Gut microbiome-derived metabolites modulate intestinal epithelial cell damage and mitigate graft-versus-host disease.

The effect of alterations in intestinal microbiota on microbial metabolites and on disease processes such as graft-versus-host disease (GVHD) is not known. Here we carried out an unbiased analysis to identify previously unidentified alterations in gastrointestinal microbiota-derived short-chain fatty acids (SCFAs) after allogeneic bone marrow transplant (allo-BMT). Alterations in the amount of only one SCFA, butyrate, were observed only in the intestinal tissue. The reduced butyrate in CD326(+) intestinal epithelial cells (IECs) after allo-BMT resulted in decreased histone acetylation, which was restored after local administration of exogenous butyrate. Butyrate restoration improved IEC junctional integrity, decreased apoptosis and mitigated GVHD. Furthermore, alteration of the indigenous microbiota with 17 rationally selected strains of high butyrate-producing Clostridia also decreased GVHD. These data demonstrate a heretofore unrecognized role of microbial metabolites and suggest that local and specific alteration of microbial metabolites has direct salutary effects on GVHD target tissues and can mitigate disease severity.

Alloreactive T cells deficient of the short-chain fatty acid receptor GPR109A induce less graft-versus-host disease.

The intestinal microbiota is essential for the fermentation of dietary fiber into short-chain fatty acids (SCFA) such as butyrate, acetate, and propionate. SCFAs can bind to the G-protein-coupled receptors GPR43 and GPR109A (HCAR2), with varying affinities to promote cellular effects in metabolism or changes in immune function. We explored the role of GPR109A as the main receptor for butyrate in mouse models of allogeneic hematopoietic cell transplantation (allo-HCT) and graft-versus-host disease (GVHD). Deletion of GPR109A in allo-HCT recipients did not affect GVHD, but transplantation of T cells from GPR109A knockout (KO) (Gpr109a-/-) mice into allo-HCT recipient mice significantly reduced GVHD morbidity and mortality compared with recipients of wild-type (WT) T cells. Recipients of Gpr109a-/- T cells exhibited less GVHD-associated target organ pathology and decreased proliferation and homing of alloreactive T cells to target tissues. Although Gpr109a-/- T cells did not exhibit immune deficits at a steady state, following allo-activation, Gpr109a-/- T cells underwent increased apoptosis and were impaired mitochondrial oxidative phosphorylation, which was reversible through antioxidant treatment with N-acetylcysteine (NAC). In conclusion, we found that GPR109A expression by allo-activated T cells is essential for metabolic homeostasis and expansion, which are necessary features to induce GVHD after allo-HCT.

Microbiota as Predictor of Mortality in Allogeneic Hematopoietic-Cell Transplantation.

BACKGROUND: Relationships between microbiota composition and clinical outcomes after allogeneic hematopoietic-cell transplantation have been described in single-center studies. Geographic variations in the composition of human microbial communities and differences in clinical practices across institutions raise the question of whether these associations are generalizable. METHODS: The microbiota composition of fecal samples obtained from patients who were undergoing allogeneic hematopoietic-cell transplantation at four centers was profiled by means of 16S ribosomal RNA gene sequencing. In an observational study, we examined associations between microbiota diversity and mortality using Cox proportional-hazards analysis. For stratification of the cohorts into higher- and lower-diversity groups, the median diversity value that was observed at the study center in New York was used. In the analysis of independent cohorts, the New York center was cohort 1, and three centers in Germany, Japan, and North Carolina composed cohort 2. Cohort 1 and subgroups within it were analyzed for additional outcomes, including transplantation-related death. RESULTS: We profiled 8767 fecal samples obtained from 1362 patients undergoing allogeneic hematopoietic-cell transplantation at the four centers. We observed patterns of microbiota disruption characterized by loss of diversity and domination by single taxa. Higher diversity of intestinal microbiota was associated with a lower risk of death in independent cohorts (cohort 1: 104 deaths among 354 patients in the higher-diversity group vs. 136 deaths among 350 patients in the lower-diversity group; adjusted hazard ratio, 0.71; 95% confidence interval [CI], 0.55 to 0.92; cohort 2: 18 deaths among 87 patients in the higher-diversity group vs. 35 deaths among 92 patients in the lower-diversity group; adjusted hazard ratio, 0.49; 95% CI, 0.27 to 0.90). Subgroup analyses identified an association between lower intestinal diversity and higher risks of transplantation-related death and death attributable to graft-versus-host disease. Baseline samples obtained before transplantation already showed evidence of microbiome disruption, and lower diversity before transplantation was associated with poor survival. CONCLUSIONS: Patterns of microbiota disruption during allogeneic hematopoietic-cell transplantation were similar across transplantation centers and geographic locations; patterns were characterized by loss of diversity and domination by single taxa. Higher diversity of intestinal microbiota at the time of neutrophil engraftment was associated with lower mortality. (Funded by the National Cancer Institute and others.).

Autophagy gene Atg16L1 prevents lethal T cell alloreactivity mediated by dendritic cells.

Atg16L1 mediates the cellular degradative process of autophagy and is considered a critical regulator of inflammation based on its genetic association with inflammatory bowel disease. Here we find that Atg16L1 deficiency leads to an exacerbated graft-versus-host disease (GVHD) in a mouse model of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Atg16L1-deficient allo-HSCT recipients with GVHD displayed increased T cell proliferation due to increased dendritic cell (DC) numbers and costimulatory molecule expression. Reduced autophagy within DCs was associated with lysosomal abnormalities and decreased amounts of A20, a negative regulator of DC activation. These results broaden the function of Atg16L1 and the autophagy pathway to include a role in limiting a DC-mediated response during inflammatory disease, such as GVHD.

An intestinal organoid-based platform that recreates susceptibility to T-cell-mediated tissue injury.

A goal in precision medicine is to use patient-derived material to predict disease course and intervention outcomes. Here, we use mechanistic observations in a preclinical animal model to design an ex vivo platform that recreates genetic susceptibility to T-cell-mediated damage. Intestinal graft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantation. We found that intestinal GVHD in mice deficient in Atg16L1, an autophagy gene that is polymorphic in humans, is reversed by inhibiting necroptosis. We further show that cocultured allogeneic T cells kill Atg16L1-mutant intestinal organoids from mice, which was associated with an aberrant epithelial interferon signature. Using this information, we demonstrate that pharmacologically inhibiting necroptosis or interferon signaling protects human organoids derived from individuals harboring a common ATG16L1 variant from allogeneic T-cell attack. Our study provides a roadmap for applying findings in animal models to individualized therapy that targets affected tissues.

Nrf2 regulates CD4+ T cell-induced acute graft-versus-host disease in mice.

Nuclear factor erythroid-derived 2-like 2 (Nrf2) is a ubiquitously expressed transcription factor that is well known for its role in regulating the cellular redox pathway. Although there is mounting evidence suggesting a critical role for Nrf2 in hematopoietic stem cells and innate leukocytes, little is known about its involvement in T-cell biology. In this study, we identified a novel role for Nrf2 in regulating alloreactive T-cell function during allogeneic hematopoietic cell transplantation (allo-HCT). We observed increased expression and nuclear translocation of Nrf2 upon T-cell activation in vitro, especially in CD4+ donor T cells after allo-HCT. Allo-HCT recipients of Nrf2 -/- donor T cells had significantly less acute graft-versus-host disease (GVHD)-induced mortality, morbidity, and pathology. This reduction in GVHD was associated with the persistence of Helios+ donor regulatory T cells in the allograft, as well as defective upregulation of the gut-homing receptor LPAM-1 on alloreactive CD8+ T cells. Additionally, Nrf2 -/- donor CD8+ T cells demonstrated intact cytotoxicity against allogeneic target cells. Tumor-bearing allo-HCT recipients of Nrf2 -/- donor T cells had overall improved survival as a result of preserved graft-versus-tumor activity and reduced GVHD activity. Our findings characterized a previously unrecognized role for Nrf2 in T-cell function, as well as revealed a novel therapeutic target to improve the outcomes of allo-HCT.

Translation of basic research in cognitive science to HIV-risk: a randomized controlled trial.

Many people enrolled in drug diversion programs are not receiving evidence-based prevention for HIV or hepatitis. This study translated basic research from cognitive science to increase screening for infection and condom use in this population. A parallel three-condition randomized trial was conducted in a drug diversion sample (N = 358), comparing a memory practice condition with two active control conditions. Outcomes were condom use frequency and testing for infection (hepatitis B/C, HIV). At 3-month follow-up, participants in the memory practice condition were at least twice as likely (OR = 2.10 or greater, p < .01) to self-report testing compared to those in the control conditions and also reported more frequent condom use compared to a health education condition [B = .37, t(1) = 2.02, p = .02]. Basic research on memory can be effectively translated to brief interventions on infection screening and risk prevention in existing drug diversion programs.

Combination of anti-CD4 antibody treatment and donor lymphocyte infusion ameliorates graft-versus-host disease while preserving graft-versus-tumor effects in murine allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is not only a well-established immunotherapy for hematologic malignancies, but is potentially useful for treating solid tumors refractory to available therapies. However, application of allo-HSCT to solid tumors is limited, despite the beneficial antitumor effects, by the risk of graft-versus-host disease (GVHD). CD4+ T cells have been implicated in several aspects of GVHD, and suppress antitumor CD8+ T-cell responses. In the present study, we investigated clinically applicable allo-HSCT protocols designed to maximize antitumor effects while reducing the risk of GVHD. We used a mouse model of allo-HSCT with s.c. tumors. We found that myeloablative conditioning was associated with better inhibition of tumor growth but with severe acute GVHD. Early treatment with anti-CD4 mAb substantially ameliorated GVHD while preserving antitumor effects, leading to improved survival in myeloablative allo-HSCT. Late treatment with anti-CD4 mAb also ameliorated GVHD to some extent. Donor lymphocyte infusion in GVHD mice treated with anti-CD4 mAb further suppressed tumor growth without exacerbating GVHD. Collectively, our results suggest that myeloablative allo-HSCT followed by anti-CD4 mAb treatment and donor lymphocyte infusion could be a potent and safe immunotherapy for patients with cancers refractory to available therapies.

Loss of lymph node fibroblastic reticular cells and high endothelial cells is associated with humoral immunodeficiency in mouse graft-versus-host disease.

Graft-versus-host disease (GVHD) is a major risk factor for prolonged humoral immunodeficiency and vaccine unresponsiveness after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the underlying mechanisms for this immunodeficiency are poorly understood. In this article, we describe previously overlooked impacts of GVHD on lymph node (LN) stromal cells involved in humoral immune responses. In major- and minor-mismatched mouse allo-HSCT models, recipients with CD8(+) T cell-mediated GVHD suffered severe and irreversible damage to LN structure. These mice were susceptible to pathogenic infection and failed to mount humoral immune responses despite the presence of peripheral T and B cells. These humoral immune defects were associated with the early loss of fibroblastic reticular cells, most notably the CD157(+) cell subset, as well as structural defects in high endothelial venules. The disruption to these LN stromal cells was dependent on alloantigens expressed by nonhematopoietic cells. Blockade of the Fas-FasL pathway prevented damage to CD157(+) fibroblastic reticular cells and ameliorated LN GVHD. However, blockade of CD62L- or CCR7-dependent migration of CD8(+) T cells to the LN was insufficient to prevent stromal cell injury. Overall, our results highlight GVHD-associated loss of functional stromal cells and LN GVHD as a possible explanation for the prolonged susceptibility to infectious disease that is experienced by allo-HSCT patients.

Affective decision-making moderates the effects of automatic associations on alcohol use among drug offenders.

BACKGROUND: This study used a dual-process model of cognition in order to investigate the possible influence of automatic and deliberative processes on lifetime alcohol use in a sample of drug offenders. OBJECTIVE: The objective was to determine if automatic/implicit associations in memory can exert an influence over an individual's alcohol use and if decision-making ability could potentially modify the influence of these associations. METHODS: 168 participants completed a battery of cognitive tests measuring implicit alcohol associations in memory (verb generation) as well as their affective decision-making ability (Iowa Gambling Task). Structural equation modeling procedures were used to test the relationship between implicit associations, decision-making, and lifetime alcohol use. RESULTS: Results revealed that among participants with lower levels of decision-making, implicit alcohol associations more strongly predicted higher lifetime alcohol use. CONCLUSION: These findings provide further support for the interaction between a specific decision function and its influence over automatic processes in regulating alcohol use behavior in a risky population. Understanding the interaction between automatic associations and decision processes may aid in developing more effective intervention components.

Gut microbiota and graft-versus-host disease: broad-spectrum antibiotic use increases post-allogeneic hematopoietic stem cell transplant graft-versus-host disease-related mortality.

Intestinal bacteria can modulate the risk of infection and graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Allo-HSCT recipients often develop neutropenic fever, which is treated with antibiotics that may target anaerobic bacteria in the gut. We retrospectively examined 857 allo-HSCT recipients and found that treatment using broad-spectrum antibiotics was associated with increased GVHD-related mortality at 5 years. Analysis of stool specimens from allo-HSCT recipients showed that broad-spectrum antibiotic administration was associated with perturbation of gut microbial composition. Studies in mice also demonstrated aggravated GVHD mortality with broad-spectrum antibiotics use. Broad-spectrum antibiotics treatment of mice with GVHD led to a loss of the protective mucus lining of the colon, compromised intestinal barrier function, as well as increased a commensal bacterium with mucus-degrading capabilities, raising the possibility that mucus degradation may contribute to murine GVHD. We demonstrate an underappreciated risk of antibiotics in allo-HSCT recipients that may exacerbate GVHD in the colon.

Image-guided intrathymic injection of multipotent stem cells supports lifelong T-cell immunity and facilitates targeted immunotherapy.

T-cell deficiency related to disease, medical treatment, or aging represents a major clinical challenge and is associated with significant morbidity and mortality in cancer and bone marrow transplantation recipients. This study describes several innovative and clinically relevant strategies to manipulate thymic function based on an interventional radiology technique for intrathymic injection of cells or drugs. We show that intrathymic injection of multipotent hematopoietic stem/progenitor cells into irradiated syngeneic or allogeneic young or aged recipients resulted in efficient and long-lasting generation of functional donor T cells. Persistence of intrathymic donor cells was associated with intrathymic presence of cells resembling long-term hematopoietic stem cells, suggesting a self-renewal capacity of the intrathymically injected cells. Furthermore, our approach enabled the induction of long-term antigen-specific T-cell-mediated antitumor immunity following intrathymic injection of progenitor cells harboring a transgenic T-cell receptor gene. The intrathymic injection of interleukin-7 prior to irradiation conferred radioprotection. In addition, thymopoiesis of aged mice improved with a single intrathymic administration of low-dose keratinocyte growth factor, an effect that was sustained even in the setting of radiation-induced injury. Taken together, we established a preclinical framework for the development of novel clinical protocols to establish lifelong antigen-specific T-cell immunity.

Intestinal Blautia Is Associated with Reduced Death from Graft-versus-Host Disease.

The relationship between intestinal microbiota composition and acute graft-versus-host disease (GVHD) after allogeneic blood/marrow transplantation (allo-BMT) is not well understood. Intestinal bacteria have long been thought to contribute to GVHD pathophysiology, but recent animal studies in nontransplant settings have found that anti-inflammatory effects are mediated by certain subpopulations of intestinal commensals. Hypothesizing that a more nuanced relationship may exist between the intestinal bacteria and GVHD, we evaluated the fecal bacterial composition of 64 patients 12 days after BMT. We found that increased bacterial diversity was associated with reduced GVHD-related mortality. Furthermore, harboring increased amounts of bacteria belonging to the genus Blautia was associated with reduced GVHD lethality in this cohort and was confirmed in another independent cohort of 51 patients from the same institution. Blautia abundance was also associated with improved overall survival. We evaluated the abundance of Blautia with respect to clinical factors and found that loss of Blautia was associated with treatment with antibiotics that inhibit anaerobic bacteria and receiving total parenteral nutrition for longer durations. We conclude that increased abundance of commensal bacteria belonging to the Blautia genus is associated with reduced lethal GVHD and improved overall survival.

Bone marrow graft-versus-host disease: evaluation of its clinical impact on disrupted hematopoiesis after allogeneic hematopoietic stem cell transplantation.

Idiopathic cytopenias are frequently observed in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We have previously reported the effect of graft-versus-host disease (GVHD) on bone marrow (BM) in murine models, indicating that the osteoblast injury mediated by donor T cells was associated with bone marrow suppression and delayed immune reconstitution. In this study, we prospectively evaluated the relevance of these findings in 51 patients. Patients with chronic GVHD manifested the loss of osteoblasts, contributing to cytopenic symptoms (P = .0427 compared with patients without cytopenic symptoms). The loss of osteoblasts was significantly associated with the extensive type of chronic GVHD (P = .012), and flow cytometric analyses revealed lower numbers of CD19(+) B cells and a significantly increased CD4 to CD8 ratio (P = .0002) in these patients. Our data, for the first time to our knowledge, summarize the detailed analyses of the effect of GVHD on BM in the clinical allo-HSCT patients.

B cells regulate antibody responses through the medullary remodeling of inflamed lymph nodes.

Lymph node (LN) structure is remodeled during immune responses, a process which is considered to play an important role in the regulation of immune function. To date, little attention has been paid to the remodeling of the medullary region, despite its proposed role as a niche for antibody-producing plasma cells. Here, we show that B cells mediate medullary remodeling of antigen-draining LNs during inflammation. This process occurs with kinetics similar to changes in plasma cell number and is accompanied by stromal renetworking which manifests as the segregation of B cells and plasma cells. Medullary remodeling depends on signaling via the lymphotoxin-ß receptor and the presence of B cells but occurs independently of T-dependent humoral responses or other immune cell subsets including T cells, monocytes and neutrophils. Moreover, reconstitution of non-cognate polyclonal B cells in B cell-deficient mice restores not only the medullary remodeling but also the antibody response by separately transferred cognate B cells, suggesting that non-cognate B cells contribute to antibody responses through medullary remodeling. We propose that non-cognate B cells mediate the expansion of the plasma cell niche in LN through medullary remodeling, thereby regulating the size of the LN plasma cell pool.

Disentangling the within- and between-person aspects of implicit alcohol associations on hazardous drinking.

Indirect measures have been used to assess the strength of automatically activated, alcohol-related associations and their relation to hazardous drinking. However, little is known about the longitudinal contributions of between-person and within-person components of implicit alcohol associations (IAAs) to college students' hazardous drinking over time. This study examined how within- and between-person variability in three measures of IAA (drinking identity, alcohol approach, and alcohol excite) are related to hazardous drinking while controlling for their explicit, self-report counterparts. First- and second-year U.S. college students (N = 506; 57% female) completed web-based assessments once every 3 months up to eight assessments, which included IAA measures (Implicit Association Tests), explicit counterparts of the IAAs, and self-reported hazardous drinking (alcohol consumption, problems, and risk of alcohol use disorder). Bayesian generalized multilevel models were used to examine between- and within-person associations among IAA, their explicit counterparts, and hazardous drinking. Results showed that between persons, mean levels of all three IAAs were positively associated with hazardous drinking over time. Once their explicit, self-report counterparts were included, however, only drinking identity IAA remained significant. Within persons, increases in drinking identity IAA were associated with increases in subsequent hazardous drinking risk, even after controlling for its explicit counterpart. These results suggest the importance of disentangling and simultaneously investigating between- and within-person processes in IAAs. Although the between-person component of IAAs may play a larger role in the prediction of hazardous drinking, examining the within-person component of IAA, at least for drinking identity, also appears to be important. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Pilot Testing of the MyCog Assessment: Rapid Detection of Cognitive Impairment in Everyday Clinical Settings.

Cognitive impairment (CI) and dementia can have profound social and emotional effects on older adults. Early detection of CI is imperative both to the identification of potentially treatable conditions and to provide services to minimize the effects of CI in cases of dementia. While primary care settings are ideal for identifying CI, it frequently goes undetected. We tailored a brief, iPad-based, cognitive assessment (MyCog) for primary care settings and piloted it in a sample of older adults. Eighty participants were recruited from an existing cohort study and completed a brief, in-person interview. CI was determined based on a diagnosis of dementia or CI in their medical record or based on a comprehensive cognitive battery performed within the past 18 months. MyCog had a sensitivity of 79% and specificity of 82%, offering a practical, scalable, primary care assessment for the routine case finding of cognitive impairment and dementia.

Prediction of cognitive impairment using higher order item response theory and machine learning models.

Timely detection of cognitive impairment (CI) is critical for the wellbeing of elderly individuals. The MyCog assessment employs two validated iPad-based measures from the NIH Toolbox® for Assessment of Neurological and Behavioral Function (NIH Toolbox). These measures assess pivotal cognitive domains: Picture Sequence Memory (PSM) for episodic memory and Dimensional Change Card Sort Test (DCCS) for cognitive flexibility. The study involved 86 patients and explored diverse machine learning models to enhance CI prediction. This encompassed traditional classifiers and neural-network-based methods. After 100 bootstrap replications, the Random Forest model stood out, delivering compelling results: precision at 0.803, recall at 0.758, accuracy at 0.902, F1 at 0.742, and specificity at 0.951. Notably, the model incorporated a composite score derived from a 2-parameter higher order item response theory (HOIRT) model that integrated DCCS and PSM assessments. The study's pivotal finding underscores the inadequacy of relying solely on a fixed composite score cutoff point. Instead, it advocates for machine learning models that incorporate HOIRT-derived scores and encompass relevant features such as age. Such an approach promises more effective predictive models for CI, thus advancing early detection and intervention among the elderly.

Bone marrow graft-versus-host disease: early destruction of hematopoietic niche after MHC-mismatched hematopoietic stem cell transplantation.

Disrupted hematopoiesis and delayed immune reconstitution are life-threatening complications of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Although graft-versus-host disease (GVHD) is a major risk factor for the bone marrow (BM) insufficiency, how GVHD impairs BM hematopoiesis has been largely unknown. We hypothesized that BM stromal niche could be a target of GVHD. In major histocompatibility complex (MHC)-mismatched murine models of GVHD, we have demonstrated the early destruction of osteoblasts that especially affected B-cell lineages. The defective B lymphopoiesis was due to the impaired ability of BM stroma and osteoblasts to support the hematopoiesis, as evidenced by the failure of GVHD-affected BM to reconstitute the hematopoietic cells. The administration of anti-CD4 monoclonal antibody (mAb) ameliorated these effects and improved B lymphopoiesis while preserving graft-versus-tumor effects. Genetic ablation of Fas-Fas ligand signaling also partially restored B lymphopoiesis. Our present study provided evidence of BM GVHD, with the identification of osteoblasts as the main target for GVHD in BM. Moreover, our data showed the potential for mAb therapies to enhance immune reconstitution in vivo for patients undergoing allo-HSCT.