Probing Clostridium difficile Infection in Complex Human Gut Cellular Models

Interactions of anaerobic gut bacteria, such as Clostridium difficile, with the intestinal mucosa have been poorly studied due to challenges in culturing anaerobes with the oxygen-requiring gut epithelium. Although gut colonization by C. difficile is a key determinant of disease outcome, precise mechanisms of mucosal attachment and spread remain unclear. Here, using human gut epithelial monolayers co-cultured within dual environment chambers, we demonstrate that C. difficile adhesion to gut epithelial cells is accompanied by a gradual increase in bacterial numbers. Prolonged infection causes redistribution of actin and loss of epithelial integrity, accompanied by production of C. difficile spores, toxins, and bacterial filaments. This system was used to examine C. difficile interactions with the commensal Bacteroides dorei, and interestingly, C. difficile growth is significantly reduced in the presence of B. dorei. Subsequently, we have developed novel models containing a myofibroblast layer, in addition to the epithelium, grown on polycarbonate or three-dimensional (3D) electrospun scaffolds. In these more complex models, C. difficile adheres more efficiently to epithelial cells, as compared to the single epithelial monolayers, leading to a quicker destruction of the epithelium. Our study describes new controlled environment human gut models that enable host–anaerobe and pathogen–commensal interaction studies in vitro

Accurate Prediction of Secreted Substrates and Identification of a Conserved Putative Secretion Signal for Type III Secretion Systems

The type III secretion system is an essential component for virulence in many Gram-negative bacteria. Though components of the secretion system apparatus are conserved, its substrates—effector proteins—are not. We have used a novel computational approach to confidently identify new secreted effectors by integrating protein sequence-based features, including evolutionary measures such as the pattern of homologs in a range of other organisms, G+C content, amino acid composition, and the N-terminal 30 residues of the protein sequence. The method was trained on known effectors from the plant pathogen Pseudomonas syringae and validated on a set of effectors from the animal pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) after eliminating effectors with detectable sequence similarity. We show that this approach can predict known secreted effectors with high specificity and sensitivity. Furthermore, by considering a large set of effectors from multiple organisms, we computationally identify a common putative secretion signal in the N-terminal 20 residues of secreted effectors. This signal can be used to discriminate 46 out of 68 total known effectors from both organisms, suggesting that it is a real, shared signal applicable to many type III secreted effectors. We use the method to make novel predictions of secreted effectors in S. Typhimurium, some of which have been experimentally validated. We also apply the method to predict secreted effectors in the genetically intractable human pathogen Chlamydia trachomatis, identifying the majority of known secreted proteins in addition to providing a number of novel predictions. This approach provides a new way to identify secreted effectors in a broad range of pathogenic bacteria for further experimental characterization and provides insight into the nature of the type III secretion signal

Propranolol for infantile hemangiomas in developing countries

Background: Propranolol is the treatment of choicefor complicated infantile hemangiomas (IH). However,in some locations, propranolol has not yet becomestandard of care. To our knowledge, until 2014,propranolol had not been used in Afghanistan totreat IH. Objectives: To raise further awareness thatpropranolol is the treatment of choice for complicatedIH, suggest a propranolol induction, maintenance,and taper protocol, show an example of therapeuticsuccess in a resource-limited country, and discusspotential challenges. Methods: At an academicteaching hospital in Kabul, Afghanistan, we conducteda retrospective chart review of patients treated withpropranolol for IH from 2014-2015. Results: Seventeenpatients were treated using a modified protocol basedon consensus recommendations. Average age was 6.3months (range 2.5 to 18 months). Thirteen patientshad focal IH and four had large segmental facial IH.Three patients were lost to follow-up. The remaining14 had good response and very few complications,including one patient co-managed by utilizing storeand-forward teledermatology. Conclusions: Patientsin resource-limited countries can be managedsuccessfully using a modified version of a propranololinduction, maintenance, and taper protocol. Indeveloping countries where dermatologists arescarce, we suggest IH may be co-managed withprimary care physicians via teledermatology

Childhood atopic dermatitis is associated with cognitive dysfunction: A National Health Interview Survey study from 2008 to 2018

© 2020 American College of Allergy, Asthma & Immunology Background: Atopic dermatitis (AD) is a common inflammatory skin disease in children and adults. Little is known regarding the association of childhood AD with cognitive dysfunction. Objective: To evaluate the association of AD and cognitive dysfunction, including memory impairment, developmental delays and attention deficit (hyperactivity) disorder in US children (age \u3c18 years). Methods: Data was analyzed from the National Health Interview Survey 2008 to 2018, which used a multistage, clustered, cross-sectional design. Results: The prevalences of cognitive dysfunction, such as memory impairment (0.87% vs 0.42%), developmental delays (6.96% vs 3.87%), and attention deficit (hyperactivity) disorder (10.78% vs 8.10%), were higher in children with vs without AD. In multivariable logistic regression models adjusting for age, sex, race, region, socioeconomic factors, allergic conditions, and mental health, childhood AD was associated with higher odds of memory impairment (adjusted odds ratio [95% confidence interval]: 1.84 [1.34-2.51]), developmental delays (1.54 [1.40-1.70]), and attention deficit (hyperactivity) disorder (1.31 [1.20-1.42]) compared with children without AD. Childhood atopic disease (defined as comorbid AD, asthma, allergic rhinitis, and food allergies) further increased the prevalence of developmental delays to 13.44% (2.10 [1.20-3.70]) in boys but not in girls. Conclusion: In a nationally representative sample of the US population, a statistically significant and positive association between childhood AD and atopic disease with cognitive dysfunction was identified (P \u3c .001). Furthermore, a dimorphic relationship with developmental delays was identified between sexes

TH2 sensitization in the skin-gut-brain axis: How early-life Th2-mediated inflammation may negatively perpetuate developmental and psychologic abnormalities

We recently reported children with comorbid atopic dermatitis (AD), asthma, allergic rhinitis, and food allergies displaying a 2.7-fold increase in developmental delays.2 To this end, we hypothesize unregulated increases in T helper-2 (Th2)–driven inflammation, such as those seen in atopic diseases, can exert deleterious effects on the developing brain. Recognizing that available information is incomplete and that many potential associations are not firmly established, we speculate these effects underlie the association between Th2 sensitization and cognitive dysfunction in children. In this review, we explore the role of Th2 sensitization in the skin-gut-brain axis and explain how it can lead to reduced connectivity and transmission in the developing brain. With a focus on AD, we explore the association between Th2 sensitization and developmental abnormalities such as developmental delays, memory impairment, autism spectrum disorder (ASD), and epilepsy/seizures. As such, we review the available literature to examine the impact of increased IL-4 exposure in early life on the brain. We explore the possible association between Th2 sensitization and psychologic dysfunction such as attention-deficit/hyperactivity disorder (ADHD), depression, anxiety, and suicidal ideation. We also examine the impact that increased exposure to glucocorticoids and neurotrophins in early life exerts on the developing brain. Last, we discuss future directions for the advancement of our knowledge as a scientific community including possible interventions to reduce developmental and psychologic aberrations in children

Pediatric Contact Dermatitis Registry Inaugural Case Data

Little is known about the epidemiology of allergic contact dermatitis (ACD) in US children. More widespread diagnostic confirmation through epicutaneous patch testing is needed. The aim was to quantify patch test results from providers evaluating US children. The study is a retrospective analysis of deidentified patch test results of children aged 18 years or younger, entered by participating providers in the Pediatric Contact Dermatitis Registry, during the first year of data collection (2015-2016). One thousand one hundred forty-two cases from 34 US states, entered by 84 providers, were analyzed. Sixty-five percent of cases had one or more positive patch test (PPT), with 48% of cases having 1 or more relevant positive patch test (RPPT). The most common PPT allergens were nickel (22%), fragrance mix I (11%), cobalt (9.1%), balsam of Peru (8.4%), neomycin (7.2%), propylene glycol (6.8%), cocamidopropyl betaine (6.4%), bacitracin (6.2%), formaldehyde (5.7%), and gold (5.7%). This US database provides multidisciplinary information on pediatric ACD, rates of PPT, and relevant RPPT reactions, validating the high rates of pediatric ACD previously reported in the literature. The registry database is the largest comprehensive collection of US-only pediatric patch test cases on which future research can be built. Continued collaboration between patients, health care providers, manufacturers, and policy makers is needed to decrease the most common allergens in pediatric consumer products