CD19(+)CD21(low) B cells and patients at risk for NIH-defined chronic graft-versus-host disease with bronchiolitis obliterans syndrome

The role of extracorporeal photopheresis in chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) is the most important cause of late morbidity and mortality in recipients of allogeneic blood and marrow transplantation. Despite increased understanding of biology of chronic GVHD, treatment options remain limited and ineffective. While corticosteroids represent the backbone of initial chronic GVHD treatment, they have significant long-term toxicity and more than half of the patients require second-line therapy. Among the second-line treatments for chronic GVHD, extracorporeal photopheresis (ECP) is one of the most extensively studied modalities. While high quality studies establishing true value of ECP in chronic GVHD patients are lacking, its benefits in chronic GVHD are well documented. Its putative immunomodulatory, but not immunosuppressive, properties represent an attractive alternative to the other strategies leading to global immunosuppression and the resulting risks of opportunistic infections or malignancy relapse.

Aberrant B-cell homeostasis in chronic GVHD

Recent studies have compelled further interest in the potential pathological role of B cells in chronic graft-versus-host disease (cGVHD). In patients with cGVHD, B cells are activated and primed for survival via B-cell activating factor and B-cell receptor-associated pathways. Understanding the signaling pathways that drive immune pathology in cGVHD will facilitate the development of new strategies to selectively target aberrantly activated B cells and restore normal B-cell homeostasis after allogeneic stem cell transplantation.

CD24(hi)CD27⁺ and plasmablast-like regulatory B cells in human chronic graft-versus-host disease

Interleukin 10 (IL-10)-producing B cells (regulatory B cells [Bregs]) regulate autoimmunity in mice and humans, and a regulatory role of IL-10-producing plasma cells has been described in mice. Dysfunction of B cells that maintain homeostasis may play a role in the pathogenesis of chronic graft-versus-host disease (cGVHD) after allogeneic stem cell transplantation. Here, we found a relation between decreased Breg frequencies and cGVHD severity. An impaired ability of B cells to produce IL-10, possibly linked to poor signal transducer and activator of transcription 3 and extracellular signal-regulated kinase phosphorylation, was found in patients with active cGVHD. IL-10 production was not confined to a single B-cell subset, but enriched in both the CD24(hi)CD27(+) and CD27(hi)CD38(hi) plasmablast B-cell compartments. In vitro plasmablast differentiation increased the frequency of IL-10-producing B cells. We confirmed that allogeneic transplant recipients had an impaired reconstitution of the memory B-cell pool. cGVHD patients had less CD24(hi)CD27(+) B cells and IL-10-producing CD24(hi)CD27(+) B cells. Patients with cGVHD had increased plasmablast frequencies but decreased IL-10-producing plasmablasts. These results suggest a role of CD24(hi)CD27(+) B-cell and plasmablast-derived IL-10 in the regulation of human cGVHD.

Biopsy-verified bronchiolitis obliterans and other noninfectious lung pathologies after allogeneic hematopoietic stem cell transplantation

Bronchiolitis obliterans (BO) is a serious complication of allogeneic hematopoietic stem cell transplantation (HSCT). Lung biopsy is the gold standard for diagnosis. This study describes the course of BO and assesses the congruity between biopsy-verified BO and a modified version of the National Institutes of Health's consensus criteria for BO syndrome (BOS) based exclusively on noninvasive measures. We included 44 patients transplanted between 2000 and 2010 who underwent lung biopsy for suspected BO. Of those, 23 were diagnosed with BO and 21 presented other noninfectious pulmonary pathologies, such as cryptogenic organizing pneumonia, diffuse alveolar damage, interstitial pneumonia, and nonspecific interstitial fibrosis. Compared with patients with other noninfectious pulmonary pathologies, BO patients had significantly lower values of forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity, and maximal mid-expiratory flow throughout follow-up, but there was no difference in the change in pulmonary function from the time of lung biopsy. The BO diagnosis was not associated with poorer overall survival. Fifty-two percent of patients with biopsy-verified BO and 24% of patients with other noninfectious pulmonary pathology fulfilled the BOS criteria. Pathological BO diagnosis was not superior to BOS criteria in predicting decrease in pulmonary function beyond the time of biopsy. A lung biopsy may provide a characterization of pathological patterns that can extend our knowledge on the pathophysiology of HSCT-related lung diseases.

CD19+CD21low B cells and CD4+CD45RA+CD31+ T cells correlate with first diagnosis of chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) is a serious and frequent complication of allogeneic hematopoietic stem cell transplantation (HCT). Currently, no biomarkers for prediction and diagnosis of cGVHD are available. We performed a large prospective study focusing on noninvasive biomarkers for National Institutes of Health-defined cGVHD patients (n = 163) in comparison to time-matched HCT recipients who never experienced cGVHD (n = 64), analyzed from day 100 after HCT. In logistic regression analysis, CD19(+)CD21(low) B cells (P = .002; hazard ratio [HR], 3.31; 95% confidence interval [CI], 1.53 to 7.17) and CD4(+)CD45RA(+)CD31(+) T cells (P < .001; HR, 3.88; 95% CI, 1.88 to 7.99) assessed on day 100 after HCT were significantly associated with subsequent development of cGVHD, independent of clinical parameters. A significant association with diagnosis of cGVHD was only observed for CD19(+)CD21(low) B cells (P = .008; HR, 3.00; 95% CI, 1.33 to 6.75) and CD4(+)CD45RA(+)CD31(+) T cells (P = .017; HR, 2.80; 95% CI, 1.19 to 6.55). CD19(+)CD21(low) B cells were found to have the highest discriminatory value with an area under the receiver operating curve of .77 (95% CI, .64 to .90). Our results demonstrate that CD19(+)CD21(low) B cells and CD4(+)CD45RA(+)CD31(+) T cells are significantly elevated in patients with newly diagnosed cGVHD.

Graft-versus-host disease biomarkers: omics and personalized medicine

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the most effective form of tumor immunotherapy available to date and the frequency of transplants continues to increase worldwide. However, while allo-HSCT usually induces a beneficial graft-versus leukemia effect, a major source of morbidity and mortality following allo-HSCT is graft-versus-host disease (GVHD). Currently available diagnostic and staging tools frequently fail to identify those at higher risk for GVHD morbidity, treatment unresponsiveness, and death. Furthermore, there are shortcomings in the risk stratification of patients before GVHD clinical signs develop. In parallel, recent years have been characterized by an explosive evolution of omics technologies, largely due to technological advancements in chemistry, engineering, and bioinformatics. Building on these opportunities, plasma biomarkers have been identified and validated as promising diagnostic and prognostic tools for acute GVHD. This review summarizes current information on the types of GVHD biomarkers, the omics tools used to identify them, the biomarkers currently validated as acute GVHD markers, and future recommendations for incorporating biomarkers into new grading algorithms for risk-stratifying patients and creating more personalized treatment courses. Future directions will include randomized evaluations of these biomarkers in multicenter prospective studies while extending on the need for biomarkers of chronic GVHD.

Impact of acute and chronic graft-versus-host disease on human B-cell generation and replication

Using B-cell rearrangement excision circle measurements, we analyzed B-cell reconstitution in a cohort of 243 patients who underwent allogeneic stem cell transplantation. Acute and chronic graft-versus-host disease (aGVHD and cGVHD, respectively) transiently increased B-cell replication but decreased overall B-cell neogenesis with a clear difference in terms of kinetics. Moreover, the impact of aGVHD in the absence of cGVHD was transient, recovering at month 6 similar values as in patients who did not suffer from GVHD. Conversely, impact of cGVHD at month 12 in multivariate analysis was independent of the previous aGVHD effect on B-cell output. Finally, we showed in patients affected with cGVHD a higher B-cell division rate that correlates with an elevated BAFF/CD19(+) B-cell ratio, supporting a B-cell hyperactivation state in vivo.

Treatment of chronic graft-versus-host disease with bortezomib

Chronic graft-versus-host disease (cGVHD) following allogeneic hematopoietic stem cell transplantation (HSCT) has emerged as a predominant complication following HSCT and has a distinct etiology. We and others have previously demonstrated that bortezomib, a proteasome inhibitor, can prevent but not treat acute GVHD in mice. To assess the effects of bortezomib on cGVHD, a mouse minor histocompatibility antigen-mismatched strain combination was used to mimic clinical cGVHD sclerodermatous pathogenesis and phenotype. Treatment of ongoing cGVHD with bortezomib ameliorated cutaneous lesions, which were also associated with a reduction in total numbers of germinal center B cells and lower B-cell activating factor gene expression levels in cutaneous tissues. Importantly, lymphoma-bearing mice receiving allogeneic HSCT with bortezomib preserved graft-versus-tumor (GVT) effects. Based on these animal studies, we initiated an intrapatient dose escalation clinical trial in patients with extensive steroid-intolerant, dependent, or resistant cGVHD. Marked clinical improvement was observed in patients, which was also associated with reductions of peripheral B cells and minimal toxicity. These results indicate that bortezomib can be of significant use in the treatment of cGVHD and may also allow for maintenance of GVT. This trial was registered at www.clinicaltrials.gov as #NCT01672229.

Current issues in chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) is a frequent and potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation. Increased transplantation of older patients and the more frequent use of unrelated donors has led to increased numbers of patients with this painful complication. Recent advances have been made in understanding the pathophysiology of chronic GVHD and in establishing precise criteria for diagnosis and classification of disease manifestations. These advances will hopefully pave the way for improving both the prophylaxis and treatment of chronic GVHD.

Current issues in chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) is a frequent and potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation. Increased transplantation of older patients and the more frequent use of unrelated donors has led to increased numbers of patients with this painful complication. Recent advances have been made in understanding the pathophysiology of chronic GVHD and in establishing precise criteria for diagnosis and classification of disease manifestations. These advances will hopefully pave the way for improving both the prophylaxis and treatment of chronic GVHD.

Factors associated with bronchiolitis obliterans syndrome and chronic graft-versus-host disease after allogeneic hematopoietic cell transplantation

Bronchiolitis obliterans syndrome (BOS) is a form of chronic graft vs. host disease (cGVHD) and a highly morbid pulmonary complication after allogeneic hematopoietic stem cell transplantation (HSCT). We assessed the prevalence and risk factors for BOS and cGVHD in a cohort of HSCT recipients, including those who received reduced intensity conditioning (RIC) HSCT. Between January 1, 2000 and June 30, 2010, all patients who underwent allogeneic HSCT at our institution (n = 1854) were retrospectively screened for the development of BOS by PFT criteria. We matched the BOS cases with two groups of control patients: (1) patients who had concurrent cGVHD without BOS and (2) those who developed neither cGVHD nor BOS. Comparisons between BOS patients and controls were conducted using t-test or Fisher's exact tests. Multivariate regression analysis was performed to examine factors associated with BOS diagnosis. All statistical analyses were performed using SAS 9.2. We identified 89 patients (4.8%) meeting diagnostic criteria for BOS at a median time of 491 days (range: 48-2067) after HSCT. Eighty-six (97%) of our BOS cohort had extra-pulmonary cGVHD. In multivariate analysis compared to patients without cGVHD, patients who received busulfan-based conditioning, had unrelated donors, and had female donors were significantly more likely to develop BOS, while ATG administration was associated with a lower risk of BOS. Our novel results suggest that busulfan conditioning, even in RIC transplantation, could be an important risk factor for BOS and cGVHD.

Biologic markers of chronic GVHD

Biologic markers of chronic GVHD may provide insight into the pathogenesis of the syndrome, identify molecular targets for novel interventions, and facilitate advances in clinical management. Despite extensive work performed to date largely focused on prediction and diagnosis of the syndrome, little synthesis of findings and validation of promising candidate markers in independent populations has been performed. Studies suggest that risk for subsequent chronic GVHD development may be associated with donor-recipient genetic polymorphism, deficiency in regulatory immune cell populations (NK, Treg, DC2), and variation in inflammatory and immunoregulatory mediators post-HCT (increased TNFα, IL-10 and BAFF, and decreased TGFβ and IL-15). Established chronic GVHD is associated with alteration in immune cell populations (increased CD3(+) T cells, Th17, CD4(+) and CD8(+) effector memory cells, monocytes, CD86 expression, BAFF/B cell ratio, and deficiency of Treg, NK cells, and naïve CD8(+) T cells). Inflammatory and immunomodulatory factors (TNFα, IL-6, IL-1β, IL-8, sIL-2R, and IL-1Ra, BAFF, anti-dsDNA, sIL-2Rα, and sCD13) are also perturbed. Little is known about biologic markers of chronic GVHD phenotype and severity, response to therapy, and prognosis.

Rituximab prophylaxis prevents corticosteroid-requiring chronic GVHD after allogeneic peripheral blood stem cell transplantation: results of a phase 2 trial

B cells are implicated in the pathophysiology of chronic graft-vs-host disease (GVHD), and phase 2 trials suggest that B cell depletion can treat established chronic GVHD. We hypothesized that posttransplantation B cell depletion could prevent the occurrence of chronic GVHD. We performed a 65-patient phase 2 trial of rituximab (375 mg/m(2) IV), administered at 3, 6, 9, and 12 months after transplantation. Rituximab administration was safe without severe infusional adverse events. The cumulative incidences of chronic GVHD and systemic corticosteroid-requiring chronic GVHD at 2 years from transplantation were 48% and 31%, respectively, both lower than the corresponding rates in a concurrent control cohort (60%, P = .1, and 48.5%, P = .015). There was no difference in relapse incidence, but treatment-related mortality at 4 years from transplantation was significantly lower in treated subjects when compared with controls (5% vs 19%, P = .02), and overall survival was superior at 4 years (71% vs 56%, P = .05). At 2 years from transplantation, the B-cell activating factor/B-cell ratio was significantly higher in subjects who developed chronic GVHD in comparison with those without chronic GVHD (P = .039). Rituximab can prevent systemic corticosteroid-requiring chronic GVHD after peripheral blood stem cell transplantation and should be tested in a prospective randomized trial.

The BAFF/APRIL system: emerging functions beyond B cell biology and autoimmunity

The BAFF system plays a key role in the development of autoimmunity, especially in systemic lupus erythematosus (SLE). This often leads to the assumption that BAFF is mostly a B cell factor with a specific role in autoimmunity. Focus on BAFF and autoimmunity, driven by pharmaceutical successes with the recent approval of a novel targeted therapy Belimumab, has relegated other potential roles of BAFF to the background. Far from being SLE-specific, the BAFF system has a much broader relevance in infection, cancer and allergy. In this review, we provide the latest views on additional roles of the BAFF system in health and diseases, as well as an update on BAFF and autoimmunity, with particular focus on current clinical trials.