IFN-γ–Stimulated Apoptotic Keratinocytes Promote Sclerodermatous Changes in Chronic Graft-Versus-Host Disease

Morphoea presenting histopathologically as mycosis fungoides: an illustrative series of four cases

AIMS

There have been exceptional reports of morphoea presenting with epidermal changes overlapping histopathologically with cutaneous T cell lymphoma of the mycosis fungoides type (MF). This phenomenon gives rise to an ambiguous clinicopathological scenario in which distinguishing these conditions may be challenging. The aim of this study is to characterise the clinical, histopathological and molecular findings of this phenomenon through a case series.

METHODS AND RESULTS

Four patients with classical clinical presentation of morphoea but unusual histopathology displaying typical findings of morphoea, together with intra-epidermal CD8 positive lymphocytes indistinguishable from MF, were identified. The clinical phenotypes of morphoea were varied, and they all presented early in the active phase of the disease. They all exhibited intra-epidermal lymphocytes with tagging and cytological atypia. Pautrier-like microabscesses were also seen. Using molecular analysis, two cases showed clonal TCR gene rearrangement. Follow-up of all cases has been consistent with classical morphoea.

CONCLUSION

Early morphoea can seldom present with atypical clonal intra-epidermal lymphocytes indistinguishable from MF. The fact that these changes can occur in several different clinical subtypes of morphoea raises the possibility that this could be a pattern of inflammation in early disease more common than currently appreciated.

Cellular senescence promotes meibomian gland dysfunction in a chronic graft-versus-host disease mouse model

PURPOSE

Aging is a well-established risk factor for meibomian gland dysfunction (MGD). We previously reported an accelerated cellular senescence phenomenon in the lacrimal glands of a murine model of chronic graft-versus-host disease (cGVHD). Herein, we aimed to elucidate the relationship between cellular senescence and MGD in cGVHD mice, utilizing the senolytic agent ABT-263.

METHODS

A cGVHD mouse model was established through allogeneic bone marrow transplantation (BMT) from B10.D2 to BALB/c mice. Subsequently, cGVHD mice were treated with either ABT-263 or vehicle. The eyelids of recipients were analyzed at 4-week intervals post-BMT in both groups.

RESULTS

Meibomian gland (MG) area was significantly smaller in cGVHD mice than in syngeneic control mice. ABT-263-treated mice retained a significantly larger MG area than their vehicle-treated counterparts. Pathological and immunohistochemical examinations revealed significant reductions in eyelid tissue inflammation and pathological fibrosis in the ABT-263 group compared to that in the vehicle-treated group. Additionally, expression of DNA damage markers, senescent cell markers, and senescence-associated secretory phenotype (SASP) factors was elevated in the eyelids of cGVHD mice compared with that in syngeneic mice. The expression of these cellular senescence-associated molecules was considerably suppressed in ABT-263-treated eyelids compared to that in vehicle-treated ones.

CONCLUSIONS

Cellular senescence, along with expression of SASP factors, exhibited increased activity in the eyelids, particularly in the MGs of cGVHD mice. ABT-263 mitigated the severity of MGD. These findings highlight the potential of targeting cellular senescence as an effective approach for MGD treatment in cGVHD.

Identification of Fibroinflammatory and Fibrotic Transcriptomic Subsets of Human Cutaneous Sclerotic Chronic Graft-Versus-Host Disease

Cutaneous sclerotic chronic graft-versus-host disease (cGVHD) is a common and highly morbid complication of allogeneic hematopoietic stem cell transplantation. Our goals were to identify signals active in the skin of patients with sclerotic cGVHD in an effort to better understand how to treat this manifestation and to explore the heterogeneity of the disease. We identified genes that are significantly upregulated in the skin of patients with sclerotic cGVHD (n = 17) compared with those in the skin of patients who underwent allogeneic hematopoietic stem cell transplantation without cutaneous cGVHD (n = 9) by bulk RNA sequencing. Sclerotic cGVHD was most associated with T helper 1, phagocytic, and fibrotic pathways. In addition, different transcriptomic groups of affected patients were discovered: those with fibrotic and inflammatory/T helper 1 gene expression (the fibroinflammatory group) and those with predominantly fibrotic/TGFβ-associated expression (the fibrotic group). Further study will help elucidate whether these gene expression findings can be used to tailor treatment decisions. Multiple proteins encoded by highly induced genes in the skin (SFRP4, SERPINE2, COMP) were also highly induced in the plasma of patients with sclerotic cGVHD (n = 16) compared with those in plasma of control patients who underwent allogeneic hematopoietic stem cell transplantation without sclerotic cGVHD (n = 17), suggesting these TGFβ and Wnt pathway mediators as candidate blood biomarkers of the disease.

A Comparison of Lymphoid and Myeloid Cells Derived from Human Hematopoietic Stem Cells Xenografted into NOD-Derived Mouse Strains

Humanized mice are an invaluable tool for investigating human diseases such as cancer, infectious diseases, and graft-versus-host disease (GvHD). However, it is crucial to understand the strengths and limitations of humanized mice and select the most appropriate model. In this study, we describe the development of the human lymphoid and myeloid lineages using a flow cytometric analysis in four humanized mouse models derived from NOD mice xenotransplanted with CD34⁺ fetal cord blood from a single donor. Our results showed that all murine strains sustained human immune cells within a proinflammatory environment induced by GvHD. However, the Hu-SGM3 model consistently generated higher numbers of human T cells, monocytes, dendritic cells, mast cells, and megakaryocytes, and a low number of circulating platelets showing an activated profile when compared with the other murine strains. The hu-NOG-EXL model had a similar cell development profile but a higher number of circulating platelets with an inactivated state, and the hu-NSG and hu-NCG developed low frequencies of immune cells compared with the other models. Interestingly, only the hu-SGM3 and hu-EXL models developed mast cells. In conclusion, our findings highlight the importance of selecting the appropriate humanized mouse model for specific research questions, considering the strengths and limitations of each model and the immune cell populations of interest.

Blockade of CD122 on memory T cells in the skin suppresses sclerodermatous graft-versus-host disease

BACKGROUND

Antigen-stimulated naïve T cells differentiate into effector and memory T cells, of which resident memory T (T_RM) cells reside permanently in organ tissues. Involvement of T_RM cells has been indicated in pathological conditions of various skin diseases. CD122, which is the β chain subunit of interleukin (IL)- 2 and IL-15 receptors, is expressed on immune cells including T_RM cells.

OBJECTIVE

To investigate whether CD122 signaling in skin CD8⁺ T_RM cells mediates the development of mucocutaneous graft-versus-host disease (GVHD).

METHODS

We used a genetically modified mouse expressing a membrane-bound form of chicken ovalbumin (OVA) under the control of the keratin 14 promoter, which develops GVHD-like erosive mucocutaneous disease resulting in sclerodermatous disease after transfer of OVA-specific T cell-receptor-transgenic CD8⁺ OT-I cells. Mice with mucocutaneous GVHD were treated with an anti-CD122 blocking antibody.

RESULTS

Administration of an anti-CD122 blocking antibody suppresses the development of acute/chronic GVHD-like mucocutaneous disease in our murine model via the reduction of CD122-expressing memory CD8⁺ T cells, including skin, memory autoaggressive CD8⁺ T cells. Moreover, blockade of CD122, even after the establishment of acute GVHD, inhibited the development of chronic GVHD-like sclerodermatous disease via the reduction of epidermal and dermal T_RM autoaggressive CD8⁺ T cells.

CONCLUSION

Skin memory CD8⁺ T cells in particular mediate the development of mucocutaneous GVHD, and blockade of CD122 may be an effective treatment strategy, especially for sclerodermatous GVHD.

Contribution of keratinocytes to dermal fibrosis

PURPOSE OF REVIEW

The cellular pathogenesis of fibrotic disorders including systemic sclerosis (SSc) remains largely speculative. Currently, the altered function of endothelial cells and fibroblasts under the influence of an inappropriate immune response are considered central pathogenic events in SSc. Adding to this complexity, novel evidence here reviewed suggests that keratinocytes may concur in the development of skin fibrosis.

RECENT FINDINGS

Epidermal equivalents (EE) generated from primary SSc keratinocytes display a distinct gene expression program when compared to healthy donor (HD) EE. SSc-EE, among others, exhibited enhanced oxidative and metabolic response pathways. Immunohistochemical studies demonstrated similarities between SSc-EE and SSc epidermis including altered keratinocyte differentiation, enhanced expression of activation markers, and reduced rate of basal keratinocytes proliferation. SSc-EE supernatants more than HD-EE modified the inflammatory and extracellular matrix deposition/resorption program of dermal fibroblasts. Further evidence indicated that the relative lack rather than the excess of interleukin-25 in keratinocytes may contribute to enhanced dermal fibrotic changes. Overall, these data support keratinocyte-intrinsic SSc-related modifications.

SUMMARY

Improved methods for engineering epidermal and skin equivalents are helping to address the question whether keratinocyte alterations in SSc are primary and capable to dysregulate dermal homeostasis or secondary following dermal fibrotic changes.

Blockade of PD-1/PD-L1 increases effector T cells and aggravates murine chronic graft-versus-host disease

T-cells mediated immunopathology is crucial for pathogenesis of chronic graft-versus-host disease (cGVHD), a common complication following allogeneic hematopoietic cell transplantation. Programmed death-1 (PD-1) regulates long-term survival and functional exhaustion of T-cell which might play a role in regulating cGVHD. We examined PD-1 expression on T cells of cGVHD mice and tested the impact of a PD-1 antibody on severity of cGVHD in murine allotransplant models. We also used a murine graft-versus-tumor (GVT) model to explore how tumor cell-derived PD-L1 affect the GVT effect and occurrence of cGVHD. PD-1 fluorescence intensity on CD4⁺ T-cells increased in mice developing cGVHD. PD-1^High T cells expressed higher levels of IFNγ and IL-17, comparing with PD-1^Low T cells. Giving the PD-1 antibody increased proportions of Th1, Th17 and Tc1 cells, but decreased proportion of Treg cells in allotransplant mice. The PD-1 antibody decreased survival of recipients and induced severe lung cGVHD. In the GVT model, knockdown of PD-L1 in A20 tumor cells enhanced GVT effect but increased cGVHD. In vitro study showed knockdown of PD-L1 in tumor cells increased cytotoxicity of T cells and reduced apoptosis of T cells. Knockdown of PD-L1 in tumor cells increased protein levels of phosphorylated AKT, Bcl-2 and Mcl-1, but decreased protein levels of Bak and Bax in co-cultured allogeneic T cells. In conclusion, expression of PD-1 on T cells increased in mice undergoing cGVHD. Intervention of the PD-1/PD-L1 pathway showed a significant impact on occurrence of cGVHD and GVT effect.