Trends in Occupational Infectious Diseases in South Korea and Classification of Industries According to the Risk of Biological Hazards Using K-Means Clustering.

Against the backdrop of the COVID-19 pandemic, it is necessary to identify these risks and determine whether the current level of management is appropriate to respond to the risk of biological hazards depending on the occupation. In this study, the incidence and fatality rates of occupational diseases were calculated using industrial accident statistics of South Korea, and trends by year using joinpoint regression and relative risk by industry using k-means clustering were evaluated for infectious diseases. We found that infectious diseases had the third highest incidence and fourth highest fatalities among all occupational diseases. In the incidence rate, joinpoints appeared in 2009 and 2018, and the annual percent change changed to 7.79, -16.63, and 82.11. The fatality rate showed a consistent increase with an annual percent change of 4.37, but it was not significant. Industries were classified into five groups according to risk, and the legal control measures of certain industries were not sufficient. Follow-up studies are needed to rectify the structural limitations of industrial accident statistics.

Leptin and Atopic Dermatitis in Korean Elementary School Children.

The prevalence of atopic dermatitis (AD) and obesity have been increasing considerably in Korean school-children. AD is a chronic pruritic recurrent inflammatory skin disorder. Leptin is secreted by adipocytes which has been suggested to be immunologically active; however, their role in AD has not yet been well understood. A total of 227 subjects out of 2,109 elementary school children were defined as having AD based on the ISAAC questionnaire survey. Ninety subjects with AD, aged between 6 and 12 years, completed scoring of severity of AD (SCORAD), skin prick testing, blood tests for total IgE, eosinophil counts, eosinophil cationic protein (ECP) and lipid profiles. Serum leptin levels were also measured. A subject with atopic AD was defined as an AD patient showing at least 1 positive reaction to allergens in skin prick testing. There were no significant differences in age, body mass index, percentage of breast milk feeding, mode of delivery, prevalence of atopy, and lipid profiles between atopic AD and non-atopic AD subjects. The serum leptin levels (log mean±SD) were significantly higher in non-atopic AD group than in the atopic AD group (0.86±0.57 ng/mL vs 0.53±0.72 ng/mL, p=0.045). Subjects with mild-to-moderate AD showed significantly higher serum leptin levels than those with severe AD (0.77±0.67 ng/mL vs 0.33±0.69 ng/mL, p=0.028). There was a marginal inverse correlation between the SCORAD index and the serum leptin concentration in total AD subjects (r=-0.216, p=0.053). The serum leptin levels were significantly higher in non-atopic AD subjects or mild-to-moderate AD subjects. Leptin did not seem to be associated with IgE-mediated inflammation in AD. Obesity-associated high leptin differed between non-atopic AD and atopic AD subjects.

Clinical and immunological effects of a forest trip in children with asthma and atopic dermatitis.

Asthma and atopic dermatitis are common allergic diseases, and their prevalence has increased in urban children. Recently, it is becoming understood that forest environment has favorable health effects in patients with chronic diseases. To investigate favorable clinical and immunologic effects of forest, we examined changes in clinical symptoms, indirect airway inflammatory marker, and serum chemokines before and after a short-term forest trip. The forest trips were performed with 21 children with asthma and 27 children with atopic dermatitis. All participating children were living in air polluted urban inner-city. We measured spirometry and fractional exhaled nitric oxide (FeNO) in children with asthma and measured scoring atopic dermatitis (SCORAD) index and Thymus and Activation-Regulated Chemokine (TARC)/CCL17 and Macrophage-Derived Chemokine (MDC)/CCL22 levels in children with atopic dermatitis before and after the forest trip. Indoor air pollutants such as indoor mold, particulate matter 10 (PM10) and total volatile organic compounds (TVOCs) of each child's home and the accommodations within forest were measured. A significant increase in forced vital capacity (FVC) and a significant decrease in FeNO were observed after the forest trip in children with asthma. SCORAD indices and MDC/CCL22 levels were significantly decreased after the forest trip in children with atopic dermatitis. Airborne mold and PM10 levels in indoor were significantly lower in the forest accommodations than those of children's homes; however, TVOC levels were not different between the two measured sites. Short-term exposure to forest environment may have clinical and immunological effects in children with allergic diseases who were living in the urban community.

Salmonella typhimurium with γ-radiation induced H2AX phosphorylation and apoptosis in melanoma.

To investigate the combinatorial effects using Salmonella and γ-radiation, the Salmonella typhimurium infection in combination with γ-radiation was investigated on melanoma. We showed that ROS expression and H2AX phosphorylation increased during stress by γ-radiation irrespective of Salmonella infection, inducing apoptosis by caspase-3 and bcl2 in tumor cells. In addition, tumor growth was suppressed by this combinatory therapy suggesting candidates for radiation therapy against melanoma.

Suppression of inflammation by recombinant Salmonella typhimurium harboring CCL22 microRNA.

Atopic dermatitis (AD) is an inflammatory, chronically relapsing, puritic skin disorder. These syndromes result from multifactorial inheritance, with interaction between genetic and environmental factors. In particular, the macrophage-derived chemokine CCL22 is directly implicated in skin inflammatory reactions and its levels are significantly elevated in serum and correlated with disease severity in AD. We tested the suppression of the CCL22 gene by microRNA (miRNA) and observed the effects in mice with inflammation similar to AD. We used Salmonella as a vector to deliver miRNA. The recombinant strain of Salmonella typhimurium expressing CCL22 miRNA (ST-miRCCL22) was prepared for in vivo knockdown of CCL22. ST-miRCCL22 was orally inoculated into mice and the CCL22 gene suppressed with CCL22 miRNA in the activated lymphocytes. IgE and interleukin-4 were inhibited and interferon-γ was induced after treatments with ST-miRCCL22 and CCL22 was suppressed. Further, Th17 cells were suppressed in the atopic mice treated with ST-miRCCL22. These results suggested that suppression of the CCL22 gene using Salmonella induced anti-inflammatory effects.

Salmonella typhimurium harboring plasmid expressing interleukin-12 induced attenuation of infection and protective immune responses.

IL-12 is known to be an essential cytokine which appears to provide protective immunity against intracellular bacteria, such as Salmonella. In this study, we investigated the possibility of developing a vaccine using IL-12 against virulent Salmonella. We used the host defense system activated by cytokine IL-12. The highly virulent Salmonella strain (Salmonella typhimurium UK-1) was transformed with cytokine-expressing plasmids. These live, wild-type pathogens were used as vaccine strains without undergoing any other biological or genetic attenuating processes. The newly developed strains induced partial protection from infections (30-40%). Of note, the interleukin-12-transformed pathogen was safe upon immunization with low doses (10(3) cfu), induced IgG responses, and stimulated protective immune responses against Salmonella typhimurium in mice (80-100%). These results suggest that IL-12 induced attenuation of wild-type Salmonella in the host infection stage and vaccine development using the wild-type strain harboring plasmid-secreting IL-12 may be considered as an alternative process for intracellular bacterial vaccine development without the inconvenience of time-consuming attenuation processes.

Therapeutic effects of recombinant Salmonella typhimurium harboring CCL22 miRNA on atopic dermatitis-like skin in mice.

Th-2-biased immune responses are known to play a key role in the pathogenesis of atopic dermatitis. In particular, the macrophage-derived chemokine CCL22 is directly implicated in Th-2-associated skin inflammatory reactions, and its levels are significantly elevated in serum and are correlated with disease severity in atopic dermatitis. In this study, we tested the development of genetic therapeutic options to treat atopic dermatitis using bacteria expressing miRNA. We constructed a recombinant strain of Salmonella typhimurium expressing CCL22 miRNA (ST-miRCCL22) for the in vivo knockdown of CCL22. The CCL22 gene was downregulated with CCL22 miRNA in activated lymphocytes. In mice with a cutaneous disease similar to atopic dermatitis, interleukin-4 was inhibited and interferon-g was induced after treatments with ST-miRCCL22. Furthermore, CCL22 levels were suppressed in the atopic mice treated with ST-miRCCL22. These results suggest that ST-miRCCL22 may be an effective genetic agent for treating atopic dermatitis.

Antitumor therapeutic effects of a genetically engineered Salmonella typhimurium harboring TNF-α in mice.

Although the use of TNF-α in the treatment of cancer is restricted due to its non-specific cytotoxicity and narrow range of applications to different cancers in clinical trials, we investigated a safe anti-cancer drug by the use of engineered bacterial capsule harboring TNF-α. The engineered bacterial capsule was designed to target cancer cells, promote a tumor-suppressive environment, and increase the efficacy of existing cancer treatments, including chemotherapy, radiotherapy, and cell therapy. The engineered bacterial capsule was constructed with Salmonella capsulizing TNF-α protein, which was produced and capsulized by Salmonella to reduce side effects of the protein. This bacterial capsule induced a tumor-suppressive environment through the activation of natural killer cells. Engineered bacterial capsule invaded tumor cells, released TNF-α, and induced apoptosis of tumor cells without apparent side effects. In a murine melanoma model, the bacterial capsule of TNF-α significantly inhibited tumor growth by 80-100% and prolonged the survival of the mice. When tested in combination with chemotherapy (cisplatin), antibiotics, and vaccine, recombinant microbial treatment increased the anti-tumor effects of existing therapies. The anti-tumor effects of the bacterial capsule of TNF-α were also observed in cervical cancer, melanoma, breast cancer, colon cancer, and renal carcinoma. These results suggest that the bacterial capsule of TNF-α is a promising strategy for TNF-α treatment.

CadC has a global translational effect during acid adaptation in Salmonella enterica serovar Typhimurium.

In Salmonella enterica serovar Typhimurium, the membrane-localized CadC is a transcriptional activator of the cadBA operon, which contributes to the acid tolerance response. Unlike in Escherichia coli, in which transcription of cadC is constitutive, in S. enterica serovar Typhimurium cadC expression is induced by low pH and lysine. Inactivation of cadC suppresses the acid-sensitive phenotype of a cadA mutation, suggesting the existence of other CadC-dependent genes in addition to the cadBA operon. Using a proteomic approach, we identified 8 of the putative CadC-induced proteins and 15 of the putative CadC-repressed proteins. The former include porin proteins OmpC and OmpF. The latter include proteins involved in glycolysis, energy production, and stress tolerance. To better understand the altered levels of OmpC and OmpF, we compared expression of ompR in S. enterica serovar Typhimurium wild-type and cadC mutant strains and determined that CadC exerted a negative influence on ompR transcription. Taken together, our findings strongly suggest that CadC may be a global regulator involved in the OmpR regulatory system during acid adaptation.

Antitumor therapeutic effects of Salmonella typhimurium containing Flt3 Ligand expression plasmids in melanoma-bearing mouse.

An attenuated strain of Salmonella typhimurium has been tested in animals and clinically as an anticancer agent due to its in vivo tumor-targeting and tumoricidal properties. We exploited a genetically-engineered S. typhimurium harboring Flt3 Ligand (Flt3L) expression vectors as a tumoricidal agent to enhance its therapeutic efficacy. Flt3L showed tumoricidal effects when expressed in tumor cells in vitro. When melanoma-bearing mice were treated locally with Salmonella, S. typhimurim with Flt3L expression vectors inhibited tumor growth more than Salmonella controls (50% vs. 0% in tumor regression rates). Moreover, it prolonged survivals of animals without induction of memory antitumor protective responses to a parental tumor re-challenge (50% vs. 0% in survival rates). These results suggest that a genetically engineered S. typhimurium with Flt3L expression vectors has the potential to be applicable as a safer and more effective tumor-targeting and tumoricidal agent.

Adenovirus-mediated suicide gene therapy using the human telomerase catalytic subunit (hTERT) gene promoter induced apoptosis of ovarian cancer cell line.

Telomerase is a ribonucleoprotein complex the function of which is to add telomeric repeats (TTAGGG)(n) to chromosomal ends, and it is known to play an important role in cellular immortalization. Telomerase is highly active in most tumor cells, yet not in normal cells. As such, it may have possible applications in cancer gene therapy. Telomerase consists of two essential components, telomerase RNA template (hTR) and catalytic subunit (hTERT). hTERT is expressed only in cells and tissues positive for telomerase activity, i.e., tumor and fetal cells. We here tested the possibility of the utilization of the hTERT promoter in targeted cancer gene therapy. We cloned the hTERT promoter in the replace of the CMV promoter and sub-cloned HSV-TK gene to be controlled by hTERT gene promoter in adenovirus shuttle plasmid. Then we constructed recombinant adenovirus Ad-hT-TK, and infected them into normal and human gynecological cancer cell lines. Through these experiments, we identified the selective tumor specific cell death by Ad-hT-TK. Furthermore, FACS analysis and TUNEL assay suggests that the reduced viability is mediated through the induction of apoptosis, indicating that this approach may be a useful method for suppressing cancer growth in targeted cancer gene therapy. These results show that Ad-hT-TK could be used for gynecological cancer gene therapy.

Comparison of responses elicited by immunization with a Legionella species common lipoprotein delivered as naked DNA or recombinant protein.

To evaluate the peptidoglycan-associated lipoprotein (PAL) antigen of Legionella pneumophila as a vaccine candidate, mice were immunized intramuscularly with pcDNA3-PAL and intraperitoneally with recombinant PAL (t-rPAL), which were compared for their ability to induce PAL-specific immune responses. The t-rPAL protein induced PAL-specific IgG antibody production significantly more than did pcDNA3-PAL. The IgG2a and IgG1 production was predominant after pcDNA3-PAL and t-rPAL administration, respectively. In particular, pcDNA3-PAL induced much higher PAL-specific cytotoxic T-lymphocyte responses than did t-rPAL. Furthermore, in vivo, CD19+ B-cell populations were dramatically increased by t-rPAL vaccination, suggesting a B-cell immunomodulatory activity of the lipoprotein. The PAL antigen was also conserved among Legionella species, as determined by PCR and immunoblot analyses. These results support a potential use of the t-rPAL protein and in particular DNA vaccines against Legionella infections.