Lacrimal Cytokines Assessment in Subjects Exposed to Different Levels of Ambient Air Pollution in a Large Metropolitan Area

Abstract

BackgroundAir pollution is one of the most environmental health concerns in the world and has serious impact on human health, particularly in the mucous membranes of the respiratory tract and eyes. However, ocular hazardous effects to air pollutants are scarcely found in the literature.DesignPanel study to evaluate the effect of different levels of ambient air pollution on lacrimal film cytokine levels of outdoor workers from a large metropolitan area.MethodsThirty healthy male workers, among them nineteen professionals who work on streets (taxi drivers and traffic controllers, high pollutants exposure, Group 1) and eleven workers of a Forest Institute (Group 2, lower pollutants exposure compared to group 1) were evaluated twice, 15 days apart. Exposure to ambient PM2.5 (particulate matter equal or smaller than 2.5 μm) was 24 hour individually collected and the collection of tears was performed to measure interleukins (IL) 2, 4, 5 and 10 and interferon gamma (IFN-γ) levels. Data from both groups were compared using Student’s t test or Mann- Whitney test for cytokines. Individual PM2.5 levels were categorized in tertiles (lower, middle and upper) and compared using one-way ANOVA. Relationship between PM2.5 and cytokine levels was evaluated using generalized estimating equations (GEE).ResultsPM2.5 levels in the three categories differed significantly (lower: ≤22 μg/m3; middle: 23–37.5 μg/m3; upper: >37.5 μg/m3; p<0.001). The subjects from the two groups were distributed unevenly in the lower category (Group 1 = 8%; Group 2 = 92%), the middle category (Group 1 = 89%; Group 2 = 11%) and the upper category (Group 1 = 100%). A significant relationship was found between IL-5 and IL-10 and PM2.5 levels of the group 1, with an average decrease of 1.65 pg/mL of IL-5 level and of 0.78 pg/mL of IL-10 level in tear samples for each increment of 50 μg/m3 of PM2.5 (p = 0.01 and p = 0.003, respectively).ConclusionHigh levels of PM2.5 exposure is associated with decrease of IL-5 and IL-10 levels suggesting a possible modulatory action of ambient air pollution on ocular surface immune response.

The Effect of Ambient Titanium Dioxide Microparticle Exposure to the Ocular Surface on the Expression of Inflammatory Cytokines in the Eye and Cervical Lymph Nodes

“…Differences between long-term environmentally exposed human subjects and short-term exposed laboratory animals may explain the discrepancy between the results of the work done here and these studies. 12,13 Airborne TiO 2 particle-exposed rats showed enlarged cervical lymph nodes in this study. Lymph nodes are distributed along the course of the lymphatic vessels throughout the body.…”

“…12 In that study, Lee et al 12 demonstrate that ozone exposure increases levels of IL-1b, IL-6, IL-17, and IFN-c in tears of mice. Conversely, Matsuda et al 13 have shown that PM 2.5 exposure does not increase levels of IL-2, IL-4, IL-5, IL-10, and IFN-c in tears of healthy workers, but instead they have found decreased IL-5 and IL-10 in tears in groups exposed to high levels of PM 2.5 . Differences between long-term environmentally exposed human subjects and short-term exposed laboratory animals may explain the discrepancy between the results of the work done here and these studies.…”

“…On the other hand, a study which has evaluated the effect of ambient air pollution on tear cytokine levels in healthy outdoor workers shows that high levels of PM 2.5 exposure are associated with decreased IL-5 and IL-10 in tears. 13 The reporting group thus wanted to evaluate the effect of PM 2.5 TiO 2 exposure on the ocular surface immune system through the use of a whole-body exposure chamber for rats. Corneal staining, tear lactic dehydrogenase (LDH) activity (a measure of cellular damage 14 ), tear mucin 5 subtypes A and C (MUC5AC) concentration, serum immunoglobulin (Ig) G and E, the size of superficial cervical lymph nodes, immunohistochemistry, and the expression of IL-4, IL-17, and IFN-c in the anterior segment iovs.arvojournals.org j ISSN: 1552-5783 of the eyeball and cervical lymph nodes were assessed and compared after 5 days of TiO 2 microparticle exposure.…”

Perfluorooctanoic acid in indoor particulate matter triggers oxidative stress and inflammation in corneal and retinal cells

“…Most studies so far have confirmed that exposure to small PM, such as PM 2.5 , is associated with several shortand long-term health problems including lung and heart diseases, the development of several types of cancer, as well as increased mortality and premature death [4][5][6][7][8] ; only few reports address the harmful effects of PM on the eyes, a delicate organ that, given its anatomical location, is extremely vulnerable to the effects of air pollution. In fact, in areas with high levels of air pollution, the number of outpatient visits because of non-specific conjunctivitis has increased [9][10][11][12] . Exposure to PM 2.5 in particular causes eye irritation, burning sensation, and allergic eye diseases, which are accompanied by dry and inflamed eyes 13 .…”

Immunologic and Non-Immunologic Mechanisms Leading to Airway Remodeling in Asthma

“…Air pollution can stimulate the expression of pro-inflammatory cytokines in the lung, not only by immune cells, but also by tissue forming cells [8,9]. Despite initiating inflammation, the inflammatory effect of air pollutants may be further increased in people with existing allergies or when appearing together with allergens [10][11][12]. The mechanism(s) by which air pollution alters the structure of the lung tissues is not well understood, but it was suggested that the interaction between the environment and epigenetic events plays a major role in the pathogenesis of asthma [13].…”