The function of IL-4Rα expression on key immune cells during experimental Nippostrongylus brasiliensis infections

Includes bibliographical references.The lifecycle of the parasitic nematode Nippostrogylus brasiliensis resembles that of the human hookworms Necator americanus and Ancylostoma duodenale and as such is a useful murine model for studying hookworm disease.abstrac

Correction: Delayed Goblet Cell Hyperplasia, Acetylcholine Receptor Expression, and Worm Expulsion in SMC-Specific IL-4Rα–Deficient Mice

Interleukin 4 receptor alpha (IL-4Ralpha) is essential for effective clearance of gastrointestinal nematode infections. Smooth muscle cells are considered to play a role in the type 2 immune response-driven expulsion of gastrointestinal nematodes. Previous studies have shown in vitro that signal transducer and activator of transcription 6 signaling in response to parasitic nematode infection significantly increases smooth muscle cell contractility. Inhibition of the IL-4Ralpha pathway inhibits this response. How this response manifests itself in vivo is unknown. In this study, smooth muscle cell IL-4Ralpha-deficient mice (SM-MHC(Cre)IL-4Ralpha(-/lox)) were generated and characterized to uncover any role for IL-4/IL-13 in this non-immune cell type in response to Nippostrongylus brasiliensis infection. IL-4Ralpha was absent from alpha-actin-positive smooth muscle cells, while other cell types showed normal IL-4Ralpha expression, thus demonstrating efficient cell-type-specific deletion of the IL-4Ralpha gene. N. brasiliensis-infected SM-MHC(Cre)IL-4Ralpha(-/lox) mice showed delayed ability to resolve infection with significantly prolonged fecal egg recovery and delayed worm expulsion. The delayed expulsion was related to a delayed intestinal goblet cell hyperplasia, reduced T helper 2 cytokine production in the mesenteric lymph node, and reduced M3 muscarinic receptor expression during infection. Together, these results demonstrate that in vivo IL-4Ralpha-responsive smooth muscle cells are beneficial for N. brasiliensis expulsion by coordinating T helper 2 cytokine responses, goblet hyperplasia, and acetylcholine responsiveness, which drive smooth muscle cell contractions

Delayed Goblet Cell Hyperplasia, Acetylcholine Receptor Expression, and Worm Expulsion in SMC-Specific IL-4Rα–Deficient Mice

Interleukin 4 receptor α (IL-4Rα) is essential for effective clearance of gastrointestinal nematode infections. Smooth muscle cells are considered to play a role in the type 2 immune response–driven expulsion of gastrointestinal nematodes. Previous studies have shown in vitro that signal transducer and activator of transcription 6 signaling in response to parasitic nematode infection significantly increases smooth muscle cell contractility. Inhibition of the IL-4Rα pathway inhibits this response. How this response manifests itself in vivo is unknown. In this study, smooth muscle cell IL-4Rα–deficient mice (SM-MHC(Cre)IL-4Rα(−/lox)) were generated and characterized to uncover any role for IL-4/IL-13 in this non–immune cell type in response to Nippostrongylus brasiliensis infection. IL-4Rα was absent from α-actin–positive smooth muscle cells, while other cell types showed normal IL-4Rα expression, thus demonstrating efficient cell-type–specific deletion of the IL-4Rα gene. N. brasiliensis–infected SM-MHC(Cre)IL-4Rα(−/lox) mice showed delayed ability to resolve infection with significantly prolonged fecal egg recovery and delayed worm expulsion. The delayed expulsion was related to a delayed intestinal goblet cell hyperplasia, reduced T helper 2 cytokine production in the mesenteric lymph node, and reduced M3 muscarinic receptor expression during infection. Together, these results demonstrate that in vivo IL-4Rα–responsive smooth muscle cells are beneficial for N. brasiliensis expulsion by coordinating T helper 2 cytokine responses, goblet hyperplasia, and acetylcholine responsiveness, which drive smooth muscle cell contractions

Nippostrongylus-induced intestinal hypercontractility requires IL-4 receptor alpha-responsiveness by T cells in mice

Gut-dwelling helminthes induce potent IL-4 and IL-13 dominated type 2 T helper cell (T H 2) immune responses, with IL-13 production being essential for Nippostrongylus brasiliensis expulsion. This T H 2 response results in intestinal inflammation associated with local infiltration by T cells and macrophages. The resulting increased IL-4/IL-13 intestinal milieu drives goblet cell hyperplasia, alternative macrophage activation and smooth muscle cell hypercontraction. In this study we investigated how IL-4-promoted T cells contributed to the parasite induced effects in the intestine. This was achieved using pan T cell-specific IL-4 receptor alpha-deficient mice (iLck cre IL-4Rα −/lox ) and IL-4Rα-responsive control mice. Global IL-4Rα −/− mice showed, as expected, impaired type 2 immunity to N. brasiliensis . Infected T cell-specific IL-4Rα-deficient mice showed comparable worm expulsion, goblet cell hyperplasia and IgE responses to control mice. However, impaired IL-4-promoted T H 2 cells in T cell-specific IL-4Rα deficient mice led to strikingly reduced IL-4 production by mesenteric lymph node CD4 + T cells and reduced intestinal IL-4 and IL-13 levels, compared to control mice. This reduced IL-4/IL-13 response was associated with an impaired IL-4/IL-13-mediated smooth muscle cell hypercontractility, similar to that seen in global IL-4Rα −/− mice. These results demonstrate that IL-4-promoted T cell responses are not required for the resolution of a primary N. brasiliensis infection. However, they do contribute significantly to an important physiological manifestation of helminth infection; namely intestinal smooth muscle cell-driven hypercontractility

Live-attenuated Mycobacterium tuberculosis vaccine MTBVAC versus BCG in adults and neonates: a randomised controlled, double-blind dose-escalation trial

Background: Infants are a key target population for new tuberculosis vaccines. We assessed the safety and immunogenicity of the live-attenuated Mycobacterium tuberculosis vaccine candidate MTBVAC in adults and infants in a region where transmission of tuberculosis is very high. Methods: We did a randomised, double-blind, BCG-controlled, dose-escalation trial at the South African Tuberculosis Vaccine Initiative site near Cape Town, South Africa. Healthy adult community volunteers who were aged 18–50 years, had received BCG vaccination as infants, were HIV negative, had negative interferon-¿ release assay (IGRA) results, and had no personal history of tuberculosis or current household contact with someone with tuberculosis were enrolled in a safety cohort. Infants born to HIV-negative women with no personal history of tuberculosis or current household contact with a person with tuberculosis and who were 96 h old or younger, generally healthy, and had not yet received routine BCG vaccination were enrolled in a separate infant cohort. Eligible adults were randomly assigned (1:1) to receive either BCG Vaccine SSI (5 × 105 colony forming units [CFU] of Danish strain 1331 in 0·1 mL diluent) or MTBVAC (5 × 105 CFU in 0·1 mL) intradermally in the deltoid region of the arm. After favourable review of 28-day reactogenicity and safety data in the adult cohort, infants were randomly assigned (1:3) to receive either BCG Vaccine SSI (2·5 × 105 CFU in 0·05 mL diluent) or MTBVAC in three sequential cohorts of increasing MTBVAC dose (2·5 × 103 CFU, 2·5 × 104 CFU, and 2·5 × 105 CFU in 0·05 mL) intradermally in the deltoid region of the arm. QuantiFERON-TB Gold In-Tube IGRA was done on days 180 and 360. For both randomisations, a pre-prepared block randomisation schedule was used. Participants (and their parents or guardians in the case of infant participants), investigators, and other clinical and laboratory staff were masked to intervention allocation. The primary outcomes, which were all measured in the infant cohort, were solicited and unsolicited local adverse events and serious adverse events until day 360; non-serious systemic adverse events until day 28 and vaccine-specific CD4 and CD8 T-cell responses on days 7, 28, 70, 180, and 360. Secondary outcomes measured in adults were local injection-site and systemic reactions and haematology and biochemistry at study day 7 and 28. Safety analyses and immunogenicity analyses were done in all participants who received a dose of vaccine. This trial is registered with ClinicalTrials.gov, number NCT02729571. Findings: Between Sept 29, 2015, and Nov 16, 2015, 62 adults were screened and 18 were enrolled and randomly assigned, nine each to the BCG and MTBVAC groups. Between Feb 12, 2016, and Sept 21, 2016, 36 infants were randomly assigned—eight to the BCG group, nine to the 2·5 × 103 CFU MTBVAC group, nine to the 2·5 × 104 CFU group, and ten to the 2·5 × 105 CFU group. Mild injection-site reactions occurred only in infants in the BCG and the 2·5 × 105 CFU MTBVAC group, with no evidence of local or regional injection-site complications. Systemic adverse events were evenly distributed across BCG and MTBVAC dose groups, and were mostly mild in severity. Eight serious adverse events were reported in seven vaccine recipients (one adult MTBVAC recipient, one infant BCG recipient, one infant in the 2·5 × 103 CFU MTBVAC group, two in the 2·5 × 104 CFU MTBVAC group, and two in the 2·5 × 105 CFU MTBVAC group), including one infant in the 2·5 × 103 CFU MTBVAC group treated for unconfirmed tuberculosis and one in the 2·5 × 105 CFU MTBVAC group treated for unlikely tuberculosis. One infant died as a result of possible viral pneumonia. Vaccination with all MTBVAC doses induced durable antigen-specific T-helper-1 cytokine-expressing CD4 cell responses in infants that peaked 70 days after vaccination and were detectable 360 days after vaccination. For the highest MTBVAC dose (ie, 2·5 × 105 CFU), these responses exceeded responses induced by an equivalent dose of the BCG vaccine up to 360 days after vaccination. Dose-related IGRA conversion was noted in three (38%) of eight infants in the 2·5 × 103 CFU MTBVAC group, six (75%) of eight in the 2·5 × 104 CFU MTBVAC group, and seven (78%) of nine in the 2·5 × 105 CFU MTBVAC group at day 180, compared with none of seven infants in the BCG group. By day 360, IGRA reversion had occurred in all three infants (100%) in the 2·5 × 103 CFU MTBVAC group, four (67%) of the six in the 2·5 × 104 CFU MTBVAC group, and three (43%) of the seven in the 2·5 × 105 CFU MTBVAC group. Interpretation: MTBVAC had acceptable reactogenicity, and induced a durable CD4 cell response in infants. The evidence of immunogenicity supports progression of MTBVAC into larger safety and efficacy trials, but also confounds interpretation of tests for M tuberculosis infection, highlighting the need for stringent endpoint definition. Funding: Norwegian Agency for Development Cooperation, TuBerculosis Vaccine Initiative, UK Department for International Development, and Biofabri

Assessing the association of diabetes and severe COVID-19 outcomes; a rapid review protocol

A rapid review protocol assessing the association of diabetes and severe COVID-19. Primary Objective: To assess the association between diabetes and severe clinical course of COVID-19 in patients hospitalised due to COVID-19. Secondary Objective: To assess the prevalence of diabetes in patients hospitalised due to COVID-19. Exploratory Objective: To report risk factors (e.g. older age, male sex, higher BMI, higher HbA1c levels) and other co-morbidities (e.g. hypertension, cardiovascular disease) in patients with diabetes hospitalised due to COVID-19 with recorded endpoint of severe clinical course of COVID-19

Screening strategies for adults with type 2 diabetes mellitus

There are insufficient randomized controlled trials to address whether screening for type 2 diabetes mellitus (T2DM) improves health outcomes. This systematic review sought to cast a wider net and synthesise evidence from non-randomised intervention studies to assess the effectiveness of T2DM screening in adults for reducing mortality and T2DM-associated morbidity. We searched PubMed/MEDLINE, Scopus, Web of Science, CINAHL, Academic Search Premier and Health Source Nursing Academic (inception onwards; last search July 2021). We included non-randomised intervention studies that assessed T2DM screening compared to no screening, in adults without known T2DM. Screening was performed independently by two reviewers. Data was abstracted by one reviewer and checked by a second, as was risk of bias (ROBINS-I) and certainty of evidence (GRADE). A narrative summary was performed. We screened 10,892 records, retrieving 67 for full-text screening with one record meeting inclusion criteria. The study was a prospective cohort comparing T2DM screening versus no screening. It included adults, 40 - 65 years, with no known T2DM from a single community practice in Ely, England (N = 4,936) and evaluated outcomes at two time periods. The study was assessed as having moderate risk of bias. There may be little or no difference in mortality between those who were invited to screening versus those who were not invited (1990-1999: adjusted hazard ratio (aHR) 0.79 [95% confidence interval (CI) 0.63 – 1.00], n = 4,936, low certainty evidence and 2000 - 2008: aHR 1.18 [95% CI 0.93 - 1.51], n = 3,002, low certainty evidence). We found only one study reporting the effectiveness of screening for T2DM in adults. Therefore, despite ongoing T2DM screening in clinical care, this review highlights an important research gap in understanding the true health benefits of screening

Understanding the Generation and Regulation of IL-4 Producing T Helper 2 Cells

A keenly sought therapeutic approach for the treatment of allergic disease is the identification and neutralization of the cytokine that regulates the differentiation of Th2 cells. Th2 cells are CD4 T cells differentiated to secrete IL-4. These cells are exciting new targets for asthma therapies due to the key role they play in allergic airway diseases. Recently the cytokine IL-25 has been shown to enhance Th2 cell activity and play important roles in mediating allergic inflammatory responses. To investigate this further we crossed IL-25 deficient mice with GFP-IL-4 reporter mice and developed an assay of in vitro and in vivo IL-4 independent Th2 differentiation. These assays were used to determine whether IL-25 was critical for the formation of Th2 cells. We found there was no physiological role for IL-25 in either the differentiation of Th2 cells or their development to effector or memory Th2 subsets. In the strong Th2 setting of a helminth infection the absence of IL-25 resulted in no defects in the effector type 2 responses associated with T helper type 2 immunity including, mucous hyperplasia, class switching to IgE and protection against challenge infections. Importantly this data challenges the newly found and growing status of the cytokine IL-25 and its proposed role in promoting Th2 responses. The second part of this thesis investigated whether the genomic organisation, which reflects commitment to Th2 cytokine expression, could provide a clearer definition of a functional in vivo Th2 cell. Two distinct IL-4 reporter mice were crossed and Th2 in vivo assays were developed that allowed tracking of the individual alleles of IL-4 in a variety of tissue types and Th2 subsets. Interestingly in vivo expression of IL-4 is mostly monoallelic yet there is a small highly activated population of biallelic IL-4 expressing Th2 cells. Physiologically each allele of IL-4 was required for a functional Th2 response with total serum IgE titres up to 4 fold lower in IL-4+/- heterozygous compared to the IL-4+/+ sufficient animals and a significant loss in protective immunity against challenge infections with helminths occurred in the IL-4+/- heterozygous animals. The similarity in deficiencies in Th2 immunity in the IL-4+/- heterozygous and IL-4-/- deficient compared to the IL-4+/+ sufficient animals lead to the proposal that the generation of biallelic Th2 cells may be required for specialised cell-to-cell mediated delivery of tailored activation signals and higher quantities of IL-4 required to mediate fully developed Th2 immune responses

Assessing the association of obesity and severe COVID-19 outcomes in adults; a rapid review protocol

A rapid review protocol to assess the association of obesity and severe COVID-19 in adults. Primary Objective: To assess the association between obesity and severe clinical course of COVID-19 in patients hospitalised due to COVID-19. Secondary Objective: To assess the prevalence of obesity in patients hospitalised due to COVID-19. Exploratory Objective: To report risk factors (e.g. older age, male sex) and other co-morbidities (e.g. hypertension, cardiovascular disease, diabetes) in patients with obesity hospitalised due to COVID-19 with recorded endpoint of severe clinical course of COVID-19