Engineering early memory B-cell-like phenotype in hydrogel-based immune organoids.

Memory B cells originate in response to antigenic stimulation in B-cell follicles of secondary lymphoid organs where naive B cells undergo maturation within a subanatomical microenvironment, the germinal centers. The understanding of memory B-cell immunology and its regulation is based primarily on sophisticated experiments that involve mouse models. To date, limited evidence exists on whether memory B cells can be successfully engineered ex vivo, specifically using biomaterials-based platforms that support the growth and differentiation of B cells. Here, we report the characterization of a recently reported maleimide-functionalized poly(ethylene glycol) (PEG) hydrogels as immune organoids towards the development of early memory B-cell phenotype and germinal center-like B cells. We demonstrate that the use of interleukin 9 (IL9), IL21, and bacterial antigen presentation as outer membrane-bound fragments drives the conversion of naive, primary murine B cells to early memory phenotype in ex vivo immune organoids. These findings describe the induction of early memory B-cell-like phenotype in immune organoids and highlight the potential of synthetic organoids as a platform for the future development of antigen-specific bona fide memory B cells for the study of the immune system and generation of therapeutic antibodies.

Structural insight into protein-protein interactions between intestinal microbiome and host.

Protein-protein interactions between the microbiome and host organism play an important role in shaping host health. These host-modulating proteins have therapeutic potential in treating microbiome-linked disorders such as inflammatory bowel disease and obesity. Structural analysis of interacting proteins provides highly mechanistic insight into the domains driving these interactions and the resulting influence on host cell processes. Here, we briefly review recent publication of microbiome protein structures involved in host binding interactions, the effects of these interactions on host physiology, and the need for further study to increase the ability to detect proteins with therapeutic potential.

Organoid Polymer Functionality and Mode of Klebsiella Pneumoniae Membrane Antigen Presentation Regulates Ex Vivo Germinal Center Epigenetics in Young and Aged B Cells.

Antibiotic-resistant bacteria are a major global health threat that continues to rise due to a lack of effective vaccines. Of concern are Klebsiella pneumoniae that fail to induce in vivo germinal center B cell responses, which facilitate antibody production to fight infection. Immunotherapies using antibodies targeting antibiotic-resistant bacteria are emerging as promising alternatives, however, they cannot be efficiently derived ex vivo, necessitating the need for immune technologies to develop therapeutics. Here, PEG-based immune organoids were developed to elucidate the effects of polymer end-point chemistry, integrin ligands, and mode of K. pneumoniae antigen presentation on germinal center-like B cell phenotype and epigenetics, to better define the lymph node microenvironment factors regulating ex vivo germinal center dynamics. Notably, PEG vinyl sulfone or acrylate failed to sustain primary immune cells, but functionalization with maleimide (PEG-4MAL) led to B cell expansion and germinal center-like induction. RNA sequencing analysis of lymph node stromal and germinal center B cells showed niche associated heterogeneity of integrin-related genes. Incorporation of niche-mimicking peptides revealed that collagen-1 promoted germinal center-like dynamics and epigenetics. PEG-4MAL organoids elucidated the impact of K. pneumoniae outer membrane-embedded protein antigen versus soluble antigen presentation on germinal centers and preserved the response across young and aged mice.

TgPRELID, a Mitochondrial Protein Linked to Multidrug Resistance in the Parasite Toxoplasma gondii.

New drugs to control infection with the protozoan parasite Toxoplasma gondii are needed as current treatments exert toxic side effects on patients. Approaches to develop novel compounds for drug development include screening of compound libraries and targeted inhibition of essential cellular pathways. We identified two distinct compounds that display inhibitory activity against the parasite's replicative stage: F3215-0002, which we previously identified during a compound library screen, and I-BET151, an inhibitor of bromodomains, the "reader" module of acetylated lysines. In independent studies, we sought to determine the targets of these two compounds using forward genetics, generating resistant mutants and identifying the determinants of resistance with comparative genome sequencing. Despite the dissimilarity of the two compounds, we recovered resistant mutants with nonsynonymous mutations in the same domain of the same gene, TGGT1_254250, which we found encodes a protein that localizes to the parasite mitochondrion (designated TgPRELID after the name of said domain). We found that mutants selected with one compound were cross resistant to the other compound, suggesting a common mechanism of resistance. To further support our hypothesis that TgPRELID mutations facilitate resistance to both I-BET151 and F3215-0002, CRISPR (clustered regularly interspaced short palindromic repeat)/CAS9-mediated mutation of TgPRELID directly led to increased F3215-0002 resistance. Finally, all resistance mutations clustered in the same subdomain of TgPRELID. These findings suggest that TgPRELID may encode a multidrug resistance factor or that I-BET151 and F3215-0002 have the same target(s) despite their distinct chemical structures. IMPORTANCE We report the discovery of TgPRELID, a previously uncharacterized mitochondrial protein linked to multidrug resistance in the parasite Toxoplasma gondii. Drug resistance remains a major problem in the battle against parasitic infection, and understanding how TgPRELID mutations augment resistance to multiple, distinct compounds will reveal needed insights into the development of new therapies for toxoplasmosis and other related parasitic diseases.

"It's Just Not the Culture": A Qualitative Study Exploring Residents' Perceptions of the Impact of Institutional Culture on Feedback.

Phenomenon: Competency-based medical education requires ongoing performance-based feedback for professional growth. In several studies, medical trainees report that the quality of faculty feedback is inadequate. Sociocultural barriers to feedback exchanges are further amplified in graduate and postgraduate medical education settings, where trainees serve as frontline providers of patient care. Factors that affect institutional feedback culture, enhance feedback seeking, acceptance, and bidirectional feedback warrant further exploration in these settings. APPROACH: Using a constructivist grounded theory approach, we sought to examine residents' perspectives on institutional factors that affect the quality of feedback, factors that influence receptivity to feedback, and quality and impact of faculty feedback. Four focus group discussions were conducted, with two investigators present at each. One facilitated the discussion, and the other observed the interactions and took field notes. We audiotaped and transcribed the discussions, and performed a thematic analysis. Measures to ensure rigor included thick descriptions, independent coding by two investigators, and attention to reflexivity. FINDINGS: We identified five key themes, dominated by resident perceptions regarding the influence of institutional feedback culture. The theme labels are taken from direct participant quotes: (a) the cultural norm lacks clear expectations and messages around feedback, (b) the prevailing culture of niceness does not facilitate honest feedback, (c) bidirectional feedback is not part of the culture, (d) faculty-resident relationships impact credibility and receptivity to feedback, and (e) there is a need to establish a culture of longitudinal professional growth. Insights: Institutional culture could play a key role in influencing the quality, credibility, and acceptability of feedback. A polite culture promotes a positive learning environment but can be a barrier to honest feedback. Feedback initiatives focusing solely on techniques of feedback giving may not enhance meaningful feedback. Further research on factors that promote feedback seeking, receptivity to constructive feedback, and bidirectional feedback would provide valuable insights.

A simulation shows that early treatment of chronic hepatitis B infection can cut deaths and be cost-effective.

Chronic hepatitis B affects between 800,000 and two million people in the United States and causes 4,000 deaths each year. Yet the costs and benefits of treatment have not been fully evaluated. Using a model that simulates disease progression, we compare treatment programs for hepatitis B that start at an early stage of the disease to treatment that begins at a late stage. Our analysis concludes that early hepatitis B care can improve health, reduce premature deaths, and prevent expensive complications, making it highly cost-effective in the long term. Our results demonstrate the importance of screening for hepatitis B among at-risk groups and then linking screening to treatment. They also illustrate how predictive models can be used to evaluate strategies for improving access to care.