Variation in blood levels of inflammatory markers related and unrelated to smoking cessation in women

Assessing the association between cigarette smoking and blood C-reactive protein levels using restructured cohort data

INTRODUCTION

Cigarette smoke exposure is known to induce inflammation, leading to elevated levels of inflammatory markers such as white blood cell (WBC) count and C-reactive protein (CRP). Despite extensive research on this relationship, longitudinal studies are limited. We aimed to explore the association between cigarette smoke exposure and WBC count and CRP levels by restructuring community cohort data.

METHODS

Data from a community cohort of the Korean population, followed biennially from 2001 to 2018, were utilized. Smoking status was determined through self-administered questionnaires. WBC and CRP levels were measured in a central laboratory with stringent quality control. Cohort data were restructured into pairs representing before and after measurements. We analyzed smoking effects on WBC and CRP using pairwise before-after tests based on changes in smoking status. Furthermore, parallel group analyses comparing changes in smoking status to no change were conducted.

RESULTS

Analysis included 4336 pairs for WBC and 3068 pairs for CRP from 10,030 participants. Pairwise analysis showed a significant decrease in WBC transitioning from current smoker to non-smoker and an increase from non-smoker to current smoker. Parallel group analysis demonstrated a significant decrease in WBC transitioning from current smoker to non-smoker compared to remaining current smoker, and an increase from non-smoker to current smoker compared to remaining non-smoker. CRP did not exhibit significant associations in either analysis.

CONCLUSIONS

In a community cohort, cigarette smoking was associated with elevated WBC count. However, CRP levels did not consistently reflect inflammation associated with cigarette smoking.

Impact of switching from cigarette smoking to tobacco heating system use on biomarkers of potential harm in a randomized trial

BACKGROUND

Smoking cessation reduces the risk of developing smoking-related diseases. Although smoking prevalence has declined, many continue smoking cigarettes. Switching completely to smoke-free alternatives like the Tobacco Heating System (THS) 2.2-a heated tobacco product for which there is evidence demonstrating significantly reduced formation and exposure to harmful chemicals compared to cigarettes-has the potential to reduce the harm caused by continuing to smoke cigarettes.

METHODS

We conducted a 6-month clinical study (NCT02396381) with a 6-month extension (NCT02649556), initially randomizing 984 adult smokers to continue smoking or switch to THS (non-mentholated), of which 672 continued into the extension study. Endpoints were evaluated at baseline and at 3, 6, and 12 months. We longitudinally assessed biomarkers of potential harm (BoPHs) known to be reversible upon smoking cessation as indicators of pathways involved in the pathogenesis of cardiovascular or respiratory diseases and carcinogenicity. The need to cough and safety profile were also assessed. Impact on eight key BoPHs was used as a proxy to evaluate harm reduction potential.

RESULTS

At 12 months, comparison of BoPH levels between the predominant THS use and cigarette smoking groups showed a positive effect in favor of switching, partially or in full, to THS.

CONCLUSION

These results provide additional evidence of the harm reduction potential of THS for smokers who would otherwise continue smoking, but they need to be verified in long-term confirmatory studies.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT0264955. Date of registration: January 7, 2016 https://clinicaltrials.gov/ct2/show/NCT02649556.

Effect of Tobacco Smoking Cessation on C-Reactive Protein Levels in A Cohort of Low-Dose Computed Tomography Screening Participants

Smokers have higher levels of C-Reactive Protein (CRP) compared to never smokers. The role of smoking cessation on CRP is still under debate. Using data from two screening studies conducted in Italy in 2000–2010 on 3050 heavy smokers (including 777 ex-smokers), we estimated multivariate odds ratios (OR) for high CRP (i.e. ≥2 mg/L) according to smoking status. Moreover, in a longitudinal analysis based on 975 current smokers, with a second measurement of CRP after an average study period of 3.4 years, we estimated the changes in CRP according to smoking cessation. Prevalence of high CRP at baseline was 35.8% among ex-smokers and 41.1% among current smokers (significant OR for ex- vs. current smokers: 0.79). After four years since smoking cessation, CRP levels significantly decreased with increasing years of cessation (significant OR for ex-smokers since more than 8 years: 0.55). In the longitudinal analysis, no significant reduction in CRP was found for time since smoking cessation (ORs: 1.21, 1.04, and 0.91 for ex-smokers since 1 year, 2–3 years, and ≥4 years, respectively). In the largest prospective study available so far, we found that smoking cessation has a favourable effect on CRP, but this benefit is not evident in the short-term.

Integrating chemical, toxicological and clinical research to assess the potential of reducing health risks associated with cigarette smoking through reducing toxicant emissions

The concept of a risk continuum for tobacco and nicotine products has been proposed, which differentiates products according to their propensity to reduce toxicant exposure and risk. Cigarettes are deemed the most risky and medicinal nicotine the least. We assessed whether a Reduced-Toxicant Prototype (RTP) cigarette could sufficiently reduce exposure to toxicants versus conventional cigarettes to be considered a distinct category in the risk continuum. We present findings from both pre-clinical and clinical studies in order to examine the potential for reduced smoke toxicant emissions to lower health risks associated with cigarette smoking. We conclude that current toxicant reducing technologies are unable to reduce toxicant emissions sufficiently to manifest beneficial disease-relevant changes in smokers. These findings point to a minimum toxicant exposure standard that future potentially reduced risk products would need to meet to be considered for full biological assessment. The RTP met WHO TobReg proposed limits on cigarette toxicant emissions, however the absence of beneficial disease relevant changes in smokers after six months reduced toxicant cigarette use, does not provide evidence that these regulatory proposals will positively impact risks of smoking related diseases. Greater toxicant reductions, such as those that can be achieved in next generation products e.g. tobacco heating products and electronic cigarettes are likely to be necessary to clearly reduce risks compared with conventional cigarettes.

A cross-sectional analysis of candidate biomarkers of biological effect in smokers, never-smokers and ex-smokers

CONTEXT

Biomarkers of biological effect (BOBE) have been proposed as potential tools to assess tobacco product use, toxicity and disease risk.

OBJECTIVE

To determine if candidate BOBE can distinguish between smokers, never-smokers and former smokers.

METHODS

Biomarker levels were compared from 143 smokers, 61 never-smokers and 61 ex-smokers.

RESULTS

In total, 27 candidate biomarkers were assessed, 14 were significantly different between smokers and never-smokers (p < 0.01) and of these 14 biomarkers, 12 were able to distinguish between smokers and former smokers (p < 0.05), which indicates the potential for reversibility.

CONCLUSIONS

A total of 12 of 27 BOBE are potentially useful tools for future product assessment.

C-reactive protein as a predictor of disease in smokers and former smokers: a review

BACKGROUND

Cigarette smoking is a classical and a major risk factor in the development of several diseases with an inflammatory component, including cardiovascular disease and chronic obstructive pulmonary disease. Improvements in assays for protein markers of inflammation have led to many studies on these factors and their roles in disease.

AIMS

C-reactive protein (CRP) is one such marker and this review focuses on the evidence for using CRP as a diagnostic marker and how levels of this protein are modified according to the smoking status of the patient, both in terms of the current amount of cigarettes smoked and how CRP levels change following smoking cessation.

CONCLUSIONS

Assay of CRP levels may be useful in monitoring disease progression and determining risk of future cardiovascular complications. However, as this marker is also an indicator of acute inflammation and challenges to the immune system, some caution must be exercised in interpreting the available data on CRP levels in patients with different chronic comorbidities.

A pilot study to examine the effects of smoking cessation on serum markers of inflammation in women at risk for cardiovascular disease

BACKGROUND

The links among smoking, inflammation, and cardiovascular disease (CVD) are well established. Several studies have demonstrated that quitting smoking reverses the risk of coronary heart disease within 5 to 10 years. However, the immediate effects of quitting smoking on inflammatory biomarkers associated with CVD risk have not been well described.

METHODS

In this pilot study, we examined a panel of circulating inflammatory biomarkers associated with CVD in "at-risk" women during the smoking cessation program. Forty-six women enrolled in a smoking cessation program consented to attend four study visits over 6 to 7 weeks. Health/medical information and blood were collected at each visit. Circulating levels of C-reactive protein (CRP), tumor necrosis factor (TNF), interleukin (IL)-6, soluble TNF receptor (sTNFR)-I, sTNFR-II, and soluble vascular cell adhesion molecule (sVCAM)-1 were measured, and changes between baseline levels (visit 1, while smoking) and visits 2 through 4 were determined.

RESULTS

Significant reductions in circulating levels of TNF, sTNFR-I, sTNFR-II, and sVCAM-1 were observed among participants over the course of the smoking cessation program. Serum levels of both IL-6 and CRP declined during the smoking cessation program; the changes were not statistically significant, however.

CONCLUSIONS

These findings suggest there are rapid consequences of smoking cessation on inflammatory biomarkers in women at risk for CVD. Additional, larger studies including diverse smokers desiring to quit are required to confirm changes in "measurable milestones" that could serve as motivating factors to assist smokers to quit.