Characterization of monocyte subtypes regarding their phenotype and development in the context of graft-versus-host disease

Evaluation of exposure to environmental stressors on heat-shock protein 70 expression in normal oral keratinocyte cells

Objectives

This study aimed to investigate the effect of cortisol, estrogen, and nicotine on heat shock protein 70 (HSP70) expressions at the level of normal oral mucosa keratinocyte cells.

Methods

In this in vitro study, keratinocytes were derived from rat oral cavity and cultured. Stressors were applied, including three groups, group 1: estrogen to simulate the postmenopausal state; group 2: cortisol to simulate psychological stress situation; group 3: nicotine to simulate smoking state. To determine the exact nature of keratinocyte cells, two surface markers, cytokeratin 18 and cytokeratin 14 were examined using the flow cytometry method. Then, the immunocytochemistry technique with three repetitions in each group was used to evaluate the HSP70 expression before and after applying the stressor.

Results

HSP70 expressions in the three stressor groups (estrogen, cortisol, and nicotine) were significantly lower than in the control group (p = 0.0001). The HSPs expression difference between cortisol and nicotine was statistically significant (p = 0.0001). Based on the results of MTT analysis, the mean cell viability of oral mucosal keratinocytes in all three intervention groups decreased compared to the control group. In the cortisol and nicotine groups, cell death was significantly higher than in the control group. In the estrogen group, cell death was significantly lower than in the nicotine group (p > 0.05).

Conclusions

The specific concentrations of cortisol, estrogen, and nicotine as stressors can effectively reduce the expression of HSP70 in normal oral mucosal keratinocytes. These phenomena can be effective in cell viability and the development of oral lichen planus.

Donor monocyte-derived macrophages promote human acute graft-versus-host disease

Myelopoiesis is invariably present and contributes to pathology in animal models of graft-versus-host disease (GVHD). In humans, a rich inflammatory infiltrate bearing macrophage markers has also been described in histological studies. In order to determine the origin, functional properties, and role in pathogenesis of these cells, we isolated single-cell suspensions from acute cutaneous GVHD and subjected them to genotype, transcriptome, and in vitro functional analysis. A donor-derived population of CD11c⁺CD14⁺ cells was the dominant population of all leukocytes in GVHD. Surface phenotype and NanoString gene expression profiling indicated the closest steady-state counterpart of these cells to be monocyte-derived macrophages. In GVHD, however, there was upregulation of monocyte antigens SIRPα and S100A8/9 transcripts associated with leukocyte trafficking, pattern recognition, antigen presentation, and costimulation. Isolated GVHD macrophages stimulated greater proliferation and activation of allogeneic T cells and secreted higher levels of inflammatory cytokines than their steady-state counterparts. In HLA-matched mixed leukocyte reactions, we also observed differentiation of activated macrophages with a similar phenotype. These exhibited cytopathicity to a keratinocyte cell line and mediated pathological damage to skin explants independently of T cells. Together, these results define the origin, functional properties, and potential pathogenic roles of human GVHD macrophages.

Review of Genetic Variation as a Predictive Biomarker for Chronic Graft-Versus-Host-Disease After Allogeneic Stem Cell Transplantation

Chronic graft-versus-host disease (cGvHD) is one of the major complications of allogeneic stem cell transplantation (HSCT). cGvHD is an autoimmune-like disorder affecting multiple organs and involves a dermatological rash, tissue inflammation and fibrosis. The incidence of cGvHD has been reported to be as high as 30% to 60% and there are currently no reliable tools for predicting the occurrence of cGvHD. There is therefore an important unmet clinical need for predictive biomarkers. The present review summarizes the state of the art for genetic variation as a predictive biomarker for cGvHD. We discuss three different modes of action for genetic variation in transplantation: genetic associations, genetic matching, and pharmacogenetics. The results indicate that currently, there are no genetic polymorphisms or genetic tools that can be reliably used as validated biomarkers for predicting cGvHD. A number of recommendations for future studies can be drawn. The majority of studies to date have been under-powered and included too few patients and genetic markers. Like in all complex multifactorial diseases, large collaborative genome-level studies are now needed to achieve reliable and unbiased results. Some of the candidate genes, in particular, CTLA4, HSPE, IL1R1, CCR6, FGFR1OP, and IL10, and some non-HLA variants in the HLA gene region have been replicated to be associated with cGvHD risk in independent studies. These associations should now be confirmed in large well-characterized cohorts with fine mapping. Some patients develop cGvHD despite very extensive immunosuppression and other treatments, indicating that the current therapeutic regimens may not always be effective enough. Hence, more studies on pharmacogenetics are also required. Moreover, all of these studies should be adjusted for diagnostic and clinical features of cGvHD. We conclude that future studies should focus on modern genome-level tools, such as machine learning, polygenic risk scores and genome-wide association study-transcription meta-analyses, instead of focusing on just single variants. The risk of cGvHD may be related to the summary level of immunogenetic differences, or whole genome histocompatibility between each donor-recipient pair. As the number of genome-wide analyses in HSCT is increasing, we are approaching an era where there will be sufficient data to incorporate these approaches in the near future.

Monocyte subsets in bone marrow grafts may contribute to a low incidence of acute graft-vs-host disease for young donors

Young donors are associated with a lower cumulative incidence of acute graft‐vs‐host disease (aGVHD) after allogenic haematopoietic stem cell transplantation (allo‐HSCT) than old donors. Although grafts are harvested from healthy donors, it is unclear whether donor age is associated with aGVHD occurrence owing to its effect on cell compositions in grafts. Moreover, the differences in monocyte subsets in grafts between young and old donors and the association between monocyte subsets in bone marrow (BM) grafts and aGVHD remain to be elucidated. In the current study, non‐classical monocytes and the CD4⁺/CD8⁺ T cell ratio were remarkably decreased in BM grafts in donors <30 years old. Multivariate analysis further revealed that the level of non‐classical monocytes in BM grafts (≥0.31 × 10⁶/kg) was an independent risk factor for the occurrence of II‐IV aGVHD. In summary, our data indicate that non‐classical monocytes in BM grafts may help identify patients at high risk for aGVHD after allo‐HSCT. Although further validation is required, our results suggest that the low level of non‐classical monocytes and a low ratio of CD4⁺/CD8⁺ T cell in BM grafts may be correlated with the lower incidence of aGVHD in young donors.

How I treat steroid-refractory acute graft-versus-host disease

Steroid-resistant or steroid-refractory acute graft-versus-host disease (SR-aGVHD) poses one of the most vexing challenges faced by providers who care for patients after allogeneic hematopoietic cell transplantation. For the past 4 decades, research in the field has been driven by the premise that persistent graft-versus-host disease (GVHD) results from inadequate immunosuppression. Accordingly, most efforts to solve this problem have relied on retrospective or prospective studies testing agents that have direct or indirect immunosuppressive effects. Retrospective studies far outnumber prospective studies, and no controlled prospective trial has shown superior results for any agent over others. Truth be told, I do not know how to treat SR-aGVHD. Preclinical work during the past decade has provided fresh insights into the pathogenesis of acute GVHD, and translation of these insights toward development of more effective treatments for patients with SR-aGVHD has at last begun. Given the limited state of current knowledge, this "How I Treat" review highlights the overriding imperative to avoid harm in caring for patients with SR-aGVHD. Prospective trials that are widely available are urgently needed to advance the field.