Klomjit, Nattawat

ABSTRACT Acute renal failure due to cast nephropathy (CAN) is a severe complication of multiple myeloma (MM). Here, we aimed to identify parameters associated with renal outcomes and survival in newly diagnosed MM patients with CAN‐related acute renal failure and to validate the IMWG criteria for renal response. CAN diagnosis was based on biopsy or clinical assessment. Of 787 registered patients, 354 met the inclusion criteria, requiring at least two therapy cycles with documented chemotherapy response, renal response, and eGFR. Baseline free light chain (FLC) levels (median 6825.65 mg/L) decreased below 500 mg/L in 67.8% of patients. According to IMWG classification, renal complete response, partial response, and minimal response were achieved in 33.9%, 19.5%, and 28.0% of patients, respectively. The best eGFR values > 60 mL/min/1.73 m 2 were observed in 33.9% of patients, while 33.3%, 22.3%, and 10.5% had best eGFR values of 30–59, 15–29, and < 15 mL/min/1.73 m 2 , respectively. Renal response correlated with baseline FLC levels, IgG kappa, eGFR, and ECOG status in multivariate analysis, as well as with myeloma response and FLC reduction in univariate analysis. Median overall survival was 77.6 months. Survival correlated with age, myeloma response, ECOG status, FLC kappa type, baseline eGFR, standard‐risk cytogenetics, and calcium levels, among other factors. A comparison of IMWG renal response criteria with classification based solely on best eGFR showed similar utility. Of 136 patients requiring dialysis, 80 (58.8%) were able to discontinue dialysis during therapy. Bortezomib containing myeloma therapy, along with significant FLC reduction, was associated with favorable outcome.

Accurate assessment of GFR is crucial to guiding drug eligibility, dosing of systemic therapy, and minimizing the risks of both undertreatment and toxicity in patients with cancer. Up to 32% of patients with cancer have baseline CKD, and both malignancy and treatment may cause kidney injury and subsequent CKD. To date, there has been lack of guidance to standardize approaches to GFR estimation in the cancer population. In this two-part statement from the American Society of Onco-Nephrology, we present key messages for estimation of GFR in patients with cancer, including the choice of GFR estimating equation, use of race and body surface area adjustment, and anticancer drug dose-adjustment in the setting of CKD. These key messages are based on a systematic review of studies assessing GFR estimating equations using serum creatinine and cystatin C in patients with cancer, against a measured GFR comparator. The preponderance of current data involving validated GFR estimating equations involves the CKD Epidemiology Collaboration (CKD-EPI) equations, with 2508 patients in whom CKD-EPI using serum creatinine and cystatin C was assessed (eight studies) and 15,349 in whom CKD-EPI with serum creatinine was assessed (22 studies). The former may have improved performance metrics and be less susceptible to shortfalls of eGFR using serum creatinine alone. Since included studies were moderate quality or lower, the American Society of Onco-Nephrology Position Committee rated the certainty of evidence as low. Additional studies are needed to assess the accuracy of other validated eGFR equations in patients with cancer. Given the importance of accurate and timely eGFR assessment, we advocate for the use of validated GFR estimating equations incorporating both serum creatinine and cystatin C in patients with cancer. Measurement of GFR via exogenous filtration markers should be considered in patients with cancer for whom eGFR results in borderline eligibility for therapies or clinical trials.

The single-cell platform mass cytometry (CyTOF) enables detection of significant changes in one million of renal cells, especially in subsets of immune cells in ischemic human kidneys distal to renal artery stenosis (RAS). We found that pro-repair cell types such as scattered tubular-progenitor-like cells, aged neutrophils, and regulatory B cells show a compensatory increase in RAS. Immune cell phenotype changes may reflect ongoing inflammation and impaired immune defense capability in the kidneys.

Background Little is known about the prognostic significance of monoclonal gammopathy of undetermined and renal significance (MGUS and MGRS) in patients with CKD. The objective of this study was to determine the clinical and kidney outcomes of patients with CKD with either MGUS or MGRS compared with those with CKD without MGUS or MGRS. Methods We conducted a retrospective cohort study from 2013 to 2018. Patients who had both CKD diagnosis and monoclonal testing were identified. Patients were divided into MGRS, MGUS, and no monoclonal gammopathy groups. Cumulative incidence functions and Cox proportional hazards regression were used to model time to event data and to evaluate the association between monoclonal gammopathy status and risk of kidney failure, with death treated as a competing risk. Results Among 1535 patients, 59 (4%) had MGRS, 648 (42%) had MGUS, and 828 (54%) had no monoclonal gammopathy. Unadjusted analysis showed that compared with no monoclonal gammopathy patients, patients with MGRS were at higher risk of kidney failure (hazard ratio [HR] [95% confidence interval]: 2.5 [1.5 to 4.2] but not patients with MGUS (HR [95% confidence interval]: 1.3 [0.97 to 1.6]), after taking death into account as a competing risk. However, in the multivariable analysis, after adjusting for age, sex, eGFR, proteinuria, and Charlson Comorbidity Index, the risk of progression to kidney failure (with death as competing risk) in the MGRS group was no longer statistically significant (HR: 0.9 [0.5 to 1.8]). The same was also true for the MGUS group compared with the group with no monoclonal gammopathy (HR: 1.3 [0.95 to 1.6]). When evaluating the association between MGUS/MGRS status and overall survival, MGRS was significantly associated with mortality in fully adjusted models compared with the group with no monoclonal gammopathy, while MGUS was not. Conclusions After adjusting for traditional risk factors, MGUS/MGRS status was not associated with a greater risk of kidney failure, but MGRS was associated with a higher risk of mortality compared with patients with no monoclonal gammopathy.

ABSTRACT Background Renal artery stenosis (RAS) is an important cause of chronic kidney disease and secondary hypertension. In animal models, renal ischemia leads to downregulation of growth factor expression and loss of intrarenal microcirculation. However, little is known about the sequelae of large-vessel occlusive disease on the microcirculation within human kidneys. Method This study included five patients who underwent nephrectomy due to renovascular occlusion and seven nonstenotic discarded donor kidneys (four deceased donors). Micro-computed tomography was performed to assess microvascular spatial densities and tortuosity, an index of microvascular immaturity. Renal protein expression, gene expression and histology were studied in vitro using immunoblotting, polymerase chain reaction and staining. Results RAS demonstrated a loss of medium-sized vessels (0.2–0.3 mm) compared with donor kidneys (P = 0.037) and increased microvascular tortuosity. RAS kidneys had greater protein expression of angiopoietin-1, hypoxia-inducible factor-1α and thrombospondin-1 but lower protein expression of vascular endothelial growth factor (VEGF) than donor kidneys. Renal fibrosis, loss of peritubular capillaries (PTCs) and pericyte detachment were greater in RAS, yet they had more newly formed PTCs than donor kidneys. Therefore, our study quantified significant microvascular remodeling in the poststenotic human kidney. RAS induced renal microvascular loss, vascular remodeling and fibrosis. Despite downregulated VEGF, stenotic kidneys upregulated compensatory angiogenic pathways related to angiopoietin-1. Conclusions These observations underscore the nature of human RAS as a microvascular disease distal to main vessel stenosis and support therapeutic strategies directly targeting the poststenotic kidney microcirculation in patients with RAS.

Background Membranous nephropathy (MN) is a common cause of proteinuria in patients receiving a hematopoietic stem cell transplant (HSCT). The target antigen in HSCT-associated MN is unknown. Methods We performed laser microdissection and tandem mass spectrometry (MS/MS) of glomeruli from 250 patients with PLA2R-negative MN to detect novel antigens in MN. This was followed by immunohistochemical (IHC)/immunofluorescence (IF) microscopy studies to localize the novel antigen. Western blot analyses using serum and IgG eluted from frozen biopsy specimen to detect binding of IgG to new 'antigen'. Results MS/MS detected a novel protein, protocadherin FAT1 (FAT1), in nine patients with PLA2R-negative MN. In all nine patients, MN developed after allogeneic HSCT (Mayo Clinic discovery cohort). Next, we performed MS/MS in five patients known to have allogeneic HSCT-associated MN (Cedar Sinai validation cohort). FAT1 was detected in all five patients by MS/MS. The total spectral counts for FAT1 ranged from 8 to 39 (mean±SD, 20.9±10.1). All 14 patients were negative for known antigens of MN, including PLA2R, THSD7A, NELL1, PCDH7, NCAM1, SEMA3B, and HTRA1. Kidney biopsy specimens showed IgG (2 to 3+) with mild C3 (0 to 1+) along the GBM; IgG4 was the dominant IgG subclass. IHC after protease digestion and confocal IF confirmed granular FAT1 deposits along the GBM. Lastly, Western blot analyses detected anti-FAT1 IgG and IgG4 in the eluate obtained from pooled frozen kidney biopsy tissue and in the serum of those with FAT1-asssociated MN, but not from those with PLA2R-associated MN. Conclusions FAT1-associated MN appears to be a unique type of MN associated with HSCT. FAT1-associated MN represents a majority of MN associated with HSCT.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in developed countries. Kidney injuries related to CLL can occur via several mechanisms. Approximately 30%–40% of CLL patients with a kidney biopsy have monoclonal-protein related lesions. However, such lesions mostly involve glomeruli with only rare instances of tubule-interstitial disorders. There is only a single case report of a CLL patient who presented with crystalline light chain proximal tubulopathy (LCPT). Fanconi syndrome (FS) may provide clinical clues in these patients. We report a case of a CLL patient who presented with hypokalemia in the setting of advanced kidney failure in which serum monoclonal IgG kappa was detected. The patient demonstrated typical signs and symptoms of FS. The urinary retinol binding protein was also extremely elevated (638 times upper normal limit). A kidney biopsy revealed non-crystalline LCPT with CLL infiltration. FS in CLL is an extremely rare presentation, as only four cases had been previously reported. Of these, only a single case had crystalline LCPT. Our case is the first report of non-crystalline LCPT in a CLL patient. Obinutuzumab and Venetoclax were started to address the CLL, and an improvement in kidney function was noted thereafter.

AbstractImmune‐modulatory properties of adipose tissue‐derived mesenchymal stem/stromal cells (MSCs) might be susceptible to metabolic disturbances. We hypothesized that the immune‐modulatory function of MSCs might be blunted in obese human subjects. MSCs were collected from abdominal subcutaneous fat of obese and lean subjects during bariatric or kidney donation surgeries, respectively. MSCs were co‐cultured in vitro for 24 h with M1 macrophages, which were determined as M1or M2 phenotypes by flow cytometry, and cytokines measured in conditioned media. In vivo, lean or obese MSCs (5 × 105), or PBS, were injected into mice two weeks after unilateral renal artery stenosis (RAS) or sham surgeries (n = 6 each). Fourteen days later, kidneys were harvested and stained with M1 or M2 markers. Lean MSCs decreased macrophages M1 marker intensity, which remained elevated in macrophages co‐cultured with obese MSCs. TNF‐α levels were four‐fold higher in conditioned media collected from obese than from lean MSCs. RAS mouse kidneys were shrunk and showed increased M1 macrophage numbers and inflammatory cytokine expression compared with normal kidneys. Lean MSCs decreased M1 macrophages, M1/M2 ratio and inflammation in RAS kidneys, whereas obese MSCs did not. MSCs isolated from lean human subjects decrease inflammatory M1 macrophages both in vivo and in vitro, an immune‐modulatory function which is blunted in MSCs isolated from obese subjects.