Pathogens and disease最新文献

Hypoxia-inducible factor (HIF)1α is a transcription factor involved in cellular metabolism and regulation of immune cell effector functions. Here, we studied the role of HIF1α in myeloid cells during pneumonia caused by the major causative pathogen, Streptococcus pneumoniae (Spneu). Mice deficient for HIF1α in myeloid cells (LysMcreHif1αfl/fl) were generated to study the in vitro responsiveness of bone marrow-derived macrophages (BMDMs) and alveolar macrophages (AMs) to the Gram-positive bacterial wall component lipoteichoic acid (LTA) and heat-killed Spneu, and the in vivo host response after infection with Spneu via the airways. Both BMDMs and AMs released more lactate upon stimulation with LTA or Spneu, indicative of enhanced glycolysis; HIF1α-deficiency in these cells was associated with diminished lactate release. In BMDMs, HIF1α-deficiency resulted in reduced secretion of tumor necrosis factor (TNF)α and interleukin (IL)-6 upon activation with Spneu but not LTA, while HIF1α-deficient AMs secreted less TNFα and IL-6 in response to LTA, and TNFα after Spneu stimulation. However, no difference was found in the host response of LysMcreHif1αfl/fl mice after Spneu infection as compared to controls. Similar in vivo findings were obtained in neutrophil (Mrp8creHif1αfl/fl) HIF1α-deficient mice. These data suggest that myeloid HIF1α is dispensable for the host defense during pneumococcal pneumonia.

Entamoeba gingivalis is a parasitic protozoan that colonizes the human oral cavity and there are two subtypes (ST1 and ST2) that have been identified to date. However, there are no reports on the molecular detection or characterization of E. gingivalis in Turkey. The objective of this study was to detect the presence of E. gingivalis in Turkish healthy individuals and those with periodontal disease and to subtype the isolates using molecular techniques. Samples from the oral cavity of 94 individuals were taken and the presence of E. gingivalis was determined by PCR using primers for SsrRNA and the amplicons were then confirmed by DNA sequencing. Each participant completed a questionnaire that included demographic data, habits and lifestyle, as well as health status. The presence of E. gingivalis was detected in a total of 19 samples (11 patients and eight healthy individuals). Molecular characterization determined that 12 samples belonged to ST1 and seven samples belonged to ST2. The presence of E. gingivalis was higher in patients with periodontal disease than in healthy individuals, and this association was statistically significant (P < .05). This study constitutes the first report of molecular detection and subtyping of E. gingivalis in Turkey.

Infection of macrophages with Mycobacterium tuberculosis induces innate immune responses designed to clear the invading bacterium. However, bacteria often survive within the intracellular environment by exploiting these responses triggered by macrophages. Here, the role of the orphan nuclear receptor Nur77 (Nr4a1) in regulating the response of macrophages infected with M. tuberculosis (Mtb) has been delineated. Nur77 is induced early during infection, regulates metabolism by binding directly at the promoter of the TCA cycle enzyme, isocitrate dehydrogenase 2 (IDH2), to act as its repressor, and shifts the balance from a proinflammatory to an anti-inflammatory phenotype. Depletion of Nur77 increased transcription of IDH2 and, consequently, the levels of intracellular succinate, leading to enhanced levels of the proinflammatory cytokine IL-1β. Further, Nur77 inhibited the production of antibacterial nitric oxide and IL-1β in a succinate dehydrogenase (SDH)-dependent manner, suggesting that its induction favors bacterial survival by suppressing bactericidal responses. Indeed, depletion of Nur77 inhibited the intracellular survival of Mtb. On the other hand, depletion of Nur77 enhanced lipid body formation, suggesting that the fall in Nur77 levels as infection progresses likely favors foamy macrophage formation and long-term survival of Mtb in the host milieu.

The obligate intracellular bacterial pathogen Chlamydia trachomatis is a leading cause of sexually transmitted infections and infectious blindness. Chlamydia undergo a biphasic developmental cycle alternating between the infectious elementary body (EB) and the replicative reticulate body (RB). The molecular mechanisms governing RB growth and RB-EB differentiation are unclear. We hypothesize that the bacterium senses host cell and bacterial energy levels and metabolites to ensure that development and growth coincide with nutrient availability. We predict that a partner switching mechanism (PSM) plays a key role in the sensing and response process acting as a molecular throttle sensitive to metabolite levels. Using purified wild type and mutant PSM proteins, we discovered that metal type impacts enzyme activity and the substrate specificity of RsbU and that RsbW prefers ATP over GTP as a phosphate donor. Immunoblotting analysis of RsbV1/V2 demonstrated the presence of both proteins beyond 20 hours post infection and we observed that an RsbV1-null strain has a developmental delay and exhibits differential growth attenuation in response to glucose levels. Collectively, our data support that the PSM regulates growth in response to metabolites and further defines biochemical features governing PSM-component interactions which could help in the development of novel PSM-targeted therapeutics.

Malaria, a mosquito-borne infectious disease, is caused by the unicellular apicomplexan protozoa of the genus Plasmodium. For malaria parasite transmission, the essential sexual stage includes production of gametocytes through gametocytogenesis in vertebrate hosts and formation of gametes from gametocytes through gametogenesis in mosquito vectors. Whereas each female gametocyte forms a single immotile macrogamete, a male gametocyte produces eight flagella-like microgametes in a process called exflagellation. We identified a conserved protein named as Py05543 (Pyp25α), required for male gametocyte exflagellation in Plasmodium yoelii, which is the ortholog of PFL1770c (PF3D7_1236600). Interestingly, PF3D7_1236600 was previously phenotypically screened to be gametocyte-essential genes during gametocytogenesis of Plasmodium falciparum, using piggyBac transposon-mediated insertional mutagenesis. In this study, using CRISPR/Cas9-mediated genome editing, the Pyp25α¯ (KO) parasite line was successfully established. We found that the KO parasites proliferated asexually in mouse blood normally. In addition, compared with that of the parental parasites, the KO parasites displayed similar levels of gametocytes formation. Unexpectedly, the KO parasites showed considerable deficiency in exflagellation of male gametes, by observing exflagellation centre formation. Taken together, our data suggested that Pyp25α gene, the ortholog of PF3D7_1236600, was nonessential for the growth of asexual parasites, required for male gametocyte exflagellation in P. yoelii.

Human trichinellosis is a serious disease with no effective treatment till now. Recently, the protective immunity induced by parasite-derived extracellular vesicles (EVs) are studied for some parasites such as Echinostoma caproni. The current study aimed to investigate the novel Trichinella spiralis-derived EVs as a potential vaccine candidate for the first time in a mouse model. Trichinella spiralis EVs were isolated and identified using transmission electron microscopy, gel electrophoresis, protein content measurements, and beads-based flow cytometry. Vaccination was done by subcutaneous injection of two doses of 3.5 μg T. spiralis-derived EVs. We observed a significant reduction in T. spiralis adult worm and muscle larval counts in mice immunized with T. spiralis-derived EVs (EVs-Ts group) and controlled inflammatory changes in the intestine and muscles. The EVs-Ts group showed a higher level of IFN- γ, whereas the IL-4 secretion was elevated more in the EVs group (EVs group) and showed a lower level after challenge with T. spiralis infection (EVs-Ts group). This implies a mixed Th1/Th2 immune response with obvious Th1 polarization. Moreover, elevation of serum T. spiralis-specific IgG was reported. In conclusion, this preliminary study provides T. spiralis EVs as a promising candidate for future development of anti-Trichinella vaccine.

Extracellular vesicles (EVs) are nano-sized-particles that play an important role in cellular cross-talk. The aim of this study was to understand the proteomic cargo of EVs, released by Retinal Pigment Epithelial (RPE) cells challenged with Candida albicans (C-CA) and Aspergillus flavus (C-AF). EVs were isolated from culture supernatant of retinal cells infected with fungal pathogens and characterized by dynamic light scattering, SEM, and western blot. EV proteome was then evaluated by mass spectrometry (LC-MS/MS). Isolated EVs were approximately 120-150 nm and higher in number in infected group compared to control. Proteomic profiling of EVs from infected cells, showed a total of 419 and 254 differentially expressed proteins, of which 218 were upregulated in C-CA group and 81 proteins were upregulated in C-AF group. Gene ontology revealed majority of proteins associated with transport, cell migration, and in activation of innate immune response. Proteins identified were annexins, calpain, and Sorcin proteins. Additionally, KEGG analysis unveiled involvement of MAPK, HIF-1, and PI3K-AKT signalling pathways. Proteomic results indicate that EVs cargo derived from fungal-infected retinal cells can activate immune signalling pathways and might contribute to the pathogenesis of endophthalmitis, indicating the potential use of EVs as theranostic marker for management of fungal infections.

Viruses and hosts must navigate environments in which each tries to outcompete the other for survival or to coexist within the same spaces. In Lewis Carrol's Through the Looking Glass, the Red Queen tells Alice, "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!" Borrowing from this idea, the Red Queen hypothesis asserts that organisms, such as viruses, must continuously adapt to environmental pressures to survive. In this commentary, we draw parallels between the Red Queen hypothesis and the experiences scientists of color navigate to thrive in academic spaces. In both phenomena, adapting to environmental pressures is necessary for survival. We identify the various pressures and bottlenecks faced by historically underrepresented groups in academia, as well as the adaptation strategies they must implement to persist in academia.

Phages are viruses that infect bacteria, relying on their genetic machinery to replicate. To survive the constant attack of phages, bacteria have developed diverse defense strategies to act against them. Nevertheless, phages rapidly co-evolve to overcome these barriers, resulting in a constant, and often surprising, molecular arms race. Thus, some phages have evolved protein inhibitors known as anti-CRISPRs (∼50-150 amino acids), which antagonize the bacterial CRISPR-Cas immune response. To date, around 45 anti-CRISPRs proteins with different mechanisms and structures have been discovered against the CRISPR-Cas type I and type II present in important animal and human pathogens such as Escherichia, Morganella, Klebsiella, Enterococcus, Pseudomonas, Staphylococcus, and Salmonella. Considering the alarming growth of antibiotic resistance, phage therapy, either alone or in combination with antibiotics, appears to be a promising alternative for the treatment of many bacterial infections. In this review, we illustrated the biological and clinical aspects of using phage therapy; furthermore, the CRISPR-Cas mechanism, and the interesting activity of anti-CRISPR proteins as a possible weapon to combat bacteria.

Adjuvants are important components of vaccines, increasing immunogenicity and modulating the immune response. SARS-CoV-2 vaccines are still being developed in order to improve worldwide access to immunization. Specific populations should be addressed in these investigations, such as pregnant women-to protect both mothers and neonates. In this study, female adult mice were immunized with Receptor-binding domain (RBD) from SARS-CoV-2 adjuvanted by a mixture of DDA and Saponin and put to mating to verify the maternal transference of IgG. For comparison, other group received RBD adjuvanted by OMVs from Neisseria meningitidis and Alum. The adjuvants enhanced IgG production and neutralization. DDA/Sap contributed to increase IgG1, IgG2a, IgG2b, and IgG3 isotypes. Total IgG avidity was considered high, as well as IgG1, IgG2a, and IgG2b avidity. IgG antibodies were effectively transferred to the offspring, predominantly IgG2a, IgG2b, and IgG3. The passive transferred immunoglobulin maintained the neutralizing ability, although it lost avidity. ELISA data was confirmed in Dot-ELISA and immunoblotting assays. DDA and Saponin seem a promising adjuvant mixture to enhance the humoral response of SARS-CoV-2 antigens. Further studies considering the effects of maternal immunization in the protection of offspring are needed, regardless the platform used in COVID-19 vaccines.