Serum macrophage migration inhibitory factor (MIF) levels after allogeneic hematopoietic stem cell transplantation

Unlocking protein-based biomarker potential for graft-versus-host disease following allogenic hematopoietic stem cell transplants

Despite the numerous advantages of allogeneic hematopoietic stem cell transplants (allo-HSCT), there exists a notable association with risks, particularly during the preconditioning period and predominantly post-intervention, exemplified by the occurrence of graft-versus-host disease (GVHD). Risk stratification prior to symptom manifestation, along with precise diagnosis and prognosis, relies heavily on clinical features. A critical imperative is the development of tools capable of early identification and effective management of patients undergoing allo-HSCT. A promising avenue in this pursuit is the utilization of proteomics-based biomarkers obtained from non-invasive biospecimens. This review comprehensively outlines the application of proteomics and proteomics-based biomarkers in GVHD patients. It delves into both single protein markers and protein panels, offering insights into their relevance in acute and chronic GVHD. Furthermore, the review provides a detailed examination of the site-specific involvement of GVHD. In summary, this article explores the potential of proteomics as a tool for timely and accurate intervention in the context of GVHD following allo-HSCT.

Identification of Cellular Compositions in Different Microenvironments and Their Potential Impacts on Hematopoietic Stem Cells HSCs Using Single-Cell RNA Sequencing with Systematical Confirmation

Hematopoietic stem cells (HSCs) are stem cells that can differentiate into various blood cells and have long-term self-renewal capacity. At present, HSC transplantation is an effective therapeutic means for many malignant hematological diseases, such as aplastic hematological diseases and autoimmune diseases. The hematopoietic microenvironment affects the proliferation, differentiation, and homeostasis of HSCs. The regulatory effect of the hematopoietic microenvironment on HSCs is complex and has not been thoroughly studied yet. In this study, we focused on mononuclear cells (MNCs), which provided an important microenvironment for HSCs and established a methodological system for identifying cellular composition by means of multiple technologies and methods. First, single-cell RNA sequencing (scRNA-seq) technology was used to investigate the cellular composition of cells originating from different microenvironments during different stages of hematopoiesis, including mouse fetal liver mononuclear cells (FL-MNCs), bone marrow mononuclear cells (BM-MNCs), and in vitro-cultured fetal liver stromal cells. Second, bioinformatics analysis showed a higher proportion and stronger proliferation of the HSCs in FL-MNCs than those in BM-MNCs. On the other hand, macrophages in in vitro-cultured fetal liver stromal cells were enriched to about 76%. Differential gene expression analysis and Gene Ontology (GO) functional enrichment analysis demonstrated that fetal liver macrophages have strong cell migration and actin skeleton formation capabilities, allowing them to participate in the hematopoietic homeostasis through endocytosis and exocytosis. Last, various validation experiments such as quantitative real-time PCR (qRT-PCR), ELISA, and confocal image assays were performed on randomly selected target genes or proteins secreted by fetal liver macrophages to further demonstrate the potential relationship between HSCs and the cells inhabiting their microenvironment. This system, which integrates multiple methods, could be used to better understand the fate of these specific cells by determining regulation mechanism of both HSCs and macrophages and could also be extended to studies in other cellular models.

The S1P1 receptor-selective agonist CYM-5442 reduces the severity of acute GVHD by inhibiting macrophage recruitment

FTY720, an agonist for four of the five known sphingosine-1-phosphate (S1P) receptors, has been reported to inhibit acute graft-versus-host disease (aGVHD). Because FTY720 functions through multiple S1P receptors, the mechanism of action through one or more of these receptors may account for its side effects. Thus, more selective S1P receptor modulators are needed to evaluate the roles of different S1P receptors and their therapeutic efficacies. In this study, we investigated the effect of an S1P1-selective agonist, CYM-5442, on the progression of aGVHD. We showed that CYM-5442 significantly inhibited but did not prevent aGVHD. CYM-5442 did not affect the infiltration of the donor T cells into the target organs, while the number of macrophages in GVHD organs was significantly reduced by CYM-5442 treatment. In vivo proliferation assays showed that the proliferation of macrophages was not suppressed by CYM-5442. Further studies using human endothelial cells demonstrated that CYM-5442 treatment downregulated CCL2 and CCL7 expression in endothelial cells, therefore reducing the migration of monocytes, from which tissue macrophages originate. Our data demonstrate the therapeutic efficacy of an S1P1-selective agonist in aGVHD and its possible mechanism of action. The results suggest that further investigations are needed regarding CYM-5442 as a potential therapeutic regimen for aGVHD.

Soluble tumor necrosis factor receptor: enbrel (etanercept) for subacute pulmonary dysfunction following allogeneic stem cell transplantation

Subacute lung disease, manifested as either obstructive (OLD) or restrictive (RLD) lung dysfunction, is a common complication following allogeneic stem cell transplantation. In each case, therapeutic options are limited, morbidity remains high, and long-term survival is poor. Between 2001 and 2008, 34 patients with noninfectious, obstructive (25) or RLD restrictive lung dysfunction (nine) received etanercept (Enbrel®, Amgen Inc.) 0.4 mg/kg/dose, subcutaneously, twice weekly, for 4 (group A) or 12 weeks (group B). Corticosteroids (if present at study entry) were kept constant for the initial 4 weeks of therapy and then tapered as tolerated. Thirty-one of 34 (91%) subjects were evaluable for response, and 10 (32%) met primary response criteria. There was no difference in response based on the duration of treatment (29% group A versus 35% group B; P = .99), the presence of RLD or OLD (33% versus 32%; P = .73), or the severity of pulmonary disease at study onset. Estimated 5-year overall survival rates following therapy were 61% (95% confidence interval, 46%-80%) for all subjects and 90% (95% confidence level, 73%-100%) for the 10 who met the primary response criteria. Five-year survival estimates for subjects treated with RLD was 44%, compared with 67% for those treated for OLD (P = .19). Etanercept was well tolerated, with no bacteremia or viremia observed. Pathogens were noted on posttherapy bronchoalveolar lavage in two cases. These data support the development of expanded clinical trials to study etanercept as a therapeutic agent for subacute lung injury after allogeneic stem cell transplantation.

Immunoregulatory gene polymorphisms and graft-versus-host disease

Graft-versus-host disease (GVHD) remains a significant complication that greatly enhances morbidity and mortality associated with hematopoietic stem cell transplantation. Key immunoregulatory molecules have been implicated in the pathogenesis of GVHD, but the mechanisms by which these molecules affect the incidence and severity of GVHD have not been fully elucidated. The effects of genetic polymorphisms in immunoregulatory molecules, including cytokines, costimulatory and adhesion molecules, pharmacogenes and growth factors, have been shown to play a central role in GVHD. The results of these polymorphism studies contribute to the identification of predictive risk factors for GVHD based on individual polymorphism makeup. This review summarizes investigations of genetic polymorphisms in immunoregulatory molecules significantly associated with GVHD over the last 5 years.

G to C transition at position -173 of MIF gene of the recipient is associated with reduced relapse rates after allogeneic stem cell transplantation

Pro-inflammatory and dendritic cell-activating properties of macrophage migration inhibitory factor (MIF) suggest a potentially important role for MIF in alloantigen-specific immune responses after allogeneic stem cell transplantation (allo-SCT). We tested whether MIF -173 G/C gene polymorphism of donor or patient had impacts on the outcomes after allo-SCT. Four hundred and fifty-four donor-patient pairs were genotyped and mortality, relapse, and development of complications were analyzed. Patient but not donor MIF -173 *C allele was associated with improved overall survival (OS) (5 years: 60.8% versus 46.3%, p=0.042) and disease free survival (DFS) (5 years: 55.4% versus 39.5%; p=0.014) due to a reduction in relapse (day 2000: 22.8% versus 42.0% p=0.006) but not due to decreased transplantation-related mortality (TRM) (p=0.44). Multivariate analysis proved patient -173 *C allele as an independent factor for reducing relapse after allo-SCT (p=0.023). Subgroup analysis showed a clear MIF -173 *C allele-related reduction in relapse for those patients who did not receive T cell depleted (TCD) SCT (p=0.01) in contrast to patients receiving TCD SCT (p=0.20). In summary, patient MIF -173 *C allele may be linked to specific, yet unrevealed functions in tumor biology and graft versus leukemia and lymphoma effects and potentially presents a novel prognostic marker for patient-tailored counseling and therapy in allo-SCT.