{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T14:44:30Z","timestamp":1782139470708,"version":"3.54.5"},"reference-count":50,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2021,10,24]],"date-time":"2021-10-24T00:00:00Z","timestamp":1635033600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["NIH\/NHLBI R00 HL141685"],"award-info":[{"award-number":["NIH\/NHLBI R00 HL141685"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["NIH\/NIAID R03 AI152003"],"award-info":[{"award-number":["NIH\/NIAID R03 AI152003"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Gram-negative (G-) bacteria are the leading cause of hospital-acquired pneumonia in the United States. The devastating damage caused by G- bacteria results from the imbalance of bactericidal effects and overwhelming inflammation. Despite decades of research, the underlying mechanisms by which runaway inflammation is developed remain incompletely understood. Clara Cell Protein 16 (CC16), also known as uteroglobin, is the major protein secreted by Clara cells and the most abundant protein in bronchoalveolar lavage fluid (BALF). However, the regulation and functions of CC16 during G- bacterial infection are unknown. In this study, we aimed to assess the regulation of CC16 in response to Klebsiella pneumoniae (K. pneu) and to investigate the role of CC16 in bronchial epithelial cells. After K. pneu infection, we found that CC16 mRNA expression was significantly decreased in bronchial epithelial cells. Our data also showed that K. pneu infection upregulated cytokine and chemokine genes, including IL-1\u03b2, IL-6, and IL-8 in BEAS-2B cells. Endogenously overexpressed CC16 in BEAS-2B cells provided an anti-inflammatory effect by reducing these markers. We also observed that endogenous CC16 can repress NF-\u03baB reporter activity. In contrast, the recombinant CC16 (rCC16) did not show an anti-inflammatory effect in K. pneu-infected cells or suppression of NF-\u03baB promoter activity. Moreover, the overexpression of CC16 reduced reactive oxygen species (ROS) levels and protected BEAS-2B cells from K. pneu-induced apoptosis.<\/jats:p>","DOI":"10.3390\/ijms222111459","type":"journal-article","created":{"date-parts":[[2021,10,24]],"date-time":"2021-10-24T22:06:16Z","timestamp":1635113176000},"page":"11459","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["CC16 Regulates Inflammation, ROS Generation and Apoptosis in Bronchial Epithelial Cells during Klebsiella pneumoniae Infection"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4353-6043","authenticated-orcid":false,"given":"Sultan","family":"Almuntashiri","sequence":"first","affiliation":[{"name":"Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, USA"},{"name":"Department of Clinical Pharmacy, College of Pharmacy, University of Hail, Hail 55473, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yohan","family":"Han","sequence":"additional","affiliation":[{"name":"Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yin","family":"Zhu","sequence":"additional","affiliation":[{"name":"Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4377-5706","authenticated-orcid":false,"given":"Saugata","family":"Dutta","sequence":"additional","affiliation":[{"name":"Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sara","family":"Niazi","sequence":"additional","affiliation":[{"name":"College of Pharmacy, University of Georgia, Augusta, GA 30912, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9900-740X","authenticated-orcid":false,"given":"Xiaoyun","family":"Wang","sequence":"additional","affiliation":[{"name":"Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Budder","family":"Siddiqui","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0361-4174","authenticated-orcid":false,"given":"Duo","family":"Zhang","sequence":"additional","affiliation":[{"name":"Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, USA"},{"name":"Vascular Biology Center, Augusta University, Augusta, GA 30912, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,24]]},"reference":[{"key":"ref_1","unstructured":"Sattar, S.B.A., and Sharma, S. (2021). Bacterial Pneumonia. StatPearls, Treasure Island (FL)."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Olasupo, O., Xiao, H., and Brown, J.D. (2018). Relative Clinical and Cost Burden of Community-Acquired Pneumonia Hospitalizations in Older Adults in the United States\u2014A Cross-Sectional Analysis. Vaccines, 6.","DOI":"10.3390\/vaccines6030059"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s13054-016-1197-5","article-title":"Treatment of Gram-negative pneumonia in the critical care setting: Is the beta-lactam antibiotic backbone broken beyond repair?","volume":"20","author":"Bassetti","year":"2016","journal-title":"Crit. Care"},{"key":"ref_4","unstructured":"Oliveira, J., and Reygaert, W.C. (2021). Gram Negative Bacteria. StatPearls, Treasure Island (FL)."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1016\/j.jinf.2005.12.002","article-title":"Analysis of microbial etiology and mortality in patients with brain abscess","volume":"53","author":"Prasad","year":"2006","journal-title":"J. Infect."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"517","DOI":"10.1097\/QCO.0000000000000687","article-title":"The current state of immunization against Gram-negative bacteria in children: A review of the literature","volume":"33","author":"Broad","year":"2020","journal-title":"Curr. Opin. Infect. Dis."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4","DOI":"10.3389\/fcimb.2018.00004","article-title":"Colonization, Infection, and the Accessory Genome of Klebsiella pneumoniae","volume":"8","author":"Martin","year":"2018","journal-title":"Front. Cell. Infect. Microbiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"S81","DOI":"10.1086\/653053","article-title":"Microbial Etiologies of Hospital-Acquired Bacterial Pneumonia and Ventilator-Associated Bacterial Pneumonia","volume":"51","author":"Jones","year":"2010","journal-title":"Clin. Infect. Dis."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"252","DOI":"10.1093\/femsre\/fux013","article-title":"Klebsiella pneumoniae: A major worldwide source and shuttle for antibiotic resistance","volume":"41","author":"Kondratyeva","year":"2017","journal-title":"FEMS Microbiol. Rev."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1111\/j.1749-6632.2000.tb05549.x","article-title":"Uteroglobin\/Clara cell 10-kDa family of proteins: Nomenclature committee report","volume":"923","author":"Klug","year":"2000","journal-title":"Ann. N. Y. Acad. Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1046\/j.1365-2222.2000.00760.x","article-title":"Clara cell secretory protein (CC16): Characteristics and perspectives as lung peripheral biomarker","volume":"30","author":"Broeckaert","year":"2000","journal-title":"Clin. Exp. Allergy"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1413","DOI":"10.1164\/rccm.201305-0892OC","article-title":"Club Cell Protein 16 and Disease Progression in Chronic Obstructive Pulmonary Disease","volume":"188","author":"Park","year":"2013","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1016\/S2213-2600(15)00196-4","article-title":"Relation between circulating CC16 concentrations, lung function, and development of chronic obstructive pulmonary disease across the lifespan: A prospective study","volume":"3","author":"Guerra","year":"2015","journal-title":"Lancet Respir. Med."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1058","DOI":"10.1136\/thx.2008.102574","article-title":"On behalf of the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) investigators Evaluation of serum CC-16 as a biomarker for COPD in the ECLIPSE cohort","volume":"63","author":"Lomas","year":"2008","journal-title":"Thorax"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"124","DOI":"10.1164\/ajrccm.161.1.9904073","article-title":"Association between Plasma CC16 Levels, the A38G Polymorphism, and Asthma","volume":"161","author":"Laing","year":"2000","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3411","DOI":"10.2147\/COPD.S174545","article-title":"Decreased serum club cell secretory protein in asthma and chronic obstructive pulmonary disease overlap: A pilot study","volume":"13","author":"Oh","year":"2018","journal-title":"Int. J. Chronic Obstr. Pulm. Dis."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Almuntashiri, S., Zhu, Y., Han, Y., Wang, X., Somanath, P.R., and Zhang, D. (2020). Club Cell Secreted Protein CC16: Potential Applications in Prognosis and Therapy for Pulmonary Diseases. J. Clin. Med., 9.","DOI":"10.3390\/jcm9124039"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1167","DOI":"10.1007\/s00134-006-0235-1","article-title":"Outcome value of Clara cell protein in serum of patients with acute respiratory distress syndrome","volume":"32","author":"Lesur","year":"2006","journal-title":"Intensiv. Care Med."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e22262","DOI":"10.1002\/jcla.22262","article-title":"Diagnostic and prognostic values of Club cell protein 16 (CC16) in critical care patients with acute respiratory distress syndrome","volume":"32","author":"Lin","year":"2018","journal-title":"J. Clin. Lab. Anal."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Buend\u00eda-Rold\u00e1n, I., Ruiz, V., Sierra, P., Montes, E., Ram\u00edrez, R., Vega, A., Salgado, A., Vargas, M.H., Mej\u00eda, M., and Pardo, A. (2016). Increased Expression of CC16 in Patients with Idiopathic Pulmonary Fibrosis. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0168552"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"347","DOI":"10.3109\/15412555.2014.948994","article-title":"Diagnostic Values For Club Cell Secretory Protein (CC16) in Serum of Patients of Combined Pulmonary Fibrosis and Emphysema","volume":"12","author":"Kokuho","year":"2015","journal-title":"COPD"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"507","DOI":"10.1183\/09031936.01.99102601","article-title":"Serum Clara cell protein (CC16), a marker of the integrity of the air-blood barrier in sarcoidosis","volume":"18","author":"Hermans","year":"2001","journal-title":"Eur. Respir. J."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"579","DOI":"10.1111\/j.1651-2227.2008.01083.x","article-title":"Clara cell protein 16 (CC16) serum levels in infants during respiratory syncytial virus infection","volume":"98","author":"Johansson","year":"2009","journal-title":"Acta Paediatr."},{"key":"ref_24","first-page":"2198","article-title":"Recombinant club cell protein 16 (CC16) ameliorates cigarette smoke-induced lung inflammation in a murine disease model of COPD","volume":"18","author":"Pang","year":"2018","journal-title":"Mol. Med. Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1467","DOI":"10.1378\/chest.14-1174","article-title":"Supplementing Defect in Club Cell Secretory Protein Attenuates Airway Inflammation in COPD","volume":"147","author":"Gamez","year":"2015","journal-title":"Chest"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"4515","DOI":"10.1016\/j.febslet.2006.07.031","article-title":"Mice lacking uteroglobin are highly susceptible to developing pulmonary fibrosis","volume":"580","author":"Lee","year":"2006","journal-title":"FEBS Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1203\/01.PDR.0000156371.89952.35","article-title":"Safety, Pharmacokinetics, and Anti-inflammatory Effects of Intratracheal Recombinant Human Clara Cell Protein in Premature Infants with Respiratory Distress Syndrome","volume":"58","author":"Levine","year":"2005","journal-title":"Pediatr. Res."},{"key":"ref_28","first-page":"1","article-title":"Mechanobiology in Lung Epithelial Cells: Measurements, Perturbations, and Responses","volume":"2","author":"Waters","year":"2012","journal-title":"Compr. Physiol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1041","DOI":"10.1096\/fasebj.8.13.7926369","article-title":"Cytokine production by epithelial cells","volume":"8","author":"Stadnyk","year":"1994","journal-title":"FASEB J."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"651","DOI":"10.2131\/jts.45.651","article-title":"Exogenous Clara cell protein 16 attenuates silica particles-induced inflammation in THP-1 macrophages by down-regulating NF-\u03baB and caspase-1 activation","volume":"45","author":"Cui","year":"2020","journal-title":"J. Toxicol. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1093\/abbs\/gmx020","article-title":"Recombinant CC16 protein inhibits the production of pro-inflammatory cytokines via NF-\u03baB and p38 MAPK pathways in LPS-activated RAW264.7 macrophages","volume":"49","author":"Pang","year":"2017","journal-title":"Acta Biochim. Biophys. Sin."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2977","DOI":"10.1016\/j.bbamcr.2016.09.012","article-title":"Activation of apoptosis signalling pathways by reactive oxygen species","volume":"1863","year":"2016","journal-title":"Biochim. Biophys. Acta\u2013Bioenerg."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1335","DOI":"10.6061\/clinics\/2012(11)19","article-title":"Airway disease: Similarities and differences between asthma, COPD and bronchiectasis","volume":"67","author":"Athanazio","year":"2012","journal-title":"Clinics"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"26","DOI":"10.5114\/kitp.2016.58961","article-title":"The role and importance of club cells (Clara cells) in the pathogenesis of some respiratory diseases","volume":"1","author":"Rokicki","year":"2016","journal-title":"Pol. J. Cardio-Thorac. Surg."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"L185","DOI":"10.1152\/ajplung.00115.2016","article-title":"Alveolar epithelial disintegrity in pulmonary fibrosis","volume":"311","author":"Kulkarni","year":"2016","journal-title":"Am. J. Physiol. Cell. Mol. Physiol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"573","DOI":"10.1164\/rccm.201006-0865CI","article-title":"A Concise Review of Pulmonary Sarcoidosis","volume":"183","author":"Baughman","year":"2011","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_37","first-page":"2","article-title":"The Acute Respiratory Distress Syndrome: Mechanisms and Perspective Therapeutic Approaches","volume":"2","author":"Gonzales","year":"2015","journal-title":"Austin J. Vasc. Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"L715","DOI":"10.1152\/ajplung.00361.2009","article-title":"Epithelial repair mechanisms in the lung","volume":"298","author":"Crosby","year":"2010","journal-title":"Am. J. Physiol. Cell. Mol. Physiol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1007\/BF02890057","article-title":"Evolution of metaplastic squamous cells of alveolar walls in pulmonary fibrosis produced by paraquat","volume":"58","author":"Fukuda","year":"1989","journal-title":"Virchows Arch. B Cell Pathol. Incl. Mol. Pathol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"E1475","DOI":"10.1073\/pnas.1117988108","article-title":"Multiple stromal populations contribute to pulmonary fibrosis without evidence for epithelial to mesenchymal transition","volume":"108","author":"Rock","year":"2011","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3091","DOI":"10.18632\/aging.101115","article-title":"The role of club cell phenoconversion and migration in idiopathic pulmonary fibrosis","volume":"8","author":"Fukumoto","year":"2016","journal-title":"Aging"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1655","DOI":"10.1001\/archinte.167.15.1655","article-title":"Understanding the Inflammatory Cytokine Response in Pneumonia and Sepsis: Results of the Genetic and Inflammatory Markers of Sepsis (GenIMS) Study","volume":"167","author":"Kellum","year":"2007","journal-title":"Arch. Intern. Med."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1342","DOI":"10.1378\/chest.107.5.1342","article-title":"Patterns of Cytokine Expression in Community-Acquired Pneumonia","volume":"107","author":"Puren","year":"1995","journal-title":"Chest"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2395","DOI":"10.1128\/AAC.00658-07","article-title":"Systemic Expression of Cytokine Production in Patients with Severe Pneumococcal Pneumonia: Effects of Treatment with a \u03b2-Lactam versus a Fluoroquinolone","volume":"52","author":"Calbo","year":"2008","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1136\/thx.54.1.51","article-title":"Circulating interleukin 6 and interleukin 10 in community acquired pneumonia","volume":"54","author":"Glynn","year":"1999","journal-title":"Thorax"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"e76","DOI":"10.1016\/j.ijid.2012.06.006","article-title":"Understanding the roles of cytokines and neutrophil activity and neutrophil apoptosis in the protective versus deleterious inflammatory response in pneumonia","volume":"17","author":"Bordon","year":"2013","journal-title":"Int. J. Infect. Dis."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"684","DOI":"10.3109\/00365521.2011.560678","article-title":"Klebsiella pneumoniae increases the risk of inflammation and colitis in a murine model of intestinal bowel disease","volume":"46","author":"Lee","year":"2011","journal-title":"Scand. J. Gastroenterol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"2204","DOI":"10.1152\/japplphysiol.00246.2005","article-title":"Dose response to rhCC10-augmented surfactant therapy in a lamb model of infant respiratory distress syndrome: Physiological, inflammatory, and kinetic profiles","volume":"99","author":"Shashikant","year":"2005","journal-title":"J. Appl. Physiol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1060","DOI":"10.3389\/fphar.2020.01060","article-title":"The rCC16 Protein Protects Against LPS-Induced Cell Apoptosis and Inflammatory Responses in Human Lung Pneumocytes","volume":"11","author":"Lin","year":"2020","journal-title":"Front. Pharmacol."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"865","DOI":"10.1136\/thoraxjnl-2018-212994","article-title":"A potential role of microvesicle-containing miR-223\/142 in lung inflammation","volume":"74","author":"Zhang","year":"2019","journal-title":"Thorax"}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/22\/21\/11459\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:22:21Z","timestamp":1760167341000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/22\/21\/11459"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,10,24]]},"references-count":50,"journal-issue":{"issue":"21","published-online":{"date-parts":[[2021,11]]}},"alternative-id":["ijms222111459"],"URL":"https:\/\/doi.org\/10.3390\/ijms222111459","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,10,24]]}}}