Crosstalk Between Intestinal Microbiota Derived Metabolites and Tissues in Allogeneic Hematopoietic Cell Transplantation

Gut microbiota plays pivotal roles in benign and malignant hematopoiesis

Accumulated evidence emerges that dynamic changes in human gut microbiota and microbial metabolites can alter the ecological balance of symbiotic hosts. The gut microbiota plays a role in various diseases through different mechanisms. More and more attention has been paid to the effects that human microbiota extends beyond the gut. This review summarized the current understanding of the roles that gut microbiota plays in hematopoietic regulation and the occurrence and development of benign and malignant hematologic diseases. The progress of the application of microbiota in treatment was discussed in order to provide new insights into clinical diagnosis and treatment in the future.

Role of mucositis in predicting gut microbiota composition in people with cancer

PURPOSE OF REVIEW

Disruption of the precious ecosystem of micro-organisms that reside in the gut - the gut microbiota - is rapidly emerging as a key driver of the adverse side effects/toxicities caused by numerous anti-cancer agents. Although the contribution of the gut microbiota to these toxicities is understood with ever increasing precision, the cause of microbial disruption (dysbiosis) remains poorly understood. Here, we discuss current evidence on the cause(s) of dysbiosis after cancer therapy, positioning breakdown of the intestinal mucosa (mucositis) as a central cause.

RECENT FINDINGS

Dysbiosis in people with cancer has historically been attributed to extensive antibiotic use. However, evidence now suggests that certain antibiotics have minimal impacts on the microbiota. Indeed, recent evidence shows that the type of cancer therapy predicts microbiota composition independently of antibiotics. Given most anti-cancer drugs have modest effects on microbes directly, this suggests that their impact on the gut microenvironment, in particular the mucosa, which is highly vulnerable to cytotoxicity, is a likely cause of dysbiosis. Here, we outline evidence that support this hypothesis, and discuss the associated clinical implications/opportunities.

SUMMARY

The concept that mucositis dictates microbiota compositions provides two important implications for clinical practice. Firstly, it reiterates the importance of prioritising the development of novel mucoprotectants that preserve mucosal integrity, and indirectly support microbial stability. Secondly, it provides an opportunity to identify dysbiotic events and associated consequences using readily accessible, minimally invasive biomarkers of mucositis such as plasma citrulline.

Gut microbiota, microbiota-derived metabolites, and graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation is one of the most effective treatment strategies for leukemia, lymphoma, and other hematologic malignancies. However, graft-versus-host disease (GVHD) can significantly reduce the survival rate and quality of life of patients after transplantation, and is therefore the greatest obstacle to transplantation. The recent development of new technologies, including high-throughput sequencing, metabolomics, and others, has facilitated great progress in understanding the complex interactions between gut microbiota, microbiota-derived metabolites, and the host. Of these interactions, the relationship between gut microbiota, microbial-associated metabolites, and GVHD has been most intensively researched. Studies have shown that GVHD patients often suffer from gut microbiota dysbiosis, which mainly manifests as decreased microbial diversity and changes in microbial composition and microbiota-derived metabolites, both of which are significant predictors of poor prognosis in GVHD patients. Therefore, the purpose of this review is to summarize what is known regarding changes in gut microbiota and microbiota-derived metabolites in GVHD, their relationship to GVHD prognosis, and corresponding clinical strategies designed to prevent microbial dysregulation and facilitate treatment of GVHD.

A steroid-resistant cockroach allergen model is associated with lung and cecal microbiome changes

The pathogenesis of asthma has been partially linked to lung and gut microbiome. We utilized a steroid-resistant chronic model of cockroach antigen-induced (CRA) asthma with corticosteroid (fluticasone) treatment to examine lung and gut microbiome during disease. The pathophysiology assessment demonstrated that mucus and airway hyperresponsiveness were increased in the chronic CRA with no alteration in the fluticasone (Flut)-treated group, demonstrating steroid resistance. Analysis of mRNA from lungs showed no decrease of MUC5AC or Gob5 in the Flut-treated group. Furthermore, flow-cytometry in lung tissue showed eosinophils and neutrophils were not significantly reduced in the Flut-treated group compared to the chronic CRA group. When the microbiome profiles were assessed, data showed that only the Flut-treated animals were significantly different in the gut microbiome. Finally, a functional analysis of cecal microbiome metabolites using PiCRUSt showed several biosynthetic pathways were significantly enriched in the Flut-treated group, with tryptophan pathway verified by ELISA with increased kynurenine in homogenized cecum samples. While the implications of these data are unclear, they may suggest a significant impact of steroid treatment on future disease pathogenesis through microbiome and associated metabolite pathway changes.

Klebsiella quasipneumoniae in intestine damages bile acid metabolism in hematopoietic stem cell transplantation patients with bloodstream infection

BACKGROUND

Bloodstream infection (BSI) is a serious hematopoietic stem cell transplantation (HSCT) complication. The intestinal microbiome regulates host metabolism and maintains intestinal homeostasis. Thus, the impact of microbiome on HSCT patients with BSI is essential.

METHODS

Stool and serum specimens of HSCT patients were prospectively collected from the pretransplant conditioning period till 4 months after transplantation. Specimens of 16 patients without BSI and 21 patients before BSI onset were screened for omics study using 16S rRNA gene sequencing and untargeted metabolomics. The predictive infection model was constructed using LASSO and the logistic regression algorithm. The correlation and influence of microbiome and metabolism were examined in mouse and Caco-2 cell monolayer models.

RESULTS

The microbial diversity and abundance of Lactobacillaceae were remarkably reduced, but the abundance of Enterobacteriaceae (especially Klebsiella quasipneumoniae) was significantly increased in the BSI group before onset, compared with the non-BSI group. The family score of microbiome features (Enterobacteriaceae and Butyricicoccaceae) could highly predict BSI (AUC = 0.879). The serum metabolomic analysis showed that 16 differential metabolites were mainly enriched in the primary bile acid biosynthesis pathway, and the level of chenodeoxycholic acid (CDCA) was positively correlated with the abundance of K. quasipneumoniae (R = 0.406, P = 0.006). The results of mouse experiments confirmed that three serum primary bile acids levels (cholic acid, isoCDCA and ursocholic acid), the mRNA expression levels of bile acid farnesol X receptor gene and apical sodium-dependent bile acid transporter gene in K. quasipneumoniae colonized mice were significantly higher than those in non-colonized mice. The intestinal villus height, crypt depth, and the mRNA expression level of tight junction protein claudin-1 gene in K. quasipneumoniae intestinal colonized mice were significantly lower than those in non-colonized mice. In vitro, K. quasipneumoniae increased the clearance of FITC-dextran by Caco-2 cell monolayer.

CONCLUSIONS

This study demonstrated that the intestinal opportunistic pathogen, K. quasipneumoniae, was increased in HSCT patients before BSI onset, causing increased serum primary bile acids. The colonization of K. quasipneumoniae in mice intestines could lead to mucosal integrity damage. The intestinal microbiome features of HSCT patients were highly predictive of BSI and could be further used as potential biomarkers.

Impact of oral microbiota on pathophysiology of GVHD

Allogeneic transplantation of hematopoietic cells is the only curative therapy for several hematopoietic disease in which patients receive cytotoxic conditioning regimens followed by infusion of hematopoietic stem cells. Although the outcomes have improved over the past decades, graft-versus-host-disease (GVHD), the most common life-threatening complication, remains a major cause of non-relapse morbidity and mortality. Pathophysiology of acute GVHD characterized by host antigen-presenting cells after tissue damage and donor T-cells is well studied, and additionally the importance of recipient microbiota in the intestine is elucidated in the GVHD setting. Oral microbiota is the second most abundant bacterial flora in the body after the intestinal tract, and it is related to chronic inflammation and carcinogenesis. Recently, composition of the oral microbiome in GVHD related to transplantation has been characterized and several common patterns, dysbiosis and enrichment of the specific bacterial groups, have been reported. This review focuses on the role of the oral microbiota in the context of GVHD.

Analysis of factors associated with hematopoietic stem-cell retransplantation: a case-control study

OBJECTIVE

to analyze the factors associated with the failure of Hematopoietic Stem Cell Transplantation (HSCT) in patients undergoing Hematopoietic Stem Cell Retransplantation (HSCR).

METHOD

this study implemented a quantitative approach and was a case-control type which addressed patients undergoing HSCR. To do so, a paired sample of two controls was used for each case (2:1). The case group consisted of the medical records of all patients who underwent HSCR (28) and the control group (56) of those who underwent only one transplant. Three variables guided the pairing: gender, diagnosis and type of transplant.

RESULTS

a total of 24 (85.71%) patients in the case group were re-transplanted due to disease relapse and four (14.29%) due to graft failure. There was a statistical difference in the analysis between patients who did not use ursodeoxycholic acid, opioid analgesics and immunosuppressants. The need for HSCR among those who used these medications inappropriately was 16.12, 12.79 and 4.5 times more likely, respectively, than those who used them correctly.

CONCLUSION

there was a difference regarding the reasons which led to the retransplantation and the analyzed subjects, and this study concluded that the predictive reason for retransplantation in the studied sample was disease relapse.

Analysis of factors associated with hematopoietic stem-cell retransplantation: a case-control study

Objective:

to analyze the factors associated with the failure of Hematopoietic Stem Cell Transplantation (HSCT) in patients undergoing Hematopoietic Stem Cell Retransplantation (HSCR).

Method:

this study implemented a quantitative approach and was a case-control type which addressed patients undergoing HSCR. To do so, a paired sample of two controls was used for each case (2:1). The case group consisted of the medical records of all patients who underwent HSCR (28) and the control group (56) of those who underwent only one transplant. Three variables guided the pairing: gender, diagnosis and type of transplant.

Results:

a total of 24 (85.71%) patients in the case group were re-transplanted due to disease relapse and four (14.29%) due to graft failure. There was a statistical difference in the analysis between patients who did not use ursodeoxycholic acid, opioid analgesics and immunosuppressants. The need for HSCR among those who used these medications inappropriately was 16.12, 12.79 and 4.5 times more likely, respectively, than those who used them correctly.

Conclusion:

there was a difference regarding the reasons which led to the retransplantation and the analyzed subjects, and this study concluded that the predictive reason for retransplantation in the studied sample was disease relapse.

Análisis de factores asociados al Retrasplante de Células Madre Hematopoyéticas: un estudio de caso-control

Resumen Objetivo: analizar los factores asociados con el fracaso del Trasplante de Células Madre Hematopoyéticas (TCMH) en pacientes sometidos al Retrasplante de Células Madre Hematopoyéticas (RCMH). Método: estudio cuantitativo de tipo caso-control que abordó pacientes sometidos al RCMH. Para esto, se utilizó una muestra pareada de dos controles para cada caso (2:1). El grupo caso estuvo formado por los registros médicos de todos los pacientes que fueron sometidos al RCMH (28) y el grupo control (56) por los que fueron sometidos a un solo trasplante. Tres variables guiaron el emparejamiento: género, diagnóstico y tipo de trasplante. Resultados: un total de 24 (85.71%) pacientes en el grupo caso fueron retransplantados debido a la recaída de la enfermedad y 4 (14.29%) por el fracaso del injerto. Hubo una diferencia estadística en el análisis entre los pacientes que no usaron ácido ursodesoxicólico, analgésicos opioides e inmunosupresores. La necesidad de RCMH entre los que usaron estos medicamentos de manera inapropiada se encontraba 16,12 - 12,79 y 4,5 veces más probable, respectivamente, que aquellos que los usaron correctamente. Conclusión: hubo diferencia en cuanto a las razones que llevaron al retrasplante de los sujetos analizados. Este estudio concluyó que la razón predictiva del retrasplante, en la muestra estudiada, fue la recidiva de la enfermedad.