Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapy for hematological malignancies. However, graft-versus-host disease (GVHD) and relapse after allo-HSCT remain major impediments. Chimeric antigen receptors (CARs) direct tumor cell recognition of adoptively transferred T cells.1–5 CD19 is an attractive CAR target, expressed in most B cell malignancies as well as normal B cells.6,7 Clinical trails using autologous CD19-targeted T cells have shown remarkable outcomes in various B cell malignancies8–15. The use of allogeneic CAR T cells poses a concern of increased GVHD, which however has not been reported in selected patients infused with donor-derived CD19-CAR T cells after allo-HSCT.16,17 To understand the mechanism whereby allogeneic CD19-CAR T cells may mediate anti-lymphoma activity without significant GVHD, we studied donor-derived CD19-CAR T cells in allo-HSCT and lymphoma models in mice. We demonstrate that alloreactive T cells expressing CD28-costimulated CD19-CARs experienced enhanced T cell stimulation, resulting in progressive loss of effector function and proliferative potential, clonal deletion, and significantly decreased GVHD. Concurrently, other CAR T cells present in bulk donor T cell populations retained their anti-lymphoma activity consistent with the requirement for engaging both the TCR and the CAR to accelerate T cell exhaustion. In contrast, first generation and 4-1BB-costimulated CARs increased GVHD. These findings could explain reduced risk of GVHD with cumulative TCR and CAR signaling.

SUMMARY Atg16L1 mediates the cellular degradative process of autophagy and is considered a critical regulator of inflammation based on its genetic association with inflammatory bowel disease. Here we find that Atg16L1 deficiency leads to an exacerbated graft-versus-host disease (GVHD) in a mouse model of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Atg16L1-deficient allo-HSCT recipients with GVHD displayed increased T cell proliferation due to increased dendritic cell (DC) numbers and co-stimulatory molecule expression. Reduced autophagy within DCs was associated with lysosomal abnormalities and decreased amounts of A20, a negative regulator of DC activation. These results broaden the function of Atg16L1 and the autophagy pathway to include a role in limiting a DC-mediated response during inflammatory disease, such as GVHD.

Primary Sjögren’s syndrome (pSS) is a complex autoimmune disease characterized by dysfunction of secretory epithelia with only palliative therapy. Patients present with a constellation of symptoms, and the diversity of symptomatic presentation has made it difficult to understand the underlying disease mechanisms. In this study, aggregation of unbiased transcriptome profiling data sets of minor salivary gland biopsies from controls and Sjögren’s syndrome patients identified increased expression of lysosome-associated membrane protein 3 (LAMP3/CD208/DC-LAMP) in a subset of Sjögren’s syndrome cases. Stratification of patients based on their clinical characteristics suggested an association between increased LAMP3 expression and the presence of serum autoantibodies including anti-Ro/SSA, anti-La/SSB, anti-nuclear antibodies. In vitro studies demonstrated that LAMP3 expression induces epithelial cell dysfunction leading to apoptosis. Interestingly, LAMP3 expression resulted in the accumulation and release of intracellular TRIM21 (one component of SSA), La (SSB), and α-fodrin protein, common autoantigens in Sjögren’s syndrome, via extracellular vesicles in an apoptosis-independent mechanism. This study defines a clear role for LAMP3 in the initiation of apoptosis and an independent pathway for the extracellular release of known autoantigens leading to the formation of autoantibodies associated with this disease. ClinicalTrials.gov Identifier: NCT00001196, NCT00001390, NCT02327884.