Intestinal microbiota controls graft-versus-host disease independent of donor-host genetic disparity

Role of the microbiota in response to and recovery from cancer therapy

Our understanding of how the microbiota affects the balance between response to and failure of cancer treatment by modulating the tumour microenvironment and systemic immune system has advanced rapidly in recent years. Microbiota-targeting interventions in patients with cancer are an area of intensive investigation. Promisingly, phase I-II clinical trials have shown that interventions such as faecal microbiota transplantation can overcome resistance to immune checkpoint blockade in patients with melanoma, improve therapeutic outcomes in treatment-naive patients and reduce therapy-induced immunotoxicities. Here, we synthesize the evidence showing that the microbiota is an important determinant of both cancer treatment efficacy and treatment-induced acute and long-term toxicity, and we discuss the complex and inter-related mechanisms involved. We also assess the potential of microbiota-targeting interventions, including bacterial engineering and phage therapy, to optimize the response to and recovery from cancer therapy.

Lipocalin-2: a novel potential therapy for GVHD

Czech et al. used mouse models of allogeneic hematopoietic stem cell transplantation (allo-HCT) to investigate the role of lipocalin-2 (LCN2) as a newfound regulator of intestinal graft-versus-host disease (GVHD). Administration of recombinant LCN2 protein after disease onset prevented GVHD progression, suggesting that it may play a role in reversing tissue damage that has already begun.

Vaginal microbiota transplantation is a truly opulent and promising edge: fully grasp its potential

Vaginal microbiota transplantation (VMT) is a cutting-edge treatment modality that has the potential to revolutionize the management of vaginal disorders. The human vagina is a complex and dynamic ecosystem home to a diverse community of microorganisms. These microorganisms play a crucial role in maintaining the health and well-being of the female reproductive system. However, when the balance of this ecosystem is disrupted, it can lead to the development of various vaginal disorders. Conventional treatments, such as antibiotics and antifungal medications, can temporarily relieve the symptoms of vaginal disorders. However, they often fail to address the underlying cause of the problem, which is the disruption of the vaginal microbiota. In recent years, VMT has emerged as a promising therapeutic approach that aims to restore the balance of the vaginal ecosystem. Several studies have demonstrated the safety and efficacy of VMT in treating bacterial vaginosis, recurrent yeast infections, and other vaginal conditions. The procedure has also shown promising results in reducing the risk of sexually transmitted infections and preterm birth in pregnant women. However, more research is needed to establish optimal donor selection, preparation, and screening protocols, as well as long-term safety and efficacy. VMT offers a safe, effective, and minimally invasive treatment option for women with persistent vaginal problems. It could improve the quality of life for millions of women worldwide and become a standard treatment option shortly. With further research and development, it could potentially treat a wide range of other health problems beyond the scope of vaginal disorders.

The graft versus leukemia effect: donor lymphocyte infusions and cellular therapy

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for many hematologic malignancies as well as non-malignant conditions. Part of the curative basis underlying HSCT for hematologic malignancies relies upon induction of the graft versus leukemia (GVL) effect in which donor immune cells recognize and eliminate residual malignant cells within the recipient, thereby maintaining remission. GVL is a clinically evident phenomenon; however, specific cell types responsible for inducing this effect and molecular mechanisms involved remain largely undefined. One of the best examples of GVL is observed after donor lymphocyte infusions (DLI), an established therapy for relapsed disease or incipient/anticipated relapse. DLI involves infusion of peripheral blood lymphocytes from the original HSCT donor into the recipient. Sustained remission can be observed in 20-80% of patients treated with DLI depending upon the underlying disease and the intrinsic burden of targeted cells. In this review, we will discuss current knowledge about mechanisms of GVL after DLI, experimental strategies for augmenting GVL by manipulation of DLI (e.g. neoantigen vaccination, specific cell type selection/depletion) and research outlook for improving DLI and cellular immunotherapies for hematologic malignancies through better molecular definition of the GVL effect.

Effect size of delayed freezing, diurnal variation, and hindgut location on the mouse fecal microbiome

Practical considerations in fecal sample collection for microbiome research include time to sample storage, time of collection, and hindgut position during terminal collections. Here, parallel experiments were performed to investigate the relative effect of these factors on microbiome composition in mice colonized with two different vendor-origin microbiomes. 16S rRNA amplicon sequencing of immediately flash-frozen feces showed no difference in alpha or beta diversity compared to samples incubated up to 9 h at room temperature. Samples collected in the morning showed greater alpha diversity compared to samples collected in the afternoon. While a significant effect of time was detected in all hindgut regions, the effect increased from cecum to distal colon. This study highlights common scenarios in microbiome research that may affect outcome measures of microbial community analysis. However, we demonstrate a relatively low effect size of these technical factors when compared to a primary experimental factor with large intergroup variability.

Role reversals: non-canonical roles for immune and non-immune cells in the gut

The intestine is home to an intertwined network of epithelial, immune, and neuronal cells as well as the microbiome, with implications for immunity, systemic metabolism, and behavior. While the complexity of this microenvironment has long since been acknowledged, recent technological advances have propelled our understanding to an unprecedented level. Notably, the microbiota and non-immune or structural cells have emerged as important conductors of intestinal immunity, and by contrast, cells of both the innate and adaptive immune systems have demonstrated non-canonical roles in tissue repair and metabolism. This review highlights recent works in the following two streams: non-immune cells of the intestine performing immunological functions; and traditional immune cells exhibiting non-immune functions in the gut.

The Prospect of Harnessing the Microbiome to Improve Immunotherapeutic Response in Pancreatic Cancer

Pancreatic ductal adenocarcinoma cancer (PDAC) is projected to become the second leading cause of cancer-related death in the United States by 2030. Patients are often diagnosed with advanced disease, which explains the dismal 5-year median overall survival rate of ~12%. Immunotherapy has been successful in improving outcomes in the past decade for a variety of malignancies, including gastrointestinal cancers. However, PDAC is historically an immunologically "cold" tumor, one with an immunosuppressive environment and with restricted entry of immune cells that have limited the success of immunotherapy in these tumors. The microbiome, the intricate community of microorganisms present on and within humans, has been shown to contribute to many cancers, including PDAC. Recently, its role in tumor immunology and response to immunotherapy has generated much interest. Herein, the current state of the interaction of the microbiome and immunotherapy in PDAC is discussed with a focus on needed areas of study in order to harness the immune system to combat pancreatic cancer.