In allogeneic-hematopoietic stem cell transplantation for acute myeloid leukemia (AML), donor T cells combat leukemia through the graft-versus-leukemia (GVL) effect, while they also pose a risk of triggering life-threatening graft-versus-host disease (GVHD) by interacting with recipient cells. The onset of GVHD hinges on the interplay between donor T cells and recipient antigen-presenting cells (APCs), sparking T-cell activation. However, effective methods to balance GVHD and GVL are lacking.
In our study, we crafted nanocapsules by layering polycationic aminated gelatin and polyanionic alginate onto the surface of T cells, examining potential alterations in their fundamental physiological functions. Subsequently, we established an AML mouse model and treated it with transplantation of bone marrow cells (BMCs) combined with encapsulated T cells to investigate the GVL and anti-GVHD effects of encapsulated T cells. In vitro co-culture was employed to probe the effects of encapsulation on immune synapses, co-stimulatory molecules, and tumor-killing pathways.
Transplantation of BMCs combined with donor T cells selectively encapsulated onto AML mice significantly alleviates GVHD symptoms while preserving essential GVL effects. Encapsulated T cells exerted their immunomodulatory effects by impeding the formation of immune synapses with recipient APCs, thereby downregulating co-stimulatory signals such as CD28-CD80, ICOS-ICOSL, and CD40L-CD40. Recipient mice receiving encapsulated T-cell transplantation exhibited a marked increase in donor Ly-5.1-BMC cell numbers, accompanied by unaltered in vivo expression levels of perforin and granzyme B. While transient inhibition of donor T-cell cytotoxicity in the tumor microenvironment was observed in vitro following single-cell nanoencapsulation, subsequent restoration to normal antitumor activity ensued, attributed to selective permeability of encapsulated vesicle shells and material degradation. Moreover, the expression of apoptotic proteins and FAS-FAS ligand pathway at normal levels was still observed in leukemia tumor cells.
Encapsulated donor T cells effectively mitigate GVHD while preserving the GVL effect by minimizing co-stimulatory signaling with APCs through early immune isolation. Subsequent degradation of nanocapsules restores T-cell cytotoxic efficacy against AML cells, mediated by cytotoxic pathways. Using transplant-encapsulated T cells offers a promising strategy to suppress GVHD while preserving the GVL effect.
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People living with HIV (PLWH) who are immune nonresponders (INRs) are at greater risk of comorbidity and mortality than are immune responders (IRs) who restore their CD4+ T cell count after antiretroviral therapy (ART). INRs have low CD4+ T cell counts (<350 c/μL), heightened systemic inflammation, and increased CD4+ T cell cycling (Ki67+). Here, we report the findings that memory CD4+ T cells and plasma samples of INRs from several cohorts are enriched in gut-derived bacterial solutes p-cresol sulfate (PCS) and indoxyl sulfate (IS) that both negatively correlated with CD4+ T cell counts. In vitro PCS or IS blocked CD4+ T cell proliferation, induced apoptosis, and diminished the expression of mitochondrial proteins. Electron microscopy imaging revealed perturbations of mitochondrial networks similar to those found in INRs following incubation of healthy memory CD4+ T cells with PCS. Using bacterial 16S rDNA, INR stool samples were found enriched in proteolytic bacterial genera that metabolize tyrosine and phenylalanine to produce PCS. We propose that toxic solutes from the gut bacterial flora may impair CD4+ T cell recovery during ART and may contribute to CD4+ T cell lymphopenia characteristic of INRs.

Hermansky-Pudlak Syndrome type-1 (HPS-1) is an autosomal recessive disorder caused by mutations in HPS1 which result in reduced expression of the HPS-1 protein, defective lysosome-related organelle (LRO) transport and absence of platelet delta granules. Patients with HPS-1 exhibit oculocutaneous albinism, colitis, bleeding and pulmonary fibrosis postulated to result from a dysregulated immune response. The effect of the HPS1 mutation on human mast cells (HuMCs) is unknown. Since HuMC granules classify as LROs along with platelet granules and melanosomes, we set out to determine if HPS-1 cutaneous and CD34+ culture-derived HuMCs have distinct granular and cellular characteristics. Cutaneous and cultured CD34+-derived HuMCs from HPS-1 patients were compared with normal cutaneous and control HuMCs, respectively, for any morphological and functional differences. One cytokine-independent HPS-1 culture was expanded, cloned, designated the HP proMastocyte (HPM) cell line and characterized. HPS-1 and idiopathic pulmonary fibrosis (IPF) alveolar interstitium showed numerous HuMCs; HPS-1 dermal mast cells exhibited abnormal granules when compared to healthy controls. HPS-1 HuMCs showed increased CD63, CD203c and reduced mediator release following FcɛRI aggregation when compared with normal HuMCs. HPM cells also had the duplication defect, expressed FcɛRI and intracytoplasmic proteases and exhibited less mediator release following FcɛRI aggregation. HPM cells constitutively released IL-6, which was elevated in patients' serum, in addition to IL-8, fibronectin-1 (FN-1) and galectin-3 (LGALS3). Transduction with HPS1 rescued the abnormal HPM morphology, cytokine and matrix secretion. Microarray analysis of HPS-1 HuMCs and non-transduced HPM cells confirmed upregulation of differentially expressed genes involved in fibrogenesis and degranulation. Cultured HPS-1 HuMCs appear activated as evidenced by surface activation marker expression, a decrease in mediator content and impaired releasibility. The near-normalization of constitutive cytokine and matrix release following rescue by HPS1 transduction of HPM cells suggests that HPS-1 HuMCs may contribute to pulmonary fibrosis and constitute a target for therapeutic intervention.