記述言語：英語   掲載種別：研究論文（学術雑誌）  

Chronic periodotitis is caused by the formation of biofilms. Prevotella intermedia, a gram-negative obligate anaerobic bacterium residing in periodontal pockets is involved in the formation of biofilms and secrets a highly potent DNA-degrading activity. Biofilm contains extracellular DNA as a structural component, suggesting that DNase activity may influence P. intermedia's own biofilm development. Neutrophil extracellular traps (NETs) have mesh-like structures and composed of DNA, histone and antibacterial proteins. NETs play an important role in protecting against infection, but it is possible that DNase of P. intermedia disrupts NETs. The lack of established genetic manipulation has significantly delayed the analysis of DNase pathogenic factors. Recently, we have succeeded in establishing a genetic manipulation technique for P. intermedia. In this study, we created strains lacking two DNase candidate genes, nucA (PIOMA14_I_0621) and nucD (PIOMA14_II_0624), that were highly conserved among P. intermedia strains. We examined biochemical analysis of DNase activity, their effection on biofilm formation, and their evasion of NETs. Here, we showed both of them possessed DNase activities which appeared to account all of DNase activities of the bacterium. The mutant analysis further demonstrated that NucA and NucD destroyed biofilm and NETs formations. Neither one was perfectly responsible for DNase activity, but rather they take turns depending on the conditions. In conclusion, the nucA and nucD genes encode DNases that cooperatively function on biofilm formation and suppress NETs formation in P. intermedia.

DOI： 10.1002/mbo3.70102

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: The precise mechanisms of respiratory infection caused by oral anaerobic bacteria remain elusive. Unexpectedly, bacterial microbiota analysis with 16S rRNA revealed "hidden" mixed infections of anaerobic bacteria and commensal oral Streptococcus species in patients with community-acquired pneumonia. The study aimed to elucidate the mechanisms by which Prevotella intermedia exacerbates oral streptococcal pneumonia. METHODS: Oral streptococci were oropharyngeally administered with the culture supernatants of P intermedia (PiSup) in mice to assess survival, microbial burden, inflammatory responses, and host response via unbiased bulk RNA sequencing. Additionally, genetically engineered strains of P intermedia were used to identify pathogenic factors. RESULTS: Seven-week-old female C57BL/6J mice treated with the combination of Streptococcus spp and PiSup exhibited significantly worse survival and increased microbial burden in the lungs and spleen when compared with Streptococcus spp and control medium. RNA sequencing of whole lung revealed disruption of neutrophilic bactericidal activity due to NADPH downregulation, accompanied by reduced myeloperoxidase production in mixed infections, leading to dysfunctional neutrophil accumulation in the lungs. Notably, PiSup from strains bearing mutations in the type IX secretion pathway (ΔporT or ΔporK) failed to worsen the mixed infection. CONCLUSIONS: P intermedia exacerbates pneumonia caused by commensal oral streptococci by inducing neutrophilic dysfunction in mixed infection. Products of the type IX secretion system should be investigated as novel targets independent of reported virulence factors.

DOI： 10.1093/infdis/jiaf278

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Objectives: In the present study, we aimed to clarify the mechanisms by which periodontal pathogens, particularly Prevotella intermedia, induce severe neutrophilic inflammation. In addition, we aimed to test the efficacy of macrolides, which has not been resolved in the neutrophilic inflammation induced by P. intermedia. Methods: NCl-H292 human airway epithelial cells were pre-incubated with clarithromycin for 2 h before incubation with P. intermedia supernatants. Then, C-X-C motif chemokine ligand 8 (CXCL8) transcription and interleukin (IL)-8 production were measured. To elucidate the signaling pathway, mitogen-activated protein kinase inhibitors were added to the cell culture, and the cells were subjected to Western blotting. Results:P. intermedia supernatants promoted CXCL8 transcription and IL-8 production, and the reactions were significantly suppressed by clarithromycin pretreatment. Only trametinib, the selective mitogen-activated extracellular signal-regulated kinase inhibitor, downregulated CXCL8 transcription and IL-8 production. Furthermore, Western blotting revealed that stimulation with P. intermedia supernatants specifically induces extracellular signal-regulated kinases (ERK) 1/2 phosphorylation, which is suppressed by clarithromycin pretreatment. Notably, the interference analysis revealed that ERK3 might be dispensable for IL-8 production under the stimulation of P. intermedia supernatants. Conclusions: Our results provide new insight into the mechanism underlying P. intermedia-induced production of IL-8 from human airway epithelial cells. Furthermore, macrolides might have therapeutic potential in regulating periodontal pathogen-induced neutrophilic inflammation in the lungs.

DOI： 10.3390/antibiotics13090909

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Evidence regarding the association of the usage of biologic agents (Etanercept, Tocilizumab, adalimumab and so on), such as anti-tumor necrosis factor α, with the incidence and risk factors of non-tuberculous Mycobacteria (NTM) infection is limited. Therefore, this study aimed to investigate the incidence and risk factors of NTM and their associations with biologic agents' usage, and also investigated the potential of Mycobacterium avium complex (MAC) antibodies as a predictor of NTM infection development. METHODS: This retrospective study included 672 patients with autoimmune diseases from four hospitals in Nagasaki, Japan, from January 1, 2011, to June 30, 2019, who fulfilled the inclusion criteria. RESULTS: Of the 672 patients, 9 (1.3%) developed complicated NTM infection, including two with disseminated infection, after the introduction of biologic agents. Of the nine patients, two died due to NTM infection but none tested positive for MAC antibodies prior to initiation of biologic agents. The mortality rate was higher in patients complicated with NTM than without NTM (22.2% vs 2.6%, P = 0.024). The corticosteroids dosage at the time of initiating the biologic agents was significantly higher in the NTM group than in the non-NTM group (median, 17 mg vs 3 mg, P = 0.0038). CONCLUSION: In the patients undergoing therapy with biologic agents, although NTM complication was rare, it could be fatal. In particular, for patients on a relatively high dose corticosteroids, careful observation is essential for identifying NTM complication, even if the MAC antibody test is negative.

DOI： 10.1016/j.resinv.2024.02.005

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Following an endobronchial examination, a young mine supervisor was treated with antibiotics for a pulmonary nontuberculous mycobacterial infection for approximately one year. However, a review of the radiological findings revealed a different possibility. Accordingly, pulmonary resection was performed, and histopathological analysis revealed numerous yeast-like fungi. Since the patient had stayed in the southwestern United States for two months in 2009, eight years previously, coccidioidomycosis was strongly suspected. The diagnosis of coccidioidomycosis was subsequently confirmed by serology and polymerase chain reaction testing of the excised specimen. Here, we report an educational case that emphasizes the importance of meticulous medical history-taking and awareness of endemic mycoses in other countries in the context of globalization.

DOI： 10.7883/yoken.JJID.2023.073

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