Propulsive cell entry diverts pathogens from immune degradation by remodeling the phagocytic synapse.

Phagocytosis is a critical immune function for infection control and tissue homeostasis. During phagocytosis, pathogens are internalized and degraded in phagolysosomes. For pathogens that evade immune degradation, the prevailing view is that virulence factors are required to disrupt the biogenesis of phagolysosomes. In contrast, we present here that physical forces from motile pathogens during cell entry divert them away from the canonical degradative pathway. This altered fate begins with the force-induced remodeling of the phagocytic synapse formation. We used the parasite Toxoplasma gondii as a model because live Toxoplasma actively invades host cells using gliding motility. To differentiate the effects of physical forces from virulence factors in phagocytosis, we employed magnetic forces to induce propulsive entry of inactivated Toxoplasma into macrophages. Experiments and computer simulations show that large propulsive forces hinder productive activation of receptors by preventing their spatial segregation from phosphatases at the phagocytic synapse. Consequently, the inactivated parasites are engulfed into vacuoles that fail to mature into degradative units, similar to the live motile parasite's intracellular pathway. Using yeast cells and opsonized beads, we confirmed that this mechanism is general, not specific to the parasite used. These results reveal new aspects of immune evasion by demonstrating how physical forces during active cell entry, independent of virulence factors, enable pathogens to circumvent phagolysosomal degradation.

A yeast-based system to study SARS-CoV-2 Mpro structure and to identify nirmatrelvir resistant mutations.

The SARS-CoV-2 main protease (Mpro) is a major therapeutic target. The Mpro inhibitor, nirmatrelvir, is the antiviral component of Paxlovid, an orally available treatment for COVID-19. As Mpro inhibitor use increases, drug resistant mutations will likely emerge. We have established a non-pathogenic system, in which yeast growth serves as an approximation for Mpro activity, enabling rapid identification of mutants with altered enzymatic activity and drug sensitivity. The E166 residue is known to be a potential hot spot for drug resistance and yeast assays identified substitutions which conferred strong nirmatrelvir resistance and others that compromised activity. On the other hand, N142A and the P132H mutation, carried by the Omicron variant, caused little to no change in drug response and activity. Standard enzymatic assays confirmed the yeast results. In turn, we solved the structures of Mpro E166R, and Mpro E166N, providing insights into how arginine may drive drug resistance while asparagine leads to reduced activity. The work presented here will help characterize novel resistant variants of Mpro that may arise as Mpro antivirals become more widely used.

Soins intégrés auprès des personnes LGBTQI+ migrantes : la place des soins psychosociaux.

INTRODUCTION: LGBTQI+ migrants are at greater risk of facing health issues, including mental health issues, especially since the arrival of COVID-19. Furthermore, they face many barriers to accessing care in Quebec. It is in this context that Clinic Mauve was implemented, which aims to remove these barriers by offering medical and psychosocial care in an integrated care setting to LGBTQI+ migrants in Montreal. PURPOSE OF RESEARCH: The purpose of this article is to identify the benefits and challenges of a model like the Clinic Mauve in addressing the psychosocial needs of LGBTQI+ migrant individuals. RESULTS: The analysis shows that the Clinic Mauve model, because of its approaches is able to remove some of the barriers to accessing care for LGBTQI+ migrants and to allow for a certain degree of empowerment of these populations. However, some challenges have been identified, which are mainly due to the lack of resources and organizational constraints. CONCLUSIONS: The article concludes that providing psychosocial care in an integrated care setting addresses some of the barriers to accessing care faced by LGBTQI+ migrants.

Tools for fundamental analysis functions of TCR repertoires: a systematic comparison.

The full set of T cell receptors (TCRs) in an individual is known as his or her TCR repertoire. Defining TCR repertoires under physiological conditions and in response to a disease or vaccine may lead to a better understanding of adaptive immunity and thus has great biological and clinical value. In the past decade, several high-throughput sequencing-based tools have been developed to assign TCRs to germline genes and to extract complementarity-determining region 3 (CDR3) sequences using different algorithms. Although these tools claim to be able to perform the full range of fundamental TCR repertoire analyses, there is no clear consensus of which tool is best suited to particular projects. Here, we present a systematic analysis of 12 available TCR repertoire analysis tools using simulated data, with an emphasis on fundamental analysis functions. Our results shed light on the detailed functions of TCR repertoire analysis tools and may therefore help researchers in the field to choose the right tools for their particular experimental design.

Barriers to and facilitators of accessing HIV services for street-involved youth in Canada and Kenya.

INTRODUCTION: UNICEF estimates that there are as many as 100 million street-involved youth (SIY) globally. Marginalized conditions put SIY at higher risk of HIV and adverse outcomes once HIV-positive. The objective of this analysis was to describe barriers and facilitators of accessing HIV prevention, testing, and treatment services as Phase I of an implementation study evaluating the use of peer navigators to increase access to HIV services. METHODS: Semi-structured interviews, focus group discussions (FGD), and theatre testing were conducted with individuals who identify as SIY, health care providers, and community stakeholders living in Canada (Toronto, Montreal, London) and Kenya (Eldoret, Huruma, Kitale). Data were analyzed using a directed content approach, guided by the socio-ecological model (SEM). RESULTS: Across the six sites were 195 participants: 64 SIY, 42 healthcare providers, and 97 community-based stakeholders. Barriers were identified at the societal (e.g. intersectional stigma and discrimination), public policy (e.g., inadequate access to basic needs, legal documentation, lack of health insurance, and limited community-based funding), institutional (e.g. lack of inclusive education and training, inadequate HIV educational outreach, and restrictive service provision), interpersonal (e.g., ineffective communication from healthcare providers), and intrapersonal levels (e.g. lack of trust and associated fear, low perception for healthcare, and lack of self-esteem). These contributed to limited HIV services utilization among SIY. Conversely, numerous facilitators were also identified at the public policy (e.g. affordable HIV services and treatment), institutional (e.g. available and accessible HIV prevention tools, HIV education and awareness programs, and holistic models of care), interpersonal level (e.g., systems navigation support, peer support, and personal relationships), and intrapersonal levels (e.g. self-efficacy) as positively supporting SIY access to HIV services. CONCLUSION: Intersectional stigma was a critical barrier in all sites, and policies and programs that foster welcoming environments for youth from diverse backgrounds and living circumstances may be better able to respond to the HIV service needs of this high risk population. Social support and navigation services were reported to facilitate access to HIV services in all sites.

Chronic Pain in Young People With Cerebral Palsy: Activity Limitations and Coping Strategies.

PURPOSE: To describe the effect of chronic pain on the activities of children and adolescents with cerebral palsy, to describe coping strategies, and to examine associations between effect of pain on activities, coping strategies, and level of pain. METHODS: Using an online survey, 27, 8- to 18-year-olds with cerebral palsy and chronic pain or their parents reported pain intensity, distribution, activity limitations (using the Child Activity Limitations Interview-21), and coping strategies (using the Pediatric Pain Coping Inventory). RESULTS: Pain intensity ranged from 3 to 10, and 89% reported pain in multiple areas, principally the lower limbs. Individuals reporting higher pain intensity had more activity limitations and were more likely to use catastrophizing coping strategies. CONCLUSIONS: Coping strategies may be an important mediator between pain and its effect on activities in children with cerebral palsy. Individualized pain management should be based on routine pain assessment.

Forsythoside A inhibits adhesion and migration of monocytes to type II alveolar epithelial cells in lipopolysaccharide-induced acute lung injury through upregulating miR-124.

Acute lung injury (ALI) is a severe disease for which effective drugs are still lacking at present. Forsythia suspensa is a traditional Chinese medicine commonly used to relieve respiratory symptoms in China, but its functional mechanisms remain unclear. Therefore, forsythoside A (FA), the active constituent of F. suspensa, was studied in the present study. Inflammation models of type II alveolar epithelial MLE-12 cells and BALB/c mice stimulated by lipopolysaccharide (LPS) were established to explore the effects of FA on ALI and the underlying mechanisms. We found that FA inhibited the production of monocyte chemoattractant protein-1 (MCP-1/CCL2) in LPS-stimulated MLE-12 cells in a dose-dependent manner. Moreover, FA decreased the adhesion and migration of monocytes to MLE-12 cells. Furthermore, miR-124 expression was upregulated after FA treatment. The luciferase report assay showed that miR-124 mimic reduced the activity of CCL2 in MLE-12 cells. However, the inhibitory effects of FA on CCL2 expression and monocyte adhesion and migration to MLE-12 cells were counteracted by treatment with a miR-124 inhibitor. Critically, FA ameliorated LPS-induced pathological damage, decreased the serum levels of tumor necrosis factor-α and interleukin-6, and inhibited CCL2 secretion and macrophage infiltration in lungs in ALI mice. Meanwhile, administration of miR-124 inhibitor attenuated the protective effects of FA. The present study suggests that FA attenuates LPS-induced adhesion and migration of monocytes to type II alveolar epithelial cells though upregulating miR-124, thereby inhibiting the expression of CCL2. These findings indicate that the potential application of FA is promising and that miR-124 mimics could also be used in the treatment of ALI.

Lrrc34 Is Highly Expressed in SSCs and Is Necessary for SSC Expansion In Vitro.

Objective To discover critical genes contributing to the stemness and maintenance of spermatogonial stem cells (SSCs) and provide new insights into the function of the leucine-rich repeat (LRR) family member Lrrc34 (leucine-rich repeat-containing 34) in SSCs from mice. Methods Bioinformatic methods, including differentially expressed gene (DEG), gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, were used to uncover latent pluripotency-related genes. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence analyses were utilized to verify the mRNA and protein expression levels, respectively. RNA interference of Lrrc34 using siRNA was performed to detect its transient impact on SSCs. Results Eight DEGs between ID4-EGFP+ (G) and ID4-EGFP+/TSPAN8High (TH), eight DEGs between G and ID4-EGFP+/TSPAN8Low (TL) and eleven DEGs between TH and TL were discovered, and eleven protein-protein interaction (PPI) modules were found to be significant in the PPI network of DEGs. One of the DEGs, Lrrc34, was selected as a potential pluripotency-related gene due to its differential expression among ID4-EGFP+ spermatogonia subsets and its interaction with fibroblast growth factor 2 in the fifth module. Immunofluorescence experiments exhibited specific expression of Lrrc34 in a subpopulation of undifferentiated spermatogonia marked by LIN28A, and RT-PCR experiments confirmed the high expression of Lrrc34 in SSCs from P7 and adult mice. The transient knockdown of Lrrc34 in SSCs resulted in reduced colony sizes and significant changes in the transcriptome and apoptotic pathways. Conclusion Lrrc34 is highly expressed in mouse SSCs and is required for SSC proliferation in vitro through effects on transcriptome and signaling transduction pathways.

[Simultaneous determination and analysis of amino acids and nucleosides in Dendrobium by UHPLC-QTRAP-MS/MS].

By using multivariate statistical analysis to evaluate essential quality, and provide scientific basis for their comprehensive utilization, we established an UHPLC-QTRAP-MS/MS method for the fast, precise, efficient determination of 21 kinds of amino acids and 10 kinds of nucleosides in different species of Dendrobium. The analysis was performed on a Waters XBridge Amide column(2.1 mm×100 mm,3.5 µm) with elution by mobile phase of 0.2% formic acid in water-0.2% formic acid in acetonitrile at a flow rate of 0.2 mL·min~(-1) with the column temperature at 30 ℃. The target compounds were analyzed by the positive ion multiple reaction monitoring(MRM) mode. The comprehensive evaluation of different species of Dendrobium was carried out by PCA and TOPSIS analysis. All 21 kinds of amino acids and 10 nucleosides showed good linearity among certain concentration range(r>0.999), the RSDs of the stability, precision, and repeatability tests were less than 3.0%. The recovery rate was in the range from 93.31% to 107.5%, and RSD was in the range of 1.1%-3.7%. The comprehensive evaluation index obtained with PCA showed that D. huoshanense was significantly higher than others regarding amino acids and D. officinale has higher nucleosides than other species. The biggest C_i difference of TOPSIS was 68.7%, and comprehensive evaluation showed that D. huoshanense produced the highest comprehensive quality. The method is precise, fast and efficient and can provide reliable basis for further researches and intrinsic quality control of Dendrobium.

Effect of the autism-associated lncRNA Shank2-AS on architecture and growth of neurons.

The pathogenic mechanism of autism is complex, and current research has shown that long noncoding RNAs (lncRNAs) may play important roles in this process. The antisense lncRNA of SH3 and multiple ankyrin repeat domains 2 (Shank2-AS) is upregulated in patients with autism spectrum disorder (ASD), whereas the expression of its sense strand gene Shank2 is downregulated. In neuronal cells, Shank2-AS and Shank2 can form a double-stranded RNA and inhibit Shank2 expression. Overexpression of Shank2-AS decreases neurite numbers and lengths, thereby inhibiting the proliferation of neuronal cells and promoting their apoptosis. Overexpression of Shank2 inhibits the abovementioned effects of Shank2-AS, and transfection of a vector containing the 10th intron of Shank2 (Shank2-AS is reverse-transcribed from this region) also blocks the function of Shank2-AS. Shank2 small interfering RNA plays a role similar to Shank2-AS. Therefore, Shank2-AS is abnormally expressed in patients with ASD and may affect the structure and growth of neurons by regulating Shank2 expression, thereby facilitating the development of ASD.

Effect of expressions of tumor necrosis factor α and interleukin 1B on peritoneal metastasis of gastric cancer.

Our study aimed to investigate effect of expressions of tumor necrosis factor α (TNF-α) and interleukin 1B (IL-1B) on peritoneal metastasis of gastric cancer (GC). From June 2012 to June 2014, a total of 60 patients with advanced peritoneal metastasis from GC were collected from Department of Gastrointestinal and Nutriology Surgery at Shengjing Hospital of China Medical University. Furthermore, 60 GC patients without peritoneal metastasis were enrolled as controls. Immunohistochemistry was performed to test TNF-α and IL-1B expression, and logistic regression analysis was employed for evaluating risk factors for peritoneal metastasis of GC. Our results showed that TNF-α expression in metastatic group and non-metastatic group was significantly different (P = 0.043), but no significant difference was found in IL-1B expression between two groups (P = 0.261). In addition, TNF-α expression in metastatic group and non-metastatic group was associated with tumor size, depth of invasion, the degree of differentiation (all P < 0.05). Logistic regression analysis indicated that tumor size, depth of invasion, the degree of differentiation and TNF-α expression were risk factors for peritoneal metastasis of GC (all P < 0.05). Our study found that TNF-α expression may play a vital role in peritoneal metastasis of GC, while IL-1B expression might not be correlated with peritoneal metastasis.

Metal-free iodine(III)-promoted synthesis of isoquinolones.

A metal-free oxidative cycloaddition reaction of substituted benzamides and alkynes has been developed for the synthesis of isoquinolones by using bis(trifluoracetoxy)iodobenzene (PIFA) and trifluoroacetic acid (TFA). Under mild conditions, a wide variety of isoquinolones were conveniently prepared via oxidative annulation of simple N-methoxybenzamide and diarylacetylene or aryl/alkyl acetylene derivatives in yields up to 87%.

Analysis of the Imaging Features and Prognosis of Pulmonary Tuberculosis Complicated with Pulmonary Embolism

OBJECTIVE: This study aimed to explore the imaging characteristics of patients with pulmonary tuberculosis complicated with pulmonary embolism and analyze the prognosis of the condition, thereby reducing the mortality and misdiagnosis rate of complications in this type of pulmonary tuberculosis. METHODS: In this retrospective study, a total of 70 patients diagnosed with pulmonary embolism by computed tomography pulmonary angiography (CTPA) from January 2016 to May 2021 in Anhui Chest Hospital were included. Among them, 35 patients with pulmonary embolism combined with pulmonary tuberculosis were set as the study group, and the other 35 patients with pulmonary embolism only were set as the control group. The imaging findings of chest CT examination, the incidence of pulmonary hypertension, the level of N-terminal proto-B-type brain natriuretic peptide (NT-proBNP), and the prognosis of patients were compared between the two groups. The incidence of deep venous embolism was evaluated by ultrasonography of the lower extremity. RESULTS: In the study group, the median age of patients was 71 years, and the ratio of males to females was 2.5 to 1. In the control group, the median age was 66 years old, and the male-to-female ratio was 2.2 to 1. There were 16 cases (16/35, 45.71%) in the study group and 10 cases (10/35, 28.57%) in the control group with an increased level of NT-proBNP. Pulmonary hypertension occurred in 10 patients (10/35, 28.57%) in the study group and 7 patients (7/35, 20.00%) in the control group. Patients who lost follow-up included 5 in the study group (5/35, 14.29%) and 3 in the control group (3/35, 8.57%). There were 17 cases (17/35, 48.57%) in the study group and 3 cases (3/35, 8.57%) in the control group with pulmonary artery widening, and the difference was significant (P < 0.001). There were 13 deaths in the study group (13/35, 37.14%) and 1 death in the control group (1/35, 2.86%), and the difference was significant (P <0.001). CONCLUSION: Special signs of pulmonary artery widening, pulmonary hypertension of varying degrees, and increased levels of NT-proBNP of varying degrees can be found in patients with pulmonary tuberculosis complicated with pulmonary embolism, and the three signs are positively correlated. The mortality of patients with pulmonary tuberculosis complicated with pulmonary embolism is significantly higher than that of patients with pulmonary embolism alone. Pulmonary tuberculosis and pulmonary embolism both occur in the ipsilateral lung, causing clinical symptoms to cover each other, thereby making diagnosis difficult.

Protective Effect of Silibinin on Lipopolysaccharide-Induced Endotoxemia by Inhibiting Caspase-11-Dependent Cell Pyroptosis.

OBJECTIVE: To explore the protective effect and the underlying mechanism of silibinin (SIB), one of the active compounds from Silybum marianum (L.) Gaertn in endotoxemia. METHODS: Mouse peritoneal macrophage were isolated via intraperitoneally injection of BALB/c mice with thioglycolate medium. Cell viability was assessed using the cell counting kit-8, while cytotoxicity was determined through lactate dehydrogenase cytotoxicity assay. The protein expressions of interleukin (IL)-1 α, IL-1 ß, and IL-18 were determined by enzyme-linked immunosorbent assay. Intracellular lipopolysaccharide (LPS) levels were measured by employing both the limulus amoebocyte lysate assay and flow cytometry. Additionally, proximity ligation assay was employed for the LPS and caspase-11 interaction. Mice were divided into 4 groups: the control, LPS, high-dose-SIB (100 mg/kg), and low-dose-SIB (100 mg/kg) groups (n=8). Zebrafish were divided into 4 groups: the control, LPS, high-dose-SIB (200 εmol/L), and low-dose-SIB (100 εmol/L) groups (n=30 for survival experiment and n=10 for gene expression analysis). The expression of caspase-11, gasdermin D (GSDMD), and N-GSDMD was determined by Western blot and the expressions of caspy2, gsdmeb, and IL-1 ß were detected using quantitative real-time PCR. Histopathological observation was performed through hematoxylineosin staining, and protein levels in bronchoalveolar lavage fluid were quantified using the bicinchoninicacid protein assay. RESULTS: SIB noticeably decreased caspase-11 and GSDMD-mediated pyroptosis and suppressed the secretion of IL-1 α, IL-1 ß, and IL-18 induced by LPS (P<0.05). Moreover, SIB inhibited the translocation of LPS into the cytoplasm and the binding of caspase-11 and intracellular LPS (P<0.05). SIB also attenuated the expression of caspase-11 and N-terminal fragments of GSDMD, inhibited the relative cytokines, prolonged the survival time, and up-regulated the survival rate in the endotoxemia models (P<0.05). CONCLUSIONS: SIB can inhibit pyroptosis in the LPS-mediated endotoxemia model, at least in part, by inhibiting the caspase-11-mediated cleavage of GSDMD. Additionally, SIB inhibits the interaction of LPS and caspase-11 and inhibits the LPS-mediated up-regulation of caspase-11 expression, which relieves caspase-11-dependent cell pyroptosis and consequently attenuates LPS-mediated lethality.

Dissolvable alginate hydrogel-based biofilm microreactors for antibiotic susceptibility assays.

Biofilms are found in many infections in the forms of surface-adhering aggregates on medical devices, small clumps in tissues, or even in synovial fluid. Although antibiotic resistance genes are studied and monitored in the clinic, the structural and phenotypic changes that take place in biofilms can also lead to significant changes in how bacteria respond to antibiotics. Therefore, it is important to better understand the relationship between biofilm phenotypes and resistance and develop approaches that are compatible with clinical testing. Current methods for studying antimicrobial susceptibility are mostly planktonic or planar biofilm reactors. In this work, we develop a new type of biofilm reactor-three-dimensional (3D) microreactors-to recreate biofilms in a microenvironment that better mimics those in vivo where bacteria tend to form surface-independent biofilms in living tissues. The microreactors are formed on microplates, treated with antibiotics of 1000 times of the corresponding minimal inhibitory concentrations (1000 × MIC), and monitored spectroscopically with a microplate reader in a high-throughput manner. The hydrogels are dissolvable on demand without the need for manual scraping, thus enabling measurements of phenotypic changes. Bacteria inside the biofilm microreactors are found to survive exposure to 1000 × MIC of antibiotics, and subsequent comparison with plating results reveals no antibiotic resistance-associated phenotypes. The presented microreactor offers an attractive platform to study the tolerance and antibiotic resistance of surface-independent biofilms such as those found in tissues.

[Quantitative monitoring of blood cytomegalovirus after allogeneic hematopoietic stem cell transplantation and its clinical significance].

OBJECTIVE: To investigate the risk factor for cytomegalovirus (CMV) viremia and its impact on the survival of patients after allogeneic hematological stem cell transplantation (allo-HSCT). METHODS: Quantitative fluorescence PCR was used to examine the quantity of CMV in mononuclear cells. All patients were tested weekly after allo-HSCT within 3 months. Univariate and multivariate analysis were used to determine the risk factors of CMV viremia. Five-year overall survival rate was compared and analyzed between the patients with or without CMV viremia. RESULTS: The incidence of CMV viremia was 72.1% (132/183). Of which, 59.1% (78/132) occurred post one month after transplantation, 40.9% (54/132) occurred within one month and 27.9% (51/183) sustained negative within three months. Two cases were clearly diagnosed as CMV disease with a incidence of 1.1%. Both univariate and multivariate analysis indicated that transplant methods and blood cyclosporine A (CsA) concentration were significantly correlated with CMV viremia. When pairwise compared the results between the different transplant methods, significant differences of CMV viremia were found between human leukocyte antigen (HLA) matched sibling and HLA mismatched relatives, unrelative donor or cord blood (all P values < 0.05). There was no significant difference between HLA mismatched relatives and unrelative donor or cord blood. Further analysis showed that the incidence of CMV viremia was much higher in those who had used antithymocyte globulin (ATG) then those not used ATG. The Kaplan-Meier survival curve showed there was no significant difference between the groups with and without CMV viremia. CONCLUSIONS: The incidence of CMV viremia after allo-HSCT is 72.1%. Administration of ATG during conditioning regimen and blood CsA concentration > 300 µg/L are the main risk factors for CMV viremia. There is no significant effect of CMV viremia on the cumulative overall survival, while prompt treatment of CMV viremia is a crucial way to prevent CMV disease.

TCA and SSRI Antidepressants Exert Selection Pressure for Efflux-Dependent Antibiotic Resistance Mechanisms in Escherichia coli.

Microbial diversity is reduced in the gut microbiota of animals and humans treated with selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs). The mechanisms driving the changes in microbial composition, while largely unknown, is critical to understand considering that the gut microbiota plays important roles in drug metabolism and brain function. Using Escherichia coli, we show that the SSRI fluoxetine and the TCA amitriptyline exert strong selection pressure for enhanced efflux activity of the AcrAB-TolC pump, a member of the resistance-nodulation-cell division (RND) superfamily of transporters. Sequencing spontaneous fluoxetine- and amitriptyline-resistant mutants revealed mutations in marR and lon, negative regulators of AcrAB-TolC expression. In line with the broad specificity of AcrAB-TolC pumps these mutants conferred resistance to several classes of antibiotics. We show that the converse also occurs, as spontaneous chloramphenicol-resistant mutants displayed cross-resistance to SSRIs and TCAs. Chemical-genomic screens identified deletions in marR and lon, confirming the results observed for the spontaneous resistant mutants. In addition, deletions in 35 genes with no known role in drug resistance were identified that conferred cross-resistance to antibiotics and several displayed enhanced efflux activities. These results indicate that combinations of specific antidepressants and antibiotics may have important effects when both are used simultaneously or successively as they can impose selection for common mechanisms of resistance. Our work suggests that selection for enhanced efflux activities is an important factor to consider in understanding the microbial diversity changes associated with antidepressant treatments. IMPORTANCE Antidepressants are prescribed broadly for psychiatric conditions to alter neuronal levels of synaptic neurotransmitters such as serotonin and norepinephrine. Two categories of antidepressants are selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs); both are among the most prescribed drugs in the United States. While it is well-established that antidepressants inhibit reuptake of neurotransmitters there is evidence that they also impact microbial diversity in the gastrointestinal tract. However, the mechanisms and therefore biological and clinical effects remain obscure. We demonstrate antidepressants may influence microbial diversity through strong selection for mutant bacteria with increased AcrAB-TolC activity, an efflux pump that removes antibiotics from cells. Furthermore, we identify a new group of genes that contribute to cross-resistance between antidepressants and antibiotics, several act by regulating efflux activity, underscoring overlapping mechanisms. Overall, this work provides new insights into bacterial responses to antidepressants important for understanding antidepressant treatment effects.

Probing mutual interactions between Pseudomonas aeruginosa and Candida albicans in a biofabricated membrane-based microfluidic platform.

Microbes are typically found in multi-species (polymicrobial) communities. Cooperative and competitive interactions between species, mediated by diffusible factors and physical contact, leads to highly dynamic communities that undergo changes in composition diversity and size. Infections can be more severe or more difficult to treat when caused by multiple species. Interactions between species can improve the ability of one or more species to tolerate anti-microbial treatments and host defenses. Pseudomonas aeruginosa (Pa), a ubiquitous bacterium, and the opportunistic pathogenic yeast, Candida albicans (Ca), are frequently found together in cystic fibrosis lung infections and wound infections. While significant progress has been made in determining interactions between Pa and Ca, there are still important questions that remain unanswered. Here, we probe the mutual interactions between Pa and Ca in a custom-made microfluidic device using biopolymer chitosan membranes that support cross-species communication. By assembling microbes in physically separated, chemically communicating populations or bringing into direct interactions in a mixed culture, in situ polymicrobial growth and biofilm morphology were qualitatively characterized and quantified. Our work reveals new dynamic details of their mutual interactions including cooperation, competition, invasion, and biofilm formation. The membrane-based microfluidic platform can be further developed to understand the polymicrobial interactions within a controlled interactive microenvironment to improve microbial infection prevention and treatment.

A yeast-based system to study SARS-CoV-2 M pro structure and to identify nirmatrelvir resistant mutations.

The SARS-CoV-2 main protease (M pro ) is a major therapeutic target. The M pro inhibitor, nirmatrelvir, is the antiviral component of Paxlovid, an orally available treatment for COVID-19. As M pro inhibitor use increases, drug resistant mutations will likely emerge. We have established a non-pathogenic system, in which yeast growth serves as a proxy for M pro activity, enabling rapid identification of mutants with altered enzymatic activity and drug sensitivity. The E166 residue is known to be a potential hot spot for drug resistance and yeast assays showed that an E166R substitution conferred strong nirmatrelvir resistance while an E166N mutation compromised activity. On the other hand, N142A and P132H mutations caused little to no change in drug response and activity. Standard enzymatic assays confirmed the yeast results. In turn, we solved the structures of M pro E166R, and M pro E166N, providing insights into how arginine may drive drug resistance while asparagine leads to reduced activity. The work presented here will help characterize novel resistant variants of M pro that may arise as M pro antivirals become more widely used.