Fast profiling of primary, secondary, conjugated, and sulfated bile acids in human urine and murine feces samples

Bile acids (BAs) are a complex class of metabolites that have been described as specific biomarkers of gut microbiota activity. The development of analytical methods allowing the quantification of an ample spectrum of BAs in different biological matrices is needed to enable a wider implementation of BAs as complementary measures in studies investigating the functional role of the gut microbiota. This work presents results from the validation of a targeted ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the determination of 28 BAs and six sulfated BAs, covering primary, secondary, and conjugated BAs. The analysis of 73 urine and 20 feces samples was used to test the applicability of the method. Concentrations of BAs in human urine and murine feces were reported, ranging from 0.5 to 50 nmol/g creatinine and from 0.012 to 332 nmol/g, respectively. Seventy-nine percent of BAs present in human urine samples corresponded to secondary conjugated BAs, while 69% of BAs present in murine feces corresponded to primary conjugated BAs. Glycocholic acid sulfate (GCA-S) was the most abundant BA in human urine samples, while taurolithocholic acid was the lowest concentrated compound detected. In murine feces, the most abundant BAs were α-murocholic, deoxycholic, dehydrocholic, and β-murocholic acids, while GCA-S was the lowest concentrated BA. The presented method is a non-invasive approach for the simultaneous assessment of BAs and sulfated BAs in urine and feces samples, and the results will serve as a knowledge base for future translational studies focusing on the role of the microbiota in health.

Alterations of the intestinal mucus layer correlate with dysbiosis and immune dysregulation in human Type 1 Diabetes

BACKGROUND

In preclinical models of Type 1 Diabetes (T1D) the integrity of the gut barrier (GB) is instrumental to avoid dysregulated crosstalk between the commensal microbiota and immune cells and to prevent autoimmunity. The GB is composed of the intestinal epithelial barrier (IEB) and of the mucus layer containing mucins and antimicrobial peptides (AMPs) that are crucial to maintain immune tolerance. In preclinical models of T1D the alterations of the GB primarily affect the mucus layer. In human T1D increased gut permeability and IEB damage have been demonstrated but the integrity of the mucus layer was never assessed.

METHODS

We evaluated GB integrity by measuring serological markers of IEB damage (serological levels of zonulin) and bacterial translocation such as lipopolysaccharide binding protein (LBP) and myeloid differentiation protein 2 (MD2), and mRNA expression of tight junction proteins, mucins and AMPs in intestinal tissue of T1D patients and healthy controls (HC). Simultaneously, we performed immunological profiling on intestinal tissue and 16S rRNA analysis on the mucus-associated gut microbiota (MAGM).

FINDINGS

Our data show a GB damage with mucus layer alterations and reduced mRNA expression of several mucins (MUC2, MUC12, MUC13, MUC15, MUC20, MUC21) and AMPs (HD4 and HD5) in T1D patients. Mucus layer alterations correlated with reduced relative abundance of short chain fatty acids (SCFA)-producing bacteria such as Bifidobacterium dentium, Clostridium butyricum and Roseburia intestinalis that regulate mucin expression and intestinal immune homeostasis. In T1D patients we also found intestinal immune dysregulation with higher percentages of effector T cells such as T helper (Th) 1, Th17 and TNF-α⁺ T cells.

INTERPRETATION

Our data show that mucus layer alterations are present in T1D subjects and associated with dysbiosis and immune dysregulation.

FUNDING

Research Grants from the Juvenile Diabetes Foundation (Grant 1-INO-2018-640-A-N to MF and 2-SRA-2019-680-S-B to JD) and from the Italian Ministry of Health (Grant RF19-12370721 to MF).

The current and future off-label uses of dalbavancin: a narrative review

Dalbavancin is a novel long-acting semi-synthetic lipoglycopeptide. It is licensed for acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci. Many studies on dalbavancin alternative use in clinical practice have been published recently, including osteomyelitis, prosthetic joint infections (PJIs), and infective endocarditis (IE). Thus, we conducted a narrative review on dalbavancin efficacy in difficult-to-treat infections, such as osteomyelitis, PJIs, and IE. We performed a comprehensive literature search through electronic databases (PubMed-MEDLINE) and search engines (Google Scholar). We included peer-reviewed publications (articles and reviews), and grey literature on dalbavancin use in osteomyelitis, PJIs, and IE. No time or language restrictions have been established. Despite the great interest in clinical practice, only observational studies and case series on the use of dalbavancin in infections other than ABSSSI are available. The reported success rate was extremely variable between studies, ranging from 44% to 100%. A low success rate has been reported for osteomyelitis and joint infections, while in endocarditis, the success rate was higher than 70% in all studies. However, there is no literature agreement about the correct regimen of dalbavancin for this type of infection heretofore. Dalbavancin showed great efficacy and a good safety profile, not only in patients with ABSSSI but also in those with osteomyelitis, PJIs, and endocarditis. Further randomized clinical trials are needed to assess the optimal dosing schedule depending on the site of infection. Implementing therapeutic drug monitoring for dalbavancin may represent the future step to achieving optimal pharmacokinetic/pharmacodynamic target attainment.

A diet enriched in omega-3 PUFA and inulin prevents type 1 diabetes by restoring gut barrier integrity and immune homeostasis in NOD mice

Introduction

The integrity of the gut barrier (GB) is fundamental to regulate the crosstalk between the microbiota and the immune system and to prevent inflammation and autoimmunity at the intestinal level but also in organs distal from the gut such as the pancreatic islets. In support to this idea, we recently demonstrated that breakage of GB integrity leads to activation of islet-reactive T cells and triggers autoimmune Type 1 Diabetes (T1D). In T1D patients as in the NOD mice, the spontaneous model of autoimmune diabetes, there are alterations of the GB that specifically affect structure and composition of the mucus layer; however, it is yet to be determined whether a causal link between breakage of the GB integrity and occurrence of autoimmune T1D exists.

Methods

Here we restored GB integrity in the NOD mice through administration of an anti-inflammatory diet (AID- enriched in soluble fiber inulin and omega 3-PUFA) and tested the effect on T1D pathogenesis.

Results

We found that the AID prevented T1D in NOD mice by restoring GB integrity with increased mucus layer thickness and higher mRNA transcripts of structural (Muc2) and immunoregulatory mucins (Muc1 and Muc3) as well as of tight junction proteins (claudin1). Restoration of GB integrity was linked to reduction of intestinal inflammation (i.e., reduced expression of IL-1β, IL-23 and IL-17 transcripts) and expansion of regulatory T cells (FoxP3⁺ Treg cells and IL-10⁺ Tr1 cells) at the expenses of effector Th1/Th17 cells in the intestine, pancreatic lymph nodes (PLN) and intra-islet lymphocytes (IIL) of AID-fed NOD mice. Importantly, the restoration of GB integrity and immune homeostasis were associated with enhanced concentrations of anti-inflammatory metabolites of the ω3/ω6 polyunsaturated fatty acids (PUFA) and arachidonic pathways and modifications of the microbiome profile with increased relative abundance of mucus-modulating bacterial species such as Akkermansia muciniphila and Akkermansia glycaniphila.

Discussion

Our data provide evidence that the restoration of GB integrity and intestinal immune homeostasis through administration of a tolerogenic AID that changed the gut microbial and metabolic profiles prevents autoimmune T1D in preclinical models.

A rare case of mycobacterial pseudoaneurysm of the superficial femoral artery

OBJECTIVE

Extrapulmonary localization of tuberculosis accounts for about 15-20% of cases. Several cases of Mycobacterium tuberculosis with vascular involvement have been described, but only few cases for limb vessels.

CASE REPORT

We report the case of a 33-year-old man from Gambia with a symptomatic pseudoaneurysm of the right superficial femoral artery. Total body positron emission tomography/computed tomography with [18F]FDG revealed an active infection. The patient underwent vascular reconstruction with a straight reversed vein graft. Molecular testing for Mycobacterium tuberculosis was non-diagnostic. Cultures of the pseudoaneurysm wall and thrombus removed during surgery grew Mycobacterium tuberculosis.

CONCLUSIONS

The diagnosis of vascular tuberculosis infection due to Mycobacterium tuberculosis is a challenge. Epidemiology remains the primary criterion for maintaining a high index of suspicion.

Intestinal Cathelicidin Antimicrobial Peptide Shapes a Protective Neonatal Gut Microbiota Against Pancreatic Autoimmunity

BACKGROUND & AIMS

Alteration of the gut microbiota is implicated in the development of autoimmune type 1 diabetes (T1D), as shown in humans and the nonobese diabetic (NOD) mouse model. However, how gut dysbiosis arises and promotes the autoimmune response remains an open question. We investigated whether early events affecting the intestinal homeostasis in newborn NOD mice may explain the development of the autoimmune response in the adult pancreas.

METHODS

We profiled the transcriptome and the microbiota in the colon between newborn NOD mice and nonautoimmune strains. We identified a seminal defect in the intestinal homeostasis of newborn NOD mice and deciphered the mechanism linking this defect to the diabetogenic response in the adult.

RESULTS

We determined that the cathelicidin-related antimicrobial peptide (CRAMP) expression was defective in the colon of newborn NOD mice, allowing inducing dysbiosis. Dysbiosis stimulated the colonic epithelial cells to produce type I interferons that pathologically imprinted the local neonatal immune system. This pathological immune imprinting later promoted the pancreatic autoimmune response in the adult and the development of diabetes. Increasing colonic CRAMP expression in newborn NOD mice by means of local CRAMP treatment or CRAMP-expressing probiotic restored colonic homeostasis and halted the diabetogenic response, preventing autoimmune diabetes.

CONCLUSIONS

We identified whether a defective colonic expression in the CRAMP antimicrobial peptide induces dysbiosis, contributing to autoimmunity in the pancreas. Hence, the manipulation of intestinal antimicrobial peptides may be considered a relevant therapeutic approach to prevent autoimmune diabetes in at-risk children.

Real-world corticosteroid use in severe pneumonia: a propensity-score-matched study

BACKGROUND

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide despite correct antibiotic use. Corticosteroids have long been evaluated as a treatment option, but heterogeneous effects on survival have precluded their widespread implementation. We aimed to evaluate whether corticosteroids might improve clinical outcomes in patients with severe CAP and high inflammatory responses.

STUDY DESIGN AND METHODS

We analyzed two prospective observational cohorts of patients with CAP in Barcelona and Rome who were admitted to intensive care with a high inflammatory response. Propensity score (PS) matching was used to obtain balance among the baseline variables in both groups, and we excluded patients with viral pneumonia or who received hydrocortisone.

RESULTS

Of the 610 patients admitted with severe CAP, 198 (32%) received corticosteroids and 387 had major criteria for severe CAP. All patients had a baseline serum C-reactive protein above 15 mg/dL. Patients who received corticosteroids were more commonly male, had more comorbidities (e.g., cancer or chronic obstructive pulmonary disease), and presented with significantly higher sequential organ failure assessment scores. Eighty-nine patients met major severity criteria (invasive mechanical ventilation and/or septic shock) and were matched per group. Twenty-eight-day mortality was lower among patients receiving corticosteroids (16 patients, 18%) than among those not receiving them (28 patients, 31%; p = 0.037). After PS matching, corticosteroid therapy reduced the 28-day mortality risk in patients who met major severity criteria (hazard ratio (HR) 0.53, 95% confidence interval (CI) 0.29-0.98) (p = 0.043). In patients who did not meet major severity criteria, no benefits were observed with corticosteroid use (HR 0.88 (95%CI 0.32-2.36).

CONCLUSIONS

Corticosteroid treatment may be of benefit for patients with CAP who have septic shock and/or a high inflammatory response and requirement for invasive mechanical ventilation. Corticosteroids appear to have no impact on mortality when these features are not present.

Prevention of the spread of multidrug-resistant organisms in nursing homes

The increase in the aged population led to a global rise in the demand for elderly healthcare services, such as long-term care facilities (LTCFs), nursing homes, residential homes. Unfortunately, the spread of multidrug-resistant organisms (MDROs) in these structures represent an urgent public health threat requiring immediate action. The aim of this review is to provide a practice guide for the prevention of infections in European LTCFs. A team of experts identify specific problems and proposed practical solutions for the management of colonized and infected patients residing in LTCFs. The heterogeneity of LTCF represents one of the main problems for the implementation of standardized surveillance and infection control programs. Crucial steps involved in the spread of infections among LTCF residents are represented by patient's accommodation, MDRO screening on admission, management of patients with rectal colonization by MDROs, management of patients at high risk of MDRO infections, MDRO transmission by staff and implementation of antimicrobial stewardship. Efforts to implement specific actions in each of these fields are required to reduce the infections in this setting.

Association between minimum inhibitory concentration, beta-lactamase genes and mortality for patients treated with piperacillin/tazobactam or meropenem from the MERINO study

INTRODUCTION

This study aims to assess the association of piperacillin/tazobactam and meropenem minimum inhibitory concentration (MIC) and beta-lactam resistance genes with mortality in the MERINO trial.

METHODS

Blood culture isolates from enrolled patients were tested by broth microdilution and whole genome sequencing at a central laboratory. Multivariate logistic regression was performed to account for confounders. Absolute risk increase for 30-day mortality between treatment groups was calculated for the primary analysis (PA) and the microbiologic assessable (MA) populations.

RESULTS

320 isolates from 379 enrolled patients were available with susceptibility to piperacillin/tazobactam 94% and meropenem 100%. The piperacillin/tazobactam non-susceptible breakpoint (MIC > 16 mg/L) best predicted 30-day mortality after accounting for confounders (odds ratio 14.9, 95% CI 2.8 - 87.2). The absolute risk increase for 30-day mortality for patients treated with piperacillin/tazobactam compared with meropenem was 9% (95% CI 3% - 15%) and 8% (95% CI 2% - 15%) for the original PA population and the post-hoc MA populations, which reduced to 5% (95% CI -1% - 10%) after excluding strains with piperacillin/tazobactam MIC values > 16 mg/L. Isolates co-harboring ESBL and OXA-1 genes were associated with elevated piperacillin/tazobactam MICs and the highest risk increase in 30-mortality of 14% (95% CI 2% - 28%).

CONCLUSION

After excluding non-susceptible strains, the 30-day mortality difference was from the MERINO trial was less pronounced for piperacillin/tazobactam. Poor reliability in susceptibility testing performance for piperacillin/tazobactam and the high prevalence of OXA co-harboring ESBLs suggests meropenem remains the preferred choice for definitive treatment of ceftriaxone non-susceptible E. coli and Klebsiella.

Role of the PD-1/PD-L1 Dyad in the Maintenance of Pancreatic Immune Tolerance for Prevention of Type 1 Diabetes

The human pancreas, like almost all organs in the human body, is immunologically tolerated despite the presence of innate and adaptive immune cells that promptly mediate protective immune responses against pathogens in situ. The PD-1/PD-L1 inhibitory pathway seems to play a key role in the maintenance of immune tolerance systemically and within the pancreatic tissue. Tissue resident memory T cells (TRM), T regulatory cells (Treg), macrophages and even β cells exhibit PD-1 or PD-L1 expression that contributes in controlling pancreatic immune homeostasis and tolerance. Dysregulation of the PD-1/PD-L1 axis as shown by animal studies and our recent experience with checkpoint inhibitory blockade in humans can lead to immune dysfunctions leading to chronic inflammatory disease and to type 1 diabetes (T1D) in genetically susceptible individuals. In this review, we discuss the role of the PD-1/PD-L1 axis in pancreatic tissue homeostasis and tolerance, speculate how genetic and environmental factors can regulate the PD-1/PD-L1 pathway, and discuss PD-1/PD-L1-based therapeutic approaches for pancreatic islet transplantation and T1D treatment.

How the Interplay Between the Commensal Microbiota, Gut Barrier Integrity, and Mucosal Immunity Regulates Brain Autoimmunity

The intestinal barrier provides the host with a strong defense line against the external environment playing also a pivotal role in the crosstalk between the gut microbiota and the immune system. Notably, increasing lines of evidence concerning autoimmune disorders such as Multiple Sclerosis (MS) report an imbalance in both intestinal microbiota composition and mucosal immunity activation, along with an alteration of gut barrier permeability, suggesting this complex network plays a crucial role in modulating the course of autoimmune responses occurring in tissues outside the gut such as the central nervous system (CNS). Here, we review current knowledge on how gut inflammation and breakage of gut barrier integrity modulates the interplay between the commensal gut microbiota and the immune system and its role in shaping brain immunity.

Experimental colitis in IL-10-deficient mice ameliorates in the absence of PTPN22

Interleukin (IL)-10 plays a key role in controlling intestinal inflammation. IL-10-deficient mice and patients with mutations in IL-10 or its receptor, IL-10R, show increased susceptibility to inflammatory bowel diseases (IBD). Protein tyrosine phosphatase, non-receptor type 22 (PTPN22) controls immune cell activation and the equilibrium between regulatory and effector T cells, playing an important role in controlling immune homoeostasis of the gut. Here, we examined the role of PTPN22 in intestinal inflammation of IL-10-deficient (IL-10^-/- ) mice. We crossed IL-10^-/- mice with PTPN22^-/- mice to generate PTPN22^-/- IL-10^-/- double knock-out mice and induced colitis with dextran sodium sulphate (DSS). In line with previous reports, DSS-induced acute and chronic colitis was exacerbated in IL-10^-/- mice compared to wild-type (WT) controls. However, PTPN22^-/- IL-10^-/- double knock-out mice developed milder disease compared to IL-10^-/- mice. IL-17-promoting innate cytokines and T helper type 17 (Th17) cells were markedly increased in PTPN22^-/- IL-10^-/- mice, but did not provide a protctive function. CXCL1/KC was also increased in PTPN22^-/- IL-10^-/- mice, but therapeutic injection of CXCL1/KC in IL-10^-/- mice did not ameliorate colitis. These results show that PTPN22 promotes intestinal inflammation in IL-10-deficient mice, suggesting that therapeutic targeting of PTPN22 might be beneficial in patients with IBD and mutations in IL-10 and IL-10R.

Loss of gut barrier integrity triggers autoimmune diabetes through microbiota-induced activation of islet-reactive T cells

Recent evidence suggests that the intestinal environment and, specifically, modifications of the microbiome profile, regulate the pathogenesis of extra-intestinal autoimmune diseases such as Type 1 Diabetes (T1D) by inducing intestinal inflammation and increasing gut permeability. Although low-grade intestinal inflammation and alterations of gut barrier integrity are found in humans and animal models of T1D, a direct causal link between enteropathy and triggering of beta cell autoimmunity is yet to be established. Here we show that breakage of the gut barrier integrity (by low-dose DSS administration) in BDC2.5XNOD mice carrying a transgenic TCR specific for a beta cell-autoantigen leads to activation of the islet-reactive T cell clone (BDC2.5) within the gut mucosa and onset of T1D. The intestinal activation of islet-reactive T cells requires the presence of gut microbiota and is abolished when mice are depleted of endogenous commensal microbiota. Importantly, we found that gut microbial antigens are directly capable to activate the diabetogenic BDC2.5 T cells with a TCR-mediated mechanism. Our results indicate that loss of the intestinal barrier continuity is directly responsible for activation of islet-specific T cells by commensal gut microbiota and provide a strong rationale to design innovative therapeutic interventions in “at risk” individuals aimed at restoring gut barrier integrity to prevent T1D.