Neutralizing gut-derived lipopolysaccharide as a novel therapeutic strategy for severe leptospirosis.

Leptospirosis is an emerging infectious disease caused by pathogenic Leptospira spp. Humans and some mammals can develop severe forms of leptospirosis accompanied by a dysregulated inflammatory response, which often results in death. The gut microbiota has been increasingly recognized as a vital element in systemic health. However, the precise role of the gut microbiota in severe leptospirosis is still unknown. Here, we aimed to explore the function and potential mechanisms of the gut microbiota in a hamster model of severe leptospirosis. Our study showed that leptospires were able to multiply in the intestine, cause pathological injury, and induce intestinal and systemic inflammatory responses. 16S rRNA gene sequencing analysis revealed that Leptospira infection changed the composition of the gut microbiota of hamsters with an expansion of Proteobacteria. In addition, gut barrier permeability was increased after infection, as reflected by a decrease in the expression of tight junctions. Translocated Proteobacteria were found in the intestinal epithelium of moribund hamsters, as determined by fluorescence in situ hybridization, with elevated lipopolysaccharide (LPS) levels in the serum. Moreover, gut microbiota depletion reduced the survival time, increased the leptospiral load, and promoted the expression of proinflammatory cytokines after Leptospira infection. Intriguingly, fecal filtration and serum from moribund hamsters both increased the transcription of TNF-α, IL-1ß, IL-10, and TLR4 in macrophages compared with those from uninfected hamsters. These stimulating activities were inhibited by LPS neutralization using polymyxin B. Based on our findings, we identified an LPS neutralization therapy that significantly improved the survival rates in severe leptospirosis when used in combination with antibiotic therapy or polyclonal antibody therapy. In conclusion, our study not only uncovers the role of the gut microbiota in severe leptospirosis but also provides a therapeutic strategy for severe leptospirosis.

Leptospira-specific immunoglobulin Y (IgY) is protective in infected hamsters.

Leptospirosis, a globally significant zoonotic disease caused by pathogenic Leptospira, continues to threaten the health and public safety of both humans and animals. Current clinical treatment of leptospirosis mainly relies on antibiotics but their efficacy in severe cases is controversial. Passive immunization has a protective effect in the treatment of infectious diseases. In addition, chicken egg yolk antibody (IgY) has gained increasing attention as a safe passive immunization agent. This study aimed to investigate whether hens produce specific IgY after immunization with inactivated Leptospira and the protective effect of specific IgY against leptospirosis. First, it was demonstrated that specific IgY could be extracted from the eggs of hens vaccinated with inactivated Leptospira and that specific IgY can specifically recognize and bind homotypic Leptospira with a high titre, as shown by MAT and ELISA. Next, we tested the therapeutic effects of IgY in early and late leptospirosis using a hamster model. The results showed that early specific IgY treatment increased the survival rate of hamsters to 100%, alleviated pathological damage to the liver, kidney, and lung, reduced leptospiral burden, and restored haematological indices as well as functional indicators of the liver and kidney. The therapeutic effect of early specific IgY was comparable to that of doxycycline. Late IgY treatment also enhanced the survival rate of hamsters and improved the symptoms of leptospirosis similar to early IgY treatment. However, the therapeutic effect of late IgY treatment was better when combined with doxycycline. Furthermore, no Leptospira colonization was observed in the kidneys, livers, or lungs of the surviving hamsters treated with specific IgY. Mechanistically, IgY was found to inhibit the growth and adhesion to cells of Leptospira. In conclusion, passive immunotherapy with specific IgY can be considered an effective treatment for leptospirosis, and may replace antibiotics regarding its therapeutic effects.

Efficient 2D MOFs nanozyme combining with magnetic SERS substrate for ultrasensitive detection of Hg2.

Biomimetic inorganic nanoenzyme is a kind of nanomaterial with long-term stability, easy preparation and low cost, which could instead of natural biological enzyme. Metal-organic framework (MOFs) as effectively nanoenzyme was attracted more attention for the adjustability and large specific surface area. This design is based on the catalase-like catalytic activity of 2D metal-organic frameworks (MOFs) and the high sensitivity of surface enhanced Raman spectroscopy (SERS) biosensors to construct a novel SERS biosensor capable of efficiently detecting mercury (Hg2+). In this study, 2D MOFs nanozyme was instead of 3D structure with more effecient catalytic site, which can catalyze o-Phenylenediamine (OPD) to OPDox with the assistance of H2O2. Besides, a magnetic composite nanomaterial Fe3O4@Ag@OPD was prepared as a signal carrier. In the presence of Hg2+, T-Hg2+-T base pairs were used to connect the two materials to realize Raman signal change. Based on this principle, the SERS sensor can realize the sensitive detection of Hg2+, the detection range is 1.0 × 10-12 âˆ¼ 1.0 × 10-2 mol‧L-1, and the detection limit is 1.36 × 10-13 mol‧L-1. This method greatly improves the reliability of SERS sensor for detecting the target, and provides a new idea for detecting metal ions in the environment.

Adiponectin in the mammalian host influences ticks' acquisition of the Lyme disease pathogen Borrelia.

Arthropod-borne pathogens cause some of the most important human and animal infectious diseases. Many vectors acquire or transmit pathogens through the process of blood feeding. Here, we report adiponectin, the most abundant adipocyte-derived hormone circulating in human blood, directly or indirectly inhibits acquisition of the Lyme disease agent, Borrelia burgdorferi, by Ixodes scapularis ticks. Rather than altering tick feeding or spirochete viability, adiponectin or its associated factors induces host histamine release when the tick feeds, which leads to vascular leakage, infiltration of neutrophils and macrophages, and inflammation at the bite site. Consistent with this, adiponectin-deficient mice have diminished pro-inflammatory responses, including interleukin (IL)-12 and IL-1ß, following a tick bite, compared with wild-type animals. All these factors mediated by adiponectin or associated factors influence B. burgdorferi survival at the tick bite site. These results suggest a host adipocyte-derived hormone modulates pathogen acquisition by a blood-feeding arthropod.

High-efficiency SERS platform based on 3D porous PPDA@Au NPs as a substrate for the detection of pesticides on vegetables.

Nowadays, the presence of highly toxic and persistent residues of pesticides in water and food around the world is becoming a serious problem, and so their rapid and sensitive detection is critical to human health. In this work, a 3D composite nanoparticle of porous PDA (polydopamine) microspheres and Au NPs (PPDA@Au NPs) was proposed as a SERS substrate to detect pesticides. Porous PDA as a substrate was first synthesized with F127 (Pluronic F127), dopamine hydrochloride, and 1,3,5-TMB (1,3,5-trimethylbenzene) under weakly alkaline conditions by a one-step method. Then, HAuCl4 was in situ reduced in the pores of PPDA spheres and grew sequentially for effecting the reducibility of PPDA. As a result, uniform 3D PPDA@Au NPs with "hot spots" were successfully synthesized as SERS substrates, which could effectively avoid the agglomeration of gold nanoparticles to greatly improve the sensitivity and uniformity of the SERS platform. At the same time, methyl parathion, 4-chlorophenol, and 2,4-D as representatives of pesticides were detected with the proposed PPDA@Au NP-based SERS platform, with detection limits lower than 7.26, 7.52, and 11 ng mL-1, separately. The current work presents a simple preparation method to prepare sensitive and uniform SERS platform PPDA@Au NPs, which have potential for applications in actual pesticide and drug testing.

Seroepidemiological Analysis of Canine Leptospira Species Infections in Changchun, China.

Leptospirosis is a significant worldwide zoonotic infectious disease that infects a wide range of animals and humans. Leptospira will colonize the animal's urinary and reproductive systems and be excreted with urine, potentially causing a wide range of infections. Dogs are an essential host for Leptospira, and epidemiological investigation studies of leptospirosis must be conducted to clarify the prevalence of leptospirosis and to reduce the risk of transmission to humans. This study aimed to investigate the seroepidemiology of leptospiral infection in dogs from Changchun, China, using Microscopic Agglutination Test (MAT). A total of 1053 canine blood samples were collected and tested by MAT. The positive rate of MAT was approximately 19.1%. The main prevalent Leptospira serogroups were L. Icterohaemorrhagiae (8.1%), L. Canicola (7.6%), L. Australis (5.3%), L. Ballum (4.7%) and L. Pyrogenes (4.2%). No statistically significant difference among different varieties, sexes and sampling seasons (p > 0.05), except the age (p < 0.05). The seropositive rate was much higher in adult and aged dogs than in juvenile dogs. Our results showed the seroprevalence and the prevalent serogroup of Canine leptospirosis in Changchun, China.

Salidroside alleviates dextran sulfate sodium-induced colitis in mice by modulating the gut microbiota.

Dysbiosis causes continuous progress of inflammatory bowel disease (IBD). Herein, we aim to explore whether Salidroside (Sal), which is a major glycoside extracted from Rhodiola rosea L., could ameliorate dextran sulfate sodium (DSS)-induced colitis by modulating the microbiota. Results showed that oral treatment with 15 mg kg-1 of Sal inhibited DSS-induced colitis in mice as evidenced by colon length, histological analysis, disease activity index (DAI) score, and the proportion and number of macrophages in the intestine. The gut microbiota of colitic mice was also partly restored by Sal. A fecal microbiota transplantation (FMT) study was designed to verify the causality. Compared with DSS-treated mice, FM from the Sal-treated donor mice significantly mitigated the symptoms of colitic mice, including reducing the DAI score, alleviating tissue damage, boosting the expression of mucin protein (mucin-2) and tight junction (TJ) proteins (occludin and zonula occludens-1 (ZO-1), and decreasing M1 macrophages in the gut. It was found that both Sal and FMT affected the structure and abundance of the gut microbiota as reflected by the decreased relative abundance of Turicibacter, Alistipes, Romboutsia and the increased relative abundance of Lactobacillus at the genus level. Moreover, the anti-inflammatory effect of Sal disappeared when the gut microbiota was depleted by antibiotics, demonstrating that Sal alleviated the intestinal inflammation in a gut microbiota-dependent manner. Thus, Sal could be a remarkable candidate as a functional food for colitis.

Salidroside protects mice from high-fat diet-induced obesity by modulating the gut microbiota.

Obesity is a systemic disease with multisystem inflammation associated with gut dysbiosis. Salidroside (SAL) which is a major glycoside extracted from Rhodiola rosea L. has a wide range of pharmacological effects, but the role of gut microbiota in the protective effects of SAL on obesity has not been studied. Herein, we aim to explore whether SAL could ameliorate high-fat diet (HFD)-induced obesity in mice by modulating microbiota. Results showed that oral treatment with SAL alleviated HFD-induced obesity in mice as evidenced by body weight and fat weight. SAL supplementation effectively attenuated fat accumulation, lipid synthesis genes expression, liver inflammation, and metabolic endotoxemia. In addition, SAL treatment alleviated intestinal damage and increased the expression of mucin protein (Mucin-2) and tight junction (TJ) proteins (Occludin and Zonula Occludens-1). 16S rRNA sequencing analysis revealed that the gut microbiota of obese mice was also partly improved by SAL via restoring the microbial community structure and diversity. A fecal microbiota transplantation (FMT) study was designed to verify the causality. Compared with fecal transplantation (FM) from the HFD-treated mice, FM from the SAL-treated mice significantly mitigate the symptoms of obese mice, including decreasing body weight, fat accumulation, and attenuating pathological damage in the gut. Thus, SAL could be a remarkable candidate to prevent obesity.

The Epidemiology of Infectious Diseases Meets AI: A Match Made in Heaven.

Infectious diseases remain a major threat to public health [...].

The Prevention Effect of Bacillus subtilis on Escherichia coli-Induced Mastitis in Mice by Suppressing the NF-κB and MAPK Signaling Pathways.

Mastitis, common inflammation of the mammary gland, caused by various factors, is a challenge for the dairy industry. Escherichia coli (E. coli), a Gram-negative opportunistic pathogen, is one of the major pathogens causing clinical mastitis which is characterized by reduced milk production and recognizable clinical symptoms. Bacillus subtilis (B. subtilis) has been reported to have the ability to limit the colonization of pathogens and has immune-stimulatory effects on epithelial cells. The purpose of this study was to explore the preventive role of B. subtilis H28 on E. coli-induced mastitis in mice. The mastitis model was established by nipple duct injection of E. coli into mice, while B. subtilis H28 was utilized 2 h before E. coli injection. Furthermore, pathological changes in the mammary gland were evaluated by hematoxylin-eosin (H&E) staining. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of proinflammatory cytokines (TNF-α, IL-1ß, and IL-6). We also observed changes in Toll-like receptor 4 (TLR4), nuclear transcription factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) expression by using western blotting. The results revealed that B. subtilis H28 pretreatment reduced neutrophil infiltration in the mammary gland tissues, significantly decreased the secretion of TNF-α, IL-1ß, and IL-6, and downregulated the activation of TLR4 and the phosphorylation of p65 NF-κB, IκB, p38, and ERK. In conclusion, our results indicated that B. subtilis H28 can ameliorate E. coli-induced mastitis and suggest a new method for the prevention of mastitis.

Clostridium butyricum and Its Culture Supernatant Alleviate the Escherichia coli-Induced Endometritis in Mice.

Endometritis is a disease with a high incidence in dairy cows and causes great economic loss to milk production. This study examined the therapeutic effects of Clostridium butyricum and its culture supernatant on Escherichia coli-induced endometritis in mice. The results showed that Clostridium butyricum and its culture supernatant effectively suppressed inflammatory responses of uterine tissues, such as uterine morphological changes, pathological damage, and the production of inflammatory cytokines. Clostridium butyricum and its culture supernatant significantly decreased uterine microbial loads. In addition, Clostridium butyricum and its culture supernatant restored reproduction outcomes in Escherichia coli-induced endometritis mice. Western blot analysis showed that Clostridium butyricum and its culture supernatant suppressed the NF-κB signaling pathway. Therefore, the anti-inflammatory mechanism of Clostridium butyricum and its culture supernatant may occur through the anti-bacterial activity and regulation of the expression of NF-κB in the uterus. The anti-inflammatory effect of the culture supernatant of C. butyricum was slightly better than that of viable C. butyricum. Therefore, our experimental results showed that Clostridium butyricum culture supernatant may be an effective drug for treating endometritis.

Prevalence of mental health problems among stranded international students during the COVID-19 pandemic.

BACKGROUND: The novel coronavirus disease (COVID-19) spread fast throughout China and the rest of the world, prompting the World Health Organization to declare a worldwide pandemic on March 11, 2020. Many countries have implemented travel bans, lockdowns, and stay-at-home policies to combat the spread of the COVID-19 pandemic. This study aimed to investigate the risk factors of mental health problems among international students stranded outside of China during the pandemic. METHODS: A qualitative study was conducted among non-Chinese international students enrolled at Chinese universities who were stranded in their home countries. The participants were recruited using a purposive sampling technique. Following informed consent, in-depth interviews were conducted with the help of a semi-structured guide. Two independent investigators transcribed and coded the interview data. The investigators established themes after going through a detailed discussion. RESULTS: Participants reported several mental health risk factors, such as a rise in hopelessness and level of uncertainty, worry, lost interest and focus, lack of support, unemployment and financial hardships, social pressure, behavioral and mood changes, sleep disorder, and increased smoking. These mental health problems will affect the concentration and deep learning, thereby increasing academic stress. In addition, we found that the outbreak of the delta-variant led to a further increase in these mental health risk factors. CONCLUSIONS: The pandemic scenario, along with international travel restrictions, increased the likelihood of mental health problems among stranded international students. Thus, preventing further rises in mental health disorders and reducing the effects of pandemic-related measures on stranded international students, such as researchers and policymakers can mitigate the pandemic's effects and achieve national or international health and educational goals. Adequate intervention for this group is strongly recommended.

Ultrasenstive SERS biosensor based on Zn2+ from ZnO nanoparticle assisted DNA enzyme amplification for detection of miRNA.

In this work, a simple and sensitive SERS biosensor was proposed for ultrasensitive detecting miRNA 122 based on ZnO nanoparticle amplification strategy and the full utilization of DNA chain. Firstly, ZnO@S1/S2 and CoFe2O4@S3 complexes can flock together with the assistance of target miRNA. Accompanied with the incremental amount of miRNA, the quantity of ZnO@S1/S2 would increase. Therefore, a significant amplification capability can be obtained by converting ZnO complexes into Zn2+ with the assistance of HCl. In this case, the DNA chain S2 can be obtained by the ZnO dissolving. In addition, through a clever design, the obtained Zn2+ can be further utilized to induce DNA enzyme cycle amplification to cleave S5 into DNA chain which was similar with DNA S2. This step greatly avoided the waste of DNA chains and improved the utilization efficiency of DNA chains. The S2 and abundant S2 analogues can complement with S4 on the Raman sensing interface to imbed lots of Raman probe DOX for obtaining strong Raman signal. By this way, with the increased number of miRNA, the S2 and abundant S2 analogues would increase, so the amount of DOX would increase to produce strong Raman signal to quantitatively detect target miRNA. As a result, this SERS biosensor based on Zn+ amplification and high utilization efficiency of DNA chain can obtain a low detection limit of 6.82 aM and wide linear range from 10 aM to 10 pM, which shown great potential in the clinical application and medical diagnosis.

Cascading of teachers training at higher education in Pakistan: An evaluation of a faculty professional development program.

Evaluation refers to a systematic collection of data and utilization of that data to improve the program or project. It provides data to judge whether the program attained its goals and to help plan future training. This study aimed to implement an exploratory sequential research framework to evaluate the Master Trainer-Faculty Professional Development Program (MT-FPFP). MT-FPDP was a teachers training program designed for higher education faculty to develop their teaching skills. The current study was divided into two phases. In phase I, qualitative data was collected through document analysis and semi-structured interviews with coordinators of MT-FPDP. A self-developed questionnaire was used for data collection from Master Trainers (MTs) in phase II. Thematic analysis, percentages, and mean scores were used to analyze the data. The findings indicated that exploratory sequential framework was a best fit for evaluating MT-FPD. MT-FPDP was discovered to be a successful university-level teachers' training program. MTs encountered several challenges during the cascade training process at Higher Education Institutions (HEIs). This work contributes to the literature from both an academic and a practical standpoint. First, this study contributes to the literature by implementing exploratory sequential framework as an evaluation design and by providing detailed information regarding the training program's objectives, design, process, implementation, and challenges. Secondly, policy-makers and decision-makers will benefit from the results of the current study. In addition, exploratory sequential framework can aid future evaluators and researchers in systematic evaluations of teachers' training and other programs both inside and outside the education profession.

Astragalus polysaccharides protects against acute leptospirosis by glycolysis-depended priming effect.

Leptospirosis, caused by pathogenic leptospira, is a neglected infectious disease that causes acute kidney injury, bleeding disorders, and even death. People can become infected with leptospirosis when they travel into epidemic areas. Except for vaccines and antibiotics, there are few reports of other drugs about prevention of leptospirosis. In this study, we show that the natural molecular compound, astragalus polysaccharides (APS), prevents against acute leptospirosis in hamsters. Pretreatment with APS improved the survival rate of hamsters with more minor organ damage and lower leptospira burden. After pretreatment with APS, the expression levels of leptospira-induced TLR2, TLR4, and TNF-α were enhanced. The priming effect of APS was studied in vitro. The data showed that leptospira-induced expressions of TNF-α and IL-1ß were higher in APS-primed peritoneal macrophage, with enhanced glucose consumption and lactate production. Transcriptomic analysis revealed that pretreatment with APS down regulated respiratory chain and mitochondrial function, up regulated glycolysis related gene expressions. After pretreatment with glycolysis inhibitor (2-DG), the priming effect of APS in leptospira infection was inhibited. Our results indicated that pretreatment with natural molecular compound, APS, protected against acute leptospirosis in hamsters by priming effect through enhanced glycolysis.

A Dual-Action Molecule Suppresses S. aureus Infection as an Inhibitor Targeting Hla Pore Formation and TLR2 Signaling.

Antibiotic resistance is the greatest challenge for the treatment of Staphylococcus aureus (S. aureus) infection under the global antibiotic resistance crisis. With the bottleneck period of the development of new antibiotics, novel alternative agents are urgently in need. In this study, the small molecule amentoflavone is identified as a dual-action inhibitor of Hla, a pore-forming virulence determinant particularly important for S. aureus pathogenicity and Toll-like receptor 2 (TLR2) signaling, which triggers inflammation response upon recognizing pathogen-associated molecular patterns. Amentoflavone treatment conferred effective protection against S. aureus pneumonia through this dual-action mechanism. Mechanically, amentoflavone effectively inhibited Hla pore formation, thereby reducing Hla-mediated cytotoxicity and tissue damage; at the same time, amentoflavone suppressed TLR2-mediated inflammatory response by blocking the interaction between TLR2 and its adapter myeloid differentiation primary response gene 88 (MyD88). Surprisingly, TLR2 signaling induced by synthetic bacterial TLR2 agonists and other heat-killed gram-positive bacteria is also blocked by amentoflavone. In summary, these results presented amentoflavone as a potential antibiotic alternative that curbed S. aureus infection by simultaneously suppressing host-damaging virulence determinants derived from bacteria and the detrimental effect of excessive inflammation derived from the host rather than bacteria viability.

The Rumen Microbiota Contributes to the Development of Mastitis in Dairy Cows.

Mastitis, a highly prevalent disease in dairy cows, is commonly caused by local infection of the mammary gland. Our previous studies have suggested that the gut microbiota plays an important role in the development of mastitis in mice. However, the effects of rumen microbiota on bovine mastitis and the related mechanisms remain unclear. In this study, we assessed the effects and mechanisms of rumen microbiota on bovine mastitis based on the subacute rumen acidosis (SARA) model induced by feeding Holstein Frisian cows a high-concentrate diet for 8 weeks. Then, the inflammatory responses in the mammary gland and the bacterial communities of rumen fluid, feces, and milk were analyzed. The results showed that SARA induced mastitis symptoms in the mammary gland; activated a systemic inflammatory response; and increased the permeability of the blood-milk barrier, gut barrier, and rumen barrier. Further research showed that lipopolysaccharides (LPS), derived from the gut of SARA cows, translocated into the blood and accumulated in the mammary glands. Furthermore, the abundance of Stenotrophomonas was increased in the rumen of SARA cows, and mastitis was induced by oral administration of Stenotrophomonas in lactating mice. In conclusion, our findings suggested that mastitis is induced by exogenous pathogenic microorganisms as well as by endogenous pathogenic factors. Specifically, the elevated abundance of Stenotrophomonas in the rumen and LPS translocation from the rumen to the mammary gland were important endogenous factors that induced mastitis. Our study provides a foundation for novel therapeutic strategies that target the rumen microbiota in cow mastitis. IMPORTANCE Mastitis is a common and frequently occurring disease of humans and animals, especially in dairy farming, which has caused huge economic losses and brought harmful substance residues, drug-resistant bacteria, and other public health risks. The traditional viewpoint indicates that mastitis is mainly caused by exogenous pathogenic bacteria infecting the mammary gland. Our study found that the occurrence of mastitis was induced by the endogenous pathway. Evidence has shown that rumen-derived LPS enters the mammary gland through blood circulation, damaging the blood-milk barrier and then inducing inflammation of the mammary gland in cows. In addition, a higher abundance of Stenotrophomonas in the rumen was closely associated with the development of mastitis. This study provides a basis for novel therapeutic strategies that exploit the rumen microbiota against mastitis in cows.

A lethal model of Leptospira infection in hamster nasal mucosa.

Leptospirosis is a fatal zoonosis caused by contact between skin or a mucosal surface and contaminated soil or water. Hamsters were infected by intraperitoneal injection fto establish experimental leptospirosis, which is not a natural route of infection. There are no reports of nasal mucosal infection in hamsters. In this study, infection of the nasal mucosa was performed to establish a model of natural infection. Both methods of infection can cause lethal models with similar symptoms in the later stages of infection, such as weight loss, blood concentration, increased neutrophils (GRAN), and decreased lymphocytes (LYM) in the blood, severe organ damage and liver function obstruction. The burden of Leptospira in the organs and blood was lower in the mucosal inoculation groups at 1 day after infection. However, mucosal infection induced a higher Leptospira burden in urine than intraperitoneal infection in the late stages of infection. After nasal mucosal infection, antibody levels were higher and lasted longer. These results indicated that the route of nasal mucosal infection is a good choice for studying leptospirosis in hamsters.