Low physical function as a risk factor for incident diabetes mellitus and insulin resistance

Major depletion of insulin sensitivity-associated taxa in the gut microbiome of persons living with HIV controlled by antiretroviral drugs

BACKGROUND

Persons living with HIV (PWH) harbor an altered gut microbiome (higher abundance of Prevotella and lower abundance of Bacillota and Ruminococcus lineages) compared to non-infected individuals. Some of these alterations are linked to sexual preference and others to the HIV infection. The relationship between these lineages and metabolic alterations, often present in aging PWH, has been poorly investigated.

METHODS

In this study, we compared fecal metagenomes of 25 antiretroviral-treatment (ART)-controlled PWH to three independent control groups of 25 non-infected matched individuals by means of univariate analyses and machine learning methods. Moreover, we used two external datasets to validate predictive models of PWH classification. Next, we searched for associations between clinical and biological metabolic parameters with taxonomic and functional microbiome profiles. Finally, we compare the gut microbiome in 7 PWH after a 17-week ART switch to raltegravir/maraviroc.

RESULTS

Three major enterotypes (Prevotella, Bacteroides and Ruminococcaceae) were present in all groups. The first Prevotella enterotype was enriched in PWH, with several of characteristic lineages associated with poor metabolic profiles (low HDL and adiponectin, high insulin resistance (HOMA-IR)). Conversely butyrate-producing lineages were markedly depleted in PWH independently of sexual preference and were associated with a better metabolic profile (higher HDL and adiponectin and lower HOMA-IR). Accordingly with the worst metabolic status of PWH, butyrate production and amino-acid degradation modules were associated with high HDL and adiponectin and low HOMA-IR. Random Forest models trained to classify PWH vs. control on taxonomic abundances displayed high generalization performance on two external holdout datasets (ROC AUC of 80-82%). Finally, no significant alterations in microbiome composition were observed after switching to raltegravir/maraviroc.

CONCLUSION

High resolution metagenomic analyses revealed major differences in the gut microbiome of ART-controlled PWH when compared with three independent matched cohorts of controls. The observed marked insulin resistance could result both from enrichment in Prevotella lineages, and from the depletion in species producing butyrate and involved into amino-acid degradation, which depletion is linked with the HIV infection.

The Association Between Polypharmacy and Physical Function in Older Adults: a Systematic Review

BACKGROUND

Reduced physical function and polypharmacy (PPha) are two highly prevalent negative effects of aging, which are expected to increase more, since demographic aging is expected to grow rapidly within the next decades. Previous research suggests that polypharmacy (PPha) is a predictor of poor physical function and vice versa in older adults and therefore we conducted a systematic review of the literature to summarize and critically analyze the relationship between physical function and PPha and vice versa in older adults, in order to provide recent scientific evidence.

METHODS

We searched MEDLINE and Embase from their inception to 19th October 2018 for English-language observational studies or trials assessing the effect of PPha on physical function and vice versa in older adults. Two investigators independently extracted study data and assessed the quality of the studies, after having screened the available studies from the literature search. Any disagreement was resolved by consensus.

RESULTS

Eighteen observational studies met the inclusion criteria. Eight studies assessed the impact of physical function on PPha and ten studies assessed the impact of PPha on physical function. Regarding the studies with PPha measurements as the outcome, all of them, except for one, found that better physical function is associated with lower risk of PPha. Likewise, all the studies with physical function measurements as the outcome, except for one, suggested that PPha is associated with lower physical function.

DISCUSSION

Evidence examining the effect of PPha on physical function and vice versa in older adults suggests a strong bidirectional association between these two factors and clinicians should be aware of this strong relationship. The limitations of our study include the high variability in PPha definitions and physical function measures, and the treatment of PPha and physical function as constant instead of time-varying variables in the studies' analyses.

Aging in HIV-Infected Subjects: A New Scenario and a New View

The prevalence of HIV-infected people aged 50 years or older is increasing rapidly; the proportion will increase from 28% to 73% in 2030. In addition, HIV-infected individuals may be more vulnerable to age-related condition. There is growing evidence that the prevalence of comorbidities and other age-related conditions (geriatric syndromes, functional or neurocognitive/mental problems, polypharmacy, and social difficulties) is higher in the HIV-infected population than in their uninfected counterparts. However, despite the potential impact of this situation on health care, little information exists about the optimal clinical management of older HIV-infected people. Here we examine the age-related conditions in older HIV-infected persons and address clinical management according to author expertise and published literature. Our aim is to advance the debate about the most appropriate management of this population, including less well-studied aspects, such as frequency of screening for psychological/mental and social and functional capabilities.

Physical Activity and Its Association with Insulin Resistance in Multicenter AIDS Cohort Study Men

The association between physical activity (PA), degree of insulin resistance (IR), and HIV infection is unclear. We hypothesized that PA might differentially affect the degree of IR through the direct and indirect influences of HIV, antiretroviral medications, and sociodemographic characteristics. The International Physical Activity Questionnaire (IPAQ) was administered to Multicenter AIDS Cohort Study (MACS) participants from 4/2010 to 3/2011 to generate metabolic equivalents (METs) total score and PA category. We determined the concurrent homeostatic model assessment IR (mmol/liter) (HOMA-IR) value from fasting glucose and insulin. We examined the HIV-PA relationship using quantile regression and the HIV-PA-HOMA-IR value relationship using linear regression. Among the 1,281 men, the proportions of men in the low (25% in HIV(+) vs. 23% in HIV(-)), moderate (26% vs. 27%), and high (49% vs. 49%) PA categories were similar by HIV status. The HOMA-IR value was higher among the HIV(+) men (p<0.001), and both HIV infection and low PA were associated with a higher degree of IR (p<0.0001 and p=0.0007). However, the PA-HOMA-IR value interaction was not different by HIV status. The HOMA-IR value was higher among HIV(+) men although the PA was similar. It is unknown if more exercise will overcome the metabolic derangements associated with HIV and its treatment.

Functional impairment, disability, and frailty in adults aging with HIV-infection

The integration of antiretroviral therapy (i.e., ART) into HIV care has dramatically extended the life expectancy of those living with HIV. However, in comparison to similar HIV-uninfected populations, HIV-infected persons experience an excess of morbidity and mortality with an early onset of aging complications including neurocognitive decline, osteoporosis, impaired physical function, frailty, and falls. Recent consensus guidelines encourage clinicians and researchers to consider functional impairment of HIV-infected adults as a measure to understand the impact of aging across a range of abilities. Despite the importance of assessing function in persons aging with HIV infection, a lack of consistent terminology and standardization of assessment tools has limited the application of functional assessments in clinical or research settings. Herein, we distinguish between different approaches used to assess function, describe what is known about function in the aging HIV population, and consider directions for future research.