Porcine circovirus type 2 and Glaesserella parasuis serotype 4 co-infection activates Snail1 to disrupt the intercellular junctions and facilitate bacteria translocation across the tracheal epithelium.

Clinically, Porcine circovirus type 2 (PCV2) often causes disease through coinfection with other bacterial pathogens, including Glaesserella parasuis (G. parasuis), which causes high morbidity and mortality. However, the mechanism of PCV2 and G. parasuis serotype 4 (GPS4) co-infection is still not fully understood. In this study, swine tracheal epithelial cells (STEC) were used as a barrier model, and our results showed that PCV2 infection increased the adhesion of GPS4 to STEC, while decreasing the levels of ZO-1, Occludin and increasing tracheal epithelial permeability, and ultimately facilitated GPS4 translocation. Snail1 is a transcriptional repressor, and has been known to induce epithelial-to-mesenchymal transition (EMT) during development or in cancer metastasis. Importantly, we found that Snail1, as a transcriptional repressor, was crucial in destroying the tracheal epithelial barrier induced by PCV2, GPS4, PCV2 and GPS4 coinfection. For the first time, we found that PCV2, GPS4, PCV2 and GPS4 coinfection cross-activates TGF-ß and p38/MAPK signaling pathways to upregulate the expression of Snail1, down-regulate the levels of ZO-1 and Occludin, and thus disrupt the integrity of tracheal epithelial barrier then promoting GPS4 translocation. Finally, PCV2 and GPS4 co-infection also can activate TGF-ß and p38/MAPK signaling pathways in vivo and upregulate Snail1, ultimately down-regulating the expression of ZO-1 and Occludin. Our study elucidates how PCV2 infection promotes GPS4 to breach the tracheal epithelial barrier and aggravate clinical manifestations.

A link between STK signalling and capsular polysaccharide synthesis in Streptococcus suis.

Synthesis of capsular polysaccharide (CPS), an important virulence factor of pathogenic bacteria, is modulated by the CpsBCD phosphoregulatory system in Streptococcus. Serine/threonine kinases (STKs, e.g. Stk1) can also regulate CPS synthesis, but the underlying mechanisms are unclear. Here, we identify a protein (CcpS) that is phosphorylated by Stk1 and modulates the activity of phosphatase CpsB in Streptococcus suis, thus linking Stk1 to CPS synthesis. The crystal structure of CcpS shows an intrinsically disordered region at its N-terminus, including two threonine residues that are phosphorylated by Stk1. The activity of phosphatase CpsB is inhibited when bound to non-phosphorylated CcpS. Thus, CcpS modulates the activity of phosphatase CpsB thereby altering CpsD phosphorylation, which in turn modulates the expression of the Wzx-Wzy pathway and thus CPS production.

Coinfection with porcine circovirus type 2 and Glaesserella parasuis serotype 4 enhances pathogenicity in piglets.

Coinfection of Porcine circovirus type 2 (PCV2) and Glaesserella parasuis type 4 (GPS4) is widespread clinically, resulting in high morbidity and mortality, however, interactions between the two pathogens during coinfection and the coinfection pathogenesis are poorly understood. In this study, a piglet model coinfected with PCV2 and GPS4 was established; coinfection of the piglets' group showed more obvious symptoms, such as high fever and emaciation, and more severe histological lesions appeared in various organs. Importantly, piglets in the coinfection group produced lower levels of PCV2 and GPS4 antibodies, and showed high levels of inflammatory cytokines, TLR2, and TLR4, while the levels of CD4, CD8, MHC II, costimulatory molecules, and IL-12p40 were decreased. In addition, a model of macrophage 3D4/21 cells coinfection with PCV2 and GPS4 was established, coinfected cells exhibited increased expression of the cytokines IL-6, IL-8, TNF-α, IL-1ß, and the receptors TLR2, TLR4, while decreased MHC II. We further demonstrate that cytokine production is associated with the activation of NF-κB and NLRP3 inflammasome signaling pathways, and TLR4 is also involved. Altogether, our findings suggest that coinfection with PCV2 and GPS4 exacerbates the inflammatory response, resulting in severe tissue damage, and probably impaired macrophage antigen presentation and T cell activation, resulting in immune dysregulation, aggravating host infection.

Highly efficient and selective capture Pb(II) through a novel metal-organic framework containing bifunctional groups.

The design and development of materials with a selective adsorption capacity for Pb(II) are very important for environmental governance and ecological safety. In this work, a novel 3D metal-organic framework ([Cd2H4L4Cl2SO4]·4H2O, Cd-MOF) is constructed using a multiple pyrazole heterocycles tetraphenylethylene-based ligand (H4L4) and CdSO4 which containing Pb(II) adsorption sites (SO42-). Studies have shown that the Cd-MOF has outstanding stability, and its maximum adsorption value of Pb(II) can be as high as 845.55 mg/g, which is higher than that of most MOFs or MOFs modified materials. It is worth emphasizing that the Cd-MOF have excellent recyclability due to the unique adsorption mechanism of the Cd-MOF. Thermodynamic studies have shown that Pb(II) adsorption of the Cd-MOF is a spontaneous endothermic process. Specific selective adsorption, exceptional stability and remarkable recyclability make the Cd-MOF a potential material for industrial capture and recovery of Pb(II) from water.

Identification of novel genes associated with anti-phagocytic functions in Streptococcus equi subsp. zooepidemicus.

The anti-phagocytic abilities of bacteria often affect bacterial pathogenicity. Here, random mutant library of Streptococcus equi subsp. zooepidemicus (SEZ) was constructed using transposon mutagenesis. After careful screening, 30 transposon mutants with different transposon insertion sites were identified by conducting quantitative phagocytosis and insertion-site confirmation assays, whose anti-phagocytic abilities were significantly reduced relative to the wild-type strain. Insertion sites of 19 strains were monocistronic, including genes coding membrane proteins, transporters, and enzymes with unknown pathological function, such as sadM, adhP, purD, guaA, alpha-galactosidase coding gene, ABC transporter permease coding gene, metallo-beta-lactamase coding gene, and three secreted enzyme coding genes spuZ, slaB, and endoS, as well as known virulence factor coding genes, such as hasA and szM. The insertion sites of another 11 strains were polycistronic. We focused on four monocistronic-mutant strains: MhtpZ, MspuZ, MslaB, and MendoS. The anti-phagocytic abilities of not only the mutants that were precoincubated with the recombinant proteins, but also the complement strains were significantly more pronounced than those of all four corresponding mutants. The polyclonal antiserum against SlaB or EndoS also significantly decreased the anti-phagocytic capacity of wild-type SEZ. All four mutants exhibited significantly decreased viability in whole blood and reduced lethality in mice relative to the wild-type strain. Thus, we identified a variety of new anti-phagocytic factors, particularly multiple SEZ secreted enzymes. These factors are instrumental in the phagocytic resistance of SEZ in the absence of opsonin. Our results provide a framework for further studies of SEZ pathogenesis and relevant vaccine development for novel potential targets.

Intelligent system to predict intradialytic hypotension in chronic hemodialysis.

BACKGROUND: Intradialytic hypotension (IDH) is a serious complication and a major risk factor of increased mortality during hemodialysis (HD). However, predicting the occurrence of intradialytic blood pressure (BP) fluctuations clinically is difficult. This study aimed to develop an intelligent system with capability of predicting IDH. METHODS: In developing and training the prediction models in the intelligent system, we used a database of 653 HD outpatients who underwent 55,516 HD treatment sessions, resulting in 285,705 valid BP records. We built models to predict IDH at the next BP check by applying time-dependent logistic regression analyses. RESULTS: Our results showed the sensitivity of 86% and specificity of 81% for both nadir systolic BP (SBP) of <90 mmHg and <100 mmHg, suggesting good performance of our prediction models. We obtained similar results in validating via test data and data of newly enrolled patients (new-patient data), which is important for simulating prospective situations wherein dialysis staff are unfamiliar with new patients. This compensates for the retrospective nature of the BP records used in our study. CONCLUSION: The use of this validated intelligent system can identify patients who are at risk of IDH in advance, which may facilitate well-timed personalized management and intervention.

hsdS, Belonging to the Type I Restriction-Modification System, Contributes to the Streptococcus suis Serotype 2 Survival Ability in Phagocytes.

Streptococcus suis serotype 2 (SS2) is an important zoonotic agent in swine and humans. Anti-phagocytosis and survival in phagocytic cells and whole blood is essential for bacteria to be pathogenic. In this study, the host specificity determinant specificity subunit (coded by hsdS) of the Type I Restriction-Modification system and two peptidoglycan-binding proteins (coded by lysM and lysM', respectively), which were simultaneously found to be subjected to transcript-level influence by hsdS, were identified to facilitate the anti-phagocytosis of SS2 to a microglia cell line BV2. Furthermore, they significantly enhanced its survival in BV2, whole blood, and a peroxidation environment (H2O2) (p < 0.05), yet not in the acidic condition based on statistical analysis of the characteristic differences between gene mutants and wild-type SS2. In contrast, another specificity subunit, coded by hsdS', that belonged to the same Type I Restriction-Modification system, only significantly reduced the survival ability of SS2 in the acidic condition when in the form of a gene-deleted mutant (p < 0.05), but it did not significantly influence the survival ability in other conditions mentioned above or have enhanced anti-phagocytosis action when compared with wild-type SS2. In addition, the mutation of hsdS significantly enhanced the secretion of nitric oxide and TNF-α by BV2 with SS2 incubation (p < 0.05). The SS2 was tested, and it failed to stimulate BV2 to produce IFN-γ. These results demonstrated that hsdS contributed to bacterial anti-phagocytosis and survival in adverse host environments through positively impacting the transcription of two peptidoglycan-binding protein genes, enhancing resistance to reactive oxygen species, and reducing the secretion of TNF-α and nitric oxide by phagocytes. These findings revealed new mechanisms of SS2 pathogenesis.

An autosomal dominant progressive congenital zonular nuclear cataract linked to chromosome 20p12.2-p11.23.

PURPOSE: To map and to identify the causal gene for autosomal dominant congenital cataract (ADCC) in a Chinese family. METHODS: A four-generation family with a history of progressive congenital cataracts was investigated. Twenty-three members of the family were examined ophthalmologically. Blood samples were collected from twenty-nine family members for genetic linkage analysis. Two-point LOD scores were calculated. Multi-point linkage analysis and haplotype construction were performed to define the optimal cosegregating interval. Direct sequence analysis of the candidate gene, beaded filament structural protein 1, filensin (BFSP1) in the critical region was carried out. RESULTS: Fifteen family members were affected with autosomal dominant progressive congenital zonular nuclear cataract (ADPCZNC). The maximum two-point LOD Score of 6.02 was obtained for marker D20S904 (theta=0). The cataract locus in this family was mapped to chromosome 20p12.2-p11.23, a 9.34 Mb (16.37 cM) interval between markers D20S186 and D20S912. Although BFSP1 was in this critical region, we found no evidence that the condition in the family was caused by a BFSP1 mutation. CONCLUSIONS: We have mapped the genetic locus of ADPCZNC to chromosome 20p12.2-p11.23 in an ADCC family. This is the first time ADPCZNC was linked to this region.