Diarrhea in patients with AIDS

Methionine aminopeptidases: Potential therapeutic target for microsporidia and other microbes

Methionine aminopeptidases (MetAPs) have emerged as a target for medicinal chemists in the quest for novel therapeutic agents for treating cancer, obesity, and other disorders. Methionine aminopeptidase is a metalloenzyme with two structurally distinct forms in humans, MetAP-1 and MetAP-2. The MetAP2 inhibitor fumagillin, which was used as an amebicide in the 1950s, has been used for the successful treatment of microsporidiosis in humans; however, it is no longer commercially available. Despite significant efforts and investments by many pharmaceutical companies, no new MetAP inhibitors have been approved for the clinic. Several lead compounds have been designed and synthesized by researchers as potential inhibitors of MetAP and evaluated for their potential activity in a wide range of diseases. MetAP inhibitors such as fumagillin, TNP-470, beloranib, and reversible inhibitors and their analogs guide new prospects for MetAP inhibitor development in the ongoing quest for new pharmacological indications. This perspective provides insights into recent advances related to MetAP, as a potential therapeutic target in drug discovery, bioactive small molecule MetAP2 inhibitors, and data on the role of MetAP-2 as a therapeutic target for microsporidiosis.

A Study Comparing Cost-Effectiveness of Combination Therapy for Preventing Opportunistic Infections Among Human Immunodeficiency Virus-Infected Adults on Antiretroviral Therapy

OBJECTIVES

India is going through an epidemiologic and demographic transition made possible by increased investment in health sector and sustained development. The country has more than 2 million people infected with human immunodeficiency virus (HIV). Information on cost-effectiveness of competing interventions is a useful contributor to decisions concerning allocation and prioritization of healthcare resources. This paper aims to study the cost, health outcomes as measured by disability-adjusted life-years (DALYs), and cost-effectiveness per DALY averted of prophylaxis for tuberculosis, diarrhea, and mouth ulcers in HIV-infected adults.

METHODS

Data were analyzed on 375 HIV-infected persons enrolled at the ART Centre in New Delhi between April 2004 and April 2006. Using estimates of the age of onset of HIV infection, cost of medicines, and antiretroviral regimen followed, we used standard methods to calculate the cost per DALY as a measure of cost-effectiveness. Sensitivity analysis was conducted to determine the robustness of cost-effectiveness results by making reasonable changes in underlying assumptions.

RESULTS

The results revealed that the incremental cost-effectiveness ratio for tuberculosis prophylaxis was ₹4821.48 ($78.86) per DALY averted compared with no prophylaxis, followed by diarrhea (₹8299.08, $135.74) and mouth ulcers (₹20 058.14, $328.07).

CONCLUSIONS

The estimates are less than the per capita gross domestic product of India, indicating that the current treatments are highly cost-effective. This will help policymakers understand the best opportunities to improve population health and help researchers to develop more standardized methods in the area, thus improving quality and comparability across cost per DALY studies.

Human Immunodeficiency Virus-Associated Diarrhea: Still an Issue in the Era of Antiretroviral Therapy

Over half of patients with human immunodeficiency virus (HIV) experience diarrhea that contributes negatively to quality of life and adherence to antiretroviral therapy (ART). Opportunistic infectious agents that cause diarrhea in patients with HIV span the array of protozoa, fungi, viruses, and bacteria. With global use of ART, the incidence of diarrhea because of opportunistic infections has decreased; however, the incidence of noninfectious diarrhea has increased. The etiology of noninfectious diarrhea in patients with HIV is multifactorial and includes ART-associated diarrhea and gastrointestinal damage related to HIV infection (i.e., HIV enteropathy). A basic algorithm for the diagnosis of diarrhea in patients with HIV includes physical examination, a review of medical history, assessment of HIV viral load and CD4+ T cell count, stool microbiologic assessment, and endoscopic evaluation, if needed. For patients with negative diagnostic results, the diagnosis of noninfectious diarrhea may be considered. Pharmacologic options for the treatment of noninfectious diarrhea are primarily supportive; however, the use of many unapproved agents is based on unstudied and anecdotal information. In addition, these agents can be associated with treatment-limiting adverse events (AEs), such as drug-drug interactions with ART regimens, abuse liability, and additional gastrointestinal AEs. Currently, crofelemer, an antisecretory agent, is the only therapy approved in the USA for the symptomatic relief of noninfectious diarrhea in patients with HIV on ART.

Noninfectious Diarrhea in HIV Seropositive Individuals: a Review of Prevalence Rates, Etiology, and Management in the Era of Combination Antiretroviral Therapy

Introduction

Diarrhea poses a substantial burden for patients with human immunodeficiency virus (HIV), negatively impacting quality-of-life (QoL) and adherence to antiretroviral therapy. During the combination antiretroviral therapy (cART) era, as incidence of opportunistic infection as a cause of diarrhea decreased, incidence of noninfectious diarrhea (including diarrhea as an adverse event [AE] of cART and HIV enteropathy) increased proportionately. A literature search was conducted for information on prevalence, etiology, and treatment options for noninfectious diarrhea in patients with HIV.

Results

For marketed antiretroviral therapies, up to 28% of patients live with >4 loose or watery stools per day. The US Food and Drug Administration (FDA) does not require pharmaceutical manufacturers to include, within approved prescribing information, prevalence rates for all grades of diarrhea. Traditionally, noninfectious diarrhea management focused on avoiding use of diarrhea-associated cART; symptom management (nonpharmacologic and/or pharmacologic); and, as a last resort, changing cART. Examining the evidence upon which this approach is based reveals that most strategies rely upon anecdotal information and case reports. This review summarizes the literature and updates clinicians on the most recent options for management of noninfectious diarrhea in patients with HIV.

Conclusion

Diarrhea in patients with HIV is a significant unmet clinical need that contributes to worsening QoL and complicates medical management. Approaching management using a stepwise method of nonpharmacologic (diet), nonprescription (over-the-counter) and, finally, prescription agent changes (modification of cART or addition of an evidence-based antidiarrheal) appears reasonable, despite a lack of clear scientific evidence to support the initial two steps of this approach. If diet modifications, including psyllium and fiber introduction, fail to resolve noninfectious diarrhea in patients with HIV, loperamide followed by crofelemer should be considered. Clinicians are encouraged to review the most recent literature, not rely upon prescribing information. Continued vigilance by HIV providers to the presence of gastrointestinal AEs, even in patients taking the most recently approved antiretroviral agents, is warranted. Additional research is justified in identifying the etiology and management of HIV-associated diarrhea in patients on successful cART regimens.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-014-0047-5) contains supplementary material, which is available to authorized users.

Crofelemer for the treatment of secretory diarrhea

Secretory diarrhea is a leading cause of morbidity and mortality worldwide. Crofelemer is a first-in-class antidiarrheal agent that simultaneously targets two distinct channels, the cystic fibrosis conductance regulator and calcium-activated chloride channel, responsible for chloride and fluid secretion in the GI tract. Crofelemer is a novel compound extracted from the stem bark latex of the Croton lechleri tree found in the western Amazonian region of South America. There is little to no systemic absorption of crofelemer when given orally and studies have shown minimal toxicity beyond mild gastrointestinal effects. In studies in diarrheal illness associated with primarily a secretory component, such as cholera, travelers' diarrhea and acute infectious diarrhea, crofelemer has shown improvements in stool consistency and duration of symptoms. Less clear, but interesting, results have been observed in other diarrheal diseases associated with a mixed pathology, including diarrhea in patients with HIV and diarrhea-predominant irritable bowel syndrome.

Native X-DING-CD4 protein secreted by HIV-1 resistant CD4+ T cells blocks activity of IL-8 promoter in human endothelial cells infected with enteric bacteria

Onsets of bacterial infections devastate the compromised immune system in AIDS patients. Damaged gut mucosa permits dissemination of bacterial toxins into deeper layers and hyper-activation of the immune system. We previously reported that the unfractionated supernatants of HIV-resistant CD4(+) T cells impeded the NF-κB/DNA binding in macrophages induced by either HIV-1 or LPS. The active component of this soluble material was identified as X-DING-CD4 (extracellular DING from CD4 T cells). We hypothesized that the anti-inflammatory effect of the X-DING-CD4 protein might extend to non-immune cells, for example endothelial cells, undergoing persistent endotoxin stimulation in the course of advanced HIV disease. To test this proposition, we evaluated the efficiency of NF-κB and Ap-1 binding to the IL-8 promoter in LPS-activated endothelial cells and control human macrophages exposed to native X-DING-CD4 protein. We found a deficiency of NF-κB- but not AP-1-DNA binding in the systems where cells were treated with native soluble X-DING-CD4 protein. The X-DING-CD4-mediated inhibition of the IL-8 promoter also resulted in a reduction of the soluble IL-8 protein in endothelial cells and human macrophages infected with a subset of enteric bacteria frequently causing diarrhea in progressive HIV disease. Bacterial endotoxin did not induce the endogenous X-DING-CD4 mRNA activity in human macrophages and transformed CD4(+)T cells, indicating that the reduction of LPS-mediated IL-8 promoter activation was not related to de novo X-DING-CD4 protein synthesis, but depended on function of the exogenous X-DING-CD4 protein. This study provides evidence that the X-DING-CD4 protein might be developed as a novel biotherapeutic to control LPS-mediated inflammation in advanced HIV disease.

Characterization of WRSs2 and WRSs3, new second-generation virG(icsA)-based Shigella sonnei vaccine candidates with the potential for reduced reactogenicity

Live, attenuated Shigella vaccine candidates, such as Shigella sonnei strain WRSS1, Shigella flexneri 2a strain SC602, and Shigella dysenteriae 1 strain WRSd1, are attenuated principally by the loss of the VirG(IcsA) protein. These candidates have proven to be safe and immunogenic in volunteer trials and in one study, efficacious against shigellosis. One drawback of these candidate vaccines has been the reactogenic symptoms of fever and diarrhea experienced by the volunteers, that increased in a dose-dependent manner. New, second-generation virG(icsA)-based S. sonnei vaccine candidates, WRSs2 and WRSs3, are expected to be less reactogenic while retaining the ability to generate protective levels of immunogenicity seen with WRSS1. Besides the loss of VirG(IcsA), WRSs2 and WRSs3 also lack plasmid-encoded enterotoxin ShET2-1 and its paralog ShET2-2. WRSs3 further lacks MsbB2 that reduces the endotoxicity of the lipid A portion of the bacterial LPS. Studies in cell cultures and in gnotobiotic piglets demonstrate that WRSs2 and WRSs3 have the potential to cause less diarrhea due to loss of ShET2-1 and ShET2-2 as well as alleviate febrile symptoms by loss of MsbB2. In guinea pigs, WRSs2 and WRSs3 were as safe, immunogenic and efficacious as WRSS1.

High-speed gel microelectrophoresis, a new and easy approach for detection of PCR-amplified microbial DNA from environmental and clinical samples in microgels using conventional equipment

AIMS

Microelectrophoresis allows the detection of DNA bands using minimal amounts of sample in a short time, but commonly requires the use of special equipment which is not available in all laboratories. This fact has limited the application of this technique in microbiology despite its advantages. In this work, we describe a new approach to perform gel microelectrophoresis, named high-speed gel microelectrophoresis (HSGME), and its application for rapid detection of bacteria, protozoa and viruses in clinical, vegetal and environmental samples.

METHODS AND RESULTS

Aliquots of 0.4-1 microl of PCR product were loaded in 2 cm 1% agarose microgels and electrophoresed at high voltage (125 V cm(-1)) in conventional submarine horizontal mini-slabs. By using HSGME, single-DNA bands obtained after specific-PCR useful in diagnosis of different diseases caused by micro-organisms were detected in 5 min.

CONCLUSIONS

HSGME is a rapid and easy procedure applicable to detection of microbial genes, which is carried out using conventional equipment and thus can be performed in any research and diagnostic laboratory.

SIGNIFICANCE AND IMPACT OF THE STUDY

The performance of HSGME saves up to 90% time, material and energy costs, as well as laboratory hazardous wastes including carcinogenic agents used for visualizing DNA bands.

Microsporidiosis: current status

PURPOSE OF REVIEW

Microsporidiosis is an emerging and opportunistic infection associated with a wide range of clinical syndromes in humans. This review highlights the research on microsporidiosis in humans during the previous 2 years.

RECENT FINDINGS

The reduced and compact microsporidian genome has generated much interest for better understanding the evolution of these parasites, and comparative molecular phylogenetic studies continue to support a relationship between the microsporidia and fungi. Through increased awareness and improved diagnostics, microsporidiosis has been identified in a broader range of human populations that, in addition to persons with HIV infection, includes travelers, children, organ transplant recipients, and the elderly.

SUMMARY

Effective commercial therapies for Enterocytozoon bieneusi, the most common microsporidian species identified in humans, are still lacking, making the need to develop tissue culture and small animal models increasingly urgent. Environmental transport modeling and disinfection strategies are being addressed for improving water safety. Questions still exist about whether microsporidia infections remain persistent in asymptomatic immune-competent individuals, reactivate during conditions of immune compromise, or may be transmitted to others at risk, such as during pregnancy or through organ donation. Reliable serological diagnostic methods are needed to supplement polymerase chain reaction or histochemistry when spore shedding may be sporadic.

Chronic Salmonella enterica serovar Typhimurium-induced colitis and cholangitis in streptomycin-pretreated Nramp1+/+ mice

Salmonella enterica subspecies 1 serovar Typhimurium is an enteric bacterial pathogen infecting a broad range of hosts. In susceptible Nramp1(-/-) (Slc11alpha1(-/-)) mice, serovar Typhimurium cannot efficiently colonize the intestine but causes a systemic typhoid-like infection. However, after pretreatment with streptomycin, these susceptible (C57BL/6 and BALB/c) mice develop acute serovar Typhimurium-induced colitis (M. Barthel et al., Infect. Immun. 71:2839-2858, 2003). It was not clear whether resistant Nramp1(+/+) (Slc11alpha1(+/+)) mouse strains would similarly develop colitis. Here we compared serovar Typhimurium infection in streptomycin-pretreated susceptible (C57BL/6) and resistant (DBA/2 and 129Sv/Ev) mouse strains: We found that acute colitis (days 1 and 3 postinfection) is strikingly similar in susceptible and resistant mice. In 129Sv/Ev mice we followed the serovar Typhimurium infection for as long as 6 weeks. After the initial phase of acute colitis, these animals developed chronic crypt-destructive colitis, including ulceration, crypt abscesses, pronounced mucosal and submucosal infiltrates, overshooting regeneration of the epithelium, and crypt branching. Moreover, we observed inflammation of the gall duct epithelium (cholangitis) in the 129Sv/Ev mice between days 14 and 43 of infection. Cholangitis was not attributable to side effects of the streptomycin treatment. Furthermore, chronic infection of 129Sv/Ev mice in a typhoid fever model did not lead to cholangitis. We propose that streptomycin-pretreated 129Sv/Ev mice provide a robust murine model for chronic enteric salmonellosis including complications such as cholangitis.

Nitazoxanide in the treatment of acquired immune deficiency syndrome-related cryptosporidiosis: results of the United States compassionate use program in 365 patients

BACKGROUND

Cryptosporidiosis in patients with acquired immune deficiency syndrome is a serious, life-threatening disease.

AIM

A large compassionate use clinical trial was conducted in the USA to make nitazoxanide available to patients with acquired immune deficiency syndrome-related cryptosporidiosis and to collect data related to safety and effectiveness of the drug in this population.

METHODS

Patients at least 3 years of age with acquired immune deficiency syndrome, diarrhoea (> or =4 stools/day for >2 weeks) and Cryptosporidium-positive stools received 500-1500 mg of nitazoxanide twice daily. Patients were evaluated at weeks 1, 2, 4 and monthly thereafter for drug safety and effectiveness including the stool examinations, review of symptoms and patient diaries. Data analysis for clinical and parasitological response was intention-to-treat.

RESULTS

Three hundred and sixty-five patients were enrolled at 165 study centres throughout the USA. The duration of treatment ranged from 1 to 1,528 days (median 62 days). Among the 357 patients included in the intent-to-treat analysis, 209 (59%) achieved a sustained clinical response while on treatment. Clinical responses were closely associated with Cryptosporidium-negative stools (P < 0.0001). No safety issues were identified at doses up to 3000 mg/day or for long durations of treatment.

CONCLUSIONS

Nitazoxanide can be considered useful therapy for treatment of with acquired immune deficiency syndrome-related cryptosporidiosis.