GVHD, IBD and primary immunodeficiencies: The gut as a target of immunopathology resulting from impaired immunity

High Amphiregulin Expression in Intestinal Biopsies of Pediatric Patients with Severe Acute Graft-Versus-Host Disease

Acute graft-versus-host disease (GvHD) is a major complication of hematopoietic cell transplantation (HCT). Despite of recent advances in prophylaxis, diagnosis and treatment it is still a serious cause of morbidity and mortality after HCT. Amphiregulin (AREG) is an epidermal growth factor receptor ligand known for restoring damaged intestinal tissue. AREG has been studied as a blood biomarker in acute GvHD and was found predictive of steroid response and mortality. However, the expression of AREG in intestinal tissue in pediatric patients with acute GvHD is unknown. The aim of this study is to analyze and evaluate AREG expression in intestinal tissue biopsies of pediatric patients with GvHD, in comparison to patients with inflammatory bowel disease (IBD) and a control group with no pathological findings to provide insights in the biological tissue expression of this potential diagnostic and prognostic biomarker. We performed a retrospective study with pediatric patients who had an intestinal biopsy performed after HCT between 2010 and 2021, patients who had a diagnosis of IBD and patients with normal findings at the University Children's Hospital Zurich. Intestinal biopsies were stained for AREG. We used a semi-quantitative score ranging from 0 (not present) to 3 (intense) to grade the AREG expression. The grading was performed by a pathologist blinded to the group allocation. Lerner scores were also performed. The median AREG scores between the groups were compared using multivariable linear regression with age and sex as confounders. The study protocol was approved by the Ethical committee of Canton Zürich, Switzerland, number 2022-01037. Overall, 59 biopsies were stained for AREG, 20 after HCT (6 patients with severe GvHD, 5 with mild GvHD and 9 without GvHD), 19 with IBD and 20 controls. The median for the AREG overall grade for control group was 2, for the HCT with severe GvHD group 2.5 (P = .060) and for the IBD group 2.5 (P = .007). The results for the AREG epithelium and lamina propria grades were similar. There were no differences in survival between patients with GvHD with overall AREG scores below and greater or equal to the median of 2.5. This study showed that AREG scores were higher in intestinal biopsies from patients with severe GvHD and IBD compared to controls and patients with mild or no GvHD. Consequently, AREG staining could potentially be used as an additional marker for severe inflammation as seen in GvHD and IBD.

Adiponectin reduces immune checkpoint inhibitor-induced inflammation without blocking anti-tumor immunity

Immune-related adverse events (irAEs) in cancer patients receiving immune checkpoint inhibitors (ICIs) cause morbidity and necessitate cessation of treatment. Comparing irAE treatments, we find that anti-tumor immunity is preserved in mice after extracorporeal photopheresis (ECP) but reduced with glucocorticosteroids, TNFα blockade, and α4β7-integrin inhibition. Local adiponectin production elicits a tissue-specific effect by reducing pro-inflammatory T cell frequencies in the colon while sparing tumor-specific T cell development. A prospective phase-1b/2 trial (EudraCT-No.2021-002073-26) with 14 patients reveals low ECP-related toxicity. Overall response rate for all irAEs is 92% (95% confidence interval [CI]: 63.97%-99.81%); colitis-specific complete remission rate is 100% (95% CI: 63.06%-100%). Glucocorticosteroid dosages could be reduced for all patients after ECP therapy. The ECP-adiponectin axis reduces intestinal tissue-resident memory T cell activation and CD4+IFN-γ+ T cells in patients with ICI-induced colitis without evidence of loss of anti-tumor immunity. In conclusion, we identify adiponectin as an immunomodulatory molecule that controls ICI-induced irAEs without blocking anti-tumor immunity.

Graft-Versus-Host Disease Mouse Models: A Clinical-Translational Perspective

A variety of graft-versus-host disease (GVHD) models have been developed in mice for the purpose of allowing laboratory investigation of the pathobiology, prevention, and treatment of GVHD in humans. While such models are crucial in advancing our knowledge in this field, there are some key limitations that need to be considered when translating laboratory discoveries into the clinical context. This chapter will discuss current clinical practices in transplantation and GVHD and the relative strengths and weaknesses of mouse models that attempt to replicate these states.

Deciphering the role of the major histocompatibility complex, the intestinal microbiome and metabolites in the pathogenesis of acute graft-versus-host disease

Allogeneic hematologic stem cell transplantation is a cornerstone in modern hematological treatment, yet its efficacy is compromised by acute Graft-versus-Host Disease. In acute Graft-versus-Host Disease, conditioning regimen induced epithelial damage leads to release of damage and pathogen associated molecular patters which in turns triggers activation of alloreactive donor T cells, ultimately resulting in destruction of healthy tissue. Advances in major histocompatibility complex typing and preclinical studies using tissue specific major histocompatibility complex deletion have illuminated the contributions of both, hematopoietic and non-hematopoietic cells to acute Graft-versus-Host Disease pathophysiology. Concurrently, high-throughput sequencing techniques have enabled researchers to recognize the significant impact of the intestinal microbiome and newly discovered metabolites in the pathophysiology of acute Graft-versus-Host Disease. In this review, we discuss the implications of major histocompatibility complex expression on hematopoietic and non-hematopoietic cells, the effect on the intestinal microbiome and the metabolic alterations that contribute to acute Graft-versus-Host Disease. By combining these findings, we hope to untangle the complexity of acute Graft-versus-Host Disease, ultimately paving the way for the development of novel and more effective treatmen options in patients.

Intestinal and Extraintestinal Findings of Graft-versus-Host Disease on CT: A Case Series with Radiological and Histopathological Correlations

Graft-versus-host disease (GVHD) is an expected and relatively common complication after allogeneic hematopoietic stem cell transplantation. It may affect different organs and typically involves the skin, liver, and gastrointestinal tract (GI-GVHD). GI-GVHD may show heterogeneous presentations with peculiar diagnostic implications. Although an endoscopic biopsy is considered the "gold standard" for the diagnosis of GI-GVHD, its broad application is limited due to the poor clinical conditions usually present in these patients, including thrombocytopenia. In the emergency department, enhanced computed tomography (CECT) has emerged as the best imaging modality for the evaluation of GI damage in frail patients. However, the role of CT in the context of either acute or chronic GI-GVHD has not been systematically investigated. Herein, we focus on the radiological features found on CECT in five patients with GI-GVHD confirmed on histology. CECT was performed for the persistence of GI symptoms in three cases (case 1, case 3, and case 4), for small bowel occlusion in one case (case 5), and for acute GI symptoms in one case (case 2). Serpiginous intestinal wall appearance with multisegmental parietal thickness and homogeneous, mucosal, or stratified small bowel enhancement were common features. Colic involvement with segmental or diffuse parietal thickness was also present. One patient (case 5) presented with inflammatory jejunal multisegmental stenosis with sub-occlusion as a chronic presentation of GI-GVHD. Regarding mesenterial findings, all five patients presented comb signs in the absence of lymphadenopathy. Extraintestinal findings included biliary tract dilatation in two cases (case 2 and case 4). These data support the utility of appropriate radiological investigation in GI-GVHD, paving the way for further serial and systematic investigations to track the appearance and evolution of GI damage in GVHD patients.

Cord Blood Transplantation for Very Early-Onset Inflammatory Bowel Disease Caused by Interleukin-10 Receptor Deficiency

PURPOSE

Interleukin-10 receptor (IL-10R) deficiency can result in life-threatening very early-onset inflammatory bowel disease (VEO-IBD). Umbilical cord blood transplantation (UCBT) is a curative therapy for patients with IL-10R deficiency. This study aimed to investigate the efficacy of UCBT in treating IL-10R deficiency and develop a predictive model based on pre-transplant factors.

METHODS

Eighty patients with IL-10R deficiency who underwent UCBT between July 2015 and April 2023 were retrospectively analyzed. Cox proportional hazards regression and random survival forest were used to develop a predictive model.

RESULTS

Median age at transplant was 13.0 months (interquartile range [IQR], 8.8-25.3 months). With a median follow-up time of 29.4 months (IQR, 3.2-57.1 months), the overall survival (OS) rate was 65.0% (95% confidence interval [CI], 55.3%-76.3%). The engraftment rate was 85% (95% CI, 77%-93%). The cumulative incidences of acute and chronic graft-versus-host disease were 48.2% (95% CI, 37.1%-59.4%) and 12.2% (95% CI, 4.7%-19.8%), respectively. VEO-IBD-associated clinical symptoms were resolved in all survivors. The multivariate analysis showed that IL-6 and stool occult blood were independent prognostic risk factors. The multivariate Cox proportional hazards regression model with stool occult blood, length- or height-for-age Z-score, medical history of sepsis, and cord blood total nucleated cells showed good discrimination ability, with a bootstrap concordance index of 0.767-0.775 in predicting OS.

CONCLUSION

Better inflammation control before transplantation and higher cord blood total nucleated cell levels can improve patient prognosis. The nomogram can successfully predict OS in patients with IL-10R deficiency undergoing UCBT.

The Role of Fecal Microbiota Transplantation in the Allogeneic Stem Cell Transplant Setting

Microbiota changes during allogeneic hematopoietic stem cell transplantation has several known causes: conditioning chemotherapy and radiation, broad-spectrum antibiotic administration, modification in nutrition status and diet, and graft-versus-host disease. This article aims to review the current knowledge about the close link between microbiota and allogeneic stem cell transplantation setting. The PubMed search engine was used to perform this review. We analyzed data on microbiota dysbiosis related to the above-mentioned affecting factors. We also looked at treatments aimed at modifying gut dysbiosis and applications of fecal microbiota transplantation in the allogeneic stem cell transplant field, with particular interest in fecal microbiota transplantation for graft-versus-host disease (GvHD), multidrug-resistant and clostridium difficile infections, and microbiota restoration after chemotherapy and antibiotic therapy.

Mechanisms of Nanoparticle Transport across Intestinal Tissue: An Oral Delivery Perspective

Oral drug administration has been a popular choice due to patient compliance and limited clinical resources. Orally delivered drugs must circumvent the harsh gastrointestinal (GI) environment to effectively enter the systemic circulation. The GI tract has a number of structural and physiological barriers that limit drug bioavailability including mucus, the tightly regulated epithelial layer, immune cells, and associated vasculature. Nanoparticles have been used to enhance oral bioavailability of drugs, as they can act as a shield to the harsh GI environment and prevent early degradation while also increasing uptake and transport of drugs across the intestinal epithelium. Evidence suggests that different nanoparticle formulations may be transported via different intracellular mechanisms to cross the intestinal epithelium. Despite the existence of a significant body of work on intestinal transport of nanoparticles, many key questions remain: What causes the poor bioavailability of the oral drugs? What factors contribute to the ability of a nanoparticle to cross different intestinal barriers? Do nanoparticle properties such as size and charge influence the type of endocytic pathways taken? In this Review, we summarize the different components of intestinal barriers and the types of nanoparticles developed for oral delivery. In particular, we focus on the various intracellular pathways used in nanoparticle internalization and nanoparticle or cargo translocation across the epithelium. Understanding the gut barrier, nanoparticle characteristics, and transport pathways may lead to the development of more therapeutically useful nanoparticles as drug carriers.

Genus unclassified_Muribaculaceae and microbiota-derived butyrate and indole-3-propionic acid are involved in benzene-induced hematopoietic injury in mice

Benzene is a group I carcinogen determined by IARC. The prevalence of benzene in occupational and general environments increases the risk of acute myeloid leukemia (AML) among workers and childhood leukemia. However, the mechanism of hematotoxicity induced by benzene remains unclear. Recently, the gut microbiota has been regarded as a pivotal part of normal and malignant hematopoiesis. Therefore, in this study, we explored the function of gut microbiota in hematopoietic injury induced by benzene by 16S rRNA sequencing. We found that benzene exposure caused bone marrow damage, hematopoietic stem and progenitor cells (HSPCs) dysfunction, and peripheral blood cell reduction. Moreover, intestinal barrier damage and gut microbiota dysbiosis were also observed in benzene-exposed mice. Interestingly, two gut flora, Lachnospiraceae_NK4A136_group and unclassified_Muribaculaceae, were significantly up-regulated and associated with hematopoietic indicators, suggesting that gut-host crosstalk might mediate benzene hematotoxicity. Microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), bile acids, and tryptophan metabolites, are the primary mediators of the gut-host crosstalk. Therefore, we conducted absolute quantitative metabolomics to investigate the impact of benzene exposure on these metabolites in mice. The results showed that the concentration of SCFA butyrate, tryptophan metabolites kynurenine, and Indole-3-propionic acid (IPA) were significantly altered after benzene exposure. However, no difference was found in bile acids. Significant correlations were found between altered metabolites and hematopoietic indicators. We then investigated the flora that derived these metabolites. Lachnospiraceae_NK4A136_group and unclassified_Muribaculaceae were enriched in the butyrate metabolism and tryptophan metabolism pathways. Correlation analysis further suggested that unclassified_Muribaculaceae was positively associated with butyrate (r = 0.588, P < 0.05) and IPA (r = 0.59, P < 0.05). The above results demonstrated that unclassified_Muribaculaceae and microbiota-derived butyrate and IPA were involved in hematopoietic toxicity caused by benzene. This study provides insight into gut microbiota-derived metabolites-host crosstalk in benzene hematopoietic toxicity.

Advantageous tactics with certain probiotics for the treatment of graft-versus-host-disease after hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) becomes a standard form of cellular therapy for patients with malignant diseases. HSCT is the first-choice of immunotherapy, although HSCT can be associated with many complications such as graft-versus-host disease (GVHD) which is a major cause of morbidity and mortality after allogeneic HSCT. It has been shown that certain gut microbiota could exert protective and/or regenerative immunomodulatory effects by the production of short-chain fatty acids (SCFAs) such as butyrate in the experimental models of GVHD after allogeneic HSCT. Loss of gut commensal bacteria which can produce SCFAs may worsen dysbiosis, increasing the risk of GVHD. Expression of G-protein coupled receptors such as GPR41 seems to be upre-gulated in the presence of commensal bacteria, which might be associated with the biology of regulatory T cells (Tregs). Treg cells are a suppressive subset of CD4 positive T lymphocytes implicated in the prevention of GVHD after allogeneic HSCT. Here, we discuss the current findings of the relationship between the modification of gut microbiota and the GVHD-related immunity, which suggested that tactics with certain probiotics for the beneficial symbiosis in gut-immune axis might lead to the elevation of safety in the allogeneic HSCT.

Immune Ablation and Stem Cell Rescue in Two Pediatric Patients with Progressive Severe Chronic Graft-Versus-Host Disease

Transplantation of allogeneic hematopoietic stem cells represents an established treatment for children with high-risk leukemia. However, steroid-refractory chronic graft-versus-host disease (SR-cGvHD) represents a severe life-threatening complication, for which there is no standard therapy. After failing several lines of immunosuppressive and biological treatment, we applied an immunoablative therapy with re-transplantation of purified CD34⁺ donor stem cells to reset the aberrant immune system. Two pediatric patients, who had been transplanted for high-risk acute lymphoblastic leukemia, underwent the procedure. Interestingly, enough stem cells could be mobilized, harvested, and purified to be used as grafts more than one year after allogeneic transplantation under intensive immunosuppressive therapy and ongoing SR-cGvHD. With a follow-up of 8 and 22 months, respectively, both patients are without immunosuppressive therapy and do not show signs of active disease. Regeneration of skin manifestations started promptly, other damaged organs did not progress and continue to show recovery from severe fibrotic transformation. Bone marrow function is robust and T cell receptor repertoires showed polyclonal immune reconstitution. In conclusion, stem cell harvest and re-transplantation of human CD34⁺-selected allogeneic stem cells is possible and represents a new therapeutic option in SR-cGvHD by resetting a profoundly disturbed immune network.