Impact of cigarette smoke exposure on host-bacterial pathogen interactions

Abstract

The human respiratory tract of individuals with normal lung function maintains a finetuned balance, being asymptomatically colonised by the normal microbiota in the upper airways and sterile in the lower tract. This equilibrium may be disrupted by the exposure to insults such as cigarette smoke. In the respiratory tract, the complex and noxious nature of inhaled cigarette smoke alters host-microorganism interaction dynamics at all anatomical levels, causing infections in many cases. Moreover, continuous exposure to cigarette smoke itself causes deleterious effects on the host that can trigger the development of chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and lung cancer. COPD is an irreversible airflow obstruction associated with emphysema, fibrosis, mucus hypersecretion and persistent colonisation of the lower airways by opportunistic pathogens. COPD patients keep a stable (without exacerbation) but progressively worsening condition and suffer periodic exacerbations caused, in most cases, by infections. Although smoking and smoking-associated diseases are associated with a high risk of infection, most therapies aim to reduce inflammatory parameters, but do not necessarily take into account the presence of persistent colonisers. The effect of cigarette smoke on host-pathogen interaction dynamics in the respiratory tract, together with current and novel therapies, is discussed.

Will chronic e-cigarette use cause lung disease?

“…Although these data will need to be repeated by other groups, it is the first report that E-Cig exposure leads to increased susceptibility to infection, which has important implications for the safety of E-Cig users. Interestingly, increased susceptibility to pathogens is a hallmark of tobacco exposure and is seen following both viral and bacterial infections (58,110,123). In addition to these aerosol exposures, a 50-fold-diluted E-Cig liquid has been shown to increase IL-4, IL-5, and IL-13 in allergen-sensitized mice when tracheally instilled (95), again suggesting that e-liquids can still have adverse effects even before they are vaporized.…”

Impact of cigarette smoking on latent tuberculosis infection: does age matter?

“…Both tuberculin skin test (TST) and T-cell based interferon-c release assays (IGRAs) are available diagnostic tool for LTBI, but IGRAs avoid the interferences from bacille Calmette-Guérin (BCG) vaccination and non-tuberculous mycobacterium (NTM). Cigarette smoke has adverse effects in respiratory immune function and is widely reported to be associated with an increased risk of respiratory a tract infection, including TB [2,3]. However, only a few studies investigated the impact of smoking on LTBI, and none of these studies used IGRAs to diagnose LTBI [4,5].…”

Analysis of the Effects of Cigarette Smoke on Staphylococcal Virulence Phenotypes

“…Invasive pneumococcal disease is 2-to 4-fold more common in cigarette smokers, and increased susceptibility to influenza and tuberculosis has also been documented (5,6). The mechanistic relationship between increased susceptibility to infection and cigarettes has yet to be elucidated; however, prior studies have focused on changes induced in the host.…”

“…Cigarette smoking increases mucus production, impairs epithelial elastic properties, decreases IgA production, and affects phagocyte activities (6). These changes facilitate bacterial colonization and exacerbate inflammatory responses leading to epithelial damage, further impairing host immunity and promoting bacterial colonization of the respiratory tract.…”

“…This continuous loop ultimately leads to chronic inflammation and increased bacterial colonization of the lungs. Lastly, direct and second-hand cigarette smoke exposures alter the normal composition of the nasopharyngeal microflora, opening the door to opportunistic pathogens such as Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae (5,6).…”