Immune functions are perturbed to a greater extent with smoking rather than moist snuff use
Cigarette smoking is a major risk factor for lung cancer, chronic obstructive pulmonary disease, and cardiovascular disease (CVD). Existing epidemiological data suggest moist snuff consumption is generally associated with reduced health risks relative to smoking, although certain CVD mortality risks may be elevated compared to non-tobacco consumption. While smoking is known to induce oxidative stress and chronic inflammation, whether smokeless tobacco products alter immune responses is unknown. Our ongoing studies indicate that while smokers exhibit many perturbations in the expression of genes involved in immune regulation, there are minimal changes in gene expression between non-tobacco consumers (NTC) and moist snuff consumers (MSC). Our objectives were to 1) evaluate several markers related to immune regulation in smokers (SMK), MSC and NTC, and 2) perform functional analyses to better understand the effects of chronic tobacco use. Sixty-one markers associated with immune regulation were measured in peripheral blood mononuclear cells from SMK (n = 40), MSC (n = 40), and NTC (n = 40). Among these, relative to NTC, seven markers were significantly suppressed in SMK, whereas in MSC, only perforin+ in lymphocytes was significantly suppressed. In a multinomial logistic regression model consisting of race, heart rate, and systolic blood pressure, markers including granzyme B+, perforin+ in lymphocytes, granzyme B+, and KLRB1+ in CD8+ cells remained as statistically significant predictors for classifying the three cohorts. Functional analysis revealed that cell-surface receptor signaling pathways and cell-cell signaling processes were downregulated in SMK relative to MSC, whereas chemotaxis, LPS-mediated signaling pathways, and the mitogen-activated protein kinase (MAPK) cascade were upregulated in SMK compared to MSC. Furthermore, a protein-protein interaction network of the 61 markers was constructed to visualize the immunosuppressive effects in SMK relative to MSC. In summary, this is the first study to demonstrate that moist snuff consumption, relative to smoking, is associated with minimal perturbations in inflammatory networks and immune function.