Ritonavir combination therapy restores intestinal function in children with advanced HIV disease

The Impact of Matrix Metalloproteinase-9 on the Sequential Steps of the Metastatic Process

In industrialized countries, cancer is the second leading cause of death after cardiovascular disease. Most cancer patients die because of metastases, which consist of the self-transplantation of malignant cells in anatomical sites other than the one from where the tumor arose. Disseminated cancer cells retain the phenotypic features of the primary tumor, and display very poor differentiation indices and functional regulation. Upon arrival at the target organ, they replace preexisting, normal cells, thereby permanently compromising the patient's health; the metastasis can, in turn, metastasize. The spread of cancer cells implies the degradation of the extracellular matrix by a variety of enzymes, among which the matrix metalloproteinase (MMP)-9 is particularly effective. This article reviews the available published literature concerning the important role that MMP-9 has in the metastatic process. Additionally, information is provided on therapeutic approaches aimed at counteracting, or even preventing, the development of metastasis via the use of MMP-9 antagonists.

Nutritional Care of the Child with Human Immunodeficiency Virus Infection in the United States

In well-resourced settings, early infant diagnosis and administration of life-saving antiretrovirals (ARVs) have significantly improved clinical outcomes in pediatric human immunodeficiency virus (HIV) infection. The dramatic increase in survival rates is associated with enhancements in overall quality of life, which reflect a multidisciplinary, holistic approach to care. Current optimism starkly contrasts with the outlook and prognosis two decades ago, when failure to thrive and wasting syndrome from uncontrolled pediatric HIV infection resulted from poor oral intake, malabsorption, chronic diarrhea, and a persistently catabolic state. The tenets of care developed from that era still hold true in that all infants, children, and adolescents with HIV require comprehensive nutritional services in addition to effective combination antiretroviral therapy (cART). This chapter will review the principles of nutrition in the pre- and post-cART eras and discuss the etiologic factors associated with malnutrition, with an emphasis on interventions that have favorably impacted the growth and body composition of infants, children and adolescents with HIV.

Younger age at HAART initiation is associated with more rapid growth reconstitution

OBJECTIVES

Patterns of growth following highly active antiretroviral therapy (HAART) administration among children are not well defined. The objective of this study was to determine rates and predictors of growth reconstitution among children on HAART.

METHODS

A study was conducted among HIV-1-infected children initiating HAART at an HIV treatment clinic in Kenya. Kaplan-Meier survival curves and Cox proportional hazards regression models compared catch-up growth (Z-score ≥ 0) at 12 months post-HAART. Multivariate linear mixed-effects models determined rates and predictors of growth following HAART.

RESULTS

One hundred and seventy-three HIV-1-infected children initiated HAART with a median age of 4.7 years [interquartile range (IQR) 2.4, 7.0]. At baseline, children below 3 years had lower weight-for-age (WAZ) and weight-for-height (WHZ) Z-scores than children 3-5 and 6-10 years (WAZ: P = 0.03; WHZ: P = 0.006). Adjusting for baseline growth, children below 3 years were two to three-fold more likely to attain population age-norms (Z-score = 0) than 6-10 years (WAZ: P = 0.055; WHZ: P = 0.005) at 12 months post-HAART. After adjustment, children below 3 years had higher increases in WAZ and WHZ following HAART than 6-10 years (WAZ: P = 0.006; WHZ: P = 0.005). Children at WHO stage at least 3 at baseline experienced more rapid WHZ reconstitution (P = 0.002). Food supplementation while on HAART was associated with increased monthly gains in weight indices (WAZ: P = 0.001; WHZ: P = 0.005), and multivitamins were associated with greater increases in height (P < 0.01).

CONCLUSION

Following HAART initiation, younger children had more rapid catch-up to the population-average weight of their peers than older children, demonstrating growth benefit of earlier HAART. In addition to HAART, food supplementation and multivitamins may also accelerate growth reconstitution.

Response to a protease-inhibitor (ritonavir)-containing combination antiretroviral regimen in HIV-infected children

INTRODUCTION

The number of antiretroviral agents available for children who are failing existing therapy is limited. Data are lacking on the use of various combination regimens and the resulting viral load dynamics in such children.

METHODS

Between March 1998 and March 2000, HIV-infected children younger than 18 years of age were studied in an open trial. The study regimen included ritonavir, with at least two drugs to which the virus was known or presumed to be sensitive. Subjects were ritonavir-naive and were included if they had high viral loads while receiving antiretroviral therapy. Patients had clinical assessments, CD4 counts and viral load monitoring.

RESULTS

Fifteen antiretroviral-experienced HIV-infected children were enrolled. Approximately 87% (13 of 15) had perinatally-acquired HIV; median age was 7.9 years (range 1.6 to 14.8). At enrolment, the median CD4 count was 557 cells/mm(3) (range 57 to 1702) and the median viral load was 72,600 copies/mL (range 3626 to 796,440). The majority of children (73.3%) had increases in CD4 counts within 12 weeks. During this period, the median increase in CD4 counts over baseline was 30.0%. Approximately 73% (eight of 11) of subjects with initial improvements in CD4 counts had sustained increases at 32 to 48 weeks. Over the first 12 weeks, 60% (nine of 15) had greater than 0.5 log(10) decreases in viral load. The improvement was sustained in 88.9% (eight of nine) of these patients at 32 to 48 weeks. Three patients discontinued therapy due to taste aversion.

CONCLUSIONS

Among pediatric patients with high viral loads while on existing therapy, the ritonavir-containing regimen was generally well tolerated. In a significant proportion of patients, modification of therapy was associated with sustained improvements in viral loads and CD4 counts over 32 to 48 weeks.

Inhibitory effect of HIV-1 Tat protein on the sodium-D-glucose symporter of human intestinal epithelial cells

OBJECTIVE

The pathophysiology of HIV-1-related intestinal dysfunction is largely unknown. We previously found that the transactivator factor peptide (Tat) produced by HIV-1 induces ion secretion and inhibits cell proliferation in human enterocytes. Because sugar malabsorption is a frequent feature in AIDS patients, we evaluated whether Tat inhibits intestinal glucose absorption.

DESIGN AND METHODS

We measured Na-D-glucose symporter (SGLT-1) activity and determined its phenotypic expression in Caco-2 cells, in the presence and absence of Tat, in uptake experiments using a non-metabolized radiolabelled glucose analogue, and by western blot analysis, respectively. alpha-Tubulin staining was used to study the effects exerted by Tat on cell structure.

RESULTS

Tat dose dependently inhibited glucose uptake by human enterocytes. This effect was prevented by anti-Tat polyclonal antibodies and by L-type Ca channels agonist Bay K8644. Western blot analysis of cellular lysates and brush-border membrane preparations showed that Tat induced SGLT-1 missorting. Tat also caused a dramatic decrease in alpha-tubulin staining, which indicates dysruption of the cytoskeleton organization.

CONCLUSIONS

Tat acutely impairs intestinal glucose absorption through SGLT-1 missorting. This result indicates that Tat is directly involved in AIDS-associated intestinal dysfunction.

Management of gastrointestinal disorders in children with HIV infection

A double scenario characterizes the epidemiology of HIV infection in children. In countries where highly active antiretroviral therapy (HAART) is available, the pattern of HIV infection is evolving into that of a chronic disease, for which control strictly depends on patients' adherence to treatment. In developing countries with no or limited access to HAART, AIDS is rapidly expanding and is loaded with a high fatality ratio, due to the combined effects of malnutrition and opportunistic infections. The digestive tract is a target of the disease in both settings. Opportunistic infections play a major role in children with severe immune impairment, with Cryptosporidium parvum being the leading agent of severe diarrhea. Several therapeutic approaches are effective in reducing fecal output, but the eradication of the parasite is rarely obtained. Other opportunistic infections may induce severe and protracted diarrhea, including atypical mycobacteria and cytomegalovirus. Diagnosis of diarrhea should be individually tailored based on presenting symptoms and risk factors. A stepwise approach is effective in limiting patient discomfort and minimizing the costs of investigations, starting with microbiologic investigation and proceeding with endoscopy and histology. Aggressive treatment of infectious diarrhea is required in severely immunocompromised children. However, antiretroviral therapy prevents the development of severe cryptosporidiosis. The liver and pancreas are also target organs in HIV infection, although functional failure is rare. The digestive-absorptive functions are impaired, with steatorrhea, nutrient malabsorption, and increased permeability occurring in 20-70% of children. Intestinal dysfunction contributes to growth failure and further immune derangement, leading to wasting, the terminal stage of AIDS. Nutritional management is crucial in HIV-infected children and is based on aggressive nutritional rehabilitation through enteral or parenteral routes and micronutrient supplementation.HIV may play a direct enteropathogenic role and is implicated in both diarrhea and intestinal dysfunction. This explains the efficacy of antiretroviral therapy in inducing remission of diarrhea and restoring intestinal function. Gastrointestinal side effects of antiretroviral drugs are increasingly observed; they are often mild and transient. Severe reactions are rare but require the withdrawal of drugs. In conclusion, severe enteric infections and intestinal dysfunction characterize the intestinal involvement of HIV infection. This is more common in, but not limited to, children who do not receive effective antiretroviral therapy. Diagnostic approaches include microbiologic and morphologic examinations and assessment of digestive processes, but immunologic and virologic data should be also carefully considered. Treatment is based upon specific anti-infectious drugs, antiretroviral therapy, and nutritional rehabilitation.

Growth, survival and viral load in symptomatic childhood human immunodeficiency virus infection

BACKGROUND

The relationships among weight and height growth, viral load and survival in HIV-infected children remain unclear.

OBJECTIVES

To determine whether weight or height growth velocity independently predicts survival and to investigate associations of weight, height and head circumference growth velocities with viral loads in symptomatic HIV-infected children.

METHODS

We analyzed data from a prospective antiretroviral study utilizing clinical endpoints (PACTG 152). Viral load [log(RNA PCR)] and anthropometric measures 12 weeks before and after viral load measures were available in 494 of 831 children. Interval changes during 24 weeks in z-scores for weight-for-age (DeltaWAZ), height-for-age (DeltaHAZ) and head circumference-for-age (DeltaHCZ) were used as growth velocity surrogates. Logistic regression determined whether DeltaWAZ and/or DeltaHAZ correlated with survival when age, viral load and CD4+ cell count were controlled. Bivariate analysis assessed correlation among viral load and DeltaWAZ, DeltaHAZ and/or DeltaHCZ.

RESULTS

Survival related significantly to height growth velocity (P = 0.03, n = 434) but not to weight growth velocity (P = 0.84, n = 446) or head circumference growth velocity (P = 0.67, n = 148). Viral load was not significantly associated with changes in weight-, height-, or head circumference-for-age z scores (P = 0.86, n = 235; P = 0.07, n = 226; and P = 0.09, n = 165, respectively) in children <30 months of age or with changes in weight- or height-for-age z scores (P = 0.27, n = 259; P = 0.11, n = 251) in older children.

CONCLUSIONS

Height growth velocity predicted survival independently of age, viral load and CD4+ cell count. Weight, height and head circumference growth velocities were not significantly associated with viral load in symptomatic HIV-infected children in this large prospective trial of nucleoside reverse transcriptase therapy.

Effects of nutritional rehabilitation on intestinal function and on CD4 cell number in children with HIV

BACKGROUND

A complex interplay of malnutrition, intestinal dysfunction, and immune impairment increases the progression of human immunodeficiency virus (HIV) disease in children. The authors tested the hypothesis that nutritional support improves intestinal and immune functions in children infected with human immunodeficiency virus (HIV).

METHODS

A questionnaire was circulated through reference centers for pediatric HIV infection to evaluate the effects of nutritional rehabilitation, total parenteral nutrition (TPN) and enteral nutrition (EN), in children. Information included changes in body weight, CD4 cell numbers, and intestinal absorption-as judged by the xylose load-before and after clinical nutritional support and the outcome of children.

RESULTS

Sixty-two children underwent nutritional support: 46 received TPN and 16 received EN. All but three had full-blown acquired immunodeficiency syndrome, and all were severely malnourished. Baseline clinical conditions were worse in children receiving TPN than in those receiving EN. Intestinal dysfunction was detected in all children who received xylose oral load. A significant increase in CD4 cell count, xylose levels, and body weight followed EN. A similar pattern was observed after TPN, but none of the parameters significantly changed. Twenty-seven children who received TPN and three who received EN eventually died. Fourteen who received TPN and eight who received EN were shifted to oral feeding, and five who received TPN and five who received EN continued with clinical nutritional support at the end of the observation period.

CONCLUSIONS

Nutritional intervention may restore intestinal absorption and increase CD4 cell numbers. The efficacy of nutritional intervention is enhanced if provided before a terminal stage of HIV infection. These data provide evidence of a close association among nutritional condition, intestinal absorption, and immune impairment.

[Intestinal absorption of D-xylose in children infected with the human immunodeficiency virus]

AIM

To evaluate the intestinal absorption in HIV-infected children children 14 months to 14 years and to investigate its relationship to diarrhea, nutritional status, immune dysfunction, classical enteric parasites and Cryptosporidium.

METHODS

Intestinal absorption was investigated by measuring serum D-xylose. Fecal samples were investigated for classical pathogens and Cryptosporidium. The sample size was calculated considering a 30% prevalence of altered D-xylose absorption in HIV-infected children with a 5% accuracy. Statistical procedures used were: descriptive measurements, multiple correspondence analysis and logistic regression.

RESULTS

D-xylose absorption was altered in only 8 out of 104 (7.7%) and Cryptosporidium was positive in 33 out of 104 (31.73%) HIV-infected children. The multiple correspondence analysis suggested an association between an altered D-xylose test and Cryptosporidium. D-xylose malabsorption was not associated with diarrhea, nutritional status, immune disfunction and classic enteric parasites.

CONCLUSIONS

Intestinal malabsorption evaluated through the D-xylose test was an uncommon finding in HIV-infected children. Intestinal dysfunction when present seems to be related to Cryptosporidium, but not to diarrhea, nutritional status, immune disfunction and classic enteric parasites.