E-cigarette use associated with lower eosinophil counts among patients with HIV
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Key takeaways:
- The association persisted despite age, gender, race, and combustion cigarette and marijuana use.
- Users who did not have HIV had higher eosinophil counts.
- Basophil counts saw similar effect modification.
BOSTON — The impact of e-cigarette use on eosinophil and basophil counts may depend on HIV serostatus, according to a study presented at the CHEST Annual Meeting.
These findings may have implications for new studies of e-cigarette use and its long-term consequences, Hamam Aneis, MD, internal medicine resident, University of Pittsburgh Medical Center (UPMC), said during his presentation.
“E-cigarette use is rapidly increasing, particularly among vulnerable populations such as people living with HIV,” Aneis told Healio. “However, there are limited studies on how e-cigarettes affect this group compared to HIV-negative individuals.”
Given the unique immune challenges faced by people living with HIV (PLWH), researchers established the Electronic Nicotine Delivery Devices and Potential Progression to Acute Lung Injury, or ENDALI, cohort at UPMC, including both HIV-positive and HIV-negative e-cigarette users and nonusers.
“The cohort aims to assess how e-cigarette use impacts self-reported asthma, dyspnea, airway obstruction (measured by spirometry), and inflammatory biomarkers in both HIV-positive and HIV-negative individuals,” Aneis said.
Study design, results
The study included 24 PLWH and 52 participants who were seronegative for HIV aged 18 to 80 years. Also, 38 of these participants used e-cigarettes at least once a week for more than 3 months (mean age, 40 years), and 38 had never used e-cigarettes (mean age, 52 years).
“E-cigarette users were generally younger and had higher rates of combustion cigarette and marijuana use compared to nonusers,” Aneis said.
Combustion cigarette use was reported by 71% of the e-cigarette users and 26% of the never users (P < .001). Similarly, marijuana use was reported by 92% of the e-cigarette users and 50% of the nonusers (P < .001).
“Another interesting finding was the trend of increased self-reported asthma in both PLWH and HIV-negative individuals who used e-cigarettes,” Aneis said.
Specifically, 29% of the e-cigarette users and 5% of the never users had a previous asthma diagnosis (P = .006). St. George’s Respiratory Questionnaire scores included 17 for the users and 7 for the never users (P = .002). Modified Medical Research Council Questionnaire scores included 1.1 for the users and 0.5 for the never users (P = .03).
Forced vital capacity (FVC) percent predicted included 99% for the users and 92% for the nonusers (P = .04). FEV1/FVC included 0.95 for the users and 0.99 for the never users (P = .04).
“The most notable finding was that e-cigarette use is negatively associated with eosinophil and basophil levels dependent upon HIV status,” Aneis said. “This differential immune response based on HIV serostatus was unexpected. This is the first description of a potential biomarker of e-cigarette use dependent on HIV status.”
The researchers said there was no association between e-cigarette use and circulating eosinophil counts in all comers. However, there was an association between e-cigarette use and lower eosinophil count among the PLWH group regardless of age, gender, race, and combustion cigarette and marijuana use (P = .03).
Additionally, there was an association between e-cigarette use and higher eosinophil count among the group that was HIV seronegative regardless of age, gender, race and combustion cigarette and marijuana use (P = .05).
These findings demonstrate that the association between e-cigarette use and eosinophil count was modified by HIV serostatus, the researchers said, with a P value of .01 for effect modification.
The association between e-cigarette use and basophil counts was similarly modified by HIV serostatus, also with a P value of .01 for effect status, the researchers continued.
Conclusions, next steps
These associations between e-cigarette and lower circulating eosinophil counts among PLWH and higher circulating eosinophil counts among participants who were HIV seronegative indicate that exposure to e-cigarettes may prompt a different immune response among PLWH, the researchers continued.
“Lower eosinophil levels in PLWH using e-cigarettes could indicate altered immune responses, potentially impacting their ability to manage allergic inflammation and respiratory health,” Aneis said.
“This observation may reflect a reduction in Th2 inflammation,” he continued. “Nevertheless, it could potentially be a sign of a decreased total CD4 T lymphocyte pool.”
Aneis noted that doctors should be aware of the differential immune responses to e-cigarette use in PLWH.
“Monitoring eosinophil counts and lung function in PLWH who use e-cigarettes could provide early indicators of respiratory health deterioration, enabling earlier intervention and tailored treatment strategies,” he said.
“Interventions should include personalized cessation plans, integrating smoking cessation counseling with support specific to PLWH, who may face unique mental health challenges such as higher rates of depression and anxiety,” he said.
Although these findings suggest directions for future studies of the long-term consequences of exposure to e-cigarettes, the researchers said, longitudinal studies are necessary for understanding how e-cigarette use impacts PLWH.
“We plan to conduct longitudinal studies to better understand the long-term impact of e-cigarette use on the immune systems of PLWH and how e-cigarettes affect markers of HIV disease activity,” Aneis said. “Additionally, the Pittsburgh Vaping Questionnaire was developed to collect detailed information on e-cigarette use and can be utilized in future studies.”
For more information:
Hamam Aneis, MD, can be reached at aneish@upmc.edu.
Perspective
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I think that this evaluation adds to the ongoing body of evidence surrounding smoking and e-cigarette use and eosinophils. The correlation between cigarette and e-cigarette smoking and blood eosinophil counts has been investigated numerous times with discordant results, and this is a unique cohort in which to evaluate this.
The subpopulation of patients living with HIV is not frequently studied with regard to cigarette smoking and COPD. In fact, they are much more frequently excluded from these studies. This study presents an interesting analysis of this group that mirrors some of the findings we have seen among COPD patients with severe disease.
Some of our prior analyses have indicated that low blood eosinophil counts confer a worse prognosis among patients with COPD with regard to lung function decline and exacerbation risk, and this abstract suggests that this could also be true for patients living with HIV who use e-cigarettes. I think this is another data point in our arsenal that we can point to in order to encourage smoking and e-cigarette cessation.
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