Association of Serum Free Light Chain Level with Long Term Kidney Function in Patients with Newly Diagnosed Multiple Myeloma.

INTRODUCTION: Multiple myeloma frequently involves the kidneys, resulting in acute, subacute, or chronic kidney disease. Patient- and treatment-related factors are associated with the long-term development of chronic kidney disease. The aim of our study was to examine the association of serum free light chain (FLC) levels, measured at the time of diagnosis of multiple myeloma, and chronic kidney disease at subsequent follow-up. METHODS: Patients with newly diagnosed multiple myeloma were identified using cancer registries at five hospitals within an integrated healthcare system. Patients without an initial serum FLC level and a baseline and follow-up eGFR were excluded. The primary outcome of interest was an eGFR <60 mL/min/1.73 m2 or dialysis dependence, and a secondary composite outcome of low eGFR, dialysis dependence, or death at the last follow-up, up to 12 months from diagnosis. Logistic regression analyses were performed to examine the association of serum FLC level with the outcomes of interest, after adjustment for several covariates. RESULTS: A total of 300 patients were identified and 149 patients (50%) met the inclusion criteria. The median serum FLC level was 634 mg/L. Patients with a median FLC level above the median had a higher frequency of hypertension (54% vs. 81%; P < 0.001) and hyperlipidemia (37% vs. 56%; P = 0.018) and were more likely to have a low eGFR at the time of diagnosis (43% vs. 66%; P=0.006) and a higher multiple myeloma stage of disease (P=0.018). On multivariable analyses, after adjustment for age, hypertension, chronic kidney disease, FLC subtype, and multiple myeloma stage, serum FLC level (per each 100 mg/L) was independently associated with higher odds for low eGFR or dialysis dependence at follow-up (adjusted odds ratio [OR] 1.021; 95% CI 1.002, 1.041; P=0.033). This association persisted for the composite outcome of low eGFR, dialysis dependence, or death (adjusted OR 1.034; 95% CI 1.006, 1.063; P=0.018). DISCUSSION/CONCLUSION: Higher serum FLC level measured at the time of multiple myeloma diagnosis is independently associated with chronic kidney disease at up to 12 months of follow-up. Additional studies are required to validate these findings.

mTORC1 Inhibition Protects Human Regulatory T Cells From Granzyme-B-Induced Apoptosis.

Regulatory T cells (Tregs) have shown great promise as a means of cellular therapy in a multitude of allo- and auto-immune diseases-due in part to their immunosuppressive potency. Nevertheless, the clinical efficacy of human Tregs in patients has been limited by their poor in vivo homeostasis. To avert apoptosis, Tregs require stable antigenic (CD3ζ/T-cell-receptor-mediated), co-stimulatory (CD28-driven), and cytokine (IL-2-dependent) signaling. Notably, this sequence of signals supports an activated Treg phenotype that includes a high expression of granzymes, particularly granzyme B (GrB). Previously, we have shown that aside from the functional effects of GrB in lysing target cells to modulate allo-immunity, GrB can leak out of the intracellular lysosomal granules of host Tregs, initiating pro-apoptotic pathways. Here, we assessed the role of inhibiting mechanistic target of rapamycin complex 1 (mTORC1), a recently favored drug target in the transplant field, in regulating human Treg apoptosis via GrB. Using ex vivo models of human Treg culture and a humanized mouse model of human skin allotransplantation, we found that by inhibiting mTORC1 using rapamycin, intracytoplasmic expression and functionality of GrB diminished in host Tregs; lowering human Treg apoptosis by in part decreasing the phosphorylation of S6K and c-Jun. These findings support the already clinically validated effects of mTORC1 inhibition in patients, most notably their stabilization of Treg bioactivity and in vivo homeostasis.

Discovery and Validation of a Urinary Exosome mRNA Signature for the Diagnosis of Human Kidney Transplant Rejection.

BACKGROUND: Developing a noninvasive clinical test to accurately diagnose kidney allograft rejection is critical to improve allograft outcomes. Urinary exosomes, tiny vesicles released into the urine that carry parent cells' proteins and nucleic acids, reflect the biologic function of the parent cells within the kidney, including immune cells. Their stability in urine makes them a potentially powerful tool for liquid biopsy and a noninvasive diagnostic biomarker for kidney-transplant rejection. METHODS: Using 192 of 220 urine samples with matched biopsy samples from 175 patients who underwent a clinically indicated kidney-transplant biopsy, we isolated urinary exosomal mRNAs and developed rejection signatures on the basis of differential gene expression. We used crossvalidation to assess the performance of the signatures on multiple data subsets. RESULTS: An exosomal mRNA signature discriminated between biopsy samples from patients with all-cause rejection and those with no rejection, yielding an area under the curve (AUC) of 0.93 (95% CI, 0.87 to 0.98), which is significantly better than the current standard of care (increase in eGFR AUC of 0.57; 95% CI, 0.49 to 0.65). The exosome-based signature's negative predictive value was 93.3% and its positive predictive value was 86.2%. Using the same approach, we identified an additional gene signature that discriminated patients with T cell-mediated rejection from those with antibody-mediated rejection (with an AUC of 0.87; 95% CI, 0.76 to 0.97). This signature's negative predictive value was 90.6% and its positive predictive value was 77.8%. CONCLUSIONS: Our findings show that mRNA signatures derived from urinary exosomes represent a powerful and noninvasive tool to screen for kidney allograft rejection. This finding has the potential to assist clinicians in therapeutic decision making.

Regulatory T cells engineered with TCR signaling-responsive IL-2 nanogels suppress alloimmunity in sites of antigen encounter.

Adoptive cell transfer of ex vivo expanded regulatory T cells (Tregs) has shown immense potential in animal models of auto- and alloimmunity. However, the effective translation of such Treg therapies to the clinic has been slow. Because Treg homeostasis is known to require continuous T cell receptor (TCR) ligation and exogenous interleukin-2 (IL-2), some investigators have explored the use of low-dose IL-2 injections to increase endogenous Treg responses. Systemic IL-2 immunotherapy, however, can also lead to the activation of cytotoxic T lymphocytes and natural killer cells, causing adverse therapeutic outcomes. Here, we describe a drug delivery platform, which can be engineered to autostimulate Tregs with IL-2 in response to TCR-dependent activation, and thus activate these cells in sites of antigen encounter. To this end, protein nanogels (NGs) were synthesized with cleavable bis(N-hydroxysuccinimide) cross-linkers and IL-2/Fc fusion (IL-2) proteins to form particles that release IL-2 under reducing conditions, as found at the surface of T cells receiving stimulation through the TCR. Tregs surface-conjugated with IL-2 NGs were found to have preferential, allograft-protective effects relative to unmodified Tregs or Tregs stimulated with systemic IL-2. We demonstrate that murine and human NG-modified Tregs carrying an IL-2 cargo perform better than conventional Tregs in suppressing alloimmunity in murine and humanized mouse allotransplantation models. In all, the technology presented in this study has the potential to improve Treg transfer therapy by enabling the regulated spatiotemporal provision of IL-2 to antigen-primed Tregs.

Donor myeloid derived suppressor cells (MDSCs) prolong allogeneic cardiac graft survival through programming of recipient myeloid cells in vivo.

Solid organ transplantation is a lifesaving therapy for patients with end-organ disease. Current immunosuppression protocols are not designed to target antigen-specific alloimmunity and are uncapable of preventing chronic allograft injury. As myeloid-derived suppressor cells (MDSCs) are potent immunoregulatory cells, we tested whether donor-derived MDSCs can protect heart transplant allografts in an antigen-specific manner. C57BL/6 (H2Kb, I-Ab) recipients pre-treated with BALB/c MDSCs were transplanted with either donor-type (BALB/c, H2Kd, I-Ad) or third-party (C3H, H2Kk, I-Ak) cardiac grafts. Spleens and allografts from C57BL/6 recipients were harvested for immune phenotyping, transcriptomic profiling and functional assays. Single injection of donor-derived MDSCs significantly prolonged the fully MHC mismatched allogeneic cardiac graft survival in a donor-specific fashion. Transcriptomic analysis of allografts harvested from donor-derived MDSCs treated recipients showed down-regulated proinflammatory cytokines. Immune phenotyping showed that the donor MDSCs administration suppressed effector T cells in recipients. Interestingly, significant increase in recipient endogenous CD11b+Gr1+ MDSC population was observed in the group treated with donor-derived MDSCs compared to the control groups. Depletion of this endogenous MDSCs with anti-Gr1 antibody reversed donor MDSCs-mediated allograft protection. Furthermore, we observed that the allogeneic mixed lymphocytes reaction was suppressed in the presence of CD11b+Gr1+ MDSCs in a donor-specific manner. Donor-derived MDSCs prolong cardiac allograft survival in a donor-specific manner via induction of recipient's endogenous MDSCs.

Regulatory CD8 T cells that recognize Qa-1 expressed by CD4 T-helper cells inhibit rejection of heart allografts.

Induction of longstanding immunologic tolerance is essential for survival of transplanted organs and tissues. Despite recent advances in immunosuppression protocols, allograft damage inflicted by antibody specific for donor organs continues to represent a major obstacle to graft survival. Here we report that activation of regulatory CD8 T cells (CD8 Treg) that recognize the Qa-1 class Ib major histocompatibility complex (MHC), a mouse homolog of human leukocyte antigen-E (HLA-E), inhibits antibody-mediated immune rejection of heart allografts. We analyzed this response using a mouse model that harbors a point mutation in the class Ib MHC molecule Qa-1, which disrupts Qa-1 binding to the T cell receptor (TCR)-CD8 complex and impairs the CD8 Treg response. Despite administration of cytotoxic T lymphocyte antigen 4 (CTLA-4) immunoglobulin (Ig), Qa-1 mutant mice developed robust donor-specific antibody responses and accelerated heart graft rejection. We show that these allo-antibody responses reflect diminished Qa-1-restricted CD8 Treg-mediated suppression of host follicular helper T cell-dependent antibody production. These findings underscore the critical contribution of this Qa-1/HLA-E-dependent regulatory pathway to maintenance of transplanted organs and suggest therapeutic approaches to ameliorate allograft rejection.

Acute Respiratory Distress Syndrome Secondary to Radiotherapy for Breast Cancer: A Case Report.

BACKGROUND Radiotherapy is often used as an adjuvant therapy in breast cancer following surgical resection of the primary malignant tumor. It has multiple respiratory side effects, but acute respiratory distress syndrome (ARDS) is a rare complication. We describe here the case of a woman with breast cancer who developed ARDS 1 week after her final radiotherapy session. CASE REPORT A 69-year-old female with breast cancer presented 1 week after her final session of radiotherapy. She had developed a sudden onset of hypotension unresponsive to fluids, oxygen desaturation unresponsive to high flow oxygen, and new bilateral infiltrates had appeared on chest x-ray (CXR) predominant in the left upper lobe, which was interestingly the main area affected by the radiotherapy beams. A diagnosis of atypical ARDS secondary to radiotherapy was established. She was intubated and a low tidal volume/high positive end-expiratory pressure (PEEP) strategy was utilized to manage her condition. After 48 hours, the infiltrates diminished remarkably, and she was extubated the following day. On discharge, she had a completely normal CXR; a computed tomography (CT) chest performed 1 month later showed complete resolution of the alveolar opacities. CONCLUSIONS ARDS remains an extremely rare complication of thoracic radiotherapy. However, physicians must be wary of its development in order to diagnose it quickly and treat accordingly.