Nocardia cyriacigeorgica infection in a patient with repeated fever and CD4+ T cell deficiency: A case report.

BACKGROUND: Nocardia pneumonia shares similar imaging and clinical features with pulmonary tuberculosis and lung neoplasms, but the treatment and anti-infective medication are completely different. Here, we report a case of pulmonary nocardiosis caused by Nocardia cyriacigeorgica (N. cyriacigeorgica), which was misdiagnosed as community-acquired pneumonia (CAP) with repeated fever. CASE SUMMARY: A 55-year-old female was diagnosed with community-acquired pneumonia in the local hospital because of repeated fever and chest pain for two months. After the anti-infection treatment failed in the local hospital, the patient came to our hospital for further treatment. Enhanced computed tomography showed multiple patchy, nodular and strip-shaped high-density shadows in both lungs. A routine haematological examination was performed and showed abnormalities in CD19+ B cells and CD4+ T cells. Positive acid-fast bifurcating filaments and branching gram-positive rods were observed in the bronchoalveolar lavage fluid of the patient under an oil microscope, which was identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry as N. cyriacigeorgica. The patient's condition quickly improved after taking 0.96 g compound sulfamethoxazole tablets three times a day. CONCLUSION: The antibiotic treatment of Nocardia pneumonia is different from that of common CAP. Attention should be given to the pathogenic examination results of patients with recurrent fever. Nocardia pneumonia is an opportunistic infection. Patients with CD4+ T-cell deficiency should be aware of Nocardia infection.

Analysis of Influencing Factors for Exercise Ventilation Efficiency of COPD Patients.

Dynamic pulmonary hyperinflation and abnormal air exchange are the primary causes of the exercise limitation of chronic obstructive pulmonary disease (COPD) patients. During exercise, COPD sufferers' lungs are dynamically hyperinflated. Increased inefficient ventilation reduces ventilation efficiency and causes a mismatch between ventilation volume and blood flow. The ventilatory equivalent for CO2 (VeqCO2) is a physiological parameter that can be measured using cardiopulmonary exercise testing. Therefore, the aim of this exploratory study was to perform cardiopulmonary exercise testing on people with COPD, investigate the impact of static pulmonary function on ventilation efficiency under the exercise state, and screen the predictive indicators of ventilation efficiency. Subject. The aim of this study was to look at the factors that influence the exercise ventilation efficiency of people with COPD. Method. A total of 76 people with COPD were recruited during the stable period. Age, gender, body height, body mass, and other basic information were recorded. The body mass index (BMI) was determined, and forced vital capacity (FVC), forced expiratory volume in one second (FEV1), residual volume/total lung capacity (RV/TLC), diffusing capacity of the lung for carbon monoxide (DLCO), and DLCO divided by the alveolar volume (DLCO/VA) were measured. The ventilatory equivalent for carbon dioxide (VE/VCO2) under the rest state (EqCO2rest), anaerobic threshold (EqCO2at), and maximum exercise state (EqCO2 max) were calculated to investigate the influencing factors for ventilation efficiency of people with COPD. Results. FEV1% was negatively correlated with EqCO2rest (r = -0.277, P value <0.05); FEV1/FVC % was negatively correlated with EqCO2rest and EqCO2at (r = -0.311, -0.287, P value <0.05); DLCO% was negatively correlated with EqCO2rest, EqCO2at, and EqCO2max (r = -0.408, -0.462, and -0.285, P value <0.05); DLCO/VA% was negatively correlated with EqCO2rest, EqCO2at, and EqCO2max (r = -0.390, -0.392, and -0.245, P value <0.05); RV/TLC was positively correlated with EqCO2rest and EqCO2at (r = 0.289, 0.258, P-value <0.05). The prediction equation from the multivariable regression analysis equation was Y = 40.04-0.075X (Y = EqCO2, X = DLCO/VA%). Conclusions. As the degree of ventilatory obstruction increased, the ventilation efficiency of the stable people with COPD under the exercise state showed a progressive decrease; the ventilation efficiency of the people with COPD decreased significantly under the maximum exercise state, and the ventilation capacity and diffusion capacity were the significant factors that affected the exercise ventilation efficiency. The diffusion function may predict the maximum ventilation efficiency and enable primary hospitals without exercise test equipment in developing countries to predict and screen patients at risk for current exercise based on limited information.

M16-Type Metallopeptidases Are Involved in Virulence for Invasiveness and Diffusion of Leptospira interrogans and Transmission of Leptospirosis.

BACKGROUND: Leptospirosis is a global zoonotic infectious disease caused by Leptospira interrogans. The pathogen rapidly invades into hosts and diffuses from bloodstream into internal organs and excretes from urine to cause transmission of leptospirosis. However, the mechanism of leptospiral invasiveness remains poorly understood. METHODS: Proteolytic activity of M16-type metallopeptidases (Lep-MP1/2/3) of L. interrogans was determined by spectrophotometry. Expression and secretion of Lep-MP1/2/3 during infection of cells were detected by quantitative reverse-transcription polymerase chain reaction, Western blot assay, and confocal microscopy. Deletion and complementation mutants of the genes encoding Lep-MP1/2/3 were generated to determine the roles of Lep-MP1/2/3 in invasiveness using transwell assay and virulence in hamsters. RESULTS: Leptospira interrogans but not saprophytic Leptospira biflexa strains were detectable for Lep-MP-1/2/3-encoding genes. rLep-MP1/2/3 hydrolyzed extracellular matrix proteins, but rLep-MP1/3 displayed stronger proteolysis than rLep-MP2, with 123.179/340.136 µmol/L Km and 0.154/0.159 s-1 Kcat values. Expression, secretion and translocation of Lep-MP1/2/3 during infection of cells were increased. ΔMP1/3 but not ΔMP2 mutant presented attenuated transmigration through cell monolayers, decreased leptospiral loading in the blood, lungs, liver, kidneys, and urine, and 10/13-fold decreased 50% lethal dose and milder histopathologic injury in hamsters. CONCLUSIONS: Lep-MP1 and 3 are involved in virulence of L. interrogans in invasion into hosts and diffusion in vivo, and transmission of leptospirosis.

vWA proteins of Leptospira interrogans induce hemorrhage in leptospirosis by competitive inhibition of vWF/GPIb-mediated platelet aggregation.

BACKGROUD: Leptospira interrogans is the major causative agent of leptospirosis, a worldwide zoonotic disease. Hemorrhage is a typical pathological feature of leptospirosis. Binding of von Willebrand factor (vWF) to platelet glycoprotein-Ibα (GPIbα) is a crucial step in initiation of platelet aggregation. The products of L. interrogans vwa-I and vwa-II genes contain vWF-A domains, but their ability to induce hemorrhage has not been determined. METHODS: Human (Hu)-platelet- and Hu-GPIbα-binding abilities of the recombinant proteins expressed by L. interrogans strain Lai vwa-I and vwa-II genes (rLep-vWA-I and rLep-vWA-II) were detected by flowcytometry, surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). Hu-platelet aggregation and its signaling kinases and active components were detected by lumiaggregometry, Western analysis, spectrophotometry and confocal microscopy. Hu-GPIbα-binding sites in rLep-vWA-I and rLep-vWA-II were identified by SPR/ITC measurements. FINDINGS: Both rLep-vWA-I and rLep-vWA-II were able to bind to Hu-platelets and inhibit rHu-vWF/ristocetin-induced Hu-platelet aggregation, but Hu-GPIbα-IgG, rLep-vWA-I-IgG and rLep-vWA-II-IgG blocked this binding or inhibition. SPR and ITC revealed a tight interaction between Hu-GPIbα and rLep-vWA-I/rLep-vWA-II with KD values of 3.87 × 10-7-8.65 × 10-8 M. Hu-GPIbα-binding of rL-vWA-I/rL-vWA-II neither activated the PI3K/AKT-ERK and PLC/PKC kinases nor affected the NO, cGMP, ADP, Ca2+ and TXA2 levels in Hu-platelets. G13/R36/G47 in Lep-vWA-I and G76/Q126 in Lep-vWA-II were confirmed as the Hu-GPIbα-binding sites. Injection of rLep-vWA-I or rLep-vWA-II in mice resulted in diffuse pulmonary and focal renal hemorrhage but this hemorrhage was blocked by rLep-vWA-I-IgG or rLep-vWA-II-IgG. INTERPRETATION: The products of L. interrogans vwa-I and vwa-II genes induce hemorrhage by competitive inhibition of vWF-mediated Hu-platelet aggregation.

A leptospiral AAA+ chaperone-Ntn peptidase complex, HslUV, contributes to the intracellular survival of Leptospira interrogans in hosts and the transmission of leptospirosis.

Leptospirosis caused by Leptospira is a zoonotic disease of global importance but it is considered as an emerging or re-emerging infectious disease in many areas in the world. Until now, the mechanisms about pathogenesis and transmission of Leptospira remains poorly understood. As eukaryotic and prokaryotic proteins can be denatured in adverse environments and chaperone-protease/peptidase complexes degrade these harmful proteins, we speculate that infection may also cause leptospiral protein denaturation, and the HslU and HslV proteins of L. interrogans may compose a complex to degrade denatured proteins that enhances leptospiral survival in hosts. Here we show that leptospiral HslUV is an ATP-dependent chaperone-peptidase complex containing ATPase associated with various cellular activity (AAA+) and N-terminal nucleophile (Ntn) hydrolase superfamily domains, respectively, which hydrolyzed casein and chymotrypsin-like substrates, and this hydrolysis was blocked by threonine protease inhibitors. The infection of J774A.1 macrophages caused the increase of leptospiral denatured protein aggresomes, but more aggresomes accumulated in hslUV gene-deleted mutant. The abundant denatured leptospiral proteins are involved in ribosomal structure, flagellar assembly, two-component signaling systems and transmembrane transport. Compared to the wild-type strain, infection of cells in vitro with the mutant resulted in a higher number of dead leptospires, less leptospiral colony-forming units and lower growth ability, but also displayed a lower half lethal dose, attenuated histopathological injury and decreased leptospiral loading in lungs, liver, kidneys, peripheral blood and urine in hamsters. Therefore, our findings confirmed that HslUV AAA+ chaperone-Ntn peptidase complex of L. interrogans contributes to leptospiral survival in hosts and transmission of leptospirosis.

Eosinophils from Murine Lamina Propria Induce Differentiation of Naïve T Cells into Regulatory T Cells via TGF-ß1 and Retinoic Acid.

Treg cells play a crucial role in immune tolerance, but mechanisms that induce Treg cells are poorly understood. We here have described eosinophils in lamina propria (LP) that displayed high aldehyde dehydrogenase (ALDH) activity, a rate-limiting step during all-trans retinoic acid (ATRA) synthesis, and expressed TGF-ß1 mRNA and high levels of ATRA. Co-incubation assay confirmed that LP eosinophils induced the differentiation of naïve T cells into Treg cells. Differentiation promoted by LP eosinophils were inhibited by blocked either TGF-ß1 or ATRA. Peripheral blood (PB) eosinophils did not produce ATRA and could not induce Treg differentiation. These data identifies LP eosinophils as effective inducers of Treg cell differentiation through a mechanism dependent on TGF-ß1 and ATRA.

RETRACTED: ChpK and MazF of the toxin-antitoxin modules are involved in the virulence of Leptospira interrogans during infection.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the corresponding author and the editorial office of Microbes and Infection. An independent reviewer of the retraction request was also appointed given that one of the authors is the Editor-in- Chief. For figure 1C, Lanes 1 and 2 appear to share some unexpected similarities, except for the bottom band, which also appear to be the band of interest. Sections of Figure 2C appear similar to sections of Figure 5D of a paper that had already appeared in Molecular Microbiology, volume 83, issue 5 (2012) 1006-1023. https://doi.org/10.1111/j.1365-2958.2012.07985.x. In figure 3A, Flow cytograms share identical/similar patterns highlighted in various colours. Peculiarly, some of these patterns can be seen as horizontal rotations of others along the axis that separates different quadrants. (ie red green & purple). Moreover, some quadrants appear to have very high densities of events that are suprisingly limited by quadrant gates (most noticeably quadrants B2 from the second column of panels. Figure 5A-B it was found that there were duplicated bands were produced. Figures 5C and 5D, it was found that bands across each individual gel appear identical. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper has not been previously published and is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a misuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process".

Identification of Leptospira interrogans phospholipase C as a novel virulence factor responsible for intracellular free calcium ion elevation during macrophage death.

BACKGROUND: Leptospira-induced macrophage death has been confirmed to play a crucial role in pathogenesis of leptospirosis, a worldwide zoonotic infectious disease. Intracellular free Ca(2+) concentration ([Ca(2+)]i) elevation induced by infection can cause cell death, but [Ca(2+)]i changes and high [Ca(2+)]i-induced death of macrophages due to infection of Leptospira have not been previously reported. METHODOLOGY/PRINCIPAL FINDINGS: We first used a Ca(2+)-specific fluorescence probe to confirm that the infection of L. interrogans strain Lai triggered a significant increase of [Ca(2+)]i in mouse J774A.1 or human THP-1 macrophages. Laser confocal microscopic examination showed that the [Ca(2+)]i elevation was caused by both extracellular Ca(2+) influx through the purinergic receptor, P2X7, and Ca(2+) release from the endoplasmic reticulum, as seen by suppression of [Ca(2+)]i elevation when receptor-gated calcium channels were blocked or P2X7 was depleted. The LB361 gene product of the spirochete exhibited phosphatidylinositol phospholipase C (L-PI-PLC) activity to hydrolyze phosphatidylinositol-4,5-bisphosphate (PIP2) into inositol-1,4,5-trisphosphate (IP3), which in turn induces intracellular Ca(2+) release from endoplasmic reticulum, with the Km of 199 µM and Kcat of 8.566E-5 S(-1). Secretion of L-PI-PLC from the spirochete into supernatants of leptospire-macrophage co-cultures and cytosol of infected macrophages was also observed by Western Blot assay. Lower [Ca(2+)]i elevation was induced by infection with a LB361-deficient leptospiral mutant, whereas transfection of the LB361 gene caused a mild increase in [Ca(2+)]i. Moreover, PI-PLCs (PI-PLC-ß3 and PI-PLC-γ1) of the two macrophages were activated by phosphorylation during infection. Flow cytometric detection demonstrated that high [Ca(2+)]i increases induced apoptosis and necrosis of macrophages, while mild [Ca(2+)]i elevation only caused apoptosis. CONCLUSIONS/SIGNIFICANCE: This study demonstrated that L. interrogans infection induced [Ca(2+)]i elevation through extracellular Ca(2+) influx and intracellular Ca(2+) release cause macrophage apoptosis and necrosis, and the LB361 gene product was shown to be a novel PI-PLC of L. interrogans responsible for the [Ca(2+)]i elevation.