National Institute of General Medical Sciences

Excessive cell death in the epithelium due to prolonged immune activation is associated with intestinal diseases such as Crohn’s disease. Mice with mutations in the Crohn’s disease susceptibility gene Atg16l1 are susceptible to inflammation associated with intestinal epithelial cell (IEC) death, including loss of antimicrobial Paneth cells triggered by infection with murine norovirus (MNV). Here, we show that intestinal disease downstream of MNV depends on IFN-α/β and IFN-λ signaling in IECs. In mouse organoids, IFNs synergize with TNF to induce RIPK1-dependent cell death, amplified by ATG16L1 deficiency. We further show that human intestinal organoids harboring the ATG16L1 risk allele exhibit heightened sensitivity to TNF and IFN co-stimulation and to serum from severe COVID-19 patients. Our findings reveal that virally triggered cytokines including IFNs exacerbate epithelial vulnerability in genetically predisposed hosts.

Interferonopathies drive autoimmunity but can also impair host responses to pathogens, including viral infections. To better understand viral susceptibility of patients with STAT1 gain-of-function (GOF) mutations, we generated conditional knockin mouse models to elucidate disease mechanisms and relevance of different immune subsets. Virally infected Stat1 GOF mice exhibited impaired early IFN-γ production from innate lymphocytes and lethality because of excess prolonged multicytokine production. The presence of the Stat1 GOF allele resulted in premature usage of interferon-stimulated gene factor 3 (ISGF3) over the normal STAT4-AP-1-dependent transcriptomic program in activated innate lymphocytes. Administration of anti-IFN-γ antibodies in wild-type (WT) mice after infection phenocopied Stat1 GOF mice presenting exaggerated inflammation despite viral control. Conversely, early administration of exogenous IFN-γ to infected Stat1 GOF mice prevented lethality and exaggerated cytokine response. Although Stat1 GOF mutations facilitate IFN-γ-mediated autoimmunity, early IFN-γ responses to viral infection via a normal STAT4 program were impaired, leading to overcompensated inflammatory responses in Stat1 GOF mice.

Microorganisms commonly exist in polymicrobial communities, where they can respond to interspecies secreted molecules by altering behaviors and physiology, however, the underlying mechanisms remain underexplored. Here we investigated interactions between Stenotrophomonas maltophilia and Pseudomonas aeruginosa, co-infecting opportunistic pathogens found in pneumonia and chronic lung infections, including in cystic fibrosis. We found that S. maltophilia forms robust protective multicellular aggregates upon exposure to P. aeruginosa secreted factors. Experimental evolution for lack of aggregation selected for fimbrial mutations and we found that fimbriae are required on both interacting S. maltophilia cells for aggregation. Untargeted metabolomics and targeted validations revealed that the quorum sensing molecule Pseudomonas quinolone signal (PQS) directly induced S. maltophilia aggregation, and co-localized with the aggregates. Further, in co-culture with P. aeruginosa, wild-type S. maltophilia formed aggregates, resulting in up to 75-fold increased survival from P. aeruginosa competition compared to fimbrial mutants. Finally, multiple other bacterial species similarly aggregated upon exposure to P. aeruginosa exoproducts, indicating a more general response. Collectively, our work identifies a novel multispecies interaction where a quorum sensing molecule from a co-infecting pathogen is sensed as a ‘danger’ signal, thereby inducing a protective multicellular response.

Biomedical data are growing exponentially in both volume and levels of complexity, due to the rapid advancement of technologies and research methodologies. Analyzing these large datasets, referred to collectively as "big data," has become an integral component of research that guides experimentation-driven discovery and a new engine of discovery itself as it uncovers previously unknown connections through mining of existing data. To fully realize the potential of big data, biomedical researchers need access to high-performance-computing (HPC) resources. However, supporting on-premises infrastructure that keeps up with these consistently expanding research needs presents persistent financial and staffing challenges, even for well-resourced institutions. For other institutions, including primarily undergraduate institutions and minority serving institutions, that educate a large portion of the future workforce in the USA, this challenge presents an insurmountable barrier. Therefore, new approaches are needed to provide broad and equitable access to HPC resources to biomedical researchers and students who will advance biomedical research in the future.

This case report presents the clinical management of a 6-month-old male infant presenting with fever, vomiting, and incessant crying. After initial conservative management, the patient was diagnosed with choledocholithiasis and cholecystitis. Due to the infant's weight, ERCP with CBD stenting was deemed inappropriate, and thus, a hepaticojejunostomy procedure was performed. The postoperative period was uneventful, with resolution of symptoms and normalization of biliary parameters. This case underscores the challenges in diagnosing and treating gallstone-related conditions in infants, highlighting the importance of surgical intervention in certain cases.

The bending modulus of a lipid bilayer quantifies its mechanical resistance to curvature. It is typically understood in terms of thickness, e.g., thicker bilayers are stiffer. Here, we describe an additional and powerful molecular determinant of stiffness — the variance in the distribution of curvature sensitivity of lipids and lipid conformations. Zwitterionic choline and ethanolamine head-groups of glycero-phospholipids dynamically explore inter- and intra-species interactions, leading to transient clustering. We demonstrate that these clusters couple strongly to negative curvature, exciting undulatory membrane modes and reducing the apparent bending modulus. Three forcefields (Martini 2, Martini 3, and all-atom CHARMM C36) each show the effect to a different extent, with the coarse-grained Martini models showing the most clustering and thus the most softening. The theory is a guide to understanding the stiffness of biological membranes with their complex composition, as well as how choices of forcefield parameterization are translated into mechanical stiffness.

Exposure therapy is a cornerstone of social anxiety treatment, yet not all patients respond. Symptoms in certain social situations, including intergroup (ie, out-group) contexts, may be particularly resistant to treatment. Exposure therapy outcomes may be improved by stimulating neural areas associated with safety learning, such as the medial prefrontal cortex (mPFC). The mPFC also plays an important role in identifying others as similar to oneself. We hypothesized that targeting the mPFC during exposure therapy would reduce intergroup anxiety and social anxiety. Participants (N = 31) with the public speaking subtype of social anxiety received active (anodal) or sham transcranial direct current stimulation (tDCS) targeting the mPFC during exposure therapy. Exposure therapy consisted of giving speeches to audiences in virtual reality. To target intergroup anxiety, half of the public speaking exposure trials were conducted with out-group audiences, defined in this study as audiences of a different ethnicity. Contrary to hypotheses, tDCS did not facilitate symptom reduction. Some evidence even suggested that tDCS temporarily increased in-group favoritism, although these effects dissipated at 1-month follow-up. In addition, collapsing across all participants, we found reductions across time for public speaking anxiety and intergroup anxiety. The data provide evidence that standard exposure therapy techniques for social anxiety can be adapted to target intergroup anxiety. Transcranial direct current stimulation targeting the mPFC may boost safety signaling, but only in contexts previously conditioned to signal safety, such as an in-group context.

Oxidative stress causes K63-linked ubiquitination of ribosomes by the E2 ubiquitin conjugase Rad6. How Rad6-mediated ubiquitination of ribosomes affects translation, however, is unclear. We therefore perform Ribo-seq and Disome-seq in Saccharomyces cerevisiae and show that oxidative stress causes ribosome pausing at specific amino acid motifs, which also leads to ribosome collisions. However, these redox-pausing signatures are lost in the absence of Rad6 and do not depend on the ribosome-associated quality control (RQC) pathway. We also show that Rad6 is needed to inhibit overall translation in response to oxidative stress and that its deletion leads to increased expression of antioxidant genes. Finally, we observe that the lack of Rad6 leads to changes during translation that affect activation of the integrated stress response (ISR) pathway. Our results provide a high-resolution picture of the gene expression changes during oxidative stress and unravel an additional stress response pathway affecting translation elongation.