Donor Nucleotide-Binding Oligomerization–Containing Protein 2 (NOD2) Single Nucleotide Polymorphism 13 Is Associated with Septic Shock after Allogeneic Stem Cell Transplantation

The Potential Role of NOD2/CARD15 Genotype as a Prognostic Indicator for Bone Marrow Transplantation Outcomes in Patients With Acute Lymphoblastic Leukemia and Acute Myeloid Leukemia: A Systematic Review

Hematopoietic stem-cell transplantation (HSCT) has emerged as a groundbreaking therapeutic option for acute myeloid leukemia (AML) and specific subtypes of acute lymphoblastic leukemia (ALL). The prognostic significance of the NOD2/CARD15 gene has been explored alongside various factors, encompassing diverse patient cohorts and gene variants. Siblings and unrelated donors used for stem cell transplantation exhibit significant associations between their genetic variations and graft-versus-host disease incidence. The transplantation of stem cells for leukemia patients involves numerous considerations, including patient survival, relapse rates, disease stage, donor and recipient ages, and compatibility. This study delved into research on the NOD2/CARD15 gene and its mutations to assess its suitability as a screening tool. A comprehensive literature search encompassing PubMed, ScienceDirect, and Google Scholar articles yielded 4,840 articles. After removing duplicates and applying inclusion and exclusion criteria, we narrowed the search results to 876 articles. Subsequent screening of abstracts and titles resulted in the selection of 230 relevant articles. Further exclusion of 198 articles unrelated to the research question led to the scrutinizing of 32 full-text articles, which were assessed against inclusion and exclusion criteria. Emphasis was placed on articles that specifically investigated the role of NOD2/CARD15 as a predictive factor for HSCT outcomes, ultimately resulting in the inclusion of 19 articles in this study. Single nucleotide polymorphisms (SNPs) such as NOD2 and CARD15 have demonstrated their potential as reliable genetic markers for predicting post-transplantation relapse and disease outcomes. Patients positive for these genetic markers have exhibited reduced overall survival and event-free survival and increased transplant-related mortality. Interventions with interferon-gamma and muramyl tripeptide phosphatidylethanolamine have been considered to mitigate the inflammatory effects of these SNPs, thus enhancing the influence of natural killer cells on abnormal cells and potentially extending patient survival. NOD2/CARD15 typing may aid in identifying patients at higher risk for relapse and improving their clinical outcomes after allogeneic stem cell transplant, particularly in ALL patients. However, no remarkable change was observed in AML patients. Additionally, this study underscores the pivotal roles of adaptive and innate immune responses and their interplay in stem cell transplant immunology.

NLRC4 gene silencing-dependent blockade of NOD-like receptor pathway inhibits inflammation, reduces proliferation and increases apoptosis of dendritic cells in mice with septic shock

Septic shock is one of the most significant health concerns across the world, involving hypo-perfusion and defects in tissue energy. The current study investigates the role of NLR family CARD domain containing protein 4 (NLRC4) in septic shock-induced inflammatory reactions, lung tissue injuries, and dendritic cell (DC) apoptosis. Septic shock mice models were established by modified cecal ligation and puncture and injected with retroviral vector expressing siRNA-NLRC4. DCs were then isolated and transfected with siRNA-NLRC4. The degree of lung tissue injury, cell cycle distribution, cell apoptosis and cell viability of DCs were assessed. NLRC4 was found to be expressed at high levels in mice with septic shock. NLRC4 silencing inhibited the activation of the NOD-like receptor (NLR) pathway as evidenced by the decreased levels of NOD1, NOD2, RIP2, and NF-κB. In addition, NLRC4 silencing reduced the inflammatory reaction as attributed by reduced levels of IL-1β, TNF-α and IL-6. Suppressed NLRC4 levels inhibited cell viability and promoted cell apoptosis evidenced by inhibited induction of DC surface markers (CD80, CD86, and MHC II), along with alleviated lung tissue injury. In conclusion, NLRC4 silencing ameliorates lung injury and inflammation induced by septic shock by negatively regulating the NLR pathway.

Infection Complications in Hematopoietic Stem Cells Transplant Recipients: Do Genetics Really Matter?

Hematopoietic stem cell transplantation (HSCT) is a highly advanced technique that offers a potential cure for an increasing number of life-threatening diseases. Enormous progress achieved in the last decade, including the refinement of donor selection and advancements in patient supportive care, had significantly improved transplant outcomes; however, invasive infections, graft-vs.-host disease (GVHD) and other serious complications still represent a major source of morbidity and mortality in HSCT recipients. The damage of anatomical barriers due to pre-transplant conditioning, a severely damaged immune function and a profound disruption in the composition of gut microbial commensals (gut microbiota) are alterations inherent to the transplant procedure that are directly implicated in the development of invasive infections and other HSCT complications. Although HLA-matching represents the most important genetic predictor of transplant outcomes, genetic variants in non-HLA genes, especially single nucleotide polymorphisms (SNPs) of genes encoding proteins associated with the immune response to tissue injury and pathogen infection have also been proposed as additional risk factors implicated in the occurrence of HSCT complications. Furthermore, although the microbiota composition is affected by several factors, recent evidence suggests that certain host genetic variants are associated with an altered composition of the gut microbiome and may, therefore, predispose some individuals to invasive infectious complications. This article summarizes the current understanding of the influence that genetic variants in non-HLA genes have on the development of infectious complications in HSCT recipients.

Comorbidities, age, and other patient-related predictors of allogeneic hematopoietic cell transplantation outcomes

INTRODUCTION

Allogeneic hematopoietic cell transplantation (HCT) provides potential cure to a large number of malignant and nonmalignant hematological disorders. With the development of non-myeloablative and reduced-intensity conditioning regimens, allogeneic HCT can nowadays be offered to a number of older or medically unfit patients. Up until the twenty-first century, chronological age was considered a hypothetical barrier. Recent reports, however, have shown that comorbidities, function, and other patient-related factors influence HCT outcomes at a higher magnitude than age alone. Areas covered: To define the eligibility of older or medically unfit patients for allogeneic HCT, a range of factors have to be considered. To solve this considerable issue, we need to further understand the mechanism and consequences of aging, such as chronic inflammation, sarcopenia, and especially the structure of frailty. Domains covering functional, physical, mental, social, nutritional, bone, and other health statuses should be evaluated and considered. Expert commentary: In this review we merge the current assessment tools with the potential approaches to objectify functional resources, as well as with possible methods to improve these resources in older or otherwise medically unfit patients prior to allogeneic HCT.

Genetic Association of Hematopoietic Stem Cell Transplantation Outcome beyond Histocompatibility Genes

The outcome of hematopoietic stem cell transplantation (HSCT) is controlled by genetic factors among which the leukocyte antigen human leukocyte antigen (HLA) matching is most important. In addition, minor histocompatibility antigens and non-HLA gene polymorphisms in genes controlling immune responses are known to contribute to the risks associated with HSCT. Besides single-nucleotide polymorphisms (SNPs) in protein coding genes, SNPs in regulatory elements such as microRNAs (miRNAs) contribute to these genetic risks. However, genetic risks require for their realization the expression of the respective gene or miRNA. Thus, gene and miRNA expression studies may help to identify genes and SNPs that indeed affect the outcome of HSCT. In this review, we summarize gene expression profiling studies that were performed in recent years in both patients and animal models to identify genes regulated during HSCT. We discuss SNP–mRNA–miRNA regulatory networks and their contribution to the risks associated with HSCT in specific examples, including forkheadbox protein 3 and regulatory T cells, the role of the miR-155 and miR-146a regulatory network for graft-versus-host disease, and the function of MICA and its receptor NKG2D for the outcome of HSCT. These examples demonstrate how SNPs affect expression or function of proteins that modulate the alloimmune response and influence the outcome of HSCT. Specific miRNAs targeting these genes and directly affecting expression of mRNAs are identified. It might be valuable in the future to determine SNPs and to analyze miRNA and mRNA expression in parallel in cohorts of HSCT patients to further elucidate genetic risks of HSCT.

Sensing danger: toll-like receptors and outcome in allogeneic hematopoietic stem cell transplantation

Pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) play key roles in initiating innate and adaptive immune responses. Based mainly on animal studies there is growing evidence to suggest that TLRs are involved in the development of chemotherapy-induced mucositis and in the propagation of graft versus host reactions as well as graft versus tumor effects in allogeneic hematopoietic stem cell transplantation (HSCT). In this review we discuss these findings along with the emerging, although still preliminary, clinical evidence, that points to a role of PRRs in determining the outcome of HSCT and new therapeutic perspectives that may be related to this development.

Risk stratification and immunogenetic risk for infections following stem cell transplantation

Patients undergoing haematopoietic stem cell transplantation (HSCT) are highly exposed to infectious agents. However, it is not known why certain HSCT recipients rapidly develop severe infections while other, despite similar immunosuppressive conditions, do not. Increasing evidence suggests that such differences may be due, in part, to polymorphisms in immune genes. Thus, the identification of genetic factors influencing susceptibility to infections in HSCT recipients may lead to the development of individualized management strategies. However, studies are challenged by several issues, including the relative small size of existing cohorts, the frequent use of prophylactic or preemptive antimicrobial agents, and the fact that genes responsible for immune functions can be inherited either from the donor or the host. Consequently, the major challenge for today's researchers is to overcome these limitations and find associations that are robust enough to be translated into reliable risk stratification strategies for infectious diseases.