for the detection of neoplastic lesions in asymptomatic HIV-infected subjects.

BACKGROUND: Although non-AIDS defining malignancies are rapidly increasing as HIV-infected subjects live longer, little is know about the results of screening for colonic neoplasms (adenomatous polyps and adenocarcinomas) in this population. METHODS: We conducted a screening colonoscopy study to determine the prevalence of colonic neoplasms in 136 asymptomatic HIV-infected subjects >or=50 years of age and 272 asymptomatic uninfected control subjects matched for age, sex, and family history of colorectal cancer. Advanced neoplasms were defined as adenomas >or=10 mm or any adenoma, regardless of size, with villous histology, high-grade dysplasia, or adenocarcinoma. RESULTS: The prevalence of neoplastic lesions was significantly higher in HIV-infected subjects than in control subjects (62.5% vs 41.2%, p<0.001), and remained highly significant after adjustment for potential confounding variables (odds ratio = 3.00; 95% confidence interval, 1.83 to 4.93). Among patients with colorectal adenocarcinoma, HIV-infected subjects were significantly younger (52.4 (SD 1.3) vs 60.3 (SD 4.0) years, p = 0.002) and were more likely to have advanced cancers (stage III or IV) than control subjects (60.0% vs 16.7%, p = 0.24). Of HIV-infected subjects with advanced neoplasms proximal to the splenic flexure, distal neoplastic lesions were absent in 88.9% of individuals and these would have been missed by flexible sigmoidoscopy. CONCLUSIONS: HIV-infected subjects have a higher prevalence of colonic neoplasms, and adenocarcinomas develop at a younger age and are more advanced than in uninfected subjects. Our findings suggest that screening colonoscopy should be offered to HIV-infected subjects, but the age of initiation and the optimal frequency of screening require further study.

A preponderance of CCR5(+) CXCR4(+) mononuclear cells enhances gastrointestinal mucosal susceptibility to human immunodeficiency virus type 1 infection.

The gastrointestinal mucosa harbors the majority of the body's CD4(+) cells and appears to be uniquely susceptible to human immunodeficiency virus type 1 (HIV-1) infection. We undertook this study to examine the role of differences in chemokine receptor expression on infection of mucosal mononuclear cells (MMCs) and peripheral blood mononuclear cells (PBMCs) by R5- and X4-tropic HIV-1. We performed in vitro infections of MMCs and PBMCs with R5- and X4-tropic HIV-1, engineered to express murine CD24 on the infected cell's surface, allowing for quantification of HIV-infected cells and their phenotypic characterization. A greater percentage of MMCs than PBMCs are infected by both R5- and X4-tropic HIV-1. Significant differences exist in terms of chemokine receptor expression in the blood and gastrointestinal mucosa; mucosal cells are predominantly CCR5(+) CXCR4(+), while these cells make up less than 20% of the peripheral blood cells. It is this cell population that is most susceptible to infection with both R5- and X4-tropic HIV-1 in both compartments. Regardless of whether viral isolates were derived from the blood or mucosa of HIV-1-infected patients, HIV-1 p24 production was greater in MMCs than in PBMCs. Further, the chemokine receptor tropism of these patient-derived viral isolates did not differ between compartments. We conclude that, based on these findings, the gastrointestinal mucosa represents a favored target for HIV-1, in part due to its large population of CXCR4(+) CCR5(+) target cells and not to differences in the virus that it contains.

HIV-related diarrhea is multifactorial and fat malabsorption is commonly present, independent of HAART.

OBJECTIVE: Highly active antiretroviral therapy (HAART) has significantly decreased the incidence of infectious diarrhea affecting HIV-infected patients. Still, diarrhea remains a common symptom in HIV. We sought to determine the incidence of fat malabsorption as a cause of diarrhea in HIV patients receiving non-HAART (nucleoside analog only) and HAART (protease inhibitor-containing) antiretroviral regimens. METHODS: From June, 1995, to April, 1999, 88 HlV-infected patients underwent evaluation for diarrhea, which included endoscopy. We examined the incidence of fat malabsorption with a 24-h stool collection for fecal fat in a cohort of these patients (N = 33). Patients were divided into two groups, those receiving protease inhibitor-containing HAART and those receiving less intensive, nucleoside analog-only, non-HAART regimens. RESULTS: Thirty of 33 patients (90.9%) had fat malabsorption. Twenty of 21 patients not receiving HAART (95.2%) had fat malabsorption with a mean of 34 +/- 38 g of stool fat and a mean stool weight of 797 +/- 454 g. Ten of 12 patients receiving HAART (83.3%) had fat malabsorption with a mean of 46 +/- 86 g of stool fat and a mean stool weight of 800 +/- 647 g. Stool weight correlated with the degree of fat malabsorption (R = 0.77). CONCLUSION: Fat malabsorption represents a commonly undiagnosed entity in HIV-infected patients with diarrhea, whether or not they are receiving HAART therapy. Fecal fat determination should be considered a routine part of the diagnostic workup of HIV-infected patients experiencing diarrhea.

Sensitive and reproducible quantitation of mucosal HIV-1 RNA and DNA viral burden in patients with detectable and undetectable plasma viral HIV-1 RNA using endoscopic biopsies.

Mucosal tissue is the main portal of entry for HIV-1 infection and, in macaques, has been demonstrated to be a significant compartment for viral replication and CD4+ T lymphocyte depletion. Quantitating tissue viral burden in addition to plasma viral load provides insights into HIV-1 pathogenesis and an additional means to gauge antiretroviral response. The aim of this study was to develop reliable, reproducible, and sensitive assays to quantitate tissue viral burden of HIV-1 RNA and DNA using 1-3 endoscopically acquired, rectosigmoid biopsies. Total DNA and RNA were simultaneously extracted following homogenization from the same tissue samples. Quantitative polymerase chain reaction (PCR) assay in the HIV-1 LTR region was used to detect viral DNA and RT-PCR for viral RNA. It was determined that HIV-1 RNA and DNA can be reproducibly quantified from a single rectosigmoid biopsy with minimal intra-assay or intra-patient variability. These results reflect high recovery of extracted nucleic acids with calculated results accurately reflecting in vivo levels. The techniques outlined differ from currently available approaches by incorporating control standards to identify loss or degradation of RNA and DNA from acquisition through the in vitro assay and permit extraction with high yields of RNA and DNA from the same tissue sample.

Despite high concordance, distinct mutational and phenotypic drug resistance profiles in human immunodeficiency virus type 1 RNA are observed in gastrointestinal mucosal biopsy specimens and peripheral blood mononuclear cells compared with plasma.

The gastrointestinal mucosa is a major lymphoid tissue reservoir for human immunodeficiency virus (HIV) replication. Genotypic and phenotypic resistance patterns of HIV type 1 (HIV-1) RNA isolated from colonic mucosa were compared with those from the plasma and peripheral blood mononuclear cells (PBMC) of 7 patients. Genotyping was performed using full-sequence analysis, and phenotyping was performed using a recombinant virus assay. Mutations in the reverse-transcriptase (kappa=.84) and protease (kappa=.73) genes were highly concordant among compartments. Similarly, phenotypic resistance patterns were highly concordant among compartments (intraclass correlation coefficient,.91). In 5 instances among 3 patients, a different genotypic result was observed between plasma and the other tissue compartments. Mixtures of wild-type and mutated HIV-1 RNA were present in the mucosa and PBMC but not in the plasma. Despite significant concordance among compartments, mucosal- and PBMC-derived viral RNA showed instances of discordance with plasma-derived virus that may suggest compartmentalization of virus.

Human immunodeficiency virus type 1 infection is associated with significant mucosal inflammation characterized by increased expression of CCR5, CXCR4, and beta-chemokines.

Mucosal inflammation is characterized by increased expression of proinflammatory cytokines and chemoattractant chemokines, resulting in infiltration of immunocompetent cells. This study compared the degree of mucosal inflammation in human immunodeficiency virus type 1 (HIV-1)-infected gut mucosa with that in tissue samples from subjects with inflammatory bowel disease (IBD) and from healthy seronegative control subjects. Gut mucosal biopsy specimens were immunohistochemically stained and were evaluated by in situ imaging. There was significantly increased expression of HIV-1 coreceptors CCR5 and CXCR4, beta-chemokine RANTES, and macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, as well as increased numbers of T cells in lamina propria of HIV-1-infected patients. The results were similar in patients with IBD and in HIV-1-infected patients, suggesting increased inflammation in the colon of HIV-1-infected patients. To further investigate the effect of inflammation in HIV-1-infected lamina propria, treatments that reduce immune activation in lamina propria must be evaluated.

Enhanced levels of functional HIV-1 co-receptors on human mucosal T cells demonstrated using intestinal biopsy tissue.

OBJECTIVE: To examine compartmental differences in co-receptor expression on CD4 lymphocytes between blood and gut using endoscopic biopsies. DESIGN: Mucosal and peripheral CD4 T cells from healthy controls were compared for co-receptor expression and vulnerability to infection by HIV-1. METHODS: Expression of CCR5 and CXCR4 was quantified by flow cytometry on isolated mucosal CD4 lymphocytes obtained from endoscopic biopsies and blood from healthy controls. Vulnerability to in vitro infection by both R5 and X4 strains was assessed by measuring p24. RESULTS: Biopsies yielded sufficient lymphocytes for flow cytometric characterization and infectivity studies. The percentage of mucosal CD4 T lymphocytes that expressed CCR5 and the per cell expression of CCR5 were both significantly increased compared with that in peripheral blood CD4 T lymphocytes. CXCR4 was expressed on the majority of CD4 lymphocytes in both compartments. In vitro infection of mucosal mononuclear cells supported greater viral replication of both R5 and X4 strains than peripheral blood mononuclear cells. CONCLUSIONS: Enhanced expression of CXCR4 and CCR5 on CD4 lymphocytes in normal intestinal mucosa predicts increased vulnerability to infection by both R5 and X4 HIV-1. Endoscopic biopsies provide a useful mucosal tissue sampling technique to identify compartmental immunologic differences that may be exploited by HIV-1 in establishing initial mucosal infection.

Infections of the liver in HIV-infected patients.

The liver is a common site of pathology in HIV-infected patients. In patients with controlled HIV and minimal immunosuppression, infection with hepatitis viruses is common owing to the risk factors of sexual transmission or parenteral drug use. In patients with AIDS, the liver is a common site of lymphohematogenous dissemination of several infectious pathogens. A thorough diagnostic approach leads to a diagnosis of most hepatobiliary processes. The therapeutic nihilism that has surrounded hepatic disease, including viral hepatitis, is unwarranted, because treatment of the underlying HIV and the hepatic process may improve the quality of life and longevity of these patients.

Hepatitis C virus/human immunodeficiency virus coinfection: clinical management issues.

The use of highly active antiretroviral therapy (HAART) has extended the healthy lifespan of patients infected with human immunodeficiency virus (HIV); deaths among people with AIDS declined for the first time in 1996, after the institution of this therapeutic approach. As the life expectancy of HIV-infected patients increases, greater attention will need to be focused on the recognition and management of potentially severe concurrent illnesses that may increase their mid- to long-range morbidity and mortality. The incidence of infection by hepatitis C virus (HCV) is increased among patients with HIV disease, reflecting shared epidemiological risks. HCV not only may have an impact on the health status of HIV-infected patients but also may decrease their quality of life and increase their health care costs. Although clinicians have been reluctant to treat viral hepatitis C in the HIV-infected population, this therapeutic nihilism is unwarranted. The majority of studies have concluded that treatment of hepatitis C in HIV-infected patients results in an initial efficacy and long-term response similar to those in the HIV-seronegative population. Furthermore, treatment of HCV infection in HCV/HIV-coinfected patients may improve tolerance for antiretroviral medications. Physicians caring for patients with HIV infection require up-to-date information to make rational decisions regarding HCV coinfection to ensure that morbidity and mortality are minimized and that quality of life and medical care costs are optimized.

Isolation of human intestinal defensins from ileal neobladder urine.

We describe the isolation of naturally occurring human intestinal defensins HD-5 and HD-6 from ileal neobladder urine and ileal mucosa. Using an antibody-based detection assay, we found multiple N-terminally processed forms of HD-5. The predominant HD-5 forms in tissue were longer than those in neobladder urine (amino acid (aa) 23-94 and 29-94 versus aa 36-94, 56-94 and 63-94) suggesting that Paneth cells store prodefensin that is processed to mature defensin during or after degranulation. Search for mature HD-6 yielded aa 69-100 as the predominant form in both sources. The ileal neobladder is a promising model to study human Paneth cell secretion.

HIV-Related hepatic disease: when and why to biopsy.

Patients infected with HIV are susceptible to a variety of hepatic processes that are related to immunosuppression or are associated with the risk factors of homosexuality and parenteral drug use. These processes present in a myriad of ways including fever, right upper quadrant pain, and hepatomegaly, or simply as asymptomatic elevations of liver tests. Care of these patients demands systematic evaluation and treatment to ensure that morbidity and mortality are minimized and quality of life and medical care costs are optimized.

Adenovirus colitis in human immunodeficiency virus infection: an underdiagnosed entity.

Adenovirus infection of the gastrointestinal tract in human immunodeficiency virus (HIV)-infected patients is rarely reported, probably because of a lack of familiarity of most pathologists with diagnostic criteria during routine light microscopy and possible misidentification as cytomegalovirus infection. We studied colonoscopic biopsy specimens from 135 HIV-infected patients with clinically suspected cytomegalovirus colitis during a 4.5-year period to morphologically identify the presence of adenovirus infection. Immunohistochemical staining for adenovirus was performed for confirmation on all suspected cases. Adenovirus infected cells showed characteristic amphophilic or eosinophilic nuclear inclusions, predominantly affecting the surface epithelium and characteristically involving goblet cells. Sixteen cases showed morphologic features of adenovirus infection, all confirmed by immunohistochemistry. Twelve cases also showed cytomegalovirus infection, whereas 4 showed adenovirus alone. In 10 cases, adenovirus colitis was not recognized during initial routine histopathologic diagnostic evaluation. Adenovirus inclusions also were discovered in the stomach, the duodenum, and the liver in single cases. Conclusions are as follows: (1) Adenovirus colitis has been underdiagnosed at our institution and, we suspect, in general. (2) The morphologic features and nuclear inclusions of adenovirus colitis are characteristic and can be identified reliably by routine light microscopy. (3) Adenovirus infection also may be diagnosed morphologically in extracolonic sites, such as the stomach, the small intestine, and the liver. (4) Coinfection of adenovirus with cytomegalovirus and other agents is seen frequently, but, less frequently, adenovirus may be identified as a sole pathogen.

Treatment of gastrointestinal cytomegalovirus infection with twice-daily foscarnet: a pilot study of safety, efficacy, and pharmacokinetics in patients with AIDS.

Ten patients with AIDS and cytomegalovirus (CMV) gastrointestinal infection were included in an open-label study to evaluate the safety, efficacy, and pharmacokinetics of 90 mg of intravenous foscarnet/kg of body weight twice daily accompanied by (pre)hydration of 500 to 750 ml. Efficacy was documented endoscopically, while safety was evaluated clinically by patient reports and physical and laboratory observation. The pharmacokinetics of foscarnet was evaluated after the first dose and following approximately 20 days of therapy. Nine patients (90%) responded histopathologically, nine (90%) responded endoscopically, and nine (90%) responded symptomatically to foscarnet therapy. Adverse events resulted in discontinuance of medication in the case of one patient. The mean maximal concentration was 621 microM following the first dose and 687 microM at steady state (P = 0.11). The apparent elimination rate constant and elimination half-life were not different between dose 1 and steady state. There were no significant changes in foscarnet excretion or renal clearance between dose 1 and steady state. The steady-state volume of distribution was 23.4 liters following the first dose and 19.0 liters at steady state (P < 0.002). Twice-daily foscarnet appeared to be safe and efficacious in the treatment of CMV gastrointestinal disease in this study, resulting in endoscopic or histologic improvement in 9 of the 10 (90%) patients. Minor changes in clearance and volume of distribution noted at steady state compared to single-dose administration are readily explained by study design, known information about foscarnet pharmacokinetics, and changes in body weight and creatinine clearance in the patients.

Diarrheal diseases associated with HIV infection.

Diarrhea is a major complication of HIV infection and adversely impacts health care costs, quality of life, and even survival of patients. There is a wide variety of potential causes of diarrhea in HIV-infected patients, and the number of pathogens found continues to increase with time. In addition, there is some controversy concerning the role of some organisms in the pathogenesis of diarrhea and the appropriate diagnostic evaluation of affected patients. This article reviews our current understanding of these pathogens and some of the diagnostic and therapeutic approaches for diarrhea associated with HIV infection.

Diagnosis and treatment of hepatic disease in patients with HIV.

Liver involvement with opportunistic infections and neoplasms is a well-recognized component of AIDS, affecting most patients. The cause of hepatic disease in these patients may be divided into hepatitis, granulomatous disease, mass lesions, vascular lesions, hepatotoxic drugs, and nonspecific findings. With a rational approach, most patients with AIDS and liver disease can be diagnosed and treated in a cost-effective manner with low morbidity.

Liver biopsy findings in 501 patients infected with human immunodeficiency virus (HIV).

Patients infected with human immunodeficiency virus (HIV) are at risk for a variety of liver diseases. We undertook a retrospective study of 501 HIV-seropositive patients to assess the yield of percutaneous liver biopsy. The most common indications for liver biopsy were liver test abnormalities (89.5%), fever for 2 weeks (71.9%), and hepatomegaly (52.0%). The most common biopsy-derived diagnosis was Mycobacterium avium complex (MAC), seen in 87 (17.4%) biopsies. Mycobacterium tuberculosis was found in 13 biopsies (2.6%). In 28 biopsies (5.6%) mycobacteria was seen, but speciation of the organism was not possible. Chronic active viral hepatitis was seen in 60 biopsies (12.0%). Opportunistic hepatic infection from other organisms was found in 14 biopsies (2.8%). The most common neoplasm was lymphoma, which was seen in 12 biopsies (2.4%). MAC infection of the liver was associated with elevated alkaline phosphatase (p = 0.01). Among patients with fever for 2 weeks after an extensive negative workup including bone marrow biopsy, 58.2% had a diagnosis by liver biopsy. Overall, 64.3% of liver biopsies yielded a histopathological diagnosis, 45.7% of which were potentially treatable. We could not evaluate whether liver biopsy had a positive effect on patient outcome and survival, nor did we attempt to prove that liver biopsy resulted in a change in treatment or a change in preprocedure clinical diagnosis. Thus, questions about the efficacy of liver biopsy cannot be answered. Liver biopsy may be a helpful diagnostic tool in HIV-positive patients with fever, liver test abnormalities or hepatomegaly.