Immunotoxic mechanisms of cigarette smoke and heat-not-burn tobacco vapor on Jurkat T cell functions

Cytotoxic effects of the cigarette smoke extract of heated tobacco products on human oral squamous cell carcinoma: the role of reactive oxygen species and CaMKK2

BACKGROUND

The increasing prevalence of heated tobacco products (HTPs) has heightened concerns regarding their potential health risks. Previous studies have demonstrated the toxicity of cigarette smoke extract (CSE) from traditional tobacco's mainstream smoke, even after the removal of nicotine and tar. Our study aimed to investigate the cytotoxicity of CSE derived from HTPs and traditional tobacco, with a particular focus on the role of reactive oxygen species (ROS) and intracellular Ca2+.

METHODS

A human oral squamous cell carcinoma (OSCC) cell line, HSC-3 was utilized. To prepare CSE, aerosols from HTPs (IQOS) and traditional tobacco products (1R6F reference cigarette) were collected into cell culture media. A cell viability assay, apoptosis assay, western blotting, and Fluo-4 assay were conducted. Changes in ROS levels were measured using electron spin resonance spectroscopy and the high-sensitivity 2',7'-dichlorofluorescein diacetate assay. We performed a knockdown of calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) by shRNA lentivirus in OSCC cells.

RESULTS

CSE from both HTPs and traditional tobacco exhibited cytotoxic effects in OSCC cells. Exposure to CSE from both sources led to an increase in intracellular Ca2+ concentration and induced p38 phosphorylation. Additionally, these extracts prompted cell apoptosis and heightened ROS levels. N-acetylcysteine (NAC) mitigated the cytotoxic effects and p38 phosphorylation. Furthermore, the knockdown of CaMKK2 in HSC-3 cells reduced cytotoxicity, ROS production, and p38 phosphorylation in response to CSE.

CONCLUSION

Our findings suggest that the CSE from both HTPs and traditional tobacco induce cytotoxicity. This toxicity is mediated by ROS, which are regulated through Ca2+ signaling and CaMKK2 pathways.

A scoping review of the toxicity and health impact of IQOS

This work aims to summarize the current evidence on the toxicity and health impact of IQOS, taking into consideration the data source. On 1 June 2022, we searched PubMed, Web of Science, and Scopus databases using the terms: 'heated tobacco product', 'heat-not-burn', 'IQOS', and 'tobacco heating system'. The search was time-restricted to update a previous search conducted on 8 November 2021, on IQOS data from 2010-2021. The data source [independent, Philip Morris International (PMI), or other manufacturers] was retrieved from relevant sections of each publication. Publications were categorized into two general categories: 1) Toxicity assessments included in vitro, in vivo, and systems toxicology studies; and 2) The impact on human health included clinical studies assessing biomarkers of exposure and biomarkers of health effects. Generally, independent studies used classical in vitro and in vivo approaches, but PMI studies combined these with modeling of gene expression (i.e. systems toxicology). Toxicity assessment and health impact studies covered pulmonary, cardiovascular, and other systemic toxicity. PMI studies overall showed reduced toxicity and health risks of IQOS compared to cigarettes, but independent data did not always conform with this conclusion. This review highlights some discrepancies in IQOS risk assessment regarding methods, depth, and breadth of data collection, as well as conclusions based on the data source.

A single and short exposure to heated tobacco vapor or cigarette smoke affects macrophage activation and polarization

The toxicity of heated tobacco products (HTP) on the immune cells remains unclear. Here, U937-differentiated macrophages were exposed to a single and short-term exposure (30 minutes) of HTP vapor or cigarette smoke (CS) in an air-liquid interface (ALI) system to evaluate the effects on macrophages' early activation and polarization. In our system, HTP released lower amounts of polycyclic aromatic hydrocarbons (PAHs), but higher nicotine levels than CS into the cell culture supernatant. Both tobacco products triggered the expression of the α-7 nicotinic receptor (α7 nAChR) and reactive oxygen species (ROS) production. When challenged with a bacterial product, lipopolysaccharide (LPS), cells exposed to HTP or CS failed to respond properly and enhance ROS production upon LPS stimuli. Furthermore, both tobacco products also impaired bacterial phagocytosis and the exposures triggered higher IL-1β secretion. The α7 nAChR antagonist treatment rescued the effects caused only by HTP exposure. The CS-exposed group switched macrophage to the pro-inflammatory M1, while HTP polarized to the suppressive M2 profile. Associated, data highlight that HTP and CS exposures similarly activate macrophages; nonetheless, the α7 nAChR pathway is only involved in HTP actions, and the distinct subsequent polarization caused by HTP or CS may influence the outcome of host defense.

Liver toxicity in rats after subchronic exposure to HTP aerosol and cigarette smoke

Background

Heated tobacco product (HTP) considered to be a novel tobacco product which was reported safer than traditional cigarettes evidenced by lower potential harmful components released. Liver is an important detoxification organ of the body, the chemical components in aerosols are metabolized in the liver after absorbed, so it is necessary to explore the effect of HTP on the liver.

Materials and Methods

The potential effect of HTP and cigarette smoke (CS) on SD rats was explored according to OECD 413 subchronic inhalation. The rats were randomly divided into Sham (air), different dosage of HTP groups (HTP_10, 23 and 50 μg nicotine/L aerosol) and Cig_23 (23 μg nicotine/L aerosol) group. After exposure, the clinical pathology, inflammation and oxidative stress were measured.

Results

The clinical pathology results showed that both HTP_50 and Cig_23 led to abnormality of ALT for male rats. CS and HTP exposure reduced the expression of IL-1β, IL-6 and TNF-α and mitochondrial medicated oxidative stress. In addition, the ATP production was reduced in Cig_23 group. Although inflammation and oxidative stress were displayed, no apoptosis were observed by TUNEL assay and these existed obvious pathological changes only in HTP_50 group, while in CS group with equivalent nicotine, hepatocytes swelling were observed in liver.

Conclusion

CS exposure induced liver damage through mitochondrial mediated oxidative stress and inflammation, which was also observed in high concentration of HTP exposure group. For the same equivalent nicotine, HTP may show lower toxic effect on liver than CS.

Comparison of the effects of active and passive smoking of tobacco cigarettes, electronic nicotine delivery systems and tobacco heating products on the expression and secretion of oxidative stress and inflammatory response markers. A systematic review

OBJECTIVES

This work attempts to summarize current knowledge on the effects of active and passive smoking of cigarettes, electronic nicotine delivery systems and tobacco heating products on the expression and secretion of oxidative stress and inflammatory response mediators, and on their possible impact on chronic obstructive pulmonary disease development.

MATERIALS AND METHODS

The literature was searched by the terms: 'smoking', 'active smoking', 'passive smoking', 'main-stream smoke', 'side-stream smoke', 'secondhand smoke', 'cigarette' 'THP', 'tobacco heating product', 'ENDS', 'electronic nicotine delivery system', 'e-cigarette', 'electronic cigarette', oxidative stress', inflammatory response' and 'gene expression'.

RESULTS

Cigarette smoking (active and passive) induces oxidative stress and inflammatory response in the airways. We present the effect of active smoking of e-cigarettes (EC) and heat-not-burn (HnB) products on the increased expression and secretion of oxidative stress and inflammatory response markers. However, there is only a limited number of studies on the effect of their second-hand smoking, and those available mainly describe aerosol composition.

DISCUSSION

The literature provides data which confirm that active and passive cigarette smoking induces oxidative stress and inflammatory response in the airways and is a key risk factor of COPD development. Currently, there is a limited number of data about ENDS and THP active and passive smoking effects on the health of smokers and never-smokers. It is particularly important to assess the effect of such products during long-term use by never-smokers who choose them as the first type of cigarettes, and for never-smokers who are passively exposed to their aerosol.

Xenobiotics Delivered by Electronic Nicotine Delivery Systems: Potential Cellular and Molecular Mechanisms on the Pathogenesis of Chronic Kidney Disease

Chronic kidney disease (CKD) is characterized as sustained damage to the renal parenchyma, leading to impaired renal functions and gradually progressing to end-stage renal disease (ESRD). Diabetes mellitus (DM) and arterial hypertension (AH) are underlying diseases of CKD. Genetic background, lifestyle, and xenobiotic exposures can favor CKD onset and trigger its underlying diseases. Cigarette smoking (CS) is a known modified risk factor for CKD. Compounds from tobacco combustion act through multi-mediated mechanisms that impair renal function. Electronic nicotine delivery systems (ENDS) consumption, such as e-cigarettes and heated tobacco devices, is growing worldwide. ENDS release mainly nicotine, humectants, and flavorings, which generate several byproducts when heated, including volatile organic compounds and ultrafine particles. The toxicity assessment of these products is emerging in human and experimental studies, but data are yet incipient to achieve truthful conclusions about their safety. To build up the knowledge about the effect of currently employed ENDS on the pathogenesis of CKD, cellular and molecular mechanisms of ENDS xenobiotic on DM, AH, and kidney functions were reviewed. Unraveling the toxic mechanisms of action and endpoints of ENDS exposures will contribute to the risk assessment and implementation of proper health and regulatory interventions.

Effect of heated tobacco products and traditional cigarettes on pulmonary toxicity and SARS-CoV-2-induced lung injury

Cigarette smoke (CS) significantly contributes to the development of chronic obstructive pulmonary disease (COPD). Heated tobacco products (HTPs), newly developed cigarette products, have been proposed as an alternative for safe cigarette smoking. Although it is plausible to think that replacing traditional cigarettes with HTPs would lower the risks of COPD, this notion requires confirmation by further investigations from sources independent of the tobacco industry. COPD is characterized by an ongoing inflammatory process in the lungs, and the renin-angiotensin system (RAS) has been implicated in the pathogenesis of COPD. Angiotensin-converting enzyme-2 (ACE2) functions as a negative regulator of RAS and has been suggested as a cellular receptor for the causative agent of SARS-CoV-2. It has been shown that smoking is most likely associated with the negative progression and adverse outcomes of SARS-CoV-2. In this study, we found that cigarette smoke extracts from traditional cigarettes (CSE) caused higher cytotoxicity and higher oxidative stress levels than extracts from HTPs (HTPE) in two lung cell lines (Calu-3 and Beas-2B). CSE and HTPE induced RAS activation, MAPK activation, and NF-kB inflammatory pathway activation, resulting in the production of inflammatory cytokines. Furthermore, CSE and a high dose of HTPE reduced tight junction proteins, including claudin 1, E-cadherin, and ZO-1, and disrupted lung epidermal tight junctions at the air-liquid interface (ALI). Finally, CSE and HTPE enhanced the spike protein S1-induced lung injury response. Together, these results suggest that HTPE induced similar lung pathogenesis relevant to COPD and SARS-CoV-2-induced lung injury caused by CSE.

Toxic mechanisms of cigarette smoke and heat-not-burn tobacco vapor inhalation on rheumatoid arthritis

Tobacco combustion exposure worsens rheumatoid arthritis (RA). Non-combustible tobacco devices, as heat-not-burn tobacco (HNBT), are emerging as harm reduction to smokers by releasing nicotine and lower combustible tobacco products. Nevertheless, HNBT toxicity remains unclear. Hence, here we investigated the impacts of the tobacco combustible product (cigarette smoke; CS) or HNBT vapor exposures on antigen-induced arthritis (AIA) in C57BL/6 mice. Animals were exposed to airflow, HNBT vapor, or CS during 1 h/twice a day, under the Health Canada Intense (HCI) smoking regime, between days 14 to 20 after the first immunization. At day 21, 16 h after the last exposures, mice were i.a. challenged and the AIA effects were evaluated 24 h later. CS- or HNBT-exposed mice presented equivalent blood nicotine levels. CS exposure worsened articular symptoms, pulmonary inflammation, and expression of lung metallothioneins. Nevertheless, CS or HNBT exposures reduced lymphoid organs' cellularity, splenocyte proliferation and IL-2 secretion. Additional in vitro CS or HNBT exposures confirmed the harmful effects on splenocytes, which were partially mediated by the activation of nicotine/α7nAchR pathway. Associated, data demonstrate the toxic mechanisms of CS or HNBT inhalation at HCI regime on RA, and highlight that further investigations are fundamental to assure the toxicity of emerging tobacco products on the immune system during specific challenges.

Hydroquinone Exposure Worsens Rheumatoid Arthritis through the Activation of the Aryl Hydrocarbon Receptor and Interleukin-17 Pathways

Rheumatoid arthritis (RA) development is strongly associated with cigarette smoke exposure, which activates the aryl hydrocarbon receptor (AhR) as a trigger for Th17 inflammatory pathways. We previously demonstrated that the exposure to hydroquinone (HQ), one of the major compounds of cigarette tar, aggravates the arthritis symptomatology in rats. However, the mechanisms related to the HQ-related RA still remain elusive. Cell viability, cytokine secretion, and gene expression were measured in RA human fibroblast-like synoviocytes (RAHFLS) treated with HQ and stimulated or not with TNF-α. Antigen-induced arthritis (AIA) was also elicited in wild type (WT), AhR ^−/− or IL-17R ^−/− C57BL/6 mice upon daily exposure to nebulized HQ (25ppm) between days 15 to 21. At day 21, mice were challenged with mBSA and inflammatory parameters were assessed. The in vitro HQ treatment up-regulated TNFR1, TNFR2 expression, and increased ROS production. The co-treatment of HQ and TNF-α enhanced the IL-6 and IL-8 secretion. However, the pre-incubation of RAHFLS with an AhR antagonist inhibited the HQ-mediated cell proliferation and gene expression profile. About the in vivo approach, the HQ exposure worsened the AIA symptoms (edema, pain, cytokines secretion and NETs formation) in WT mice. These AIA effects were abolished in HQ-exposed AhR ^−/− and IL-17R ^−/− animals though. Our data demonstrated the harmful HQ influence over the onset of arthritis through the activation and proliferation of synoviocytes. The HQ-related RA severity was also associated with the activation of AhR and IL-17 pathways, highlighting how cigarette smoke compounds can contribute to the RA progression.

Predicting related factors of immunological response to hepatitis B vaccine in hemodialysis patients based on integration of decision tree classification and logistic regression

The non/hypo-response rate of the hepatitis B vaccine among hemodialysis (HD) patients is still high, it is of great significance to explore the influencing factors and their relationships. To study the related factors and their relationships using logistic regression model and Chi-squared Automatic Interaction Detection (CHAID) decision tree model. A randomized controlled trial was conducted between February 2014 and May 2015 in China. HD patients being serologically negative for HBsAg and anti-HBs were randomly assigned to receive three intramuscular injections of the standard dose (20 µg) or high dose (60 µg) of recombinant hepatitis B vaccine at months 0, 1, and 6. Those with anti-HBs concentrations <100 mIU/mL, and ≥100 mIU/mL at month 7 were considered as non/hypo-response and high-level response, respectively. The non/hypo-response was 31.34% (89/284). After adjustment for confounders, logistic analysis showed that males (OR = 2.203, 95%CI: 1.109-4.367) and those with higher dialysis frequency (>4 times per 2 weeks) (OR = 1.918, 95%CI: 1.015-3.626) had a significant risk of non/hypo-response. While the CHAID analysis showed that gender, dose, and dialysis frequency were influencing factors of non/hypo-response, and gender is most important. The interaction between gender and dialysis frequency had the greatest effect on immunization, and followed by the interaction between dialysis frequency and vaccine dose. Taken together, gender, dose and dialysis frequency were influencing factors of hepatitis B vaccine in HD patients.