SND1 promotes Th1/17 immunity against chlamydial lung infection through enhancing dendritic cell function.

To date, no reports have linked the multifunctional protein, staphylococcal nuclease domain-containing protein 1 (SND1), to host defense against intracellular infections. In this study, we investigated the role and mechanisms of SND1, by using SND1 knockout (SND1-/-) mice, in host defense against the lung infection of Chlamydia muridarum, an obligate intracellular bacterium. Our data showed that SND1-/- mice exhibited significantly greater body weight loss, higher organism growth, and more severe pathological changes compared with wild-type mice following the infection. Further analysis showed significantly reduced Chlamydia-specific Th1/17 immune responses in SND1-/- mice after infection. Interestingly, the dendritic cells (DCs) isolated from SND1-/- mice showed lower costimulatory molecules expression and IL-12 production, but higher IL-10 production compared with those from wild-type control mice. In the DC-T cell co-culture system, DCs isolated from SND1-/- infected mice showed significantly reduced ability to promote Chlamydia-specific IFN-γ producing Th1 cells but enhanced capacity to induce CD4+T cells into Foxp3+ Treg cells. Adoptive transfer of DCs isolated from SND1-/- mice, unlike those from wild-type control mice, failed to protect the recipients against challenge infection. These findings provide in vivo evidence that SND1 plays an important role in host defense against intracellular bacterial infection, and suggest that SND1 can promote Th1/17 immunity and inhibit the expansion of Treg cells through modulation of the function of DCs.

Semaphorin 3E Protects against Chlamydial Infection by Modulating Dendritic Cell Functions.

Recent studies have identified semaphorin 3E (Sema3E) as a novel mediator of immune responses. However, its function in immunity to infection has yet to be investigated. Using a mouse model of chlamydial lung infection, we show that Sema3E plays a significant role in the host immune response to the infection. We found that Sema3E is induced in the lung after chlamydial infection, and Sema3E deficiency has a detrimental impact on disease course, dendritic cell (DC) function, and T cell responses. Specifically, we found that Sema3E knockout (KO) mice exhibited higher bacterial burden, severe body weight loss, and pathological changes after Chlamydia muridarum lung infection compared with wild-type (WT) mice. The severity of disease in Sema3E KO mice was correlated with reduced Th1/Th17 cytokine responses, increased Th2 response, altered Ab response, and a higher number of regulatory CD4 T cells. Moreover, DCs isolated from Sema3E KO mice showed lower surface expression of costimulatory molecules and production of IL-12, but higher expression of PD-L1, PD-L2, and IL-10 production. Functional DC-T cell coculture studies revealed that DCs from infected Sema3E KO mice failed to induce Th1 and Th17 cell responses compared with DCs from infected WT mice. Upon adoptive transfer, mice receiving DCs from Sema3E KO mice, unlike those receiving DCs from WT mice, were not protected against challenge infection. In conclusion, our data evidenced that Sema3E acts as a critical factor for protective immunity against intracellular bacterial infection by modulating DC functions and T cell subsets.

Th17/Treg Imbalance: Implications in Lung Inflammatory Diseases.

Regulatory T cells (Tregs) and T helper 17 cells (Th17) are two CD4+ T cell subsets with antagonist effects. Th17 cells promote inflammation, whereas Tregs are crucial in maintaining immune homeostasis. Recent studies suggest that Th17 cells and Treg cells are the foremost players in several inflammatory diseases. In this review, we explore the present knowledge on the role of Th17 cells and Treg cells, focusing on lung inflammatory diseases, such as chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), sarcoidosis, asthma, and pulmonary infectious diseases.

NK cells modulate T cell responses via interaction with dendritic cells in Chlamydophila pneumoniae infection.

Protective immune response to chlamydial infection is largely dependent on cell-mediated immune responses with IFN-γ production. Recent studies have shown the critical role of NK cells in bridging innate and adaptive immune responses. In this study, we investigated the effect of NK cells on T cell responses during Chlamydophila pneumoniae (Cpn) lung infection. The results showed that NK cells play a protective role in Cpn infection and influence T cell immunity largely though modulating dendritic cells (DCs) function. Specifically, we found that NK depletion significantly impaired type 1 T cell responses, but enhanced FOXP3+Treg cells and IL-10-producing CD4+T cells. The alteration of T cell responses was associated with more disease severity and higher chlamydial growth in the lung. Further analysis of DC phenotype and cytokine profile found that DCs from NK cell-depleted mice expressed lower levels of co-stimulatory molecules and produced higher levels of IL-10 than those from control IgG-treated mice. More importantly, the adoptive transfer of DCs from NK cell-depleted mice induced a much lower degree of type 1 T cell responses but a higher amount of FOXP3+ Treg cells and IL-10-producing CD4+T cells in the recipient mice than DCs from IgG-treated mice. In contrast to the strong protective effect observed in recipients of DCs from IgG-treated mice, the recipients of DCs from NK cell-depleted mice failed to be protected against Cpn infection. The data suggest that NK cells play a critical role in coordinating innate and adaptive immunity in Cpn lung infection by modulating the DC function to influence T cell responses.

Recent advances in management of acute liver failure.

Acute liver failure (ALF) is a life-threatening illness, where a previously normal liver fails within days to weeks. Sudden loss of synthetic and detoxification function of liver results in jaundice, encephalopathy, coagulopathy, and multiorgan failure. The etiology of ALF varies demographically. The mortality of ALF is as high as 40-50%. The initial care of patients with ALF depends on prompt recognition of the condition and early detection of etiology. Management includes intensive care support, treatment of specific etiology if present and early detection of candidates for liver transplantation. Liver transplantation remains the only therapeutic intervention with proven survival benefit in patients with irreversible ALF. Living related liver transplantation, auxiliary liver transplantation, and  ABO-incompatible liver transplantation are coming up in a big way. Liver assist devices and hepatocyte transplant remain experimental and further advances are required. Public health measures to control hepatitis A, B, E, and drug-induced liver injury will reduce the incidence and mortality of ALF.

Interaction of silver nanoparticles with serum proteins affects their antimicrobial activity in vivo.

The emergence of multidrug-resistant bacteria is a global threat for human society. There exist recorded data that silver was used as an antimicrobial agent by the ancient Greeks and Romans during the 8th century. Silver nanoparticles (AgNPs) are of potential interest because of their effective antibacterial and antiviral activities, with minimal cytotoxic effects on the cells. However, very few reports have shown the usage of AgNPs for antibacterial therapy in vivo. In this study, we deciphered the importance of the chosen methods for synthesis and capping of AgNPs for their improved activity in vivo. The interaction of AgNPs with serum albumin has a significant effect on their antibacterial activity. It was observed that uncapped AgNPs exhibited no antibacterial activity in the presence of serum proteins, due to the interaction with bovine serum albumin (BSA), which was confirmed by UV-Vis spectroscopy. However, capped AgNPs [with citrate or poly(vinylpyrrolidone)] exhibited antibacterial properties due to minimized interactions with serum proteins. The damage in the bacterial membrane was assessed by flow cytometry, which also showed that only capped AgNPs exhibited antibacterial properties, even in the presence of BSA. In order to understand the in vivo relevance of the antibacterial activities of different AgNPs, a murine salmonellosis model was used. It was conclusively proved that AgNPs capped with citrate or PVP exhibited significant antibacterial activities in vivo against Salmonella infection compared to uncapped AgNPs. These results clearly demonstrate the importance of capping agents and the synthesis method for AgNPs in their use as antimicrobial agents for therapeutic purposes.

Semaphorins in immune cell function, inflammatory and infectious diseases.

The Semaphorin family is a group of proteins studied broadly for their functions in nervous systems. They consist of eight subfamilies ubiquitously expressed in vertebrates, invertebrates, and viruses and exist in membrane-bound or secreted forms. Emerging evidence indicates the relevance of semaphorins outside the nervous system, including angiogenesis, cardiogenesis, osteoclastogenesis, tumour progression, and, more recently, the immune system. This review provides a broad overview of current knowledge on the role of semaphorins in the immune system, particularly its involvement in inflammatory and infectious diseases, including chlamydial infections.

IFNγ-Producing B Cells Play a Regulating Role in Infection-Mediated Inhibition of Allergy.

The hygiene hypothesis suggests that some infections may inhibit the development of allergic diseases, but the mechanism remains unclear. Our previous study has shown that Chlamydia muridarum (Cm) lung infection can inhibit local eosinophilic inflammation induced by ovalbumin (OVA) through the modulation of dendritic cell (DC) and T cell responses in mice. In this study, we explored the role of B cells in the chlamydial-infection-mediated modulation of allergic responses. The results showed that adoptive transfer of B cells isolated from Cm-infected mice (Cm-B cells), unlike those from naïve mice (naïve B cells), could effectively inhibit allergic airway eosinophilia and mucus overproduction, as well as Th2 cytokine responses. In addition, total IgE/IgG1 and OVA-specific IgE/IgG1 antibodies in the serum were also decreased by the adoptive transfer of Cm-B cells. Intracellular cytokine analysis showed that B cells from Cm-infected mice produced higher levels of IFNγ than those from naïve mice. More interestingly, the inhibiting effect of adoptively transferred Cm-B cells on allergic reactions was virtually abolished by the simultaneous blockade of IFNγ using a monoclonal antibody. The results suggest that B cells modulated by chlamydial lung infection could play a regulatory role in OVA-induced acute allergic responses in the lung via the production of IFNγ. The results provide new insights into the targets related to the prevention and treatment of allergic diseases.

Exogenous Semaphorin 3E treatment protects against chlamydial lung infection in mice.

Recent studies reported that semaphorins play a significant role in various settings of the immune response. In particular, Semaphorin 3E (Sema3E), a secreted semaphorin protein, is involved in cell proliferation, migration, inflammatory responses, and host defence against infections. However, the therapeutic function of Sema3E in bacterial infection has not been investigated. Our data showed that exogenous Sema3E treatment protects mice from chlamydial infection with lower bacterial burden, reduced body weight loss, and pathological lung changes. Cytokine analysis in the lung and spleen revealed that Sema3E-Fc treated mice, compared to saline-Fc treated mice, showed enhanced production of IFN-γ and IL-17 but reduced IL-4 and IL-10 production. Cellular analysis showed that Sema3E treatment leads to enhanced Th1/Th17 response but reduced Treg response in lungs following chlamydial infection. Moreover, Sema3E treatment also enhanced the recruitment of pulmonary dendritic cells, which express higher co-stimulatory but lower inhibitory surface molecules. The data demonstrate that Sema3E plays a vital role in protective immunity against chlamydial lung infection, mainly through coordinating functions of T cells and DCs.

A Retrospective Quality Analysis of External Ventricular Drain Infection Rates Following Stroke Diagnoses and Other Brain Injuries: Comparison of Emergency Room and ICU/OR Setting.

Objective The purpose of this study was to analyze the incidence of infections in patients following placement of External Ventricular Drain (EVD) in either the Emergency Room (ER) or the Intensive Care Unit (ICU)/ Operating Room (OR) at a single Comprehensive Stroke Center. Methods Retrospective analysis of post-procedure infection rates in 710 patients with EVDs placed on site between 2010 and 2018 was performed. We analyzed cases between sex, age, stroke and non-stroke related and further requirement of conversion of the EVD to a ventriculoperitoneal (VP) shunt. Results Significant decrease in EVD related infection (ERIs) rates following the shift in EVD placement from ER to ICU/OR (from 13% to 7.7%, p=.03) among all ages, sex and type of brain injury was observed. Furthermore, our data also shows that the rate of conversion of EVDs to VP shunts is independent of the setting where EVD was placed, but increases in patients who develop ERIs. 23.1% of stroke patients that developed an ERI required a conversion to VP shunt while 67.3% of non-stroke patients that developed an ERI required further VP shunt (p<.001) showing that non-stroke EVD patients with infections are more likely to require VP shunt. Conclusion This is one of the larger retrospective studies conducted on EVD related infections. ERIs were significantly higher when EVDs were placed in the ER. Moreover, our results highlight the relation between ERIs and further requirement of conversion EVD to VP shunt. These figures highlight the importance of focusing on infection rates, and the implications CSF infection has on the long-term care of patients.

A fission yeast platform for heterologous expression of mammalian adenylyl cyclases and high throughput screening.

The fission yeast Schizosaccharomyces pombe uses a cAMP signaling pathway to link glucose-sensing to Protein Kinase A activity in order to regulate cell growth, sexual development, gluconeogenesis, and exit from stationary phase. We previously used a PKA-repressed fbp1-ura4 reporter to conduct high throughput screens (HTSs) for inhibitors of heterologously-expressed mammalian cyclic nucleotide phosphodiesterases (PDEs). Here, we describe the successful expression of all ten mammalian adenylyl cyclase (AC) genes, along with the human GNAS Gαs gene. By measuring expression of an fbp1-GFP reporter together with direct measurements of intracellular cAMP levels, we can detect both basal AC activity from all ten AC genes as well as GNAS-stimulated activity from eight of the nine transmembrane ACs (tmACs; AC2-AC9). The ability to use this platform to conduct HTS for novel chemical probes that reduce PKA activity was demonstrated by a pilot screen of the LOPAC®1280 library, leading to the identification of diphenyleneiodonium chloride (DPI) as an inhibitor of basal AC activity. This screening technology could open the door to the development of therapeutic compounds that target GNAS or the ACs, an area in which there is significant unmet need.

NK-DC Crosstalk in Immunity to Microbial Infection.

The interaction between natural killer (NK) cell and dendritic cell (DC), two important cellular components of innate immunity, started to be elucidated in the last years. The crosstalk between NK cells and DC, which leads to NK cell activation, DC maturation, or apoptosis, involves cell-cell contacts and soluble factors. This interaction either in the periphery or in the secondary lymphoid organs acts as a key player linking innate and adaptive immune responses to microbial stimuli. This review focuses on the mechanisms of NK-DC interaction and their relevance in antimicrobial responses. We specifically aim to emphasize the ability of various microbial infections to differently influence NK-DC crosstalk thereby contributing to distinct adaptive immune response.

Bilirubin, aspartate aminotransferase and platelet count score: a novel score for differentiating patients with chronic hepatitis B with acute flare from acute hepatitis B.

BACKGROUND: Early therapy improves the outcome in patients with chronic hepatitis B with acute flare (CHB-AF). However in mesoendemic countries, it is difficult to differentiate CHBAF from acute hepatitis B (AHB). The aim of this study was to formulate a clinical score to differentiate CHB-AF from AHB in patients presenting with an acute hepatitis-like picture. METHODS: Patients with a protracted clinical course of >2 months with elevated liver enzymes and positive hepatitis B virus DNA, who had undergone liver biopsy were included in this study. The clinical and laboratory profiles were compared between patients with biopsy suggestive of CHB-AF and AHB. RESULTS: Of the 75 patients included, 32 patients had a liver biopsy suggestive of CHB-AF. At 6 months, HBsAg clearance was lower in the CHB-AF group (9.4 vs. 76.7%). Presence of prodrome, platelet count, aspartate aminotransferase (AST), alanine aminotransferase and bilirubin levels and presence of anti-core antibody (IgM anti HBc) were lower in CHB-AF group (P<0.01). Using the receiver operating characteristic curve, peak bilirubin level, peak AST levels and least platelet count within the first 8 weeks had the highest predictive power. Optimal values of platelet <2.4×105/µL, peak bilirubin <4.5 mg/dL and AST <550 IU/L were given a point each. On internal validation a score of 2 had 86% specificity, 70.1% sensitivity and 82.7% diagnostic accuracy in predicting CHB-AF. CONCLUSION: Bilirubin, AST and platelet count (BAP) score may be helpful in differentiating CHB-AF from AHB. A score of >2 could strongly suggest CHB-AF. However the score requires further validation.

Acidic pH induced STM1485 gene is essential for intracellular replication of Salmonella.

During the course of infection, Salmonella has to face several potentially lethal environmental conditions, one such being acidic pH. The ability to sense and respond to the acidic pH is crucial for the survival and replication of Salmonella. The physiological role of one gene (STM1485) involved in this response, which is upregulated inside the host cells (by 90- to 113-fold) is functionally characterized in Salmonella pathogenesis. In vitro, the ΔSTM1485 neither exhibited any growth defect at pH 4.5 nor any difference in the acid tolerance response. The ΔSTM1485 was compromised in its capacity to proliferate inside the host cells and complementation with STM1485 gene restored its virulence. We further demonstrate that the surface translocation of Salmonella pathogenicity island-2 (SPI-2) encoded translocon proteins, SseB and SseD were reduced in the ΔSTM1485. The increase in co-localization of this mutant with lysosomes was also observed. In addition, the ΔSTM1485 displayed significantly reduced competitive indices (CI) in spleen, liver and mesenteric lymph nodes in murine typhoid model when infected by intra-gastric route. Based on these results, we conclude that the acidic pH induced STM1485 gene is essential for intracellular replication of Salmonella.