Enhanced expression of NLRP3 inflammasome components by monocytes of patients with pulmonary paracoccidioidomycosis is associated with smoking and intracellular hypoxemia Publication date: Available online 23 November 2019 Source: Microbes and Infection Author(s): Barbara Casella Amorim, Ana Carla Pereira-Latini, Márjorie de Assis Golim, Raul Lopes Ruiz Júnior, Hugo Hyung Bok Yoo, Maria Sueli Parreira de Arruda, Aldo Henrique Tavares, Ricardo Souza Cavalcante, Rinaldo Poncio Mendes, Alessandra Pontillo, James Venturini Abstract Paracoccidioidomycosis (PCM) is a systemic mycosis caused by thermally dimorphic fungi of the genus Paracoccidioides that affects predominantly 30-60-year-old male rural workers. The main clinical forms of the disease are acute/subacute, chronic (CF); almost all CF patients develop pulmonary fibrosis, and they also exhibit emphysema due to smoke. An important cytokine in this context, IL-1β, different from the others, is produced by an intracellular multimolecular complex called inflammasome that is activated by pathogens and/or host signs of damage. Inflammasome has been recognized for its contribution to chronic inflammatory diseases, from that, we hypothesized that this activation could be involved in paracoccidioidomycosis, contributing to chronic inflammation. While inflammasome activation has been demonstrated in experimental models of P. brasiliensis infection, no information is available in patients, leading us to investigate the participation of NLRP3-inflammasome machinery in CF/PCM patients from a Brazilian endemic area. Our findings showed increased priming in mRNA levels of NLRP3 inflammasome genes by monocytes of PCM patients in vitro than healthy controls. Similar intracellular protein expression of NLRP3, CASP-1, ASC, and IL-1β were also observed in freshly isolated monocytes of PCM patients and smoker controls. Increased expression of NLRP3 and ASC was observed in monocytes from PCM patients under hypoxia in comparison with smoker controls. For the first time, we showed that primed monocytes of CF-PCM patients were associated with enhanced expression of components of NLRP3-inflammasome due to smoke. Also, hypoxemia boosted this machinery. These findings reinforce the systemic low-grade inflammation activation observed in PCM during and after treatment.

Metformin promotes Mycobacterium tuberculosis killing and increases the production of human β-defensins in lung epithelial cells and macrophages Publication date: Available online 2 November 2019 Source: Microbes and Infection Author(s): Adrian Rodriguez-Carlos, Claudia Valdez-Miramontes, Paulina Marin-Luevano, Irma González-Curiel, Jose A. Enciso-Moreno, Bruno Rivas-Santiago Abstract Diabetes has been associated with an increased risk of developing tuberculosis. The reasons related to the increased susceptibility to develop TB in type 2 diabetes mellitus (T2DM) individuals, has not been completely elucidated. However, this susceptibility has been attributed to several factors including failures and misfunctioning of the immune system. In the present study, we aimed to determine the role of anti-hyperglycemic drugs such as glyburide, insulin, and metformin to promote the killing of mycobacteria through the regulation of innate immune molecules such as host defense peptides (HDP) in lung epithelial cells and macrophages. Our results showed that metformin reduces bacillary loads in macrophages and lung epithelial cells which correlates with higher production of β-defensin-2, -3 and -4. Since β-defensins are crucial molecules for controlling Mycobacterium tuberculosis growth, the present results suggest that the use of metformin would be the first choice in the treatment for T2DM2, in patients within tuberculosis-endemic areas.

Anti-tuberculosis (TB) chemotherapy dynamically rescues Th1 and CD8+ T effector levels in Han Chinese pulmonary TB patients Publication date: Available online 1 November 2019 Source: Microbes and Infection Author(s): Guobao Li, Fang Yang, Xing He, Zhi Liu, Jiang Pi, Yuzhen Zhu, Xue Ke, Shuyan Liu, Min Ou, Huixin Guo, Zhuoran Zhang, Gucheng Zeng, Guoliang Zhang Abstract CD4+/CD8+ T cells play a major role in conferring immune protection against tuberculosis (TB), but it remains unknown how the immune responses of CD4+/CD8+ T cells exactly correlate with the clinical variables and disease statuses during anti-TB chemotherapy. To address this, several major immune parameters of CD4+/CD8+ T cells in peripheral blood derived from pulmonary TB patients and healthy volunteers were evaluated. We observed that active TB infection induced lower CD3+ T cell and CD4+ T cell levels but higher CD8+T cell levels, while anti-TB chemotherapy reversed these effects. Also, anti-TB treatment induced enhanced production of IL-2 and IFN-γ but reduced expression of IL-10 and IL-6. Moreover, the dynamic changes of CD3, CD4, and CD8 levels did not show a significant association with sputum smear positivity. However, the frequencies of IL-2+CD4+ or IL-10 + CD4+ T effector subpopulation or IL-1β production in peripheral blood showed significant difference between patients positive for sputum smear and patients negative for sputum smear after anti-TB treatment. These findings implicated that recovery of Th1/CD8+T cell effector levels might be critical immunological events in pulmonary TB patients after treatment and further suggested the importance of these immunological parameters as potential biomarkers for prediction of TB progress and prognosis.

T.B. Blues Publication date: Available online 17 October 2019 Source: Microbes and Infection Author(s): Sophia Häfner

Immunization with the basic membrane protein (BMP) family ABC transporter elicits protection against Enterococcus faecium in a murine infection model Publication date: Available online 1 October 2019 Source: Microbes and Infection Author(s): Sally Waheed Yousief, Mohammed Bahey-El-Din, Taha Ibrahim Zaghloul Abstract Enterococcus faecium is evolving as a multi-resistant pathogen causing infections with high morbidity and mortality. A protective vaccine against E. faecium is lacking up till now. ATP-binding cassette (ABC) transporter proteins have important functions in bacteria to maintain survival and homeostasis. In the present study, we evaluated the basic membrane protein (BMP) family ABC transporter substrate-binding protein, designated herein as BMP, as a potential vaccine candidate against E. faecium. Recombinant BMP of E. faecium was expressed in Escherichia coli, and purified by metal affinity chromatography. Swiss albino mice were immunized with the recombinant BMP combined with Bacillus Calmette–Guérin (BCG) and/or alum as adjuvants. Mice immunized with BMP combined with alternating BCG and alum developed BMP-specific IgG and were protected against E. faecium challenge as evidenced from organ bioburden and histopathological examination. Furthermore, serum from immunized mice showed enhanced opsonophagocytic activity and protected mice against E. faecium challenge by passive immunization. Bioinformatic analysis revealed appreciable degrees of homology between E. faecium BMP and proteins from other pathogens which suggests BMP could be a useful vaccine against multiple pathogens. To our knowledge, this is the first report of in-vivo evaluation of BMP as a potential vaccine candidate against E. faecium.

Coxiella burnetii: international pathogen of mystery Publication date: Available online 28 September 2019 Source: Microbes and Infection Author(s): Amanda L. Dragan, Daniel E. Voth Abstract Coxiella burnetii is an intracellular bacterium that causes acute and chronic Q fever. This unique pathogen has been historically challenging to study due to obstacles in genetically manipulating the organism and the inability of small animal models to fully mimic human Q fever. Here, we review the current state of C. burnetii research, highlighting new approaches that allow the mechanistic study of infection in disease relevant settings.

Another protein in the wall Publication date: Available online 17 September 2019 Source: Microbes and Infection Author(s): Sophia Häfner Abstract Article highlight based on “VraSR has an important role in immune evasion of Staphylococcus aureus with low level vancomycin resistance" by Caihong Gao et al.

Complement mediated Klebsiella pneumoniae capsule changes Publication date: Available online 29 August 2019 Source: Microbes and Infection Author(s): Trine S. Jensen, Katharina V. Opstrup, Gunna Christiansen, Pernille V. Rasmussen, Mikkel E. Thomsen, Daniel L. Justesen, Henrik C. Schønheyder, Mads Lausen, Svend Birkelund Abstract The Gram-negative bacterium Klebsiella pneumoniae is an opportunistic pathogen, which can cause life-threatening infections such as sepsis. Worldwide, emerging multidrug resistant K. pneumoniae infections are challenging to treat, hence leading to increased mortality. Therefore, understanding the interactions between K. pneumoniae and the immune system is important to develop new treatment options. We characterized ten clinical K. pneumoniae isolates obtained from blood of bacteremia patients. The interaction of the isolates with human serum was investigated to elucidate how K. pneumoniae escapes the host immune system, and how complement activation by K. pneumoniae changed the capsule structure. All K. pneumoniae isolates activated the alternative complement pathway despite serum resistance of seven isolates. One serum sensitive isolate activated two or all three pathways, and this isolate was lysed and had numerous membrane attack complexes in the outer membrane. However, we also found deposition of complement components in the capsule of serum resistant isolates resulting in morphological capsule changes and capsule shedding. These bacteria did not lyse, and no membrane attack complex was observed despite deposition of C5b-9 within the capsule, indicating that the capsule of serum resistant K. pneumoniae isolates is a defense mechanism against complement-mediated lysis.

Phosphoglycerate mutase affects Stenotrophomonas maltophilia attachment to biotic and abiotic surfaces Publication date: Available online 17 August 2019 Source: Microbes and Infection Author(s): Layla Ramos-Hegazy, Shubham Chakravarty, Gregory G. Anderson Abstract Stenotrophomonas maltophilia biofilm formation is of increasing medical concern, particularly for lung infections. However, the molecular mechanisms facilitating the biofilm lifestyle in S. maltophilia are poorly understood. We generated and screened a transposon mutant library for mutations that lead to altered biofilm formation compared to wild type. One of these mutations, in the gene for glycolytic enzyme phosphoglycerate mutase (gpmA), resulted in impaired attachment on abiotic and biotic surfaces. As adherence to a surface is the initial step in biofilm developmental processes, our results reveal a unique factor that could affect S. maltophilia biofilm initiation and, possibly, subsequent development.

Ripk3 licenced protection against microbial infection in the absence of Caspase1-11 inflammasome Publication date: Available online 17 August 2019 Source: Microbes and Infection Author(s): Bojan Shutinoski, Rajen Patel, Julianna J. Tomlinson, Michael G. Schlossmacher, Subash Sad Abstract Receptor interacting protein kinase 3 (Ripk3) is a signal relay protein involved in initiation of programmed cell death (necroptosis) and modulation of inflammasome activation. While caspase 1 and 11 are pro-inflammatory caspases responsible for unleashing inflammation and cell death by enzymatic activation of the executioners of inflammation and cell death (pyroptosis). Upon Salmonella infection, the host mounts a pro-inflammatory response which require Ripk3 and Caspase1/11. Here we show that bone marrow derived macrophages with combined deficiency of Ripk3 and Casp1/11 are highly resistant to Salmonella induced cell death, and that these macrophages show an anti-inflammatory cytokine profile. We confirm what was previously known that mice deficient in Casp1/11 have impaired ability to control Salmonella burden, and that the absence of Ripk3 alone does not influence the innate immune responses to Salmonella infection. However, we describe a synergistic role of Ripk3 and Casp1/11 in regulating Salmonella in vivo burden and that Ripk3-dependent host protection in the absence of Casp1/11 is evident during infection by sifA-expressing Salmonella. In summary, we show that the Ripk3 protection to Salmonella infection is obscured by presence of Caspase 1/11 and that the Ripk3-dependent protection requires a phagosome-bound Salmonella.