Comparative Outcomes of Endoscopic Mucosal Resection for Laterally Spreading Lesions in Inflammatory Bowel Disease.

BACKGROUND: The role of endoscopic mucosal resection (EMR) for laterally spreading lesions (LSLs) in inflammatory bowel disease (IBD) remains controversial despite its effectiveness in the general population. We aim to characterize outcomes of EMR for IBD-associated LSLs compared to controls without IBD. METHODS: We performed a retrospective observational cohort study of patients with IBD who underwent EMR and endoscopic follow-up for LSLs, compared to a control group without IBD. The primary outcome was histologic recurrence; secondary outcomes included en bloc resection and adverse events. Factors associated with recurrence were identified using multivariate mixed effects logistic regression. RESULTS: A total of 210 pre-malignant lesions in 155 patients were included. By histology, 91% were adenoma/low-grade dysplasia or sessile serrated lesions. Average lesion size was 22.9 mm (SD 11.3 mm) in the IBD group, and 21.5 mm (SD 12.4 mm) in the control group. Recurrence occurred in 30.4% of IBD-associated lesions (7/23) compared to 20.9% of controls (39/187; OR=2.51, CI .59-10.71). En bloc resection was less common in the IBD group (2/23, 8.7%, 95% CI 1.1-28.0) versus controls (106/187, 57.9%, 95% CI 50.4-65.2). After adjusting for lesion size and histology, recurrence appeared more common in patients with IBD compared to controls (OR=3.08, 95% CI 1.04-9.13). CONCLUSIONS: Recurrence of LSLs after EMR appears more frequent in patients with IBD. Given the added complexity, EMR in patients with IBD should be performed in expert centers with close endoscopic surveillance.

ChatGPT4 Outperforms Endoscopists for Determination of Postcolonoscopy Rescreening and Surveillance Recommendations.

BACKGROUND & AIMS: Large language models including Chat Generative Pretrained Transformers version 4 (ChatGPT4) improve access to artificial intelligence, but their impact on the clinical practice of gastroenterology is undefined. This study compared the accuracy, concordance, and reliability of ChatGPT4 colonoscopy recommendations for colorectal cancer rescreening and surveillance with contemporary guidelines and real-world gastroenterology practice. METHODS: History of present illness, colonoscopy data, and pathology reports from patients undergoing procedures at 2 large academic centers were entered into ChatGPT4 and it was queried for the next recommended colonoscopy follow-up interval. Using the McNemar test and inter-rater reliability, we compared the recommendations made by ChatGPT4 with the actual surveillance interval provided in the endoscopist's procedure report (gastroenterology practice) and the appropriate US Multisociety Task Force (USMSTF) guidance. The latter was generated for each case by an expert panel using the clinical information and guideline documents as reference. RESULTS: Text input of de-identified data into ChatGPT4 from 505 consecutive patients undergoing colonoscopy between January 1 and April 30, 2023, elicited a successful follow-up recommendation in 99.2% of the queries. ChatGPT4 recommendations were in closer agreement with the USMSTF Panel (85.7%) than gastroenterology practice recommendations with the USMSTF Panel (75.4%) (P < .001). Of the 14.3% discordant recommendations between ChatGPT4 and the USMSTF Panel, recommendations were for later screening in 26 (5.1%) and for earlier screening in 44 (8.7%) cases. The inter-rater reliability was good for ChatGPT4 vs USMSTF Panel (Fleiss κ, 0.786; 95% CI, 0.734-0.838; P < .001). CONCLUSIONS: Initial real-world results suggest that ChatGPT4 can define routine colonoscopy screening intervals accurately based on verbatim input of clinical data. Large language models have potential for clinical applications, but further training is needed for broad use.

Anti-TIGIT antibody improves PD-L1 blockade through myeloid and Treg cells.

Tiragolumab, an anti-TIGIT antibody with an active IgG1κ Fc, demonstrated improved outcomes in the phase 2 CITYSCAPE trial (ClinicalTrials.gov: NCT03563716 ) when combined with atezolizumab (anti-PD-L1) versus atezolizumab alone1. However, there remains little consensus on the mechanism(s) of response with this combination2. Here we find that a high baseline of intratumoural macrophages and regulatory T cells is associated with better outcomes in patients treated with atezolizumab plus tiragolumab but not with atezolizumab alone. Serum sample analysis revealed that macrophage activation is associated with a clinical benefit in patients who received the combination treatment. In mouse tumour models, tiragolumab surrogate antibodies inflamed tumour-associated macrophages, monocytes and dendritic cells through Fcγ receptors (FcγR), in turn driving anti-tumour CD8+ T cells from an exhausted effector-like state to a more memory-like state. These results reveal a mechanism of action through which TIGIT checkpoint inhibitors can remodel immunosuppressive tumour microenvironments, and suggest that FcγR engagement is an important consideration in anti-TIGIT antibody development.

Immune heterogeneity in small-cell lung cancer and vulnerability to immune checkpoint blockade.

Atezolizumab (anti-PD-L1), combined with carboplatin and etoposide (CE), is now a standard of care for extensive-stage small-cell lung cancer (ES-SCLC). A clearer understanding of therapeutically relevant SCLC subsets could identify rational combination strategies and improve outcomes. We conduct transcriptomic analyses and non-negative matrix factorization on 271 pre-treatment patient tumor samples from IMpower133 and identify four subsets with general concordance to previously reported SCLC subtypes (SCLC-A, -N, -P, and -I). Deeper investigation into the immune heterogeneity uncovers two subsets with differing neuroendocrine (NE) versus non-neuroendocrine (non-NE) phenotypes, demonstrating immune cell infiltration hallmarks. The NE tumors with low tumor-associated macrophage (TAM) but high T-effector signals demonstrate longer overall survival with PD-L1 blockade and CE versus CE alone than non-NE tumors with high TAM and high T-effector signal. Our study offers a clinically relevant approach to discriminate SCLC patients likely benefitting most from immunotherapies and highlights the complex mechanisms underlying immunotherapy responses.

Generation of antigen-specific mature T cells from RAG1-/-RAG2-/-B2M-/- stem cells by engineering their microenvironment.

Pluripotent stem cells (PSCs) are a promising source of allogeneic T cells for off-the-shelf immunotherapies. However, the process of differentiating genetically engineered PSCs to generate mature T cells requires that the same molecular elements that are crucial for the selection of these cells be removed to prevent alloreactivity. Here we show that antigen-restricted mature T cells can be generated in vitro from PSCs edited via CRISPR to lack endogenous T cell receptors (TCRs) and class I major histocompatibility complexes. Specifically, we used T cell precursors from RAG1-/-RAG2-/-B2M-/- human PSCs expressing a single TCR, and a murine stromal cell line providing the cognate human major histocompatibility complex molecule and other critical signals for T cell maturation. Possibly owing to the absence of TCR mispairing, the generated T cells showed substantially better tumour control in mice than T cells with an intact endogenous TCR. Introducing the T cell selection components into the stromal microenvironment of the PSCs overcomes inherent biological challenges associated with the development of T cell immunotherapies from allogeneic PSCs.

A Preliminary Controlled Trial of Endoscopic Ultrasound-guided Fiducial Markers to Guide Pancreas Surgery.

OBJECTIVE: Endoscopic ultrasound (EUS) is routinely used for fiducial marker placement (FMP) to guide stereotactic radiation of pancreatic tumors, but EUS-FMP explicitly to guide surgery has not been studied in a prospective, controlled manner. Multipurpose EUS systems have been developed that facilitate simultaneous EUS-FMP at the time of biopsy. We aimed to evaluate the feasibility of EUS-FMP to guide pancreatic resection. METHODS: In this prospective trial, we enrolled patients with resectable pancreas masses undergoing tissue sampling and placed preloaded fiducials immediately after biopsy. Intraprocedure confirmation of carcinoma, neuroendocrine, and nonlymphomatous neoplasia by rapid on-site evaluation and lesion size <4 cm was required. The main outcomes were the feasibility and ease of preoperative placement and intraoperative detection of the markers using predefined Likert scales. RESULTS: In 20 patients, EUS-FMP was successful before planned surgery and placement was technically straightforward (Likert Scale: 9.1 ± 1.3; range: 1, most challenging to 10, most facile). Intraoperative detection was feasible and improved when compared with a pre-established comparator of 5 representing an equivalent lesion without a marker (Likert Scale: 7.8 ± 2.2; range: 1, most difficult to 10, most facile; P = 0.011). The mean tumor size on EUS was 1.7 ± 0.9 (range: 0.5 to 3.6) cm. CONCLUSION: EUS-FMP is feasible and safe for resectable pancreatic tumors before surgery and may assist in perioperative detection. Preloaded fiducials may be considered for placement at the time of initial referral for EUS-fine needle biopsy.

Mass Spectrometry-Based Tissue Imaging of the Tumor Microenvironment.

Multiplex ion beam imaging (MIBI) and imaging mass cytometry (IMC) enable highly multiplexed antibody (40+) staining of frozen or formalin fixed, paraffin-embedded (FFPE) human or murine tissues through detection of metal ions liberated from primary antibodies by time-of-flight mass spectrometry (TOF). These methods make detection of more than 50 targets theoretically possible while maintaining spatial orientation. As such, they are ideal tools to identify the multiple immune, epithelial, and stromal cell subsets in the tumor microenvironment and to characterize spatial relationships and tumor-immune status in either murine models or human samples. This chapter summarizes methods for antibody conjugation and validation, staining, and preliminary data collection using IMC or MIBI in both human and mouse pancreatic adenocarcinoma samples. These protocols are intended to facilitate use of these complex platforms in not only tissue-based tumor immunology studies but also tissue-based oncology or immunology studies more broadly.

Human T cell generation is restored in CD3δ severe combined immunodeficiency through adenine base editing.

CD3δ SCID is a devastating inborn error of immunity caused by mutations in CD3D, encoding the invariant CD3δ chain of the CD3/TCR complex necessary for normal thymopoiesis. We demonstrate an adenine base editing (ABE) strategy to restore CD3δ in autologous hematopoietic stem and progenitor cells (HSPCs). Delivery of mRNA encoding a laboratory-evolved ABE and guide RNA into a CD3δ SCID patient's HSPCs resulted in a 71.2% ± 7.85% (n = 3) correction of the pathogenic mutation. Edited HSPCs differentiated in artificial thymic organoids produced mature T cells exhibiting diverse TCR repertoires and TCR-dependent functions. Edited human HSPCs transplanted into immunodeficient mice showed 88% reversion of the CD3D defect in human CD34+ cells isolated from mouse bone marrow after 16 weeks, indicating correction of long-term repopulating HSCs. These findings demonstrate the preclinical efficacy of ABE in HSPCs for the treatment of CD3δ SCID, providing a foundation for the development of a one-time treatment for CD3δ SCID patients.

Obligate role for Rock1 and Rock2 in adult stem cell viability and function.

The ability of stem cells to rapidly proliferate and differentiate is integral to the steady-state maintenance of tissues with high turnover such as the blood and intestine. Mutations that alter these processes can cause primary immunodeficiencies, malignancies and defects in barrier function. The Rho-kinases, Rock1 and Rock2, regulate cell shape and cytoskeletal rearrangement, activities essential to mitosis. Here, we use inducible gene targeting to ablate Rock1 and Rock2 in adult mice, and identify an obligate requirement for these enzymes in the preservation of the hematopoietic and gastrointestinal systems. Hematopoietic cell progenitors devoid of Rho-kinases display cell cycle arrest, blocking the differentiation to mature blood lineages. Similarly, these mice exhibit impaired epithelial cell renewal in the small intestine, which is ultimately fatal. Our data reveal a novel role for these kinases in the proliferation and viability of stem cells and their progenitors, which is vital to maintaining the steady-state integrity of these organ systems.

Equitable Implementation of Mailed Stool Test-Based Colorectal Cancer Screening and Patient Navigation in a Safety Net Health System.

BACKGROUND: Mailed stool testing programs increase colorectal cancer (CRC) screening in diverse settings, but whether uptake differs by key demographic characteristics is not well-studied and has health equity implications. OBJECTIVE: To examine the uptake and equity of the first cycle of a mailed stool test program implemented over a 3-year period in a Central Texas Federally Qualified Health Center (FQHC) system. DESIGN: Retrospective cohort study within a single-arm intervention. PARTICIPANTS: Patients in an FQHC aged 50-75 at average CRC risk identified through electronic health records (EHR) as not being up to date with screening. INTERVENTIONS: Mailed outreach in English/Spanish included an introductory letter, free-of-charge fecal immunochemical test (FIT), and lab requisition with postage-paid mailer, simple instructions, and a medical records update postcard. Patients were asked to complete the FIT or postcard reporting recent screening. One text and one letter reminded non-responders. A bilingual patient navigator guided those with positive FIT toward colonoscopy. MAIN MEASURES: Proportions of patients completing mailed FIT in response to initial cycle of outreach and proportion of those with positive FIT completing colonoscopy; comparison of whether proportions varied by demographics and insurance status obtained from the EHR. KEY RESULTS: Over 3 years, 33,606 patients received an initial cycle of outreach. Overall, 19.9% (n = 6672) completed at least one mailed FIT, 5.6% (n = 374) tested positive during that initial cycle, and 72.5% (n = 271 of 374) of those with positive FIT completed a colonoscopy. Hispanic/Latinx, Spanish-speaking, and uninsured patients were more likely to complete mailed FIT compared with white, English-speaking, and commercially insured patients. Spanish-speaking patients were more likely to complete colonoscopy after positive FIT compared with English-speaking patients. CONCLUSIONS: Mailed FIT outreach with patient navigation implemented in an FQHC system was effective in equitably reaching patients not up to date for CRC screening.

Association of Standardized Radiology Reporting and Management of Abdominal CT and MRI With Diagnosis of Pancreatic Cancer.

BACKGROUND & AIMS: Follow-up of abdominal computed tomography (CT) and magnetic resonance imaging (MRI) findings suspicious for pancreatic cancer may be delayed if documentation is unclear. We evaluated whether standardized reporting and follow-up of imaging results reduced time to diagnosis of pancreatic cancer. METHODS: We used a quasi-experimental stepped-wedge cluster design to evaluate the effectiveness of newly implemented radiology reporting system. The system standardizes the reporting of CT and MRI reports using hashtags that classify pancreatic findings. The system also automates referral of patients with findings suspicious for pancreatic cancer to a multidisciplinary care team for rapid review and follow-up. The study examined 318,331 patients who underwent CT or MRI that included the abdomen from 2016 through 2019 who had not had an eligible CT or MRI in the preceding 24 months. We evaluated the association of the intervention with incidence of pancreatic cancer within 60 days and 120 days after imaging. RESULTS: Thirty-eight percent of patients received the intervention, and 1523 patients (0.48%) were diagnosed with pancreatic cancer. In multivariable analysis accounting for age, race/ethnicity, sex, Charlson comorbidity, history of cancer, diabetes, and 4-month calendar period, the intervention was associated with nearly 50% greater odds of diagnosing pancreatic cancer within 60 days (adjusted odds ratio, 1.47; 95% confidence interval, 1.05-2.06) and 120 days (adjusted odds ratio, 1.46; 95% confidence interval, 1.04-2.06). CONCLUSIONS: In this large quasi-experimental, community-based observational study, implementing standardized reporting of abdominal CT and MRI reports with clinical navigation was effective for increasing the detection and diagnosis of pancreatic cancer.

The Metabolic Landscape of Thymic T Cell Development In Vivo and In Vitro.

Although metabolic pathways have been shown to control differentiation and activation in peripheral T cells, metabolic studies on thymic T cell development are still lacking, especially in human tissue. In this study, we use transcriptomics and extracellular flux analyses to investigate the metabolic profiles of primary thymic and in vitro-derived mouse and human thymocytes. Core metabolic pathways, specifically glycolysis and oxidative phosphorylation, undergo dramatic changes between the double-negative (DN), double-positive (DP), and mature single-positive (SP) stages in murine and human thymus. Remarkably, despite the absence of the complex multicellular thymic microenvironment, in vitro murine and human T cell development recapitulated the coordinated decrease in glycolytic and oxidative phosphorylation activity between the DN and DP stages seen in primary thymus. Moreover, by inducing in vitro T cell differentiation from Rag1-/- mouse bone marrow, we show that reduced metabolic activity at the DP stage is independent of TCR rearrangement. Thus, our findings suggest that highly conserved metabolic transitions are critical for thymic T cell development.

Multiplexed proteomics of autophagy-deficient murine macrophages reveals enhanced antimicrobial immunity via the oxidative stress response.

Defective autophagy is strongly associated with chronic inflammation. Loss-of-function of the core autophagy gene Atg16l1 increases risk for Crohn's disease in part by enhancing innate immunity through myeloid cells such as macrophages. However, autophagy is also recognized as a mechanism for clearance of certain intracellular pathogens. These divergent observations prompted a re-evaluation of ATG16L1 in innate antimicrobial immunity. In this study, we found that loss of Atg16l1 in myeloid cells enhanced the killing of virulent Shigella flexneri (S.flexneri), a clinically relevant enteric bacterium that resides within the cytosol by escaping from membrane-bound compartments. Quantitative multiplexed proteomics of murine bone marrow-derived macrophages revealed that ATG16L1 deficiency significantly upregulated proteins involved in the glutathione-mediated antioxidant response to compensate for elevated oxidative stress, which simultaneously promoted S.flexneri killing. Consistent with this, myeloid-specific deletion of Atg16l1 in mice accelerated bacterial clearance in vitro and in vivo. Pharmacological induction of oxidative stress through suppression of cysteine import enhanced microbial clearance by macrophages. Conversely, antioxidant treatment of macrophages permitted S.flexneri proliferation. These findings demonstrate that control of oxidative stress by ATG16L1 and autophagy regulates antimicrobial immunity against intracellular pathogens.

Effectiveness and Cost-effectiveness of Mailed FIT in a Safety Net Clinic Population.

BACKGROUND: Mailed fecal immunochemical testing (FIT) can increase colorectal cancer (CRC) screening rates, including for vulnerable patients, but its cost-effectiveness is unclear. OBJECTIVE: We sought to examine the effectiveness and cost-effectiveness of the initial cycle of our mailed FIT program from November 2017 to July 2019 in a federally qualified health center (FQHC) system in Central Texas. DESIGN: Single group intervention and economic analysis PARTICIPANTS: Eligible patients were those ages 50-75 who had been seen recently in a system practice and were not up to date with screening. INTERVENTION: The program mailing packet included an introductory letter in plain language, the FIT itself, easy to read instructions, and a postage-paid lab mailer, supplemented with written and text messaging reminders. MAIN MEASURES: We measured effectiveness based on completion of mailed FIT and cost-effectiveness in terms of cost per person screened. Costs were measured using detailed micro-costing techniques from the perspective of a third-party payer and expressed in 2019 US dollars. Direct costs were based on material supply costs and detailed observations of labor required, valued at the wage rate. KEY RESULTS: Of the 22,838 eligible patients who received program materials, mean age was 59.0, 51.5% were female, and 43.9% were Latino. FIT were successfully completed by 19.2% (4395/22,838) patients at an average direct cost of $5275.70 per 500-patient mailing. Assuming completed tests from the mailed intervention represent incremental screening, the direct cost per patient screened, compared with no intervention, was $54.83. Incorporating start-up and indirect costs increases total costs to $7014.45 and cost per patient screened to $72.90. Alternately, assuming 2.5% and 5% screening without the intervention increased the direct (total) cost per patient screened to $60.03 ($80.80) and $67.05 ($91.47), respectively. CONCLUSIONS: Mailed FIT is an effective and cost-effective population health strategy for CRC screening in vulnerable patients.

A functional genomics screen identifying blood cell development genes in Drosophila by undergraduates participating in a course-based research experience.

Undergraduate students participating in the UCLA Undergraduate Research Consortium for Functional Genomics (URCFG) have conducted a two-phased screen using RNA interference (RNAi) in combination with fluorescent reporter proteins to identify genes important for hematopoiesis in Drosophila. This screen disrupted the function of approximately 3500 genes and identified 137 candidate genes for which loss of function leads to observable changes in the hematopoietic development. Targeting RNAi to maturing, progenitor, and regulatory cell types identified key subsets that either limit or promote blood cell maturation. Bioinformatic analysis reveals gene enrichment in several previously uncharacterized areas, including RNA processing and export and vesicular trafficking. Lastly, the participation of students in this course-based undergraduate research experience (CURE) correlated with increased learning gains across several areas, as well as increased STEM retention, indicating that authentic, student-driven research in the form of a CURE represents an impactful and enriching pedagogical approach.

Organoid-Induced Differentiation of Conventional T Cells from Human Pluripotent Stem Cells.

The ability to generate T cells from pluripotent stem cells (PSCs) has the potential to transform autologous T cell immunotherapy by facilitating universal, off-the-shelf cell products. However, differentiation of human PSCs into mature, conventional T cells has been challenging with existing methods. We report that a continuous 3D organoid system induced an orderly sequence of commitment and differentiation from PSC-derived embryonic mesoderm through hematopoietic specification and efficient terminal differentiation to naive CD3+CD8αß+ and CD3+CD4+ conventional T cells with a diverse T cell receptor (TCR) repertoire. Introduction of an MHC class I-restricted TCR in PSCs produced naive, antigen-specific CD8αß+ T cells that lacked endogenous TCR expression and showed anti-tumor efficacy in vitro and in vivo. Functional assays and RNA sequencing aligned PSC-derived T cells with primary naive CD8+ T cells. The PSC-artificial thymic organoid (ATO) system presented here is an efficient platform for generating functional, mature T cells from human PSCs.

Frustrated Phagocytic Spreading of J774A-1 Macrophages Ends in Myosin II-Dependent Contraction.

Conventional studies of dynamic phagocytic behavior have been limited in terms of spatial and temporal resolution due to the inherent three-dimensionality and small features of phagocytosis. To overcome these issues, we use a series of frustrated phagocytosis assays to quantitatively characterize phagocytic spreading dynamics. Our investigation reveals that frustrated phagocytic spreading occurs in phases and is punctuated by a distinct period of contraction. The spreading duration and peak contact areas are independent of the surface opsonin density, although the opsonin density does affect the likelihood that a cell will spread. This reinforces the idea that phagocytosis dynamics are primarily dictated by cytoskeletal activity. Structured illumination microscopy reveals that F-actin is reorganized during the course of frustrated phagocytosis. F-actin in early stages is consistent with that observed in lamellipodial protrusions. During the contraction phase, it is bundled into fibers that surround the cell and is reminiscent of a contractile belt. Using traction force microscopy, we show that cells exert significant strain on the underlying substrate during the contraction phase but little strain during the spreading phase, demonstrating that phagocytes actively constrict during late-stage phagocytosis. We also find that late-stage contraction initiates after the cell surface area increases by 225%, which is consistent with the point at which cortical tension begins to rise. Moreover, reducing tension by exposing cells to hypertonic buffer shifts the onset of contraction to occur in larger contact areas. Together, these findings provide further evidence that tension plays a significant role in signaling late-stage phagocytic activity.

Cell Surface Access Is Modulated by Tethered Bottlebrush Proteoglycans.

The hyaluronan-rich pericellular matrix (PCM) plays physical and chemical roles in biological processes ranging from brain plasticity, to adhesion-dependent phenomena such as cell migration, to the onset of cancer. This study investigates how the spatial distribution of the large negatively charged bottlebrush proteoglycan, aggrecan, impacts PCM morphology and cell surface access. The highly localized pericellular milieu limits transport of nanoparticles in a size-dependent fashion and sequesters positively charged molecules on the highly sulfated side chains of aggrecan. Both rat chondrocyte and human mesenchymal stem cell PCMs possess many unused binding sites for aggrecan, showing a 2.5x increase in PCM thickness from ∼7 to ∼18 µm when provided exogenous aggrecan. Yet, full extension of the PCM occurs well below aggrecan saturation. Hence, cells equipped with hyaluronan-rich PCM can in principle manipulate surface accessibility or sequestration of molecules by tuning the bottlebrush proteoglycan content to alter PCM porosity and the number of electrostatic binding sites.