Roles Of Heat Shock Proteins In Healthy Coal Workers And Coal Workers With Pneumoconiosis, COPD And Lung Cancer

Coal dust is one of the most serious occupational hazards. Exposure to coal dustwill result in pneumoconiosis. chronic obstructive pulmonary disease (COPD), andlung cancer. Oxidative stress mainly contributes to the mechanism of pneumoconiosisand COPD. Coal dust particles principally target two main cells i.e. alveolarmacrophages and epithelial cells. The alveolar macrophages are generally considereda key cell in relation to mineral dust induced disorders. During macrophagesactivation, a wide range of products including ROS, cytokines, proteases, and antiproteases may be released. The most important cellular effects of ROS may includedamage to cell membranes by means of lipid peroxidation processes, oxidation ofproteins, and damage to the DNA of target cells. Oxidative DNA damage may havevarious consequences ranging from cell death and tissue destruction to cell or tissueproliferation. In addition to these direct interactions with DNA, ROS may also act asregulators of intracellular signaling cascades and transcription factors of a variety ofgenes including those of proinflammatory cytokines, adhesion molecules, andproto-oncogenes.Heat shock proteins (Hsps) are highly conserved proteins which are triggered in all organisms exposed to environmental stressors such as elevated temperature, hypoxia, and heavy metals. Based upon their apparent molecular weights, Hsps are divided into many groups such as high-molecular-mass HSPs (≥100 kD), HSP90 (81 to 99 kD), HSP70 (65 to 80 kD), HSP60 (55 to 64 kD), HSP40 (35 to 54 kD), and small HSPs (≤34 kD). Hsps function as molecular chaperones, binding to the nascent polypeptides to assist them proper refolding, assembling and translocating, and facilitating the misfolding peptides to repair or targeting damaged polypeptides for degradation. Under oxidation, Hsps can bind to denatured proteins and help them to degradation or repair. Hsps can also promote some regulatory cytokines to release and alleviate inflammation.In this study, we presume Hsps may play roles in preventing damage from oxidation and inflammation caused by coal dust. Therefore, we test the hypothesis by analyzing Hsps levels in lymphocytes and plasma. Hsp27. Hsp70 and Hsc70 in lymphocytes were detected using flow cytometre.and Hsp27 and Hsp70 in plasma were measured using enzyme link immunosorbent assay (ELISA) kit. Association of Hsps with pneumoconiosis, COPD, and lung cancer were analyzed by independent Student's t-test and Binaiy Logistic model in SPSS software.Part I Lymphocytes reactivity to BPDE in healthy coal minersHsp27, Hsp70 and Hsc70 levels of peripheral blood lymphocytes were detected in 117 subjects including 75 healthy male coal miners and 42 healthy men without the exposure to coal. Hsp27, Hsp70 and Hsc70 levels were detected by flow cytometre in lymphocytes in basal condition and after treatment by BPDE for 2h in vitro. respectively. Differences between healthy coal miners and healthy non-coal workers were analyzed by independent T-test. Results showed that no significant differences of basal Hsp27, Hsp70and Hsc70 levels were found between healthy coal miners and healthy non-coal workers. Both Hsp27 and Hsc70 levels in lymphocytes of healthy non-coal workers decreased after treatment with BPDE compared with basal ]evels(P<0.05 respectively); whereas, Hsp70 levels in lymphocytes of healthy non-coal workers increased after treatment with BPDE compared with basal levels (T＜0.01). However, no significant differences in Hsp27. Hsp70 and Hsc70 levels were found in lymphocytes from healthy coal miners after treatment with BPDE (P>0.05) compared with basal condition. It is also noted that the Hsp27 levels in healthy coal miners were significantly correlated to their cumulative coal dust exposure (r =0. 517. P<0.01). We suggested that as a result of long period coal dust toxicity, lymphocytes reactivity to BPDE in healihy coal miners is obviously deteriorated that would increase the risk of several coal dust correlated lung diseases in coal miners. Lymphocyte Hsp27 levels may be useful for evaluating cumulative coal dust exposure.Part II Biological significance of Hsps in lymphocytes of coal miners with pneumoconiosis, COPD and lung cancerSection 1. Biological significance of Hsps in lymphocytes of coal miners withpneumoconiosisHsp27 and Hsp70 play roles in protecting cells against oxidative stress. Hsp27 and Hsp70 function as molecular chaperones. facilitating misfolding peptides to proper re-folding or targeting damaged polypeptides for degradation. In present study, we presume Hsps are important in preventing damage from oxidative stress in coal workers' pneumoconiosis. Hsp27, Hsp70 and Hsc70 in peripheral blood lymphocytes were measured by flow cytometre in 75 healthy coal miners and 52 patients with coal workers' pneumoconiosis. Hsp27 in lymphocytes of patients with coal workers' pneumoconiosis was increased significantly compared with healthy coal miners (P<0.01), whereas no obvious differences of Hsp70 and Hsc70 levels were found between the patients with coal workers' pneumoconiosis and healthy coal miners. Hsp27 levels were found closely associated to the prevalence of pneumoconiosis in coal miners (adjusted OR= 10.87. 95% CI: 4.255-27.778, P<0.01). Our results suggested that up-regulation of Hsp27 may contribute to increasing risk of pneumonias in coal miners, and damaged inductivity of Hsp70 in lymphocytes also plays an important role in the development of pneumoconiosis in coal miners.Section II Expressions of Hsps in coal miners with COPDIn present study, lymphocyte Hsp27, Hsp70 and Hsc70 levels were measured by flow cytometer in 75 healthy coal miners and 52 coal miners with COPD. Association of Hsp27, Hsp70 and Hsc70 with COPD in coal miners were analyzed by Binary Logistic regression model. Our results showed that Hsp27 and Hsc70 in lymphocytes of coal miners with COPD increased significantly compared with healthy coal miners (P＜0.01 respectively). Association of Hsp27, Hsc70 levels with COPD showed statistical significance (Hsp27: adjusted OR=2.604, 95%CI: 1.168-5.814, P＜0.05; Hsc70: adjusted OR=2.326, 95%CI: 1.005-5.376, P＜0.05). Both increased Hsp27 and Hsc70 levels will contribute to elevated COPD prevalence in coal miners. Coal miners with COPD or with pneumoconiosis showed different pattern of Hsps expressions which might imply to different lung diseases caused by coal dust exposour. This character makes Hsps more valuable in indicating different coal dust correlated lung diseases.Section III Association of Hsp27, Hsp70 and Hsc70 in lymphocytes with lung cancerin coal minersTo investigate the association of Hsps with lung cancer in coal miners, we detected Hsp27, Hsp70 and Hsc70 in lymphocytes using flow cytometer in 75 healthy coal miners and 51 coal miners with lung cancer. Association of Hsp27, Hsp70 and Hsc70 with lung cancer was analyzed by independent Student's t-test and Binary Logistic regression model. Our results showed that Hsp27 and Hsp70 levels in lymphocytes of coal miners with lung cancer decreased significantly compared with healthy coal miners (P<0.01 and P<0.05 respectively). In particular, decreased Hsp27 expression was closely associated to increased prevalence of lung cancer in coal miners (Hsp27: adjusted OR=4.729, 95%C1: 1.789-12.503, P＜0.01). We considered that the deteriorated Hsps expression may enhance the risk of lung cancer in coal miners.Part III Biological significance of plasma Hsp27 and Hsp70 in coal miners withpneumoconiosis and lung cancerFew studies are available about the significance and mechanism of plasma Hsps in coal miners. In present study, we detected Hsp27 and Hsp70 in plasma of 38 healthy coal miners, 50 coal miners with pneumoconiosis and 55 with lung cancer using ELISA kit, for exploring the roles of plasma Hsps in lung cancer and pneumoconiosis in coal miners. Associations of Hsps and pneumoconiosis as well as lung cancer in coal miners were analyzed by Binary Logistic regression model. Our data showed that plasma Hsp27 levels in healthy coal miners was significantly higher than in coal miners with lung cancer and pneumoconiosis (P<0.01 respectively). However, plasma Hsp70 levels in healthy coal miners was obviously lower than in coal miners with pneumoconiosis (P<0.01), and also lower than in coal miners with lung cancer though the trend was not statistically significance. Associations of decreased plasma Hsp27 levels and prevalence both of lung cancer and pneumoconiosis in coal miners showed of statistically significance(adjusted OR= 3.513, 95%CI: 1.223-10.092, P＜0.05 and adjusted OR=8.772, 95% CI: 2.141-35.714, P<0.01 respectively), whereas, increased plasma Hsp70 levels also displayed a close associatjion with the prevalence of pneumoconiosis in coal miners (adjust OR=25.00, 95% CI: 5.556-111.111, P＜0.01). However, neither lung function nor intracellular Hsps levels were correlated with plasma Hsp27 and Hsp70. We concluded that increased Hsp70 or decreased Hsp27 in plasma might play important roles in the development of pneumoconiosis or lung cancer in coal miners. Further study is needed to know more about plasma Hsps.ConclusionsIn present study, we detected Hsp27, Hsp70 and Hsc70 in lymphocytes and plasma of healthy coal miners and coal miners with pneumoconiosis, COPD and lung cancer using flow cytometer or ELISA respectively. Associations of Hsp27, Hsp70 and Hsc70 with pneumoconiosis, COPD, and lung cancer were analyzed by independent Student's t-test and Binary Logistic methods. Our results suggested that: 1. Inductivity of lymphocytes decreased in healthy coal miners, though there were nosignificant differences of basal Hsp27, Hsp70 and Hsc70 levels in lymphocytesbetween healthy coal miners and healthy non-coal workers. 2. Increased Hsp27 levels in lymphocytes of healthy coal miners were significantly correlated with their cumulative coal dust exposure (r=0,517, P＜0.01). Hsp27 in lymphocytes may be useful for evaluating cumulative coal dust exposure.3. Lymphocyte Hsp27 levels increased in coal miners with pneumoconiosis, however. Hsp27 and Hsc70 levels increased in coal miners with COPD. It can be concluded that different Hsps may indicate various diseases.4. Elevated plasma Hsp27 may serve as protective factor against coal dust toxicity. whereas elevated Hsp70 in plasma may be a dangerous signal for the development of pneumoconiosis and lung cancer in coal miners.