Prevalence and Associated Factors of Depression and Anxiety Among Healthcare Workers During the Coronavirus Disease 2019 Pandemic:A Nationwide Study in Korea

Background@#A healthcare system’s collapse due to a pandemic, such as the coronavirus disease 2019 (COVID-19), can expose healthcare workers (HCWs) to various mental health problems. This study aimed to investigate the impact of the COVID-19 pandemic on the depression and anxiety of HCWs. @*Methods@#A nationwide questionnaire-based survey was conducted on HCWs who worked in healthcare facilities and public health centers in Korea in December 2020. Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) were used to measure depression and anxiety. To investigate factors associated with depression and anxiety, stepwise multiple logistic regression analysis was performed. @*Results@#A total of 1,425 participating HCWs were included. The mean depression score (PHQ-9) of HCWs before and after COVID-19 increased from 2.37 to 5.39, and the mean anxiety score (GAD-7) increased from 1.41 to 3.41. The proportion of HCWs with moderate to severe depression (PHQ-9 ≥ 10) increased from 3.8% before COVID-19 to 19.5% after COVID-19, whereas that of HCWs with moderate to severe anxiety (GAD-7 ≥ 10) increased from 2.0% to 10.1%. In our study, insomnia, chronic fatigue symptoms and physical symptoms after COVID-19, anxiety score (GAD-7) after COVID-19, living alone, and exhaustion were positively correlated with depression. Furthermore, post-traumatic stress symptoms, stress score (Global Assessment of Recent Stress), depression score (PHQ-9) after COVID-19, and exhaustion were positively correlated with anxiety. @*Conclusion@#In Korea, during the COVID-19 pandemic, HCWs commonly suffered from mental health problems, including depression and anxiety. Regularly checking the physical and mental health problems of HCWs during the COVID-19 pandemic is crucial, and social support and strategy are needed to reduce the heavy workload and psychological distress of HCWs.

Combination Analysis of PCDHGA12and CDO1 DNA Methylation in Bronchial Washing Fluid for Lung Cancer Diagnosis

Background@#When suspicious lesions are observed on computer-tomography (CT), invasive tests are needed to confirm lung cancer. Compared with other procedures, bronchoscopy has fewer complications. However, the sensitivity of peripheral lesion through bronchoscopy including washing cytology is low. A new test with higher sensitivity through bronchoscopy is needed. In our previous study, DNA methylation of PCDHGA12 in bronchial washing cytology has a diagnostic value for lung cancer. In this study, combination of PCDHGA12 and CDO1 methylation obtained through bronchial washing cytology was evaluated as a diagnostic tool for lung cancer. @*Methods@#A total of 187 patients who had suspicious lesions in CT were enrolled. PCDHGA12methylation test, CDO1 methylation test, and cytological examination were performed using 3-plex LTE-qMSP test. @*Results@#Sixty-two patients were diagnosed with benign diseases and 125 patients were diagnosed with lung cancer. The sensitivity of PCDHGA12 was 74.4% and the specificity of PCDHGA12 was 91.9% respectively. CDO1 methylation test had a sensitivity of 57.6% and a specificity of 96.8%. The combination of both PCDHGA12 methylation test and CDO1 methylation test showed a sensitivity of 77.6% and a specificity of 90.3%. The sensitivity of lung cancer diagnosis was increased by combining both PCDHGA12 and CDO1 methylation tests. @*Conclusion@#Checking DNA methylation of both PCDHGA12 and CDO1 genes using bronchial washing fluid can reduce the invasive procedure to diagnose lung cancer.

Workload of Healthcare Workers During the COVID-19 Outbreak in Korea: A Nationwide Survey

Background@#As the coronavirus disease 2019 (COVID-19) pandemic is ongoing, heavy workload of healthcare workers (HCWs) is a concern. This study investigated the workload of HCWs responding to the COVID-19 outbreak in South Korea. @*Methods@#A nationwide cross-sectional survey was conducted from September 16 to October 15, 2020, involving 16 healthcare facilities (4 public medical centers, 12 tertiary-care hospitals) that provide treatment for COVID-19 patients. @*Results@#Public medical centers provided the majority (69.4%) of total hospital beds for COVID-19 patients (n = 611), on the other hand, tertiary care hospitals provided the majority (78.9%) of critical care beds (n = 57). The number of beds per doctor (median [IQR]) in public medical centers was higher than in tertiary care hospitals (20.2 [13.0, 29.4] versus 3.0 [1.3, 6.6], P = 0.006). Infectious Diseases physicians are mostly (80%) involved among attending physicians. The number of nurses per patient (median [interquartile range, IQR]) in tertiarycare hospitals was higher than in public medical centers (4.6 [3.4–5] vs. 1.1 [0.8–2.1], P =0.089). The median number of nurses per patient for COVID-19 patients was higher than the highest national standard in South Korea (3.8 vs. 2 for critical care). All participating healthcare facilities were also operating screening centers, for which a median of 2 doctors, 5 nurses, and 2 administrating staff were necessary. @*Conclusion@#As the severity of COVID-19 patients increases, the number of HCWs required increases. Because the workload of HCWs responding to the COVID-19 outbreak is much greater than other situations, a workforce management plan regarding this perspective is required to prevent burnout of HCWs.

Healthcare worker infected with Middle East Respiratory Syndrome during cardiopulmonary resuscitation in Korea, 2015 / 한국역학회지

OBJECTIVES: During the outbreak of the Middle East Respiratory Syndrome (MERS) in Korea in 2015, the Korea Centers for Disease Control and Prevention (KCDC) confirmed a case of MERS in a healthcare worker in Daejeon, South Korea. To verify the precise route of infection for the case, we conducted an in-depth epidemiological investigation in cooperation with the KCDC.METHODS: We reviewed the MERS outbreak investigation report of the KCDC, and interviewed the healthcare worker who had recovered from MERS. Using the media interview data, we reaffirmed and supplemented the nature of the exposure.RESULTS: The healthcare worker, a nurse, was infected while performing cardiopulmonary resuscitation (CPR) for a MERS patient in an isolation room. During the CPR which lasted for an hour, a large amount of body fluid was splashed. The nurse was presumed to have touched the mask to adjust its position during the CPR. She suggested that she was contaminated with the MERS patient’s body fluids by wiping away the sweat from her face during the CPR.CONCLUSIONS: The possible routes of infection may include the following: respiratory invasion of aerosols contaminated with MERS-coronavirus (MERS-CoV) through a gap between the face and mask; mucosal exposure to sweat contaminated with MERS-CoV; and contamination during doffing of personal protective equipment. The MERS guidelines should reflect this case to decrease the risk of infection during CPR.

Healthcare worker infected with Middle East Respiratory Syndrome during cardiopulmonary resuscitation in Korea, 2015 / 한국역학회지

OBJECTIVES: During the outbreak of the Middle East Respiratory Syndrome (MERS) in Korea in 2015, the Korea Centers for Disease Control and Prevention (KCDC) confirmed a case of MERS in a healthcare worker in Daejeon, South Korea. To verify the precise route of infection for the case, we conducted an in-depth epidemiological investigation in cooperation with the KCDC. METHODS: We reviewed the MERS outbreak investigation report of the KCDC, and interviewed the healthcare worker who had recovered from MERS. Using the media interview data, we reaffirmed and supplemented the nature of the exposure. RESULTS: The healthcare worker, a nurse, was infected while performing cardiopulmonary resuscitation (CPR) for a MERS patient in an isolation room. During the CPR which lasted for an hour, a large amount of body fluid was splashed. The nurse was presumed to have touched the mask to adjust its position during the CPR. She suggested that she was contaminated with the MERS patient’s body fluids by wiping away the sweat from her face during the CPR. CONCLUSIONS: The possible routes of infection may include the following: respiratory invasion of aerosols contaminated with MERS-coronavirus (MERS-CoV) through a gap between the face and mask; mucosal exposure to sweat contaminated with MERS-CoV; and contamination during doffing of personal protective equipment. The MERS guidelines should reflect this case to decrease the risk of infection during CPR.

Double primary lung adenocarcinoma diagnosed by epidermal growth factor receptor mutation status / 영남의대학술지

A nodular density was detected on a chest radiograph taken from a 57-year-old Korean woman who was visiting a hospital for a routine check. Chest computed tomography revealed a 4.8 cm lobulated mass in the right lung and another focal nodular lesion in the left lung; biopsies of both lungs revealed adenocarcinoma. We conducted DNA sequencing and peptide nucleic acid clamping to investigate the potential double primary lung cancer. The results verified that the mass in the right lung had a mutation in the epidermal growth factor receptor, whereas the nodule in the left lung had a wild-type sequence, showing that these two were genetically different cancers from one another. Thus, we demonstrate that genetic testing is useful in determining double primary lung cancer, and we herein report on this case.

Double primary lung adenocarcinoma diagnosed by epidermal growth factor receptor mutation status / 영남의대학술지

A nodular density was detected on a chest radiograph taken from a 57-year-old Korean woman who was visiting a hospital for a routine check. Chest computed tomography revealed a 4.8 cm lobulated mass in the right lung and another focal nodular lesion in the left lung; biopsies of both lungs revealed adenocarcinoma. We conducted DNA sequencing and peptide nucleic acid clamping to investigate the potential double primary lung cancer. The results verified that the mass in the right lung had a mutation in the epidermal growth factor receptor, whereas the nodule in the left lung had a wild-type sequence, showing that these two were genetically different cancers from one another. Thus, we demonstrate that genetic testing is useful in determining double primary lung cancer, and we herein report on this case.

High-dose Sulbactam Treatment for Ventilator-Associated Pneumonia Caused by Carbapenem-Resistant Acinetobacter Baumannii / 대한구급학회지

BACKGROUND: Several antibiotics can be used to treat ventilator-associated pneumonia caused by carbapenem-resistant A. baumannii (CRAB-VAP) including high-dose sulbactam. However, the effectiveness of high-dose sulbactam therapy is not well known. We report our experience with high-dose sulbactam for treatment of CRAB-VAP. METHODS: Medical records of patients with CRAB-VAP who were given high-dose sulbactam between May 2013 and June 2015 were reviewed. RESULTS: Fifty-eight patients with CRAB-VAP were treated with high-dose sulbactam. The mean age was 72.0 ± 15.2 years, and the acute physiology and chronic health evaluation II (APACHE II) score was 15.1 ± 5.10 at the time of CRAB-VAP diagnosis. Early clinical improvement was observed in 65.5% of patients, and 30-day mortality was 29.3%. Early clinical failure (odds ratio [OR]: 8.720, confidence interval [CI]: 1.346-56.484; p = 0.023) and APACHE II score ≥ 14 at CRAB-VAP diagnosis (OR: 10.934, CI: 1.047-114.148; p = 0.046) were associated with 30-day mortality. CONCLUSIONS: High-dose sulbactam therapy may be effective for the treatment of CRAB-VAP. However, early clinical failure was observed in 35% of patients and was associated with poor outcome.

High-dose Sulbactam Treatment for Ventilator-Associated Pneumonia Caused by Carbapenem-Resistant Acinetobacter Baumannii / 대한중환자의학회지

BACKGROUND: Several antibiotics can be used to treat ventilator-associated pneumonia caused by carbapenem-resistant A. baumannii (CRAB-VAP) including high-dose sulbactam. However, the effectiveness of high-dose sulbactam therapy is not well known. We report our experience with high-dose sulbactam for treatment of CRAB-VAP. METHODS: Medical records of patients with CRAB-VAP who were given high-dose sulbactam between May 2013 and June 2015 were reviewed. RESULTS: Fifty-eight patients with CRAB-VAP were treated with high-dose sulbactam. The mean age was 72.0 ± 15.2 years, and the acute physiology and chronic health evaluation II (APACHE II) score was 15.1 ± 5.10 at the time of CRAB-VAP diagnosis. Early clinical improvement was observed in 65.5% of patients, and 30-day mortality was 29.3%. Early clinical failure (odds ratio [OR]: 8.720, confidence interval [CI]: 1.346-56.484; p = 0.023) and APACHE II score ≥ 14 at CRAB-VAP diagnosis (OR: 10.934, CI: 1.047-114.148; p = 0.046) were associated with 30-day mortality. CONCLUSIONS: High-dose sulbactam therapy may be effective for the treatment of CRAB-VAP. However, early clinical failure was observed in 35% of patients and was associated with poor outcome.

A 45-Year-Old Man With Recurrent Dyspnea and Hemoptysis during Exercise: Exercise-Induced Pulmonary Hemorrhage/Edema / 결핵및호흡기질환

A 45-year-old man presented with dyspnea and hemoptysis during exercise. A chest computed tomography (CT) revealed multifocal diffuse patchy ground glass opacity and interlobular septal thickening in both the lungs. Permeability pulmonary edema or pulmonary hemorrhage was suspected. Serologic studies for autoimmune disorders and vasculitis were negative. There was no laboratory evidence of coagulopathy, other hematopoietic disease or infectious disease. Considering correlation with exercise, we diagnosed exercise-induced pulmonary hemorrhage (EIPH) or exercise-induced pulmonary edema (EIPE). The patient was managed with antifibrinolytics, antibiotics, and antitussive agent. After a week, follow-up chest CT revealed completely resolved pulmonary hemorrhage. About 2 months after the first event, he visited again with dyspnea and hemoptysis during running. In the present study, we report a case of recurrent pulmonary hemorrhage after exercise.

Tracheal Stenosis after Tracheostomy Treated Successfully with Papillotome Electrocautery / 결핵및호흡기질환

A 39-year-old woman presented with symptoms of dyspnea. Ten years previously, she had received a tracheostomy because of the decision to not continue taking an anticonvulsant drug. Presently, chest computed tomography showed diffuse stenosis and focal web at the cervical trachea. We performed bronchoscopy and found a two-thirds reduction of the upper trachea due to the web-like fibrotic stenosis. Papillotome electrocautery removed the stenotic lesion. Endobronchial electrocautery is a valuable tool with potential for therapy of an endobronchial obstructing airway lesion. We report this case to introduce the successful treatment with papillotome electrocautery.

Successful Removal of Endobronchial Lipoma by Flexible Bronchoscopy Using Electrosurgical Snare / 결핵및호흡기질환

A 62-year-old man with a chronic cough presented with atelectasis of the left upper lobe on chest X-ray. Chest computed tomography showed an atelectasis in the left upper lobe with bronchial wall thickening, stenosis, dilatation, and mucoid impaction. We performed bronchoscopy and found a well-circumscribed mass on the left upper lobe bronchus. The mass was removed by flexible bronchoscopy using an electrosurgical snare and diagnosed with lipoma. An endobronchial lipoma is a rare benign tumor that can be treated by a surgical or endoscopic approach. We report the successful removal of endobronchial lipoma via flexible bronchoscopic electrosurgical snare.

Quantitative PCR for Etiologic Diagnosis of Methicillin-Resistant Staphylococcus aureus Pneumonia in Intensive Care Unit / 결핵및호흡기질환

BACKGROUND: Ventilator-associated pneumonia (VAP) requires prompt and appropriate treatment. Since methicillin-resistant Staphylococcus aureus (MRSA) is a frequent pathogen in VAP, rapid identification of it, is pivotal. Our aim was to evaluate the utility of quantitative polymerase chain reaction (qPCR) as a useful method for etiologic diagnoses of MRSA pneumonia. METHODS: We performed qPCR for mecA, S. aureus-specific femA-SA, and S. epidermidis-specific femA-SE genes from bronchoalveolar lavage or bronchial washing samples obtained from clinically-suspected VAP. Molecular identification of MRSA was based on the presence of the mecA and femA-SA gene, with the absence of the femA-SE gene. To compensate for the experimental and clinical conditions, we spiked an internal control in the course of DNA extraction. We estimated number of colony-forming units per mL (CFU/mL) of MRSA samples through a standard curve of a serially-diluted reference MRSA strain. We compared the threshold cycle (Ct) value with the microbiologic results of MRSA. RESULTS: We obtained the mecA gene standard curve, which showed the detection limit of the mecA gene to be 100 fg, which corresponds to a copy number of 30. We chose cut-off Ct values of 27.94 (equivalent to 1x10(4) CFU/mL) and 21.78 (equivalent to 1x10(5) CFU/mL). The sensitivity and specificity of our assay were 88.9% and 88.9% respectively, when compared with quantitative cultures. CONCLUSION: Our results were valuable for diagnosing and identifying pathogens involved in VAP. We believe our modified qPCR is an appropriate tool for the rapid diagnosis of clinical pathogens regarding patients in the intensive care unit.

Role of Microbiologic Culture Results of Specimens Prior to Onset of Ventilator-Associated Pneumonia in the Patients Admitted to Intensive Care Unit / 결핵및호흡기질환

BACKGROUND: Patients with ventilator-associated pneumonia (VAP) in intensive care unit (ICU) have a high mortality rate. The routine surveillance cultures obtained previously or an ATS guideline for hospital-acquired pneumonia was used in selecting initial antimicrobials. The object of this study was to compare the respiratory samples before VAP and bronchoalveolar lavage (BAL) culture. METHODS: 54 patients underwent fiberoptic bronchoscopy to obtain BAL samples. We reviewed microbiologic specimen results of prior respiratory specimens (pre-VAP) and BAL. RESULTS: Among 51 patients with 54 VAP episodes, 52 microorganisms of pre-VAP and 56 BAL samples were isolated. Pre-VAP included 21.2% of MRSA, and 32.6% of multidrug resistant-Acinetobacter baumannii (MDR-AB). BAL samples comprised 25.0% of MRSA, 26.7% of MDR-AB, 14.3% of Stenotrophomonas maltophilia and 3.6% of Klebsiella pneumonia in order. In pre-VAP samples compared to BAL samples, only 35.2% were identical. In BAL samples compared to pre-VAP samples obtained in 5 days before the onset of VAP, only 43.6% were identical. However, among BAL samples compared to pre-VAP samples obtained after more than 5 days, 13.3% were identical (p=0.037). CONCLUSION: Based on these data, pre-VAP samples obtained prior to 5 day onset of VAP may help to predict the causative microorganisms and to select appropriate initial antimicrobials.

Promoter Methylation of CDKN2A, RARbeta, and RASSF1A in Non-Small Cell Lung Carcinoma: Quantitative Evaluation Using Pyrosequencing / 결핵및호흡기질환

BACKGROUND: While qualitative analysis of methylation has been reviewed, the quantitative analysis of methylation has rarely been studied. We evaluated the methylation status of CDKN2A, RARbeta, and RASSF1A promoter regions in non-small cell lung carcinomas (NSCLCs) by using pyrosequencing. Then, we evaluated the association between methylation at the promoter regions of these tumor suppressor genes and the clinicopathological parameters of the NSCLCs. METHODS: We collected tumor tissues from a total of 53 patients with NSCLCs and analyzed the methylation level of the CDKN2A, RARbeta, and RASSF1A promoter regions by using pyrosequencing. In addition, we investigated the correlation between the hypermethylation of CDKN2A and the loss of p16INK4A immunoexpression. RESULTS: Hypermethylation of CDKN2A, RARbeta, and RASSF1A promoter regions were 16 (30.2%), 22 (41.5%), and 21 tumors (39.6%), respectively. The incidence of hypermethylation at the CDKN2A promoter in the tumors was higher in undifferentiated large cell carcinomas than in other subtypes (p=0.002). Hyperrmethylation of CDKN2A was significantly associated with p16INK4A immunoexpression loss (p=0.045). With regard to the clinicopathological characteristics of NSCLC, certain histopathological subtypes were found to be strongly associated with the loss of p16INK4A immunoexpression (p=0.016). Squamous cell carcinoma and undifferentiated large cell carcinoma showed p16INK4A immunoexpression loss more frequently. The Kaplan-Meier survival curves analysis showed that methylation level and patient survival were barely related to one another. CONCLUSION: We quantitatively analyzed the promoter methylation status by using pyrosequencing. We showed a significant correlation between CDKN2A hypermethylation and p16INK4A immunoexpression loss.

Year-in-Review of Lung Cancer / 결핵및호흡기질환

In the last several years, we have made slow but steady progress in understanding molecular biology of lung cancer. This review is focused on advances in understanding the biology of lung cancer that have led to proof of concept studies on new therapeutic approaches. The three selected topics include genetics, epigenetics and non-coding RNA. This new information represents progress in the integration of molecular mechanisms that to identify more effective ways to target lung cancer.

MicroRNA-23a: A Novel Serum Based Diagnostic Biomarker for Lung Adenocarcinoma / 결핵및호흡기질환

BACKGROUND: MicroRNAs (miRNAs) have demonstrated their potential as biomarkers for lung cancer diagnosis. In recent years, miRNAs have been found in body fluids such as serum, plasma, urine and saliva. Circulating miRNAs are highly stable and resistant to RNase activity along with, extreme pH and temperatures in serum and plasma. In this study, we investigated serum miRNA profiles that can be used as a diagnostic biomarker of non-small cell lung cancer (NSCLC). METHODS: We compared the expression profile of miRNAs in the plasma of patients diagnosed with lung cancer using an miRNA microarray. The data from this assay were validated by quantitative real-time PCR (qRT-PCR). RESULTS: Six miRNAs were overexpressed and three miRNAs were underexpressed in both tissue and serum from squamous cell carcinoma (SCC) patients. Sixteen miRNAs were overexpressed and twenty two miRNAs were underexpressed in both tissue and serum from adenocarcinoma (AC) patients. Of the four miRNAs chosen for qRT-PCR analysis, the expression of miR-23a was consistent with microarray results from AC patients. Receiver operating characteristic (ROC) curve analyses were done and revealed that the level of serum miR-23a was a potential marker for discriminating AC patients from chronic obstructive pulmonary disease (COPD) patients. CONCLUSION: Although a small number of patients were examined, the results from our study suggest that serum miR-23a can be used in the diagnosis of AC.

The Effect of Tissue Plasminogen Activator on TGF-beta1 Pre-Treated Human Mesothelial Cell Line / 결핵및호흡기질환

BACKGROUND: In an effort to find alternative therapeutic agents to prevent excessive fibrosis as a sequela to complicated parapneumonic effusion or empyema, we examined the effect of tissue plasminogen activator (tPA) as a fibrinolytic agent combined with talc or transforming growth factor (TGF)-beta1 in a human pleural mesothelial cell line, MeT-5A. METHODS: MeT-5A cells were stimulated with various doses of talc, doxycycline or TGF-beta1 for 24 h and then were treated with tPA for an additional 24 h. Cell viability was measured by MTT assay. The production of interleukin (IL)-8 and vascular endothelial growth factor (VEGF) in the culture supernatants was measured by ELISA. Real-time PCR was carried out for measurement of type I collagen mRNA. RESULTS: MeT-5A cells treated with talc showed a dose-dependent increase in production of IL-8. Talc also increased production of type I collagen mRNA at low doses, but talc did not influence the induction of VEGF. Addition of tPA to talc-stimulated cells showed further increases in the production of IL-8, but tPA did not influence the production of VEGF or type I collagen mRNA. TGF-beta1 increased the production of both VEGF and collagen type I mRNA, both of which were effectively inhibited by additional tPA treatment in MeT-5A cells. CONCLUSION: TGF-beta1 is a potent inducer of collagen synthesis without induction of IL-8 in MeT-5A cells. Addition of tPA after TGF-beta1 stimulation inhibited further fibrosis by direct inhibition of collagen mRNA synthesis as well as by inhibition of VEGF production.

TP53 Mutations in Korean Patients with Non-small Cell Lung Cancer

Although TP53 mutations have been widely studied in lung cancer, the majority of studies have focused on exons 5-8 of the gene. In addition, TP53 mutations in Korean patients with lung cancers have not been investigated. We searched for mutations in the entire coding exons, including splice sites of the gene, in Korean patients with non-small cell lung cancer (NSCLC). Mutations of the gene were determined by direct sequencing in 176 NSCLCs. Sixty-nine mutations (62 different mutations) were identified in 65 tumors. Of the 62 mutations, 12 were novel mutations. TP53 mutations were more frequent in males, ever-smokers and squamous cell carcinomas than in females, never-smokers and adenocarcinomas, respectively (all comparisons, P<0.001). Missense mutations were most common (52.2%), but frameshift, nonsense, and splice-site mutations were frequently observed at frequencies of 18.8%, 15.9% and 10.1%, respectively. Of the 69 mutations, 9 (13.0%) were found in the oligomerization domain. In addition, the proportion of mutations in the oligomerization domain was significantly higher in adenocarcinomas than in squamous cell carcinomas (23.5% vs. 2.9%, P=0.01). Our study provides clinical and molecular characteristics of TP53 mutations in Korean patients with NSCLCs.

Nitric Oxide Synthesis is Modulated by 1,25-Dihydroxyvitamin D3 and Interferon-gamma in Human Macrophages after Mycobacterial Infection

BACKGROUND: Little information is available the role of Nitric Oxide (NO) in host defenses during human tuberculosis (TB) infection. We investigated the modulating factor(s) affecting NO synthase (iNOS) induction in human macrophages. METHODS: Both iNOS mRNA and protein that regulate the growth of mycobacteria were determined using reverase transcriptase-polymerase chain reaction and western blot analysis. The upstream signaling pathways were further investigated using iNOS specific inhibitors. RESULTS: Here we show that combined treatment with 1,25-dihydroxyvitamin D3 (1,25-D3) and Interferon (IFN)-gamma synergistically enhanced NO synthesis and iNOS expression induced by Mycobacterium tuberculosis (MTB) or by its purified protein derivatives in human monocyte-derived macrophages. Both the nuclear factor-kappaB and MEK1-ERK1/2 pathways were indispensable in the induction of iNOS expression, as shown in toll like receptor 2 stimulation. Further, the combined treatment with 1,25-D3 and IFN-gamma was more potent than either agent alone in the inhibition of intracellular MTB growth. Notably, this enhanced effect was not explained by increased expression of cathelicidin, a known antimycobacterial effector of 1,25-D3. CONCLUSION: These data support a key role of NO in host defenses against TB and identify novel modulating factors for iNOS induction in human macrophages.