Resilient anatomy and local plasticity of naive and stress haematopoiesis.

The bone marrow adjusts blood cell production to meet physiological demands in response to insults. The spatial organization of normal and stress responses are unknown owing to the lack of methods to visualize most steps of blood production. Here we develop strategies to image multipotent haematopoiesis, erythropoiesis and lymphopoiesis in mice. We combine these with imaging of myelopoiesis1 to define the anatomy of normal and stress haematopoiesis. In the steady state, across the skeleton, single stem cells and multipotent progenitors distribute through the marrow enriched near megakaryocytes. Lineage-committed progenitors are recruited to blood vessels, where they contribute to lineage-specific microanatomical structures composed of progenitors and immature cells, which function as the production sites for each major blood lineage. This overall anatomy is resilient to insults, as it was maintained after haemorrhage, systemic bacterial infection and granulocyte colony-stimulating factor (G-CSF) treatment, and during ageing. Production sites enable haematopoietic plasticity as they differentially and selectively modulate their numbers and output in response to insults. We found that stress responses are variable across the skeleton: the tibia and the sternum respond in opposite ways to G-CSF, and the skull does not increase erythropoiesis after haemorrhage. Our studies enable in situ analyses of haematopoiesis, define the anatomy of normal and stress responses, identify discrete microanatomical production sites that confer plasticity to haematopoiesis, and uncover unprecedented heterogeneity of stress responses across the skeleton.

Working up an appetite to promote repair.

Immune-derived hunger hormones restore tissue after infection.

The Negative Regulative Roles of BdPGRPs in the Imd Signaling Pathway of Bactrocera dorsalis.

Peptidoglycan recognition proteins (PGRPs) are key regulators in insects' immune response, functioning as sensors to detect invading pathogens and as scavengers of peptidoglycan (PGN) to reduce immune overreaction. However, the exact function of PGRPs in Bactrocera dorsalis is still unclear. In this study, we identified and functionally characterized the genes BdPGRP-LB, BdPGRP-SB1 and BdPGRP-SC2 in B. dorsalis. The results showed that BdPGRP-LB, BdPGRP-SB1 and BdPGRP-SC2 all have an amidase-2 domain, which has been shown to have N-Acetylmuramoyl-l-Alanine amidase activity. The transcriptional levels of BdPGRP-LB and BdPGRP-SC2 were both high in adult stages and midgut tissues; BdPGRP-SB1 was found most abundantly expressed in the 2nd instar larvae stage and adult fat body. The expression of BdPGRP-LB and BdPGRP-SB1 and AMPs were significantly up-regulated after injury infected with Escherichia coli at different time points; however, the expression of BdPGRP-SC2 was reduced at 9 h, 24 h and 48 h following inoculation with E. coli. By injection of dsRNA, BdPGRP-LB, BdPGRP-SB1 and BdPGRP-SC2 were knocked down by RNA-interference. Silencing of BdPGRP-LB, BdPGRP-SB1 and BdPGRP-SC2 separately in flies resulted in over-activation of the Imd signaling pathway after bacterial challenge. The survival rate of the ds-PGRPs group was significantly reduced compared with the ds-egfp group after bacterial infection. Taken together, our results demonstrated that three catalytic PGRPs family genes, BdPGRP-LB, BdPGRP-SB1 and BdPGRP-SC2, are important negative regulators of the Imd pathway in B. dorsalis.

Pelvic inflammatory disease in the adolescent and young adult: An update.

Pelvic inflammatory disease (PID) is an infection of the female upper genital tract that is typically polymicrobial with classic core involvement of Neisseria gonorrhoeae and/or Chlamydia trachomatis, though other endogenous flora from the vagino-cervical areas can be involved as well. It is often a sexually transmitted disease but other etiologic routes are also noted. A variety of risk factors have been identified including adolescence, young adulthood, adolescent cervical ectropion, multiple sexual partners, immature immune system, history of previous PID, risky contraceptive practices and others. An early diagnosis and prompt treatment are necessary to reduce risks of PID complications such as chronic pelvic pain, ectopic pregnancy and infertility. Current management principles of PID are also reviewed. It is important for clinicians to screen sexually active females for common sexually transmitted infections such as Chlamydia trachomatis and provide safer sex education to their adolescent and young adult patients. Clinicians should provide comprehensive management to persons with PID and utilize established guidelines such as those from the US Centers for Disease Control and Prevention (CDC).

Naturally-occurring and cultured bacteriophages in human therapy.

OBJECTIVE: The aim of the study was to show the importance of developing techniques that could exploit the potential of bacteriophages as therapeutics or food supplements. MATERIALS AND METHODS: PubMed database was searched using the following combination of keywords: (bacteriophage) AND (human therapy); (natural bacteriophage) AND (application). RESULTS: The increasing antibiotic resistance of many bacterial strains is making standard antibiotic treatments less effective. Phage therapy provides a non-antibiotic alternative with greater specificity and without harmful effects on the human microbiota. Phages target their specific bacteria, replicate, and then, destroy the host pathogen. Bacteriophages may be administered by several routes, including topical, oral and intravenous. They not only destroy the host pathogen but, in some cases, increase the sensitivity of host bacteria to antibiotics. Various studies have shown that combining phage therapy and antibiotic treatment can be effective against bacterial infections. Clinical trials of phage therapy have shown promising results for various human diseases and conditions. With advances in genetic engineering and molecular techniques, bacteriophages will be able to target a wide range of bacteria. CONCLUSIONS: In the future, phage therapy promises to become an effective therapeutic option for bacterial infections. Since many potentially beneficial bacteriophages can be found in food, supplements containing bacteriophages could be designed to remodel gut microbiota and eliminate pathogenic bacteria. Remodeling of gut microbiota could correct gut dysbiosis. The order of phages known to have these promising activities is Caudovirales, especially the families Siphoviridae and Myoviridae.

Cytosolic detection of phagosomal bacteria-Mechanisms underlying PAMP exodus from the phagosome into the cytosol.

The metazoan innate immune system senses bacterial infections by detecting highly conserved bacterial molecules, termed pathogen-associated molecular patterns (PAMPs). PAMPs are detected by a variety of host pattern recognition receptors (PRRs), whose function is to coordinate downstream immune responses. PRR activities are, in part, regulated by their subcellular localizations. Accordingly, professional phagocytes can detect extracellular bacteria and their PAMPs via plasma membrane-oriented PRRs. Conversely, phagocytosed bacteria and their PAMPs are detected by transmembrane PRRs oriented toward the phagosomal lumen. Even though PAMPs are unable to passively diffuse across membranes, phagocytosed bacteria are also detected by PRRs localized within the host cell cytosol. This phenomenon is explained by phagocytosis of bacteria that specialize in phagosomal escape and cytosolic residence. Contrary to this cytosolic lifestyle, most bacteria studied to date spend their entire intracellular lifestyle contained within phagosomes, yet they also stimulate cytosolic PRRs. Herein, we will review our current understanding of how phagosomal PAMPs become accessible to cytosolic PRRs, as well as highlight knowledge gaps that should inspire future investigations.

Trauma-induced heme release increases susceptibility to bacterial infection.

Infection is a common complication of major trauma that causes significantly increased morbidity and mortality. The mechanisms, however, linking tissue injury to increased susceptibility to infection remain poorly understood. To study this relationship, we present a potentially novel murine model in which a major liver crush injury is followed by bacterial inoculation into the lung. We find that such tissue trauma both impaired bacterial clearance and was associated with significant elevations in plasma heme levels. While neutrophil (PMN) recruitment to the lung in response to Staphylococcus aureus was unchanged after trauma, PMN cleared bacteria poorly. Moreover, PMN show > 50% less expression of TLR2, which is responsible, in part, for bacterial recognition. Administration of heme effectively substituted for trauma. Finally, day 1 trauma patients (n = 9) showed similar elevations in free heme compared with that seen after murine liver injury, and circulating PMN showed similar TLR2 reduction compared with volunteers (n = 6). These findings correlate to high infection rates.

Hepatic FGF21 preserves thermoregulation and cardiovascular function during bacterial inflammation.

Sickness behaviors, including anorexia, are evolutionarily conserved responses to acute infections. Inflammation-induced anorexia causes dramatic metabolic changes, of which components critical to survival are unique depending on the type of inflammation. Glucose supplementation during the anorectic period induced by bacterial inflammation suppresses adaptive fasting metabolic pathways, including fibroblast growth factor 21 (FGF21), and decreases survival. Consistent with this observation, FGF21-deficient mice are more susceptible to mortality from endotoxemia and polybacterial peritonitis. Here, we report that increased circulating FGF21 during bacterial inflammation is hepatic derived and required for survival through the maintenance of thermogenesis, energy expenditure, and cardiac function. FGF21 signaling downstream of its obligate coreceptor, ß-Klotho (KLB), is required in bacterial sepsis. However, FGF21 modulates thermogenesis and chronotropy independent of the adipose, forebrain, and hypothalamus, which are operative in cold adaptation, suggesting that in bacterial inflammation, either FGF21 signals through a novel, undescribed target tissue or concurrent signaling of multiple KLB-expressing tissues is required.

A Novel 29-Messenger RNA Host-Response Assay From Whole Blood Accurately Identifies Bacterial and Viral Infections in Patients Presenting to the Emergency Department With Suspected Infections: A Prospective Observational Study.

OBJECTIVES: The rapid diagnosis of acute infections and sepsis remains a serious challenge. As a result of limitations in current diagnostics, guidelines recommend early antimicrobials for suspected sepsis patients to improve outcomes at a cost to antimicrobial stewardship. We aimed to develop and prospectively validate a new, 29-messenger RNA blood-based host-response classifier Inflammatix Bacterial Viral Non-Infected version 2 (IMX-BVN-2) to determine the likelihood of bacterial and viral infections. DESIGN: Prospective observational study. SETTING: Emergency Department, Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin, Germany. PATIENTS: Three hundred twelve adult patients presenting to the emergency department with suspected acute infections or sepsis with at least one vital sign change. INTERVENTIONS: None (observational study only). MEASUREMENTS AND MAIN RESULTS: Gene expression levels from extracted whole blood RNA was quantified on a NanoString nCounter SPRINT (NanoString Technologies, Seattle, WA). Two predicted probability scores for the presence of bacterial and viral infection were calculated using the IMX-BVN-2 neural network classifier, which was trained on an independent development set. The IMX-BVN-2 bacterial score showed an area under the receiver operating curve for adjudicated bacterial versus ruled out bacterial infection of 0.90 (95% CI, 0.85-0.95) compared with 0.89 (95% CI, 0.84-0.94) for procalcitonin with procalcitonin being used in the adjudication. The IMX-BVN-2 viral score area under the receiver operating curve for adjudicated versus ruled out viral infection was 0.83 (95% CI, 0.77-0.89). CONCLUSIONS: IMX-BVN-2 demonstrated accuracy for detecting both viral infections and bacterial infections. This shows the potential of host-response tests as a novel and practical approach for determining the causes of infections, which could improve patient outcomes while upholding antimicrobial stewardship.

Bacterial infections adversely influence the risk of decompensation and survival in compensated cirrhosis.

BACKGROUND & AIMS: The prognosis of compensated cirrhosis is good until decompensation. In decompensated cirrhosis, bacterial infections (BIs) are common and increase the risk of death. The incidence and prognostic implications of BIs in compensated cirrhosis are less-well characterized. This study aimed to assess whether BIs influence the risk of decompensation and survival in patients with compensated cirrhosis. METHODS: This is a cohort study nested to the PREDESCI study, a double-blind, multicenter, randomized controlled trial designed to assess whether ß-blockers could prevent decompensation of cirrhosis. Patients with compensated cirrhosis and hepatic venous pressure gradient ≥10 mmHg were included. Development of BIs during follow-up was prospectively registered. Using a competing-risk time-dependent regression analysis, we investigated whether BIs affect the risk of decompensation and survival. Decompensation was defined as development of ascites, bleeding or overt encephalopathy. RESULTS: A total of 201 patients were randomized and followed for a median of 36 months (IQR 24-47 months); 34 patients (17%) developed BIs, which occurred before decompensation in 33 cases, and 29 (14%) developed ascites. Respiratory and urinary tract infections were the most frequent BIs. Decompensation occurred in 26% patients with BIs vs. 16% without BIs. Patients with BIs were at higher risk of decompensation (subdistribution hazard ratio [SHR] 2.93; 95% CI 1.02-8.42; p = 0.047) and of developing ascites (SHR 3.55; 95% CI 1.21-10.47; p = 0.022) than those without BIs. Risk of death was also higher in patients with BIs (subdistribution HR 6.93; 95% CI 2.64-18.18; p <0.001), although decompensation occurred before death in 71% of such cases. CONCLUSIONS: BIs have a marked impact on the natural history of compensated cirrhosis, significantly increasing the risk of decompensation, mainly that of ascites, and increasing the risk of death, which usually occurs after decompensation. Our results suggest that BIs may constitute a target to prevent decompensation. LAY SUMMARY: It is widely known that bacterial infections are common and increase the mortality risk in patients with decompensated cirrhosis. However, the relevance of bacterial infections in compensated cirrhosis has not been well studied. This study shows that in patients with compensated cirrhosis and clinically significant portal hypertension, bacterial infections occur as frequently as the development of ascites, which is the most frequent decompensating event. Bacterial infections increase the risk of progression to decompensation, mainly by increasing the risk of ascites, and also increase the risk of death, which usually occurs after decompensation. CLINICALTRIALS. GOV IDENTIFIER: NCT01059396.

Bacterial detection by NAIP/NLRC4 elicits prompt contractions of intestinal epithelial cell layers.

The gut epithelium serves to maximize the surface for nutrient and fluid uptake, but at the same time must provide a tight barrier to pathogens and remove damaged intestinal epithelial cells (IECs) without jeopardizing barrier integrity. How the epithelium coordinates these tasks remains a question of significant interest. We used imaging and an optical flow analysis pipeline to study the dynamicity of untransformed murine and human intestinal epithelia, cultured atop flexible hydrogel supports. Infection with the pathogen Salmonella Typhimurium (STm) within minutes elicited focal contractions with inward movements of up to ∼1,000 IECs. Genetics approaches and chimeric epithelial monolayers revealed contractions to be triggered by the NAIP/NLRC4 inflammasome, which sensed type-III secretion system and flagellar ligands upon bacterial invasion, converting the local tissue into a contraction epicenter. Execution of the response required swift sublytic Gasdermin D pore formation, ion fluxes, and the propagation of a myosin contraction pulse across the tissue. Importantly, focal contractions preceded, and could be uncoupled from, the death and expulsion of infected IECs. In both two-dimensional monolayers and three-dimensional enteroids, multiple infection-elicited contractions coalesced to produce shrinkage of the epithelium as a whole. Monolayers deficient for Caspase-1(-11) or Gasdermin D failed to elicit focal contractions but were still capable of infected IEC death and expulsion. Strikingly, these monolayers lost their integrity to a markedly higher extent than wild-type counterparts. We propose that prompt NAIP/NLRC4/Caspase-1/Gasdermin D/myosin-dependent contractions allow the epithelium to densify its cell packing in infected regions, thereby preventing tissue disintegration due to the subsequent IEC death and expulsion process.

The potential role of necroptosis in clinical diseases (Review).

As an important type of programmed cell death in addition to apoptosis, necroptosis occurs in a variety of pathophysiological processes, including infections, liver diseases, kidney injury, neurodegenerative diseases, cardiovascular diseases, and human tumors. It can be triggered by a variety of factors, such as tumor necrosis factor receptor and Toll­like receptor families, intracellular DNA and RNA sensors, and interferon, and is mainly mediated by receptor­interacting protein kinase 1 (RIP1), RIP3, and mixed lineage kinase domain­like protein. A better understanding of the mechanism of necroptosis may be useful in the development of novel drugs for necroptosis­related diseases. In this review, the focus is on the molecular mechanisms of necroptosis, exploring the role of necroptosis in different pathologies, discussing their potential as a novel therapeutic target for disease therapy, and providing suggestions for further study in this area.

[Mechanism of gut-microbiota-liver axis in the pathogenesis of intestinal failure-associated liver disease].

Intestinal failure (IF) is defined as the critical reduction of functional intestines below the minimum needed to absorb nutrients and fluids, so that intravenous supplementation with parenteral nutrition (PN) is required to maintain health and/or growth. Although the benefits are evident, patients receiving PN can suffer from serious cholestasis due to lack of enteral feeding and small intestinal bacterial overgrowth (SIBO). One such complication that may arise is intestinal failure-associated liver disease (IFALD). Evidences from recent studies suggest that alterations in the intestinal microbiota, as well as intraluminal bile acid driven signaling, may play a critical role in both hepatic and intestinal injury. Since Marshall first proposed the concept of the gut-liver axis in 1998, the role of gut-liver axis disorders in the development of IFALD has received considerable attention. The conversation between gut and liver is the key to maintain liver metabolism and intestinal homeostasis, which influences each other and is reciprocal causation. However, as a "forgotten organ" , intestinal microbiota on the pathogenesis of IFALD has not been well reflected. As such, we propose, for the first time, the concept of gut-microbiota-liver axis to emphasize the importance of intestinal microbiota in the interaction of gut-liver axis. Analysis and research on gut-microbiota-liver axis will be of great significance for understanding the pathogenesis of IFALD and improving the prevention and treatment measures.

Fever response to ibuprofen in viral and bacterial childhood infections.

OBJECTIVE: to compare the antipyretic effects of ibuprofen in febrile children with serious bacterial infections (SBI), and children with a presumed viral infection. METHODS: A prospective cross- sectional study was conducted in a pediatric Emergency department between October 2018 and March 2020 for children aged 3 months to 4 years with a rectal temperature ≥ 38.5 °C. Patients received 10 mg/kg of ibuprofen oral suspension. Rectal temperature was measured 60 and 120 min after administration. Laboratory and imaging evaluations were performed for each study participant in order to identify serious bacterial infection. RESULTS: Ninety patients were included, of which 18 were diagnosed with serious bacterial infections. There was no significant difference in age, fever at presentation and duration of fever between the groups. No significant difference was noted in body temperature reduction at 60 and 120 min after ibuprofen administration (1.09 ± 0.75 °C vs 0.89 ± 0.58 °C, mean difference -0.12 °C, 95% CI -0.54-0.15 °C; 1.85 ± 0.53 °C vs 1.78 ± 0.83 °C, mean difference - 0.07 °C, 95% CI -0.49-0.36 °C, in the SBI and non-SBI groups respectively). CONCLUSION: Fever response to Ibuprofen administration is not indicative of serious bacterial infections in children under 4 years of age. Larger prospective studies are required to define whether the lack of response to Ibuprofen has any impact on the management of febrile children.

Clinicopathological profile and outcomes of infection-related glomerulonephritis in adults.

INTRODUCTION: Infection-related glomerulonephritis (IRGN) is an example of immune-mediated glomerular injury, with changing profile over the years. We analyzed the clinicopathological profile of IRGN from a single center. MATERIALS AND METHODS: Adult renal biopsies between July 2018 and January 2020 were screened, and biopsies with IRGN were included. The demographic, clinical, and laboratory data up to 6 months were analyzed. RESULTS: 27 patients were included, with 63% having evidence of current/recent infection, Staphylococcus and Streptococcus being most common (29.4%). The mean eGFR at presentation was 16.7 mL/min/1.73m2, with crescents in 70.4% of cases. 59.3% required dialysis, and 40.7% received steroids. Complete recovery was seen in 84.6%, while 11.1% developed chronic kidney disease, and 3.7% progressed to end-stage renal disease. Persistent proteinuria, hematuria, and hypertension at 6 months were seen in 11.1, 7.4, and 3.7%, respectively. There was significant negative correlation between renal recovery and history of diabetes, interstitial fibrosis and tubular atrophy (IFTA), glomerulosclerosis, and IgA deposits. There was no significant impact of steroid use on outcome. CONCLUSION: IRGN can have an aggressive course in adults, with renal recovery continuing beyond 3 months. IFTA, glomerulosclerosis, IgA deposits, and history of DM are significant negative predictors of clinical outcome, and there is no proven benefit of steroids.

Mechanism of gut-microbiota-liver axis in the pathogenesis of intestinal failure-associated liver disease / 中华胃肠外科杂志

Intestinal failure (IF) is defined as the critical reduction of functional intestines below the minimum needed to absorb nutrients and fluids, so that intravenous supplementation with parenteral nutrition (PN) is required to maintain health and/or growth. Although the benefits are evident, patients receiving PN can suffer from serious cholestasis due to lack of enteral feeding and small intestinal bacterial overgrowth (SIBO). One such complication that may arise is intestinal failure-associated liver disease (IFALD). Evidences from recent studies suggest that alterations in the intestinal microbiota, as well as intraluminal bile acid driven signaling, may play a critical role in both hepatic and intestinal injury. Since Marshall first proposed the concept of the gut-liver axis in 1998, the role of gut-liver axis disorders in the development of IFALD has received considerable attention. The conversation between gut and liver is the key to maintain liver metabolism and intestinal homeostasis, which influences each other and is reciprocal causation. However, as a "forgotten organ" , intestinal microbiota on the pathogenesis of IFALD has not been well reflected. As such, we propose, for the first time, the concept of gut-microbiota-liver axis to emphasize the importance of intestinal microbiota in the interaction of gut-liver axis. Analysis and research on gut-microbiota-liver axis will be of great significance for understanding the pathogenesis of IFALD and improving the prevention and treatment measures.

Advances in Optical Detection of Human-Associated Pathogenic Bacteria.

Bacterial infection is a global burden that results in numerous hospital visits and deaths annually. The rise of multi-drug resistant bacteria has dramatically increased this burden. Therefore, there is a clinical need to detect and identify bacteria rapidly and accurately in their native state or a culture-free environment. Current diagnostic techniques lack speed and effectiveness in detecting bacteria that are culture-negative, as well as options for in vivo detection. The optical detection of bacteria offers the potential to overcome these obstacles by providing various platforms that can detect bacteria rapidly, with minimum sample preparation, and, in some cases, culture-free directly from patient fluids or even in vivo. These modalities include infrared, Raman, and fluorescence spectroscopy, along with optical coherence tomography, interference, polarization, and laser speckle. However, these techniques are not without their own set of limitations. This review summarizes the strengths and weaknesses of utilizing each of these optical tools for rapid bacteria detection and identification.

Bacteria and Antibiotics in Wound Healing.

This review of the literature concerning bacteria, antibiotics and tissue repair shows there are extensive data supporting microbial interference with wound healing once bacterial burden exceeds 104 CFU per unit of measure, The mechanism of bacterial interference lies largely in prolonging the inflammatory phase of tissue repair. Reducing the microbial bioburden allows tissue repair to continue. Systemic and topical antimicrobials appear critical to reducing the bioburden and facilitating repair. The current controversy over the use of antimicrobials in patients with chronically infected wounds, in particular, revolves around the definition of infection. The reliance on classic clinical signs of inflammation to support antimicrobial use in these patients is tenuous due to the lack of correlation of these signs with the microbial burden known to impair tissue repair.

Epidemiologic and clinical profiles of bacterial myocarditis. Report of two cases and data from a pooled analysis.

We aimed to characterize the epidemiology, diagnostic peculiarities and outcome determinants of bacterial myocarditis. Two cases from our institution and literature reports were collected ending up with a total of 66 cases. In 37 (56%) patients, the diagnosis was confirmed by magnetic resonance and histopathological criteria. The other patients were classified as having possible myocarditis. Only occurrence of rhythm disturbances was associated with the specific diagnosis of myocarditis (p = 0.04). Thirty-two (48%) patients presented with severe sepsis that was associated with a worse prognosis. At multivariate analysis, left ventricular ejection fraction (LVEF) at admission and heart rhythm disturbances were associated with incomplete recovery (odds ratio (OR) 1.1, 95% (CI) 1.03-1.2, p = 0.004 and OR 6.6, 95% CI 1.35-32.5, p = 0.02, respectively). In summary, bacterial myocarditis is uncommon. Most commonly, it is secondary to septic dissemination of bacteria or to transient secondary myocardial toxicity.