Swaminathan, Sundararaman

ABSTRACT Background Immunomodulatory agents (IMiDs) are a cornerstone in the successful management of multiple myeloma (MM). However, acquired IMiD resistance leading to disease relapses remains a major barrier. Hydrogen peroxide generation and oxidative stress are key mediators that determine IMiD's effectiveness in MM. Iron plays a key role in the generation of oxidative stress; therefore, cellular iron levels are tightly governed. FTH1 is the major iron storage protein that tightly regulates cellular iron availability. Hence, the present study is targeted to investigate the role of FTH1 in MM and IMiD resistance. Methods IMiD‐sensitive and IMiD‐resistant MM cells were analyzed for expression of iron‐metabolism genes. CRISPR‐cas9‐mediated knockout of FTH1 was performed and the after‐effects were assessed through multiple experiments. Results Initial analysis showed a positive correlation between FTH1 expression and IMiD resistance in MM cells. FTH1 ‐KO reduced IMiD sensitivity in the KMS11 cell line but had no effect on the RPMI8226 cell line. RNA‐seq data showed downregulation of ER‐stress and calcium signaling genes after FTH1 ‐KO. Further, KMS11‐ FTH1 KO cells exhibited lower intracellular ROS, labile‐iron, and mitochondrial superoxide levels along with increased CD63, suggesting activation of L‐ferritin secretory pathways. Conclusion Data reveals a link between FTH1 , labile iron, ROS, and IMiD resistance in MM cells.

The indications for immune checkpoint inhibitor (ICI) use in cancer treatment continue to expand. This is attributable to their proven anticancer activity in addition to their tolerability and favorable toxicity profile as compared to conventional chemotherapeutic agents. ICIs work by blocking the inhibitory signals between tumor cells and T-cells, thereby enhancing the T-cell cytotoxic activity to inhibit tumor growth. Because of their immune-stimulating effect, ICIs are linked to adverse renal outcomes in both native and transplanted kidneys. The risk of kidney allograft rejection in the setting of ICI use has been reported to be around 40%, leading to an increased risk of graft loss. In this report, we review the literature examining outcomes in kidney transplant recipients receiving ICIs for various oncologic indications.

AbstractBackgroundUrinary Tract Infections are the most common post‐transplant infection and can have varied presentations. This study aimed to describe the outcomes of kidney transplant recipients with asymptomatic histologic pyelonephritis on allograft biopsy. Histologic Pyelonephritis was defined as neutrophil cast or neutrophilic tubulitis, interstitial infiltrates with predominant neutrophils, and no evidence of rejection or glomerulonephritis on biopsy.MethodsThe study included 123 kidney transplant recipients, of whom 95 underwent protocol biopsies, and 28 had biopsies for elevated creatinine within the first 2 years of a kidney transplant.ResultsThe mean age of the cohort was 55.3 years, with 52% females and 78% deceased donor transplants. The risk factors for asymptomatic histologic pyelonephritis were recipient female sex (OR 1.89, 1.3–2.7, diabetes mellitus (OR 2.479, 1.687–3.645), and deceased donation (OR 1.69, 1.098–2.63). The incidence of asymptomatic pyelonephritis on protocol biopsy was 1.7%, with 52% having positive urine cultures and Escherichia coli being the most common bacteria. Subjects with asymptomatic pyelonephritis had inferior graft survival compared to the matched cohort HR 1.88 (1.06–3.35), p = .0281. In addition, of these 123 subjects, 68 (55%) subsequently developed pyelonephritis, and 34 subjects had pyelonephritis within 6 months after this episode. Subjects with recurrent infections exhibited lower survival HR 2.86 (1.36–6.02) and a trend toward higher rejection risk.ConclusionAsymptomatic histologic pyelonephritis can occur in kidney transplant recipients and is associated with inferior graft survival.

Abstract Bone marrow (BM) niche plays critical roles in promoting progression and chemoresistance of multiple myeloma (MM), but the iron metabolism bridging the malignant plasma cells and BM stromal cells (BMSCs) has not been well elucidated. Using in vitro and in vivo models of interaction of MM and BMSCs, we identified that iron level was augmented due to the elevated expression of transferrin in MM cells, and the accumulation of iron desensitized MM cells to proteasome inhibitors (PIs) treatment and promoted productions of cholesterol and lanosterol. Simultaneously, direct contact with BMSCs remarkably upregulated the protein level of GPX4, a ROS eraser, to obviate ferroptosis in MM cells. Mechanistic studies revealed that CD40/CD40 ligand (CD40L) signaling promoted the expressions of transferrin and SUMO-specific protease 3 (SENP3), and SENP3 stabilized GPX4 protein via deSUMOylation modification. GPX4 inhibitor induced ferroptosis was cell-cell contact dependent, since blocking CD40/CD40L interaction, or depletion of Cd40l in BMSCs from Cd40lfl/fl;Prx1Cre/+ mice, eliminated the anti-MM efficacy of RSL3 in the Vk*MYC mouse model of myeloma, but not in the patient-derived xenografts (PDX) model. Our study deciphers mechanism of iron metabolism in regulating MM chemoresistance, and clarifies the therapeutic potential of non-apoptosis strategies in managing refractory or relapsed MM patients.