SPM-1-producing Pseudomonas aeruginosa: analysis of the ancestor relationship using multilocus sequence typing, pulsed-field gel electrophoresis, and automated ribotyping

In Brazil, the spread of an endemic clone of SPM-1-producing Pseudomonas aeruginosa has been reported. Recently, a higher genomic variety has been observed among the SPM-1-producing P. aeruginosa isolates. The principal aim of this study was to analyze through multilocus sequence typing (MLST) analysis whether the recently isolated SPM-1-producing P. aeruginosa descend or not from a common ancestor. A total of 50 SPM-1-producing P. aeruginosa exhibiting 11 distinct ribotyping genotypes collected from 11 different Brazilian cities were studied. Three IMP-1-producing P. aeruginosa and two non-metallo-beta-lactamase-producing P. aeruginosa isolates were included in the study as controls. For assignment of allelic numbers and subsequent determination of sequence type (ST), the obtained sequences were compared to existing sequences in the MLST database (www.pubmlst.org/paeruginosa). The eBURSTv3 software was used in this study for establishing the evolutionary relationship and phylogenetic analysis. A total of 5 different STs were identified among 55 P. aeruginosa isolates. All of the SPM-1-producing P. aeruginosa presented an identical allelic profile (ST277), except for one strain. The three IMP-1-producing P. aeruginosa strains were classified as belonging to the ST593, whereas the non-metallo-beta-lactamase-producing P. aeruginosa showed two new distinct STs, ST594 and ST595. Our study shows that SPM-1-producing P. aeruginosa isolates as well as the IMP producers evaluated in this study descend from a common ancestor.     

Air pollution in autoimmune rheumatic diseases: A review

Air pollution consists of a heterogeneous mixture of gasses and particles that include carbon monoxide, nitrates, sulfur dioxide, ozone, lead, toxic by-product of tobacco smoke and particulate matter. Oxidative stress and inflammation induced by inhaled pollutants may result in acute and chronic disorders in the respiratory system, as well as contribute to a state of systemic inflammation and autoimmunity. This paper reviews the mechanisms of air contaminants influencing the immune response and autoimmunity, and it focuses on studies of inhaled pollutants triggering and/or exacerbating rheumatic diseases in cities around the world. Remarkably, environmental factors contribute to the onset of autoimmune diseases, especially smoking and occupational exposure to silica in rheumatoid arthritis and systemic lupus erythematosus. Other diseases such as scleroderma may be triggered by the inhalation of chemical solvents, herbicides and silica. Likewise, primary vasculitis associated with anti-neutrophil cytoplasmic antibody (ANCA) may be triggered by silica exposure. Only few studies showed that air pollutants could trigger or exacerbate juvenile idiopathic arthritis and systemic lupus erythematosus. In contrast, no studies of tropospheric pollution triggering inflammatory myopathies and spondyloarthropathies were carried out. In conclusion, air pollution is one of the environmental factors involved in systemic inflammation and autoimmunity. Further studies are needed in order to evaluate air pollutants and their potentially serious effects on autoimmune rheumatic diseases and the mechanisms involved in the onset and the exacerbation of these diseases.     

Quantitation of infectious myonecrosis virus in different tissues of naturally infected Pacific white shrimp, Litopenaeus vannamei, using real-time PCR with SYBR Green chemistry

The Pacific white shrimp, Litopenaeus vannamei, is the most important shrimp species in volume in world aquaculture. However, in recent decades, outbreaks of diseases, especially viral diseases, have led to significant economic losses, threatening the sustainability of shrimp farming worldwide. In 2004, Brazilian shrimp farming was seriously affected by a new disease caused by the Infectious myonecrosis virus (IMNV). Thus, disease control based on rapid and sensitive pathogen detection methods has become a priority. In this study, a specific quantitation method for IMNV was developed using real-time PCR with SYBR Green chemistry and viral load of the principal target tissues of chronically infected animals was quantified. The quantitative analysis revealed that mean viral load ranged from 5.08 × 10⁸ to 1.33 × 10⁶ copies/μg of total RNA in the hemolymph, 5.096 × 10⁵ to 1.26 × 10³ copies/μg in the pleopods, 6.85 × 10⁸ to 3.09 × 10⁴ copies/μg in muscle and 8.15 × 10⁶ to 3.90 × 10³ copies/μg in gills. Different viral loads of IMNV were found with greater values in the hemolymph and muscle, followed by the pleopods and gills.     

Human pregnancy levels of estrogen and progesterone contribute to humoral immunity by activating TFH/B cell axis

Circulating T_FH (cT_FH) cells express CXCR5, PD-1, and, when activated, ICOS, and release IL-21. According to the production of IFN-γ, IL-4, and IL-17 and expression of FoxP3, these cells are also classified as cT_FH1, cT_FH2, cT_FH17, and cT_FR cells, respectively. This CD4⁺T-cell subset is pivotal to efficient humoral immunity, and pregnancy appears to favor IgG production. Here, not only pregnancy amplified the in vivo production of anti-HBsAg IgG in HBV immunized women, but the frequency of cT_FH cells was directly correlated with estradiol levels. In vitro, pregnancy-related dose of 17-β-estradiol (E2) directly increased the percentage of different cT_FH subsets. While E2 and progesterone (P4) increased the proportion of differentiated T_FH cells derived from naïve CD4⁺T-cells, only E2 amplified the release of IL-21 in those cell cultures. In addition, E2 and P4 increased the proportion of memory B cells and plasma cells, respectively. In SEB-activated B/T_FH cell co-cultures, E2, in the presence of P4, increased the production of total IgG. Finally, among the hormones, P4 was stronger in upregulating the percentage of IL-10⁺T_FR cells. Collectively, our findings suggested that E2 and P4 cooperate in the humoral immune response by favoring the expansion of different cT_FH and B cell subsets.     

Skeletal development of Kinosternon scorpioides limbs (Chelonia: Kinosternidae)

The morphological study of limbs is important for the understanding of tetrapod biology, where it can be applied to taxonomy and phylogeny, as well ecology and behavior. In this study area, osteogenesis is a subject in Kinosternidae, which has been little researched. The main aim of this study was to characterize the skeletogenesis of Kinosternon scorpioides limbs. Samples were histologically processed, and the embryos were cleared with potassium hydroxide and stained with alcian blue and alizarin red. It was observed that the limbs arose in embryonic Stage 10 as mesenchymal condensate cells. The first stylopodium chondrification centers were noted at Stage 14. Zeugopodium chondrification centers appeared at Stage 15; carpal, metacarpal, tarsal, and metatarsal regions were observed at Stage 16, and the cartilage molds of all bones limbs were present at Stage 18. Ossification began in the humerus and femur at Stage 20, and continued into the radius, ulna, tibia, and fibula bones. By Stage 23, it was already effectively directed toward the bone epiphyses in both limbs. At Stage 26 and hatching, only articular cartilages remained, and in the majority of samples the carpal region showed no affinity for alcian blue or alizarin red staining. This study acts as an indicative parameter of the taxon's normal development and can contribute to the phylogenetic understanding of this group.     

Dual function of Langerhans cells in skin TSLP-promoted TFH differentiation in mouse atopic dermatitis

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Rare Pathogenic Variants in Mitochondrial and Inflammation-Associated Genes May Lead to Inflammatory Cardiomyopathy in Chagas Disease

Abstract

Cardiomyopathies are an important cause of heart failure and sudden cardiac death. Little is known about the role of rare genetic variants in inflammatory cardiomyopathy. Chronic Chagas disease cardiomyopathy (CCC) is an inflammatory cardiomyopathy prevalent in Latin America, developing in 30% of the 6 million patients chronically infected by the protozoan Trypanosoma cruzi, while 60% remain free of heart disease (asymptomatic (ASY)). The cytokine interferon-γ and mitochondrial dysfunction are known to play a major pathogenetic role. Chagas disease provides a unique model to probe for genetic variants involved in inflammatory cardiomyopathy.

Methods

We used whole exome sequencing to study nuclear families containing multiple cases of Chagas disease. We searched for rare pathogenic variants shared by all family members with CCC but absent in infected ASY siblings and in unrelated ASY.

Results

We identified heterozygous, pathogenic variants linked to CCC in all tested families on 22 distinct genes, from which 20 were mitochondrial or inflammation-related – most of the latter involved in proinflammatory cytokine production. Significantly, incubation with IFN-γ on a human cardiomyocyte line treated with an inhibitor of dihydroorotate dehydrogenase brequinar (enzyme showing a loss-of-function variant in one family) markedly reduced mitochondrial membrane potential (ΔψM), indicating mitochondrial dysfunction.

Conclusion

Mitochondrial dysfunction and inflammation may be genetically determined in CCC, driven by rare genetic variants. We hypothesize that CCC-linked genetic variants increase mitochondrial susceptibility to IFN-γ-induced damage in the myocardium, leading to the cardiomyopathy phenotype in Chagas disease. This mechanism may also be operative in other inflammatory cardiomyopathies.