IL-Y Aggravates Murine Chronic Graft-Versus-Host Disease by Enhancing T and B Cell Responses

Structure and assembly of the human IL-12 signaling complex

Interleukin (IL)-12 is a heterodimeric pro-inflammatory cytokine. Our cryoelectron microscopy structure determination of human IL-12 in complex with IL-12Rβ1 and IL-12Rβ2 at a resolution of 3.75 Å reveals that IL-12Rβ2 primarily interacts with the IL-12p35 subunit via its N-terminal Ig-like domain, while IL-12Rβ1 binds to the p40 subunit with its N-terminal fibronectin III domain. This binding mode of IL-12 with its receptors is similar to that of IL-23 but shows notable differences with other cytokines. Through structural information and biochemical assays, we identified Y62, Y189, and K192 as key residues in IL-12p35, which bind to IL-12Rβ2 with high affinity and mediate IL-12 signal transduction. Furthermore, structural comparisons reveal two distinctive conformational states and structural plasticity of the heterodimeric interface in IL-12. As a result, our study advances our understanding of IL-12 signal initiation and opens up new opportunities for the engineering and therapeutic targeting of IL-12.

Therapeutic efficacy of rituximab combined with cyclosporin A on B-cell dysregulation in chronic graft-versus-host disease

OBJECTIVE

Chronic graft-versus-host disease (cGVHD) is a significant complication following allogenic hematopoietic stem cell transplantation, often necessitating therapeutic interventions such as rituximab (RTX) and cyclosporin A (CsA). This study aims to elucidate the mechanisms by which RTX and CsA jointly address B-cell dysregulation in cGVHD, providing a theoretical foundation and scientific rationale for the treatment and prognostic evaluation of this condition.

METHODS

A total of 30 cGVHD mouse models were established by subjecting recipient mice to total body irradiation followed by injection of a mixed suspension of bone marrow cells and splenocytes from donor mice. From Day 2 to Day 29 post-model establishment, the mice received subcutaneous administration of RTX and CsA. Throughout the study, body weight, clinical cGVHD scores, and survival rates were monitored. Blood samples were collected via the orbital venous plexus. Serum levels of B-cell activating factor (BAFF) and pro-inflammatory factors were measured using enzyme-linked immunosorbent assay (ELISA), and the ratio of regulatory B cells (Bregs) in the blood sample was assessed via flow cytometry.

RESULTS

Mice with cGVHD exhibited a 14.5% decrease in body weight, elevated clinical scores, and more severe symptoms compared to the control group. Notably, all mice in both the cGVHD and control groups survived until the conclusion of the study. Induction of cGVHD resulted in B-cell dysregulation, evidenced by elevated serum BAFF levels and a decreased proportion of Bregs. However, treatment with RTX combined with CsA ameliorated B-cell dysregulation and significantly reduced serum levels of pro-inflammatory factors in cGVHD mice, with decreases of 39.78% in TNF-α and 37.89% in IL-6.

CONCLUSION

The combination of RTX and CsA effectively mitigates B-cell dysregulation in cGVHD, thereby reducing the severity and progression of the disease.

Murine models of graft versus host disease (GVHD): Focus on ocular GVHD

Graft versus host disease (GVHD) remains a major and serious complication of allogeneic hematopoietic stem cell transplantation. Based on the time of onset, clinical phenotypes, progression kinetics, and pathophysiology, GVHD is stratified into acute, chronic, and overlapping types. The eyes are among the most commonly affected organs in GVHD. Mouse models have played an important role in understanding the several key elements of GVHD pathobiology. The current review discusses the immunology, pathology, and key phenotypic features of mouse models of systemic GVHD. Furthermore, a critical appraisal of mouse models of ocular GVHD (oGVHD) is provided. The disease mechanisms underlying the ocular surface, meibomian gland, and lacrimal gland injury in these models are reviewed, and the relevance of oGVHD murine models to clinical oGVHD is also included.

PD-L1's Role in Preventing Alloreactive T Cell Responses Following Hematopoietic and Organ Transplant

Over the past decade, Programmed Death-Ligand 1 (PD-L1) has emerged as a prominent target for cancer immunotherapies. However, its potential as an immunosuppressive therapy has been limited. In this review, we present the immunological basis of graft rejection and graft-versus-host disease (GVHD), followed by a summary of biologically relevant molecular interactions of both PD-L1 and Programmed Cell Death Protein 1 (PD-1). Finally, we present a translational perspective on how PD-L1 can interrupt alloreactive-driven processes to increase immune tolerance. Unlike most current therapies that block PD-L1 and/or its interaction with PD-1, this review focuses on how upregulation or reversed sequestration of this ligand may reduce autoimmunity, ameliorate GVHD, and enhance graft survival following organ transplant.

IL-39 promotes chronic graft-versus-host disease by increasing T and B Cell pathogenicity

BACKGROUND

Chronic graft-versus-host disease (cGVHD) remains a major complication during the late phase of allogeneic hematopoietic stem cell transplantation (allo-HSCT). IL-39, a newly described pro-inflammatory cytokine belonging to the IL-12 family, plays a role in lupus development. Recently, IL-39 has been identified as a pathogenic factor in acute GVHD (aGVHD). However, the role of IL-39 in the pathogenesis of cGVHD remains unclear.

METHODS

We constructed a recombinant IL-39 plasmid and established scleroderma and lupus-like cGVHD models. Quantitative PCR and enzyme-linked immunosorbent assay (ELISA) were used to detect IL-39 expression in mice and patients post transplantation, respectively. Hydrodynamic gene transfer (HGT) was performed to achieve IL-39 overexpression in vivo. Multiparameter flow cytometry, western blotting, and assays in vitro were performed to investigate the effect of IL-39 on cGVHD.

RESULTS

The relative expression of IL-23p19 and EBi3 was significantly increased in the intestine of cGVHD mice on day 40 post allo-HSCT, and IL-39 levels were significantly elevated in the serum of patients following allo-HSCT. Overexpression of IL-39 significantly aggravated the severity of cGVHD. Increased IL-39 levels promoted T-cell activation and germinal center responses, and may exacerbate thymic damage. Consistently, blocking IL-39 markedly ameliorated immune dysregulation in the cGVHD mice. Furthermore, we found that IL-39 was produced by B cells, CD11b⁺ cells, and CD8⁺T cells after activation. Stimulation of IL-39 led to upregulation of the IL-39 receptor on CD4⁺T cells and further caused activation of the STAT1/STAT3 pathway, through which IL-39 may exert its pro-inflammatory effects.

CONCLUSION

Our study reveals a critical role for IL-39 in cGVHD pathogenesis and indicates that IL-39 may serve as a potential therapeutic target for cGVHD prevention.

P16-positive secondary tongue squamous cell carcinoma following allogeneic hematopoietic stem cell transplantation: A case report and literature review

As a method to improve the survival rate of patients with hematological malignancies, allogeneic hematopoietic stem cell transplantation (allo-HSCT) has increasingly been used for treatment. However, some potentially serious complications after allo-HSCT, including graft-versus-host disease, graft failure, infection, end-organ toxicity, and secondary malignancies, will determine the success of hematopoietic reconstitution. Here, we describe a case of a patient with p16-positive tongue squamous cell carcinoma (TSCC) following allo-HSCT. A 62-year-old man who had previously received allo-HSCT due to acute lymphocytic leukemia (AML) presented with erosions on the back of the tongue surrounded by multiple white patches, which were compatible with oral chronic graft-versus-host disease (cGVHD). During follow-up, a circular-like erosive lesion appeared on the right dorsal surface of the tongue. Biopsy of this lesion confirmed early invasive TSCC (T2N0M0). Partial glossectomy and tongue reconstruction were performed after cessation of immunosuppressants. Immunohistochemical (IHC) staining was positive for p16 and ki-67, suggesting a probable active human papillomavirus (HPV) infection. Six months after surgery, the patient showed no signs of metastasis or recurrence nor progression of oral GVHD.