Quantification of Multi-Compartment Flow with Spectral Diffusion MRI.

Purpose: Estimation of multi-compartment intravoxel 'flow' in fD in ml/100g/min with multi-b-value diffusion weighted imaging and a multi-Gaussian model in the kidneys. Theory and Methods: A multi-Gaussian model of intravoxel flow using water transport time to quantify f D (ml/100g/min) is presented and simulated. Multi-compartment anisotropic DWI signal is simulated with Rician noise and SNR=50 and analyzed with a rigid bi-exponential, a rigid tri-exponential and diffusion spectrum imaging model of intravoxel incoherent motion (spectral diffusion) to study extraction of multi-compartment flow. The regularization parameter for spectral diffusion is varied to study the impact on the resulting spectrum and computation speed. The application is demonstrated in a two-center study of 54 kidney allografts with 9 b-value advanced DWI that were split by function (CKD-EPI 2021 eGFR<45ml/min/1.73m2) and fibrosis (Banff 2017 interstitial fibrosis and tubular atrophy score 0-6) to demonstrate multi-compartment flow of various kidney pathologies. Results: Simulation of anisotropic multi-compartment flow from spectral diffusion demonstrated strong correlation to truth for both three-compartment anisotropic diffusion ( y = 1.08 x + 0.1 , R 2 = 0.71 ) and two-compartment anisotropic diffusion ( y = 0.91 + 0.6 , R 2 = 0.74 ), outperforming rigid models in cases of variable compartment number. Use of a fixed regularization parameter set to λ = 0.1 increased computation up to 208-fold and agreed with voxel-wise cross-validated regularization (concordance correlation coefficient=0.99). Spectral diffusion of renal allografts showed decreasing trend of tubular and vascular flow with higher levels of fibrosis, and significant increase in tissue parenchyma flow (f-stat=3.86, p=0.02). Tubular f D was significantly decreased in allografts with impaired function (eGFR<45ml/min/1.73m2)(Mann-Whitney U t-stat=-2.14, p=0.04). Conclusions: Quantitative multi-compartment intravoxel 'flow' can be estimated in ml/100g/min with f D from multi-Gaussian diffusion with water transport time, even with moderate anisotropy such as in kidneys. The use of spectral diffusion with a multi-Gaussian model and a fixed regularization parameter is particularly promising in organs such as the kidney with variable numbers of physiologic compartments.

Plasma proteomics of acute tubular injury.

The kidney tubules constitute two-thirds of the cells of the kidney and account for the majority of the organ's metabolic energy expenditure. Acute tubular injury (ATI) is observed across various types of kidney diseases and may significantly contribute to progression to kidney failure. Non-invasive biomarkers of ATI may allow for early detection and drug development. Using the SomaScan proteomics platform on 434 patients with biopsy-confirmed kidney disease, we here identify plasma biomarkers associated with ATI severity. We employ regional transcriptomics and proteomics, single-cell RNA sequencing, and pathway analysis to explore biomarker protein and gene expression and enriched biological pathways. Additionally, we examine ATI biomarker associations with acute kidney injury (AKI) in the Kidney Precision Medicine Project (KPMP) (n = 44), the Atherosclerosis Risk in Communities (ARIC) study (n = 4610), and the COVID-19 Host Response and Clinical Outcomes (CHROME) study (n = 268). Our findings indicate 156 plasma proteins significantly linked to ATI with osteopontin, macrophage mannose receptor 1, and tenascin C showing the strongest associations. Pathway analysis highlight immune regulation and organelle stress responses in ATI pathogenesis.

Focal Segmental Glomerulosclerosis.

Focal segmental glomerular sclerosis (FSGS) is a histological lesion characterized by sclerosis in sections (segmental) of some glomeruli (focal) in association with podocyte injury. Historically, FSGS has often been characterized as a disease, but it is a heterogeneous entity based on etiology, clinical course, and therapeutic approach. A unifying feature is podocyte injury and loss, which can be primary or the result of secondary maladaptive responses to glomerular stressors. FSGS has been demonstrated over time to carry a large health burden and remains a leading glomerular cause of ESRD globally. Recent clinical practice guidelines highlight the unmet scientific need for better understanding of disease pathogenesis, particularly for immunologic etiologies, as well as more targeted therapeutic drug development. In this review, we will discuss the current FSGS classification scheme, pathophysiologic mechanisms of injury, and treatment guidelines, along with emerging and investigational therapeutics.

Defining the Nature and Clinicopathologic Significance of Mallory-Denk-like Inclusions in Ovarian Fibromas: A Potential Degenerative Phenomenon Associated With Torsion.

Mallory-Denk bodies (MBD), described in alcoholic hepatitis, are composed of intermediate filaments admixed with other proteins. These cytoplasmic inclusions are irregularly shaped and eosinophilic as seen under the light microscope. MBD-like inclusions have rarely been described outside the hepatobiliary tree. Though rare, intracytoplasmic inclusions have been reported in ovarian fibromas. This study evaluates a series of torsed ovarian fibromas with intracytoplasmic inclusions resembling MDBs. Forty-three ovarian fibromas were retrieved from the pathology archives. The H&E slides were evaluated for the presence of MBD-like inclusions and histologic evidence of torsion. The cases with histologic features of torsion were included in the study group while the nontorsed fibromas formed the control group. Among the 15 cases of fibromas with torsion, MBD-like intracytoplasmic inclusions were seen in 5 cases, predominantly in the interface between necrotic areas and viable stroma. None of the cases from the control group showed any inclusions. There was no significant difference in the size of the fibroma or patient demographics between cases with and without inclusions. The inclusions were positive for cytokeratin and ubiquitin while being negative for per acidic Schiff and periodic acid-Schiff with diastase reaction, in the 3 cases selected for immunohistochemistry and special stains. Electron microscopy of the index case revealed a predominance of type 3 Mallory hyaline. This is the first report describing MDB-like inclusions in ovarian fibromas. These MDB-like inclusions appear to be limited to a fraction of ovarian fibromas that underwent torsion, suggesting that these inclusions likely result from subacute hypoxic damage to the cells.

Defining the molecular correlate of arteriolar hyalinosis in kidney disease progression by integration of single cell transcriptomic analysis and pathology scoring.

Arteriolar hyalinosis in kidneys is an independent predictor of cardiovascular disease, the main cause of mortality in chronic kidney disease (CKD). The underlying molecular mechanisms of protein accumulation in the subendothelial space are not well understood. Using single cell transcriptomic data and whole slide images from kidney biopsies of patients with CKD and acute kidney injury in the Kidney Precision Medicine Project, the molecular signals associated with arteriolar hyalinosis were evaluated. Co-expression network analysis of the endothelial genes yielded three gene set modules as significantly associated with arteriolar hyalinosis. Pathway analysis of these modules showed enrichment of transforming growth factor beta / bone morphogenetic protein (TGFß / BMP) and vascular endothelial growth factor (VEGF) signaling pathways in the endothelial cell signatures. Ligand-receptor analysis identified multiple integrins and cell adhesion receptors as over-expressed in arteriolar hyalinosis, suggesting a potential role of integrin-mediated TGFß signaling. Further analysis of arteriolar hyalinosis associated endothelial module genes identified focal segmental glomerular sclerosis as an enriched term. On validation in gene expression profiles from the Nephrotic Syndrome Study Network cohort, one of the three modules was significantly associated with the composite endpoint (> 40% reduction in estimated glomerular filtration rate (eGFR) or kidney failure) independent of age, sex, race, and baseline eGFR, suggesting poor prognosis with elevated expression of genes in this module. Thus, integration of structural and single cell molecular features yielded biologically relevant gene sets, signaling pathways and ligand-receptor interactions, underlying arteriolar hyalinosis and putative targets for therapeutic intervention.

The use of plasma biomarker-derived clusters for clinicopathologic phenotyping: results from the Boston Kidney Biopsy Cohort.

Background: Protein biomarkers may provide insight into kidney disease pathology but their use for the identification of phenotypically distinct kidney diseases has not been evaluated. Methods: We used unsupervised hierarchical clustering on 225 plasma biomarkers in 541 individuals enrolled into the Boston Kidney Biopsy Cohort, a prospective cohort study of individuals undergoing kidney biopsy with adjudicated histopathology. Using principal component analysis, we studied biomarker levels by cluster and examined differences in clinicopathologic diagnoses and histopathologic lesions across clusters. Cox proportional hazards models tested associations of clusters with kidney failure and death. Results: We identified three biomarker-derived clusters. The mean estimated glomerular filtration rate was 72.9 ± 28.7, 72.9 ± 33.4 and 39.9 ± 30.4 mL/min/1.73 m2 in Clusters 1, 2 and 3, respectively. The top-contributing biomarker in Cluster 1 was AXIN, a negative regulator of the Wnt signaling pathway. The top-contributing biomarker in Clusters 2 and 3 was Placental Growth Factor, a member of the vascular endothelial growth factor family. Compared with Cluster 1, individuals in Cluster 3 were more likely to have tubulointerstitial disease (P < .001) and diabetic kidney disease (P < .001) and had more severe mesangial expansion [odds ratio (OR) 2.44, 95% confidence interval (CI) 1.29, 4.64] and inflammation in the fibrosed interstitium (OR 2.49 95% CI 1.02, 6.10). After multivariable adjustment, Cluster 3 was associated with higher risks of kidney failure (hazard ratio 3.29, 95% CI 1.37, 7.90) compared with Cluster 1. Conclusion: Plasma biomarkers may identify clusters of individuals with kidney disease that associate with different clinicopathologic diagnoses, histopathologic lesions and adverse outcomes, and may uncover biomarker candidates and relevant pathways for further study.

Circulating Plasma Biomarkers in Biopsy-Confirmed Kidney Disease.

BACKGROUND AND OBJECTIVES: Biomarkers for noninvasive assessment of histopathology and prognosis are needed in patients with kidney disease. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Using a proteomics assay, we measured a multimarker panel of 225 circulating plasma proteins in a prospective cohort study of 549 individuals with biopsy-confirmed kidney diseases and semiquantitative assessment of histopathology. We tested the associations of each biomarker with histopathologic lesions and the risks of kidney disease progression (defined as ≥40% decline in eGFR or initiation of KRT) and death. RESULTS: After multivariable adjustment and correction for multiple testing, 46 different proteins were associated with histopathologic lesions. The top-performing markers positively associated with acute tubular injury and interstitial fibrosis/tubular atrophy were kidney injury molecule-1 (KIM-1) and V-set and Ig domain-containing protein 2 (VSIG2), respectively. Thirty proteins were significantly associated with kidney disease progression, and 35 were significantly associated with death. The top-performing markers for kidney disease progression were placental growth factor (hazard ratio per doubling, 5.4; 95% confidence interval, 3.4 to 8.7) and BMP and activin membrane-bound inhibitor (hazard ratio, 3.0; 95% confidence interval, 2.1 to 4.2); the top-performing markers for death were TNF-related apoptosis-inducing ligand receptor-2 (hazard ratio, 2.9; 95% confidence interval, 2.0 to 4.0) and CUB domain-containing protein-1 (hazard ratio, 2.4; 95% confidence interval, 1.8 to 3.3). CONCLUSION: We identified several plasma protein biomarkers associated with kidney disease histopathology and adverse clinical outcomes in individuals with a diverse set of kidney diseases. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2021_12_28_CJN09380721.mp3.

Kidney Tubulointerstitial Fibrosis and Tubular Secretion.

RATIONALE & OBJECTIVE: Tubular secretion plays an important role in the efficient elimination of endogenous solutes and medications, and lower secretory clearance is associated with risk of kidney function decline. We evaluated whether histopathologic quantification of interstitial fibrosis and tubular atrophy (IFTA) is associated with lower tubular secretory clearance in persons undergoing kidney biopsy. STUDY DESIGN: Cross-sectional. SETTINGS & PARTICIPANTS: The Boston Kidney Biopsy Cohort is a study of persons undergoing native kidney biopsies for clinical indications. EXPOSURES: Semiquantitative score of IFTA reported by 2 trained pathologists. OUTCOMES: We measured plasma and urine concentrations of 9 endogenous secretory solutes using a targeted liquid chromatography/mass spectrometry assay. We used linear regression to test associations of urine-to-plasma ratios (UPRs) of these solutes with IFTA score after controlling for estimated glomerular filtration rate (eGFR) and albuminuria. RESULTS: Among 418 participants, mean age was 53 years, 51% were women, 64% were White, and 18% were Black. Mean eGFR was 50mL/min/1.73m2, and median urinary albumin-creatinine ratio was 819mg/g. Compared with individuals with≤25% IFTA, those with>50% IFTA had 12%-37% lower UPRs for all 9 secretory solutes. Adjusting for age, sex, race, eGFR, and urine albumin and creatinine levels attenuated the associations, yet a trend of lower secretion across groups remained statistically significant (P<0.05 for trend) for 7 of 9 solutes. A standardized composite secretory score incorporating UPR for all 9 secretory solutes using the min-max method showed similar results (P<0.05 for trend). LIMITATIONS: Single time point and spot measures of secretory solutes. CONCLUSIONS: Greater IFTA severity is associated with lower clearance of endogenous secretory solutes even after adjusting for eGFR and albuminuria.

More Specialties, Fewer Problems: Using Collaborative Competency Between Infectious Diseases, Podiatry, and Pathology to Improve the Care of Patients with Diabetic Foot Osteomyelitis.

BACKGROUND: Diabetic foot osteomyelitis is a common infection where treatment involves multiple services, including infectious diseases, podiatry, and pathology. Despite its ubiquity in the hospital, consensus on much of its management is lacking. METHODS: Representatives from infectious diseases, podiatry, and pathology interested in quality improvement developed multidisciplinary institutional recommendations culminating in an educational intervention describing optimal diagnostic and therapeutic approaches to diabetic foot osteomyelitis (DFO). Knowledge acquisition was assessed by preintervention and postintervention surveys. Inpatients with forefoot DFO were retrospectively reviewed before and after intervention to assess frequency of recommended diagnostic and therapeutic maneuvers, including appropriate definition of surgical bone margins, definitive histopathology reports, and unnecessary intravenous antibiotics or prolonged antibiotic courses. RESULTS: A postintervention survey revealed significant improvements in knowledge of antibiotic treatment duration and the role of oral antibiotics in managing DFO. There were 104 consecutive patients in the preintervention cohort (April 1, 2018, to April 1, 2019) and 32 patients in the postintervention cohort (November 5, 2019, to March 1, 2020), the latter truncated by changes in hospital practice during the coronavirus disease 2019 pandemic. Noncategorizable or equivocal disease reports decreased from before intervention to after intervention (27.0% versus 3.3%, respectively; P = .006). We observed nonsignificant improvement in correct bone margin definition (74.0% versus 87.5%; P = .11), unnecessary peripherally inserted central catheter line placement (18.3% versus 9.4%; P = .23), and unnecessary prolonged antibiotics (21.9% versus 5.0%; P = .10). In addition, by working as an interdisciplinary group, many solvable misunderstandings were identified, and processes were adjusted to improve the quality of care provided to these patients. CONCLUSIONS: This quality improvement initiative regarding management of DFO led to improved provider knowledge and collaborative competency between these three departments, improvements in definitive pathology reports, and nonsignificant improvement in several other clinical endpoints. Creating collaborative competency may be an effective local strategy to improve knowledge of diabetic foot infection and may generalize to other common multidisciplinary conditions.

Plasma Kidney Injury Molecule 1 in CKD: Findings From the Boston Kidney Biopsy Cohort and CRIC Studies.

RATIONALE & OBJECTIVE: Plasma kidney injury molecule 1 (KIM-1) is a sensitive marker of proximal tubule injury, but its association with risks of adverse clinical outcomes across a spectrum of kidney diseases is unknown. STUDY DESIGN: Prospective, observational cohort study. SETTING & PARTICIPANTS: 524 individuals enrolled into the Boston Kidney Biopsy Cohort (BKBC) Study undergoing clinically indicated native kidney biopsy with biopsy specimens adjudicated for semiquantitative scores of histopathology by 2 kidney pathologists and 3,800 individuals with common forms of chronic kidney disease (CKD) enrolled into the Chronic Renal Insufficiency Cohort (CRIC) Study. EXPOSURE: Histopathologic lesions and clinicopathologic diagnosis in cross-sectional analyses, baseline plasma KIM-1 levels in prospective analyses. OUTCOMES: Baseline plasma KIM-1 levels in cross-sectional analyses, kidney failure (defined as initiation of kidney replacement therapy) and death in prospective analyses. ANALYTICAL APPROACH: Multivariable-adjusted linear regression models tested associations of plasma KIM-1 levels with histopathologic lesions and clinicopathologic diagnoses. Cox proportional hazards models tested associations of plasma KIM-1 levels with future kidney failure and death. RESULTS: In the BKBC Study, higher plasma KIM-1 levels were associated with more severe acute tubular injury, tubulointerstitial inflammation, and more severe mesangial expansion after multivariable adjustment. Participants with diabetic nephropathy, glomerulopathies, and tubulointerstitial disease had significantly higher plasma KIM-1 levels after multivariable adjustment. In the BKBC Study, CKD in 124 participants progressed to kidney failure and 85 participants died during a median follow-up time of 5 years. In the CRIC Study, CKD in 1,153 participants progressed to kidney failure and 1,356 participants died during a median follow-up time of 11.5 years. In both cohorts, each doubling of plasma KIM-1 level was associated with an increased risk of kidney failure after multivariable adjustment (hazard ratios of 1.19 [95% CI, 1.03-1.38] and 1.10 [95% CI, 1.06-1.15] for BKBC and CRIC, respectively). There was no statistically significant association of plasma KIM-1 levels with death in either cohort. LIMITATIONS: Generalizability and unmeasured confounding. CONCLUSIONS: Plasma KIM-1 is associated with underlying tubulointerstitial and mesangial lesions and progression to kidney failure in 2 cohort studies of individuals with kidney diseases.

Recessive, gain-of-function toxicity in an APOL1 BAC transgenic mouse model mirrors human APOL1 kidney disease.

People of recent sub-Saharan African ancestry develop kidney failure much more frequently than other groups. A large fraction of this disparity is due to two coding sequence variants in the APOL1 gene. Inheriting two copies of these APOL1 risk variants, known as G1 and G2, causes high rates of focal segmental glomerulosclerosis (FSGS), HIV-associated nephropathy and hypertension-associated end-stage kidney disease. Disease risk follows a recessive mode of inheritance, which is puzzling given the considerable data that G1 and G2 are toxic gain-of-function variants. We developed coisogenic bacterial artificial chromosome (BAC) transgenic mice harboring either the wild-type (G0), G1 or G2 forms of human APOL1. Expression of interferon gamma (IFN-γ) via plasmid tail vein injection results in upregulation of APOL1 protein levels together with robust induction of heavy proteinuria and glomerulosclerosis in G1/G1 and G2/G2 but not G0/G0 mice. The disease phenotype was greater in G2/G2 mice. Neither heterozygous (G1/G0 or G2/G0) risk variant mice nor hemizygous (G1/-, G2/-) mice had significant kidney injury in response to IFN-γ, although the heterozygous mice had a greater proteinuric response than the hemizygous mice, suggesting that the lack of significant disease in humans heterozygous for G1 or G2 is not due to G0 rescue of G1 or G2 toxicity. Studies using additional mice (multicopy G2 and a non-isogenic G0 mouse) supported the notion that disease is largely a function of the level of risk variant APOL1 expression. Together, these findings shed light on the recessive nature of APOL1-nephropathy and present an important model for future studies.

Cadherin-11, Sparc-related modular calcium binding protein-2, and Pigment epithelium-derived factor are promising non-invasive biomarkers of kidney fibrosis.

Kidney fibrosis constitutes the shared final pathway of nearly all chronic nephropathies, but biomarkers for the non-invasive assessment of kidney fibrosis are currently not available. To address this, we characterize five candidate biomarkers of kidney fibrosis: Cadherin-11 (CDH11), Sparc-related modular calcium binding protein-2 (SMOC2), Pigment epithelium-derived factor (PEDF), Matrix-Gla protein, and Thrombospondin-2. Gene expression profiles in single-cell and single-nucleus RNA-sequencing (sc/snRNA-seq) datasets from rodent models of fibrosis and human chronic kidney disease (CKD) were explored, and Luminex-based assays for each biomarker were developed. Plasma and urine biomarker levels were measured using independent prospective cohorts of CKD: the Boston Kidney Biopsy Cohort, a cohort of individuals with biopsy-confirmed semiquantitative assessment of kidney fibrosis, and the Seattle Kidney Study, a cohort of patients with common forms of CKD. Ordinal logistic regression and Cox proportional hazards regression models were used to test associations of biomarkers with interstitial fibrosis and tubular atrophy and progression to end-stage kidney disease and death, respectively. Sc/snRNA-seq data confirmed cell-specific expression of biomarker genes in fibroblasts. After multivariable adjustment, higher levels of plasma CDH11, SMOC2, and PEDF and urinary CDH11 and PEDF were significantly associated with increasing severity of interstitial fibrosis and tubular atrophy in the Boston Kidney Biopsy Cohort. In both cohorts, higher levels of plasma and urinary SMOC2 and urinary CDH11 were independently associated with progression to end-stage kidney disease. Higher levels of urinary PEDF associated with end-stage kidney disease in the Seattle Kidney Study, with a similar signal in the Boston Kidney Biopsy Cohort, although the latter narrowly missed statistical significance. Thus, we identified CDH11, SMOC2, and PEDF as promising non-invasive biomarkers of kidney fibrosis.

IL-23 reshapes kidney resident cell metabolism and promotes local kidney inflammation.

Interstitial kidney inflammation is present in various nephritides in which serum interleukin 23 (IL-23) is elevated. Here we showed that murine and human renal tubular epithelial cells (TECs) expressing the IL-23 receptor (IL-23R) responded to IL-23 by inducing intracellular calcium flux, enhancing glycolysis, and upregulating calcium/calmodulin kinase IV (CaMK4), which resulted in suppression of the expression of the arginine-degrading enzyme arginase 1 (ARG1), thus increasing in situ levels of free L-arginine. Limited availability of arginine suppressed the ability of infiltrating T cells to proliferate and produce inflammatory cytokines. TECs from humans and mice with nephritis expressed increased levels of IL-23R and CaMK4 but reduced levels of ARG1. TEC-specific deletion of Il23r or Camk4 suppressed inflammation, whereas deletion of Arg1 exacerbated inflammation in different murine disease models. Finally, TEC-specific delivery of a CaMK4 inhibitor specifically curbed renal inflammation in lupus-prone mice without affecting systemic inflammation. Our data offer the first evidence to our knowledge of the immunosuppressive capacity of TECs through a mechanism that involves competitive uptake of arginine and signify the importance of modulation of an inflammatory cytokine in the function of nonlymphoid cells, which leads to the establishment of an inflammatory microenvironment. New approaches to treat kidney inflammation should consider restoring the immunosuppressive capacity of TECs.

The Associations of Plasma Biomarkers of Inflammation With Histopathologic Lesions, Kidney Disease Progression, and Mortality-The Boston Kidney Biopsy Cohort Study.

BACKGROUND: Soluble tumor necrosis factor receptor (sTNFR)-1, sTNFR-2, YKL-40, monocyte chemoattractant protein (MCP)-1, and soluble urokinase plasminogen activator receptor (suPAR) have emerged as promising biomarkers of inflammation but have not been evaluated across diverse types of kidney diseases. METHODS: We measured these plasma biomarkers in 523 individuals enrolled into a prospective, observational cohort study of patients undergoing clinically indicated native kidney biopsy at 3 tertiary care hospitals. Two kidney pathologists adjudicated biopsy specimens for semiquantitative scores of histopathology. Proportional hazard models tested associations between biomarkers and risks of kidney disease progression (composite of ≥40% estimated glomerular filtration rate [eGFR] decline or end-stage kidney disease [ESKD]) and death. RESULTS: Mean eGFR was 56.4±36 ml/min per 1.73 m2 and the median proteinuria (interquartile range) was 1.6 (0.4, 3.9) g/g creatinine. The most common primary clinicopathologic diagnoses were proliferative glomerulonephritis (29.2%), nonproliferative glomerulopathy (18.1%), advanced glomerulosclerosis (11.3%), and diabetic kidney disease (11.1%). sTNFR-1, sTNFR-2, MCP-1, and suPAR were associated with tubulointerstitial and glomerular lesions. YKL-40 was not associated with any histopathologic lesions after multivariable adjustment. During a median follow-up of 65 months, 182 participants suffered kidney disease progression and 85 participants died. After multivariable adjustment, each doubling of sTNFR-1, sTNFR-2, YKL-40, and MCP-1 was associated with increased risks of kidney disease progression, with hazard ratios ranging from 1.21 to 1.47. Each doubling of sTNFR-2, YKL-40, and MCP-1 was associated with increased risks of death, with hazard ratios ranging from 1.33 to 1.45. suPAR was not significantly associated with kidney disease progression or death. CONCLUSIONS: sTNFR-1, sTNFR-2, YKL-40, MCP-1, and suPAR are associated with underlying histopathologic lesions and adverse clinical outcomes across a diverse set of kidney diseases.

Aberrantly glycosylated IgG elicits pathogenic signaling in podocytes and signifies lupus nephritis.

Lupus nephritis (LN) is a serious complication occurring in 50% of patients with systemic lupus erythematosus (SLE) for which there is a lack of biomarkers, a lack of specific medications, and a lack of a clear understanding of its pathogenesis. The expression of calcium/calmodulin kinase IV (CaMK4) is increased in podocytes of patients with LN and lupus-prone mice, and its podocyte-targeted inhibition averts the development of nephritis in mice. Nephrin is a key podocyte molecule essential for the maintenance of the glomerular slit diaphragm. Here, we show that the presence of fucose on N-glycans of IgG induces, whereas the presence of galactose ameliorates, podocyte injury through CaMK4 expression. Mechanistically, CaMK4 phosphorylates NF-κB, upregulates the transcriptional repressor SNAIL, and limits the expression of nephrin. In addition, we demonstrate that increased expression of CaMK4 in biopsy specimens and in urine podocytes from people with LN is linked to active kidney disease. Our data shed light on the role of IgG glycosylation in the development of podocyte injury and propose the development of "liquid kidney biopsy" approaches to diagnose LN.

Fine-Tuning Lipid Metabolism by Targeting Mitochondria-Associated Acetyl-CoA-Carboxylase 2 in BRAFV600E Papillary Thyroid Carcinoma.

Background: BRAFV600E acts as an ATP-dependent cytosolic kinase. BRAFV600E inhibitors are widely available, but resistance to them is widely reported in the clinic. Lipid metabolism (fatty acids) is fundamental for energy and to control cell stress. Whether and how BRAFV600E impacts lipid metabolism regulation in papillary thyroid carcinoma (PTC) is still unknown. Acetyl-CoA carboxylase (ACC) is a rate-limiting enzyme for de novo lipid synthesis and inhibition of fatty acid oxidation (FAO). ACC1 and ACC2 genes encode distinct isoforms of ACC. The aim of our study was to determine the relationship between BRAFV600E and ACC in PTC. Methods: We performed RNA-seq and DNA copy number analyses in PTC and normal thyroid (NT) in The Cancer Genome Atlas samples. Validations were performed by using assays on PTC-derived cell lines of differing BRAF status and a xenograft mouse model derived from a heterozygous BRAFWT/V600E PTC-derived cell line with knockdown (sh) of ACC1 or ACC2. Results:ACC2 mRNA expression was significantly downregulated in BRAFV600E-PTC vs. BRAFWT-PTC or NT clinical samples. ACC2 protein levels were downregulated in BRAFV600E-PTC cell lines vs. the BRAFWT/WT PTC cell line. Vemurafenib increased ACC2 (and to a lesser extent ACC1) mRNA levels in PTC-derived cell lines in a BRAFV600E allelic dose-dependent manner. BRAFV600E inhibition increased de novo lipid synthesis rates, and decreased FAO due to oxygen consumption rate (OCR), and extracellular acidification rate (ECAR), after addition of palmitate. Only shACC2 significantly increased OCR rates due to FAO, while it decreased ECAR in BRAFV600E PTC-derived cells vs. controls. BRAFV600E inhibition synergized with shACC2 to increase intracellular reactive oxygen species production, leading to increased cell proliferation and, ultimately, vemurafenib resistance. Mice implanted with a BRAFWT/V600E PTC-derived cell line with shACC2 showed significantly increased tumor growth after vemurafenib treatment, while vehicle-treated controls, or shGFP control cells treated with vemurafenib showed stable tumor growth. Conclusions: These findings suggest a potential link between BRAFV600E and lipid metabolism regulation in PTC. BRAFV600E downregulates ACC2 levels, which deregulates de novo lipid synthesis, FAO due to OCR, and ECAR rates. ShACC2 may contribute to vemurafenib resistance and increased tumor growth. ACC2 rescue may represent a novel molecular strategy for overcoming resistance to BRAFV600E inhibitors in refractory PTC.

N-glycosylated IgG in patients with kidney transplants increases calcium/calmodulin kinase IV in podocytes and causes injury.

Transplant glomerulopathy (TG) is a major cause of late allograft loss. Increased urine podocin/creatinine ratio in TG signifies accelerated podocyte loss. The mechanisms that lead to podocyte injury in TG remain unclear. We report that IgG from kidney transplant recipients with TG, but not from those without TG, cause a reduction in the expression of nephrin, significant podocyte actin cytoskeleton, and motility changes. These changes are preceded by increased expression of calcium/calmodulin kinase IV (CAMK4). Mechanistically, we found that CAMK4 phosphorylates GSK3ß (glycogen synthase kinase 3 beta), activates the Wnt pathway and stabilizes the nephrin transcriptional repressor SNAIL. Silencing neonatal Fc Receptor (FcRn) or CAMK4 prevented the podocyte-damaging effects of IgG from patients with TG. Furthermore, we show that removal of N-linked glycosyl residues from these IgG did not interfere with its entry into the podocytes but eliminated its ability to upregulate CAMK4 and cause podocyte injury. The translational value of these findings is signified by the fact that CAMK4 is increased in podocytes of patients with TG but not in those without TG despite other forms of renal dysfunction. Our results offer novel considerations to limit podocyte injury in patients with kidney transplants, which may lead to eventual glomerular destabilization and transplant glomerulopathy.