How does the combined effect of smoking and HIV infection influence the aging-related manifestations?

A recent Scientific Reports study investigated whether the combination of human immunodeficiency virus (HIV) infection and smoking influence bone mineral density (BMD), lung function (FEV1), forced vital capacity (FVC), aortic pulse-wave velocity (PWV), appendicular skeletal muscle mass index (ASMI), insulin resistance (HOMA-IR) and renal function.

Study: Combined effects of smoking and HIV infection on the occurrence of aging-related manifestations. Image Credit: Nopphon_1987/Shutterstock.com

Background

The life expectancy of people living with HIV (PLWH) has increased due to the advent of combined antiretroviral therapy (ART). At present, the median life expectancy of this group of people is higher than 50 years.

However, they die much earlier than non-infected people, predominantly due to the development of age-related comorbidities, such as cardiovascular diseases, diabetes, chronic obstructive pulmonary diseases, osteoporosis, and renal insufficiency. 

Besides enhancing the risk of mortality, each of the aforementioned comorbidities independently worsens the quality of life of patients.

Two conditions, namely, increased central adiposity and reduced limb muscles, are linked with five-year all-cause mortality in HIV infection. It is imperative to understand whether the increased mortality risk is linked to HIV disease and ART or other factors, such as environmental and aging. 

Identifying modifiable risk factors could help reduce or reverse the development of comorbidities. Several studies have shown that tobacco smoking is a modifiable risk factor that influences the manifestations of osteoporosis and lung/heart diseases.

In comparison to the general population, a higher tobacco smoking rate has been documented among PLWH. However, no studies have determined whether this could be a key driving factor for age-related diseases and the generation of comorbidities in PLWH.

In addition, it is not clear whether HIV infection influences the association between smoking and the generation of comorbidities. It is important to understand whether HIV and tobacco smoking exert ill effects independently or via potential interactions.

About the study

The current study examined the association between smoking and biological parameters, such as bone mineral density, arterial stiffness, kidney function, insulin resistance, and muscle mass, in PLWH and non-HIV patients.

This study evaluated multiple systemic manifestations linked to PLWH, and each was assessed separately to understand their influence on disease outcomes better. 

This study recruited individuals living with HIV from the CARDAMONE study, which is a cross-sectional monocentric study of adult PLWH. All participants were recruited between 2009 and 2012.

The participants' eligibility criteria were that their plasma HIV RNA must be below 50 copies/ml and were under c-ART. None of the participants had undergone any major cardiovascular event, such as chronic heart failure. 

For the control group, people without HIV infection were selected. Current and former smokers were distinguished. It must be noted that this study defined smokers to be those who smoked more than 100 cigarettes in their lifetime.

Study findings

A total of 629 patients were recruited in this study, where the PLWH group contained 239 participants, and the control group comprised 390 participants. Based on 1:1 age- and gender-matching, 189 patients were assigned to each group, i.e., PLWH and control.

The mean age of the participants was 49.8 years. No statistically significant difference was observed between the two study groups regarding mean past cigarette smoke exposure.

In comparison to the control group, a higher rate of tobacco smokers and sarcopenia were present in the PLWH group. The latter group exhibited a lower estimated glomerular filtration rate (eGFR), body mass index (BMI), and musculoskeletal parameters, such as lumbar and hip BMD and ASMI, compared to the control.

The current study indicated that tobacco smoking acts synergistically with HIV infection to develop age-related complications. Here, smoking was found to be more robustly associated with carotid intima-media thickness and myocardial infarction in PLWH compared to the control group.

The findings conform with those reported in previous studies, which indicated a higher decline in lung function in the PLWH group compared to non-HIV-infected subjects. It must be noted that no difference in arterial stiffness was observed between smoking and HIV categories.

Typically, this parameter is a strong indicator of increased cardiovascular events, particularly atherosclerosis, in both the general population and PLWH. Taken together, the expression of manifestations induced by cigarette smoking varied based on the HIV status.

Conclusions

The current study highlighted that HIV infection and smoking synergistically interact and elevate each other’s negative impact on aging. Particularly, this interaction manifests detrimental effects on lung function, muscle mass, and bone mineral density.

Considering the study findings, governments and policymakers must focus on the cessation of tobacco to improve the health outcomes of the general population, particularly those with HIV.

Written by

Dr. Priyom Bose

Priyom holds a Ph.D. in Plant Biology and Biotechnology from the University of Madras, India. She is an active researcher and an experienced science writer. Priyom has also co-authored several original research articles that have been published in reputed peer-reviewed journals. She is also an avid reader and an amateur photographer.