The Role of B Cell Targeting in Chronic Graft-Versus-Host Disease

Bortezomib Maintenance After Allogeneic Transplantation in Newly Diagnosed Myeloma Patients Results in Decreased Incidence and Severity of Chronic GVHD

Allogeneic hematopoietic cell transplantation (HCT) has curative potential in myeloma but remains hampered by high rates of relapse and chronic graft-versus-host disease (GVHD). We hypothesized that bortezomib (BTZ) as maintenance therapy after allo HCT could not only decrease the incidence of relapse but also the incidence and severity of chronic GVHD. The primary endpoint of this study was to determine whether BTZ maintenance decreases the incidence and severity of chronic GVHD using National Institutes of Health (NIH) criteria. The secondary endpoints were to determine the immunosuppression burden, organ involvement and survival (overall survival, progression-free survival) in patients either receiving or not receiving BTZ. In this retrospective study, we compared the outcome of 46 myeloma patients who received BTZ after upfront tandem auto-allo HCT between 2008 and 2020 to 61 patients without maintenance. We explored the impact of BTZ maintenance on incidence and severity of chronic GVHD using the 2014 NIH criteria. At 2 years, incidences of overall (61.2% versus 83.6%; P = .001), and moderate/severe chronic GVHD (44.5% versus 77.0%; P = .001) were significantly lower in BTZ recipients who had less mouth (43% versus 67%; P = .018) and eyes (9% versus 41%; P = .001) involvement at initial diagnosis. We report a lower use of systemic steroids (45.1% versus 76.4%; P < .001), mycophenolate mofetil (15.5% versus 28.2%; P = .031) and tacrolimus (34.5% versus 70.6%; P < .001) in BTZ recipients. Probability of being alive and off systemic immunosuppressants at 3 years was 77% in BTZ recipients and 56% in controls (P = .046). To date, there is no difference in survival between both groups. In summary, BTZ maintenance improved incidence and severity of chronic GVHD and should be considered as a valid option in myeloma patients receiving upfront tandem auto-allo HCT.

Conglomeration of T- and B-Cell Matrix Responses Determines the Potency of Human Bone Marrow Mesenchymal Stromal Cells

Cell manufacturing facilities need to define the potency of mesenchymal stromal cells (MSCs) as cellular therapeutics in advanced clinical trials or marketing approval. Since MSCs' mechanism of action in humans is not well defined, more than a single functional property of MSCs needs to be captured as a surrogate measure of potency utilizing assay matrix technologies. However, the current limitation is the sole investigation of MSC-mediated T-cell suppression as a surrogate measure of potency. We investigated the effect of MSCs on B-cell matrix responses to be incorporated into the assay matrix potency analytical system. Our results demonstrate that MSCs inhibit B-cell differentiation and block pan-antibody secretion upon activation of B cells in the PBMCs. In contrast, MSCs are inferior in blocking B-cell matrix responses when purified B cells are used. Mechanistic analysis has demonstrated that MSC-mediated inhibition of B-cell matrix responses is non-contact dependent and Tryptophan metabolic pathway plays a major role, akin to the mechanism of MSC-mediated T-cell suppression. MSCs also inhibit both T-cell and B-cell responses when both of these lymphoid populations are concurrently activated in the PBMCs. Secretome analysis of MSC and T/B cell-activated PBMC cocultures identified direct and inverse correlative matrix signatures between humoral antibody isotypes and secretory molecules. The current analysis of the combined and concomitant investigation of T-cell and B-cell matrix responses fulfills the potency assay matrix strategy by incorporating MSCs' interaction with more than a single inflammatory immune responder.

Cell-based therapy in prophylaxis and treatment of chronic graft-versus-host disease

Hematopoietic allogeneic stem cell transplantation (allo-SCT) is a curative option for patients with hematological malignancies. However, due to disparities in major and minor histocompatibility antigens between donor and recipient, severe inflammatory complications can occur, among which chronic graft-versus-host disease (cGVHD) can be life-threatening. A classical therapeutic approach to the prevention and treatment of cGVHD has been broad immunosuppression, but more recently adjuvant immunotherapies have been tested. This review summarizes and discusses immunomodulatory approaches with T cells, including chimeric antigen receptor (CAR) and regulatory T cells, with natural killer (NK) cells and innate lymphoid cells (ILCs), and finally with mesenchymal stromal cells (MSC) and extracellular vesicles thereof. Clinical studies and pre-clinical research results are presented likewise.

Mangiferin Promotes Bregs Level, Activates Nrf2 Antioxidant Signaling, and Inhibits Proinflammatory Cytokine Expression in Murine Splenic Mononuclear Cells In Vitro

Recent studies indicated that regulatory B cells (Bregs) and nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant signaling pathway play important roles in the pathogenesis of chronic graft-versus-host disease (cGVHD). Mangiferin (MA), a polyphenol compound, has been reported to activate Nrf2/antioxidant-responsive element (ARE) signaling pathway. This study was aimed to investigate the effects of MA on Bregs and Nrf2 antioxidant signaling in murine splenic mononuclear cells (MNCs) in vitro. Our results revealed that MA could increase the Bregs level in murine splenic MNCs. Moreover, MA up-regulated the expression of Bregs-associated immunosuppressive factor interleukin-10 (IL-10) by activating the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) signaling in murine splenic MNCs. Meanwhile, MA inhibited the proinflammatory cytokines IL-2 and interferon-γ (INF-γ) at both mRNA and protein levels. MA also enhanced the transcription and protein expression of Nrf2 and NADPH quinine oxidoreductase 1 (NQO1), whereas decreased that of Kelch-like ECH-associated protein 1 (Keap1) in murine splenic MNCs. Moreover, MA promoted the proliferation and inhibited the apoptosis of murine splenic MNCs. These results suggested that MA exerts immunosuppressive effects by upregulating the Bregs level, activating the Nrf2 antioxidant pathway, and inhibiting the expression of pro-immunoinflammatory factors. MA, as a natural immunomodulatory and anti-inflammatory agent, may have a potential role in the prophylaxis and treatment of cGVHD.

Update on ocular graft-versus-host disease

Ocular graft-versus-host disease (oGVHD) occurs as a complication following hematopoietic stem cell transplantation and is associated with significant ocular morbidity resulting in a marked reduction in the quality of life. With no current consensus on treatment protocols, management becomes challenging as recurrent oGVHD often refractory to conventional treatment. Most authors now diagnose and grade the disease based on criteria provided by the National Institutes of Health Consensus Conference (NIH CC) or the International Chronic oGVHD (ICCGVHD) consensus group. This article will provide an insight into the diagnostic criteria of oGVHD, its classification, and clinical severity grading scales. The inflammatory process in oGVHD can involve the entire ocular surface including the eyelids, meibomian gland, corneal, conjunctiva, and lacrimal system. The varied clinical presentations and treatment strategies employed to manage them have been discussed in the present study. The recent advances in ocular surface imaging in oGVHD patients such as the use of meibography and in vivo confocal microscopy may help in early diagnosis and prognostication of the disease. Researching tear proteomics and identification of novel potential tear biomarkers in oGVHD patients is an exciting field as they may help in objectively diagnosing the disease and monitoring the response to treatment.