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The concept of mRNA-based vaccines emerged more than three decades ago. Groundbreaking discoveries and technological advancements over the past 20 years have resolved the major roadblocks that initially delayed application of this new vaccine modality. The rapid development of nucleoside-modified COVID-19 mRNA vaccines demonstrated that this immunization platform is easy to develop, has an acceptable safety profile and can be produced at a large scale. The flexibility and ease of antigen design have enabled mRNA vaccines to enter development for a wide range of viruses as well as for various bacteria and parasites. However, gaps in our knowledge limit the development of next-generation mRNA vaccines with increased potency and safety. A deeper understanding of the mechanisms of action of mRNA vaccines, application of novel technologies enabling rational antigen design, and innovative vaccine delivery strategies and vaccination regimens will likely yield potent novel vaccines against a wide range of pathogens.Following the success of the COVID-19 vaccines, mRNA vaccines have now entered development for a wide range of infectious diseases. This Review discusses mRNA vaccine design considerations, delivery strategies and mechanisms of action, assessing mRNA vaccines currently in development for various viruses, bacteria and parasites. The challenges, limitations and opportunities facing next-generation mRNA vaccines are considered.

The adult dentate gyrus generates new granule cells (GCs) that develop over several weeks and integrate into the preexisting network. Although adult hippocampal neurogenesis has been implicated in learning and memory, the specific role of new GCs remains unclear. We examined whether immature adult-born neurons contribute to information encoding. By combining calcium imaging and electrophysiology in acute slices, we found that weak afferent activity recruits few mature GCs while activating a substantial proportion of the immature neurons. These different activation thresholds are dictated by an enhanced excitation/inhibition balance transiently expressed in immature GCs. Immature GCs exhibit low input specificity that switches with time toward a highly specific responsiveness. Therefore, activity patterns entering the dentate gyrus can undergo differential decoding by a heterogeneous population of GCs originated at different times.

Microscopic colitis (MC) is a relatively common cause of chronic watery diarrhea, especially in older persons. Associated symptoms, including abdominal pain and arthralgias, are common. The diagnosis is based upon characteristic histological findings in the presence of diarrhea. The two types of MC, collagenous and lymphocytic colitis, share similar clinical features, with the main difference being the presence or absence of a thickened subepithelial collagen band. There are several treatment options for patients with MC, although only budesonide has been well studied in multiple controlled clinical trials. This review will describe the clinical features, epidemiology, pathophysiology, diagnostic criteria, and treatment of patients with MC.

Proactive efforts towards the development of new vaccines and antivirals, and the elimination of bottlenecks in vaccine development, will be essential to containing and eradicating future pandemics.

Cure rates after fecal microbiota transplantation for recurrent Clostridium difficile infection (CDI) were lower in randomized controlled trials than in open-label and observational studies, lower for enema than for colonoscopy or oral delivery, and lower for refractory versus recurrent CDI. Abstract Background Fecal microbiota transplantation (FMT) is highly effective for treating recurrent Clostridium difficile infection (CDI) in observational studies (>90%), but cure rates in clinical trials are lower. We performed a systematic review and meta-analysis to assess the efficacy of FMT for recurrent CDI in open-label studies and clinical trials . Methods A systematic search from January 1978 to March 2017 was performed to include clinical trials of FMT for CDI. We analyzed CDI resolution by calculating weighted pooled rates (WPRs). Results Thirteen trials were included, comprising 610 patients with CDI treated with single FMT. Overall, 439 patients had clinical cure (WPR, 76.1%; 95% confidence interval (CI), 66.4%–85.7%). There was significant heterogeneity among studies (I2 = 91.35%). Cure rates were lower in randomized trials (139/216 patients; WPR, 67.7%; 95% CI, 54.2%–81.3%) than in open-label studies (300/394 patients; WPR, 82.7%; 71.1%–94.3%) (P < .001). Subgroup analysis by FMT delivery modality showed lower cure rates with enema than colonoscopy (WPR, 66.3% vs 87.4%; P < .001) but no difference between colonoscopy and oral delivery (WPR, 87.4% vs 81.4%; P = .17). Lower rates were seen for studies including both recurrent and refractory CDI than for those including only recurrent CDI (WPR, 63.9% vs 79%; P < .001). Conclusions FMT was associated with lower cure rates in randomized trials than in open-label and in observational studies. Colonoscopy and oral route are more effective than enema for stool delivery. The efficacy also seems to be higher for recurrent than for refractory CDI.

Most known pathogenic point mutations in humans are C•G to T•A substitutions, which can be directly repaired by adenine base editors (ABEs). In this study, we investigated the efficacy and safety of ABEs in the livers of mice and cynomolgus macaques for the reduction of blood low-density lipoprotein (LDL) levels. Lipid nanoparticle–based delivery of mRNA encoding an ABE and a single-guide RNA targeting PCSK9 , a negative regulator of LDL, induced up to 67% editing (on average, 61%) in mice and up to 34% editing (on average, 26%) in macaques. Plasma PCSK9 and LDL levels were stably reduced by 95% and 58% in mice and by 32% and 14% in macaques, respectively. ABE mRNA was cleared rapidly, and no off-target mutations in genomic DNA were found. Re-dosing in macaques did not increase editing, possibly owing to the detected humoral immune response to ABE upon treatment. These findings support further investigation of ABEs to treat patients with monogenic liver diseases. Base editors are effective and safe for cholesterol reduction in non-human primates.

Induction of intrinsic liver regeneration is an unmet need that can be achieved by temporally activating key hepatocyte regenerative pathways. Here, we establish an efficient, safe, non-integrative method to transiently express hepatocyte-growth-factor (HGF) and epidermal-growth-factor (EGF) in hepatocytes via nucleoside-modified, lipid-nanoparticle-encapsulated mRNA (mRNA-LNP) delivery in mice. We confirm specific hepatotropism of mRNA-LNP via intravenous injection of firefly luciferase encoding mRNA-LNP, with protein expression lasting about 3 days. In the liver, virtually all hepatocytes are transfected along with a subpopulation of endothelial and Kupffer cells. In homeostasis, HGF mRNA-LNP efficiently induce hepatocyte proliferation. In a chronic liver injury mouse model recapitulating non-alcoholic fatty liver disease, injections of both HGF and EGF mRNA-LNP sharply reverse steatosis and accelerate restoration of liver function. Likewise, HGF and EGF mRNA-LNP accelerate liver regeneration after acetaminophen-induced acute liver injury with rapid return to baseline ALT levels. This study introduces mRNA-LNP as a potentially translatable safe therapeutic intervention to harness liver regeneration via controlled expression of endogenous mitogens in vivo. When severely or chronically injured, the liver loses ability to regenerate. Here, the authors utilize transient lipid nanoparticle-enclosed HGF and EGF-encoding mRNA delivery to induce hepatocyte proliferation and harness recovery of liver function in murine acute and chronic liver injury models.

The growing recognition of the older inflammatory bowel disease (IBD) patient is heightened by the entry of the 77.2 million baby boomers who will turn 65 beginning of 2011. It is anticipated that this will occur at a rate of 10,000 per day or 4 million per year for the next 19 years. The management of IBD in this population is complex because of problems with co-morbidities, polypharmacy, impaired mobility, and cognition, as well as difficult social and financial issues. This review focuses on the older IBD patient's unique concerns and provides guidance in their diagnosis and management.

In the contemporary context of an acute need for sustainability and swift response to imminent crises such as global warming, pandemics and economic system disruptions, the focus on responsible decision making, ethical risk assessment and mitigation at all organizational levels is an overarching goal. Our aim is to introduce a deterministic method for investigating the stability of complex systems, in order to find the most important elements of such systems and their impact on different scenarios. The novelty of the current approach lies in its compact format and intuitive nature, designed to accommodate a limited amount of computational resources. The proposed modelling method involves the mapping of complex systems from a diversity of disciplines (economic markets, resource management domain and the community impact of suburbanisation) onto a sequence of chemical reactions and involving a subsequent mathematical analysis. Mapping the results back onto the use cases shows that one can retrieve a considerable amount of detail, making the modelling strategy general enough to be adaptable and scalable while also detailed enough to provide valuable insights for practical scenarios.