Hyperphagia contributes to the normal body composition and protein-energy balance in HIV-infected asymptomatic men

Management and Complications of Short Bowel Syndrome: an Updated Review

Short bowel syndrome (SBS) is defined as loss of bowel mass from surgical resection, congenital defects, or disease. Intestinal failure (IF) includes the subset of SBS unable to meet nutrition needs with enteral supplements and requires parenteral nutrition (PN). The parenteral treatment of SBS is now a half-century old. Recent pharmacologic treatment (GLP-2 analogues) has begun to make a significant impact in the care and ultimate management of these patients such that the possibility of reducing PN requirements in formerly PN-dependent patients is a now a real possibility. Finally, newer understanding and possible treatment for some of the complications related to IF have more recently evolved and will be an emphasis of this report. This review will focus on developments over the last 10 years with the goal of updating the reader to new advances in our understanding of the care and feeding of the SBS patient.

Effect of probiotic bacteria on microbial host defense, growth, and immune function in human immunodeficiency virus type-1 infection

The hypothesis that probiotic administration protects the gut surface and could delay progression of Human Immunodeficiency Virus type1 (HIV-1) infection to the Acquired Immunodeficiency Syndrome (AIDS) was proposed in 1995. Over the last five years, new studies have clarified the significance of HIV-1 infection of the gut associated lymphoid tissue (GALT) for subsequent alterations in the microflora and breakdown of the gut mucosal barrier leading to pathogenesis and development of AIDS. Current studies show that loss of gut CD4+ Th17 cells, which differentiate in response to normal microflora, occurs early in HIV-1 disease. Microbial translocation and suppression of the T regulatory (Treg) cell response is associated with chronic immune activation and inflammation. Combinations of probiotic bacteria which upregulate Treg activation have shown promise in suppressing pro inflammatory immune response in models of autoimmunity including inflammatory bowel disease and provide a rationale for use of probiotics in HIV-1/AIDS. Disturbance of the microbiota early in HIV-1 infection leads to greater dominance of potential pathogens, reducing levels of bifidobacteria and lactobacillus species and increasing mucosal inflammation. The interaction of chronic or recurrent infections, and immune activation contributes to nutritional deficiencies that have lasting consequences especially in the HIV-1 infected child. While effective anti-retroviral therapy (ART) has enhanced survival, wasting is still an independent predictor of survival and a major presenting symptom. Congenital exposure to HIV-1 is a risk factor for growth delay in both infected and non-infected infants. Nutritional intervention after 6 months of age appears to be largely ineffective. A meta analysis of randomized, controlled clinical trials of infant formulae supplemented with Bifidobacterium lactis showed that weight gain was significantly greater in infants who received B. lactis compared to formula alone. Pilot studies have shown that probiotic bacteria given as a supplement have improved growth and protected against loss of CD4+ T cells. The recognition that normal bacterial flora prime neonatal immune response and that abnormal flora have a profound impact on metabolism has generated insight into potential mechanisms of gut dysfunction in many settings including HIV-1 infection. As discussed here, current and emerging studies support the concept that probiotic bacteria can provide specific benefit in HIV-1 infection. Probiotic bacteria have proven active against bacterial vaginosis in HIV-1 positive women and have enhanced growth in infants with congenital HIV-1 infection. Probiotic bacteria may stabilize CD4+ T cell numbers in HIV-1 infected children and are likely to have protective effects against inflammation and chronic immune activation of the gastrointestinal immune system.

Energy expenditure in HIV infection

Energy intake recommendations for adults should be based preferably on direct measurements of total daily energy expenditure (TDEE) in corresponding populations who are maintaining healthy body weight and satisfactory physical activity levels. During adolescence, pregnancy, and lactation, energy requirements should be based on TDEE plus the additional energy required to advance these physiologic states. With illness, energy expenditure and energy intake change, but nutritional intervention is not necessarily beneficial. This article reviews data on energy expenditure in HIV infection with a focus on adults, adolescents aged ≥14 y, and pregnant and lactating women. Resting energy expenditure (REE) in adults with untreated asymptomatic HIV is ~ 10% higher than in healthy control subjects. In asymptomatic adults receiving antiretroviral therapy, REE may be similarly increased. HIV wasting and secondary infections are also associated with increased REE. In contrast, TDEE is typically normal in asymptomatic HIV and decreased in HIV wasting and secondary infection. No direct measurements of REE or TDEE are available in adolescents or in pregnant or lactating women with HIV. On the basis of current data, energy intake may need to increase by ~ 10% in adults with asymptomatic HIV to maintain body weight. In adolescents and in pregnant and lactating women with asymptomatic HIV, energy requirements should approximate recommendations for their uninfected counterparts until further data are available. In the resource-rich world, the energy expenditure changes associated with HIV are unlikely to contribute to significant weight loss. More data are needed on energy expenditure in HIV-infected populations from developing nations, where concurrent malnutrition and coinfections are common.

Reliability of scored patient generated subjective global assessment for nutritional status among HIV infected adults in TASO, Kampala

OBJECTIVE

Establish the reliability of the scored Patient Generated-Subjective Global Assessment (PG-SGA) in determining nutritional status among Antiretroviral Therapy (ART) naive HIV-infected adults.

METHODS

A descriptive, cross sectional study among outpatient medical clinics, in The AIDS Support Organization (TASO), Mulago Centre, Kampala, Uganda. The study group (n=217) consisted of male (n=60) and female (n=157) HIV patients (18-67 years). Purposive sampling was used. Anthropometry (weight, height, BMI), nutritional history (body weight, dietary intake, gastrointestinal symptoms, functional capacity and infections), and clinical status were assessed. Sensitivity and specificity of PG-SGA were determined using Receiver Operating Characteristic (ROC) curve. Data collection was done from April-May 2008.

RESULTS

Only 12% of the subjects were underweight and over half (58.2%) had normal weight. The PG-SGA had low sensitivity (69.2%) and specificity (57.1%) at categorizing the risk for malnutrition indicated by BMI< 18.5.

CONCLUSION

There was a high prevalence of malnutrition among the study group. Overall, this study indicated the PG-SGA could not adequately discriminate between underweight and normal patients. The tool was not reliable enough for determining nutritional status in this population.

Position of the American Dietetic Association: Nutrition Intervention and Human Immunodeficiency Virus Infection

It is the position of the American Dietetic Association that efforts to optimize nutritional status through individualized medical nutrition therapy, assurance of food and nutrition security, and nutrition education are essential to the total system of health care available to people with human immunodeficiency virus (HIV) infection throughout the continuum of care. Broad-based efforts to improve health care access and treatment have stabilized HIV prevalence levels in many parts of the world and led to longer survival for people living with HIV infection. Confounding clinical and social issues, such as medication interactions, comorbidities, wasting, lipodystrophy, food insecurity, aging, and other related conditions further complicate disease management. With greater understanding of the mechanisms of HIV disease and its impact on body function, development of new treatments, and wider ranges of populations affected, the management of chronic HIV infection continues to become more complex and demanding. Achievement of food and nutrition security and management of nutrition-related complications of HIV infection remain significant challenges for clients with HIV infection and health care professionals. Registered dietitians and dietetic technicians, registered, should integrate their efforts into the overall health care strategies to optimize their clinical and social influence for people living with HIV infection.

Plasma citrulline is a biomarker of enterocyte mass and an indicator of parenteral nutrition in HIV-infected patients

BACKGROUND

Plasma citrulline is a biomarker of enterocyte mass and function in humans.

OBJECTIVE

We evaluated citrulline in the reemerging context of diarrhea in HIV-infected patients receiving highly active antiretroviral therapy.

DESIGN

This study prospectively measured citrulline in 6 groups of HIV-1 patients (n = 115): 1) undetectable viral load without chronic diarrhea (a; n = 40) and with protease inhibitor-associated toxic chronic diarrhea (b; n = 26), 2) detectable viral load and CD4 > 200/mm(3) without (a; n = 6) and with (b; n = 11) chronic diarrhea, and 3) detectable viral load and CD4 <200/mm(3) without chronic diarrhea (a; n = 7) and with opportunistic intestinal infections or HIV enteropathy (b; n = 25). The influence of diarrhea on citrulline was assessed by comparing the a and b subgroups with healthy control subjects (n = 100).

RESULTS

Citrulline was slightly decreased (22-30 micromol/L) in groups 1b and 2b and was <22 micromol/L in 19 of 25 patients in group 3b. In group 3b, a citrulline concentration <10 micromol/L was associated with a clinical indication for parenteral nutrition (n = 6 of 8 compared with 2 of 17 if the citrulline concentration was >10 micromol/L; P < 0.05). Citrulline correlated positively with albumin (P < 0.01) and BMI (P < 0.05) and negatively with C-reactive protein (P < 0.01). When antiinfectious and nutritional therapies were successful (n = 18 of 25), citrulline normalized in 2-12 wk. Neither chronic hepatic or pancreatic disease nor lipodystrophy and the metabolic syndrome affected citrulline. Compared with control subjects (38 +/- 8 micromol/L), patients without chronic diarrhea (groups 1a, 2a, and 3a) had normal citrulline concentrations (36 +/- 6 micromol/L).

CONCLUSIONS

Plasma citrulline is a reliable biomarker of enterocyte functional mass in HIV patients. Citrulline does not allow the etiologic diagnosis of enteropathy, but it can discriminate between protease inhibitor toxic diarrhea and infectious enteropathy and quantify the functional consequences, which makes it an objective tool for indicating the need for parenteral nutrition.

Citrulline as a biomarker of intestinal failure due to enterocyte mass reduction

BACKGROUND & AIMS

In human, citrulline (plasma concentration about 40 micromol/L) is an amino acid involved in intermediary metabolism and that is not incorporated in proteins. Circulating citrulline is mainly produced by enterocytes of the small bowel. For this reason plasma or serum citrulline concentration has been proposed as a biomarker of remnant small bowel mass and function. This article reviews this concept and its metabolic basis.

METHODS

Conditions in which there is a significantly reduced small bowel enterocyte mass and function and a plasma or serum citrulline were measured in adults and children. These studies included patients with a short bowel syndrome, villous atrophy states, Crohn's disease, during monitoring of digestive toxicity of chemotherapy and radiotherapy or follow-up of patients after small bowel transplantation.

RESULTS

In all these situations, with more than 500 studied patients a decreased level of plasma citrulline correlated with the reduced enterocyte mass independently of nutritional and inflammatory status. A close correlation between small bowel remnant length and citrullinemia was found. In addition, diagnosis of intestinal failure was assessed through plasma citrulline levels in severe small bowel diseases in which there is a marked enterocyte mass reduction.

DISCUSSION

The threshold for establishing a diagnosis of intestinal failure is lower in villous atrophy disease (10mumol/L) than in short bowel syndrome (20mumol/L). Compromised renal function is an important factor when considering plasma citrulline levels as a marker of intestinal failure as this potentially can increase circulating citrulline values.

CONCLUSIONS

Reduced plasma citrulline levels are an innovative quantitative biomarker of significantly reduced enterocyte mass and function in different disease states in humans.

The energetics of wasting diseases

PURPOSE OF REVIEW

Unintentional weight loss or wasting continues to be a nutritional problem in the treatment of HIV/AIDS, cancer and many other diseases. Although wasting is a general sign of energy imbalance, the relative contribution of increased energy demands and decreased energy intake remains incompletely understood.

RECENT FINDINGS

Until the development of the method using doubly labeled water for measuring total energy expenditure, it was difficult to obtain unbiased estimates of total energy expenditure, particularly in clinical populations. Although costly, this technique provides greater insight in the energy requirements of clinical populations and the relative contributions of energy expenditure, energy intake and disease to wasting diseases. Although data are available in only a small portion of wasting diseases, the data suggest that even in the presence of increased demands for resting metabolic rate, total energy expenditure is often reduced because of decreased physical activity.

SUMMARY

Wasting is often the result of endocrine disorders accompanying the disease process itself. This, coupled with reduced energy intake, is often the primary contributor to wasting.

Dysregulated Energy Expenditure in HIV-Infected Patients: A Mechanistic Review

Metabolic abnormalities are common in patients with human immunodeficiency virus (HIV) infection and range from protein catabolism to lipodystrophy and dyslipidemia associated with the use of highly active antiretroviral therapy. One abnormality is increased resting energy expenditure, which even occurs in clinically stable HIV-infected patients. Increased resting energy expenditure may aggravate the tendency towards weight loss and wasting, which are independent predictors of mortality. Despite much investigation, the factors associated with altered resting energy expenditure remain unclear; viral load, CD4 cell count, use of antiretroviral drugs, body composition, hormones, and proinflammatory cytokines have been imputed. Mechanisms that could explain increased resting energy expenditure include the HIV accessory protein viral protein R, antiretroviral drugs that affect mitochondrial function, and futile cycling within adipocytes. Other components of energy expenditure are also important to overall energy balance and may also be affected. Identifying unifying mechanisms will be an important step to finding effective treatments for HIV-related alterations in energy expenditure and to reversing metabolic risks in patients with HIV infection.

Nutritional and metabolic abnormalities in pre-AIDS HIV infection

Since the earliest reports of human immunodeficiency virus (HIV) disease, undernutrition has been associated with HIV infection, typically with the late stages of the disease (namely acquired immunodeficiency syndrome), and may advance to severe wasting and cachexia. Specific micronutrient deficiencies are also recognized to occur with HIV infection, but their actual effect on the clinical course of the disease is hard to assess. The studies reviewed provide more insight into the complex interface between undernutrition and, in some cases, obesity and HIV/acquired immunodeficiency syndrome and highlight the possibility of alleviating or curing undernutrition by means of simple and comparatively inexpensive dietary adjustments.

Whole body leucine flux in HIV-infected patients treated with or without protease inhibitors

The present study was carried out to assess the effects of protease inhibitor (PI) therapy on basal whole body protein metabolism and its response to acute amino acid-glucose infusion in 14 human immunodeficiency virus (HIV)-infected patients. Patients treated with PIs (PI+, 7 patients) or without PIs (PI-, 7 patients) were studied after an overnight fast during a 180-min basal period followed by a 140-min period of amino acid-glucose infusion. Protein metabolism was investigated by a primed constant infusion of l-[1-(13)C]leucine. Dual-energy X-ray absorptiometry for determination of fat-free mass (FFM) and body fat mass measured body composition. In the postabsorptive state, whole body leucine balance was 2.5 times (P < 0.05) less negative in the PI+ than in the PI- group. In HIV-infected patients treated with PIs, the oxidative leucine disposal during an acute amino acid-glucose infusion was lower (0.58 +/- 0.09 vs. 0.81 +/- 0.07 micromol x kg FFM(-1) x min(-1) using plasma [(13)C]leucine enrichment, P = 0.06; or 0.70 +/- 0.10 vs. 0.99 +/- 0.08 micromol x kg FFM(-1) x min(-1) using plasma [(13)C]ketoisocaproic acid enrichment, P = 0.04 in PI+ and PI- groups, respectively) than in patients treated without PIs. Consequently, whole body nonoxidative leucine disposal (an index of protein synthesis) and leucine balance (0.50 +/- 0.10 vs. 0.18 +/- 0.06 micromol x kg FFM x (-1) x min(-1) in PI+ and PI- groups respectively, P < 0.05) were significantly improved during amino acid-glucose infusion in patients treated with PIs. However, whereas the response of whole body protein anabolism to an amino acid-glucose infusion was increased in HIV-infected patients treated with PIs, any improvement in lean body mass was detected.

Investigating heterogeneity in studies of resting energy expenditure in persons with HIV/AIDS: a meta-analysis

BACKGROUND

There is conflict in the literature about the extent of alterations of resting energy expenditure (REE) in persons with HIV.

OBJECTIVE

The study was conducted to ascertain the mean difference in REE (in kJ) per kilogram of fat-free mass (FFM; REE/FFM) between HIV-positive subjects and control subjects and to investigate heterogeneity in the literature.

DESIGN

A meta-analysis comparing classical and Bayesian methods was conducted. Heterogeneity was investigated by using subgroup analysis, metaregression, and a mixed indirect comparison.

RESULTS

Of 58 studies meeting the inclusion criteria, 32 included both HIV-positive and control groups; 24 of these 32 were included. Thirty-seven studies were used in the mixed indirect comparison, and 30 were used in the subgroup comparisons of the HIV-symptomatic, lipodystrophy, weight-losing, and weight-stable subgroups and the healthy (HIV-negative) control group. Mean REE/FFM was significantly higher in 732 HIV-positive subjects than in 340 control subjects [11.93 kJ/kg (95% CI: 8.44,15.43 kJ/kg) and 12.47 kJ/kg (95% CI: 8.19,16.57 kJ/kg), classical and Bayesian random effects, respectively]; the test for heterogeneity was significant (P < 0.001). Both the mixed indirect comparison and the subgroup analysis indicated that REE/FFM was highest in the symptomatic subgroup; however, the small number of studies investigating symptomatic subjects limited statistical comparisons. The presence of lipodystrophy, use of highly active antiretroviral therapy, subject age, and method of body-composition measurement could not explain the heterogeneity in the data with the use of metaregression.

CONCLUSIONS

REE/FFM (kJ/kg) is significantly higher in HIV-positive subjects than in healthy control subjects. Symptomatic HIV infection may contribute to the variations reported in the literature.