Predisposition to cortical neurodegenerative changes in brains of hypertension prone rats.

BACKGROUND: Substantial evidence suggests that hypertension is a significant risk factor for cognitive decline. However, it is unclear whether the genetic predisposition to hypertension is also associated with cellular dysfunction that promotes neurodegeneration. METHODS: Changes in blood pressure were evaluated following dietary salt-loading or administration of a regular diet in Sabra Normotensive (SBN/y) and Sabra Hypertension-prone rats (SBH/y). We performed quantitative RT-PCR and immunofluorescence staining in brain cortical tissues before salt loading and 6 and 9 months after salt loading. To examine the expression of brain cortical proteins involved in the gene regulation (Histone Deacetylase-HDAC2; Histone Acetyltransferase 1-HAT1), stress response (Activating Transcription Factor 4-ATF4; Eukaryotic Initiation Factor 2- eIF2α), autophagy (Autophagy related 4A cysteine peptidase- Atg4a; light-chain 3-LC3A/B; mammalian target of rapamycin complex 1- mTORC1) and apoptosis (caspase-3). RESULTS: Prior to salt loading, SBH/y compared to SBN/y expressed a significantly higher level of cortical HAT1 (protein), Caspase-3 (mRNA/protein), LC3A, and ATF4 (mRNA), lower levels of ATG4A (mRNA/protein), LC3A/B, HDAC2 (protein), as well as a lower density of cortical neurons. Following dietary salt loading, SBH/y but not SBN/y developed high blood pressure. In hypertensive SBH/y, there was significant upregulation of cortical HAT1 (protein), Caspase-3 (protein), and eIF2α ~ P (protein) and downregulation of HDAC2 (protein) and mTORC1 (mRNA), and cortical neuronal loss. CONCLUSIONS: The present findings suggest that genetic predisposition to hypertension is associated in the brain cortex with disruption in autophagy, gene regulation, an abnormal response to cellular stress, and a high level of cortical apoptosis, and could therefore exacerbate cellular dysfunction and thereby promote neurodegeneration.

Dysregulated UPR and ER Stress Related to a Mutation in the Sdf2l1 Gene Are Involved in the Pathophysiology of Diet-Induced Diabetes in the Cohen Diabetic Rat.

The Cohen Diabetic rat is a model of type 2 diabetes mellitus that consists of the susceptible (CDs/y) and resistant (CDr/y) strains. Diabetes develops in CDs/y provided diabetogenic diet (DD) but not when fed regular diet (RD) nor in CDr/y given either diet. We recently identified in CDs/y a deletion in Sdf2l1, a gene that has been attributed a role in the unfolded protein response (UPR) and in the prevention of endoplasmic reticulum (ER) stress. We hypothesized that this deletion prevents expression of SDF2L1 and contributes to the pathophysiology of diabetes in CDs/y by impairing UPR, enhancing ER stress, and preventing CDs/y from secreting sufficient insulin upon demand. We studied SDF2L1 expression in CDs/y and CDr/y. We evaluated UPR by examining expression of key proteins involved in both strains fed either RD or DD. We assessed the ability of all groups of animals to secrete insulin during an oral glucose tolerance test (OGTT) over 4 weeks, and after overnight feeding (postprandial) over 4 months. We found that SDF2L1 was expressed in CDr/y but not in CDs/y. The pattern of expression of proteins involved in UPR, namely the PERK (EIF2α, ATF4 and CHOP) and IRE1 (XBP-1) pathways, was different in CDs/y DD from all other groups, with consistently lower levels of expression at 4 weeks after initiation of DD and coinciding with the development of diabetes. In CDs/y RD, insulin secretion was mildly impaired, whereas in CDs/y DD, the ability to secrete insulin decreased over time, leading to the development of the diabetic phenotype. We conclude that in CDs/y DD, UPR participating proteins were dysregulated and under-expressed at the time point when the diabetic phenotype became overt. In parallel, insulin secretion in CDs/y DD became markedly impaired. Our findings suggest that under conditions of metabolic load with DD and increased demand for insulin secretion, the lack of SDF2L1 expression in CDs/y is associated with UPR dysregulation and ER stress which, combined with oxidative stress previously attributed to the concurrent Ndufa4 mutation, are highly likely to contribute to the pathophysiology of diabetes in this model.

Critical Stepwise Decline of Antibodies against SARS-CoV-2 among Chronic Hemodialysis Patients 180 Days Post Comirnaty Vaccine.

BACKGROUND: The reduced immune response of maintenance hemodialysis patients to coronavirus disease 2019 (COVID-19) vaccines is a major concern. OBJECTIVES: To analyze the late (6 months after full vaccination) antibody response and compare it to early post-vaccination titer. METHODS: We conducted a multicenter prospective study of 13 hemodialysis units in Israel. RESULTS: We demonstrated that the low titers observed among ESRD patients 2-3 months after vaccination with the Comirnaty vaccine (median 63.8 AU/ml) declined to critically lower values 6 months after full vaccination. (Mediananti S antibodies, 31 AU/ml). Seropositivity significantly declined among hemodialysis patients from 89% to 74% (P < 0.0001), although it did not significantly change among controls. CONCLUSIONS: We recommend all patients on hemodialysis receive a booster COVID-19 vaccine 6 months after the second dose.

A Novel Rodent Model of Hypertensive Cerebral Small Vessel Disease with White Matter Hyperintensities and Peripheral Oxidative Stress.

Cerebral small vessel disease (CSVD) is the second most common cause of stroke and a major contributor to dementia. Manifestations of CSVD include cerebral microbleeds, intracerebral hemorrhages (ICH), lacunar infarcts, white matter hyperintensities (WMH) and enlarged perivascular spaces. Chronic hypertensive models have been found to reproduce most key features of the disease. Nevertheless, no animal models have been identified to reflect all different aspects of the human disease. Here, we described a novel model for CSVD using salt-sensitive 'Sabra' hypertension-prone rats (SBH/y), which display chronic hypertension and enhanced peripheral oxidative stress. SBH/y rats were either administered deoxycorticosteroid acetate (DOCA) (referred to as SBH/y-DOCA rats) or sham-operated and provided with 1% NaCl in drinking water. Rats underwent neurological assessment and behavioral testing, followed by ex vivo MRI and biochemical and histological analyses. SBH/y-DOCA rats show a neurological decline and cognitive impairment and present multiple cerebrovascular pathologies associated with CSVD, such as ICH, lacunes, enlarged perivascular spaces, blood vessel stenosis, BBB permeability and inflammation. Remarkably, SBH/y-DOCA rats show severe white matter pathology as well as WMH, which are rarely reported in commonly used models. Our model may serve as a novel platform for further understanding the mechanisms underlying CSVD and for testing novel therapeutics.

Mesenchymal Stem Cell-Derived Extracellular Vesicles as Proposed Therapy in a Rat Model of Cerebral Small Vessel Disease.

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been employed in the past decade as therapeutic agents in various diseases, including central nervous system (CNS) disorders. We currently aimed to use MSC-EVs as potential treatment for cerebral small vessel disease (CSVD), a complex disorder with a variety of manifestations. MSC-EVs were intranasally administrated to salt-sensitive hypertension prone SBH/y rats that were DOCA-salt loaded (SBH/y-DS), which we have previously shown is a model of CSVD. MSC-EVs accumulated within brain lesion sites of SBH/y-DS. An in vitro model of an inflammatory environment in the brain demonstrated anti-inflammatory properties of MSC-EVs. Following in vivo MSC-EV treatment, gene set enrichment analysis (GSEA) of SBH/y-DS cortices revealed downregulation of immune system response-related gene sets. In addition, MSC-EVs downregulated gene sets related to apoptosis, wound healing and coagulation, and upregulated gene sets associated with synaptic signaling and cognition. While no specific gene was markedly altered upon treatment, the synergistic effect of all gene alternations was sufficient to increase animal survival and improve the neurological state of affected SBH/y-DS rats. Our data suggest MSC-EVs act as microenvironment modulators, through various molecular pathways. We conclude that MSC-EVs may serve as beneficial therapeutic measure for multifactorial disorders, such as CSVD.

Minimal Change Disease Following the Pfizer-BioNTech COVID-19 Vaccine.

We report on the development of minimal change disease (MCD) with nephrotic syndrome and acute kidney injury (AKI), shortly after first injection of the BNT162b2 COVID-19 vaccine (Pfizer-BioNTech). A 50-year-old previously healthy man was admitted to our hospital following the appearance of peripheral edema. Ten days earlier, he had received the first injection of the vaccine. Four days after injection, he developed lower leg edema, which rapidly progressed to anasarca. On admission, serum creatinine was 2.31 mg/dL and 24-hour urinary protein excretion was 6.9 grams. As kidney function continued to decline over the next days, empirical treatment was initiated with prednisone 80 mg/d. A kidney biopsy was performed and the findings were consistent with MCD. Ten days later, kidney function began to improve, gradually returning to normal. The clinical triad of MCD, nephrotic syndrome, and AKI has been previously described under a variety of circumstances, but not following the Pfizer-BioNTech COVID-19 vaccine. The association between the vaccination and MCD is at this time temporal and by exclusion, and by no means firmly established. We await further reports of similar cases to evaluate the true incidence of this possible vaccine side effect.

Diabetes induces remodeling of the left atrial appendage independently of atrial fibrillation in a rodent model of type-2 diabetes.

BACKGROUND: Diabetic patients have an increased predisposition to thromboembolic events, in most cases originating from thrombi in the left atrial appendage (LAA). Remodeling of the LAA, which predisposes to thrombi formation, has been previously described in diabetic patients with atrial fibrillation, but whether remodeling of the LAA occurs in diabetics also in the absence of atrial fibrillation is unknown. To investigate the contribution of diabetes, as opposed to atrial fibrillation, to remodeling of the LAA, we went from humans to the animal model. METHODS: We studied by echocardiography the structure and function of the heart over multiple time points during the evolution of diabetes in the Cohen diabetic sensitive rat (CDs/y) provided diabetogenic diet over a period of 4 months; CDs/y provided regular diet and the Cohen diabetic resistant (CDr/y), which do not develop diabetes, served as controls. All animals were in sinus rhythm throughout the study period. RESULTS: Compared to controls, CDs/y developed during the evolution of diabetes a greater heart mass, larger left atrial diameter, wider LAA orifice, increased LAA depth, greater end-diastolic and end-systolic diameter, and lower E/A ratio-all indicative of remodeling of the LAA and left atrium (LA), as well as the development of left ventricular diastolic dysfunction. To investigate the pathophysiology involved, we studied the histology of the hearts at the end of the study. We found in diabetic CDs/y, but not in any of the other groups, abundance of glycogen granules in the atrial appendages , atria  and ventricles, which may be of significance as glycogen granules have previously been associated with cell and organ dysfunction in the diabetic heart. CONCLUSIONS: We conclude that our rodent model of diabetes, which was in sinus rhythm, reproduced structural and functional alterations previously observed in hearts of human diabetics with atrial fibrillation. Remodeling of the LAA and of the LA in our model was unrelated to atrial fibrillation and associated with accumulation of glycogen granules. We suggest that myocardial accumulation of glycogen granules is related to the development of diabetes and may play a pathophysiological role in remodeling of the LAA and LA, which predisposes to atrial fibrillation, thromboembolic events and left ventricular diastolic dysfunction in the diabetic heart.

[HYPERTENSION AS A CAUSE OF RENAL DISEASE - FACT OR FICTION?]

BACKGROUND: The possible link between hypertension and chronic kidney disease has been preoccupying the medical world for over a century. The cause-effect relationship between malignant hypertension and renal disease is clear and agreed upon, but when hypertension is at milder levels, this relationship becomes blurred. Does indeed non-malignant hypertension also cause kidney disease that can lead to end-stage kidney failure? In this review, we provide evidence based primarily on epidemiologic data, from which it can be concluded that the higher the blood pressure is, starting from normal blood pressure and above, the higher is the risk of developing kidney disease and loss of renal function. Does treatment of hypertension prevent kidney injury secondary to hypertension? The evidence points to the issue that hypertension slows down the rate of decline in glomerular filtration rate, but only in the presence of significant urinary protein excretion, whereas in the absence of proteinuria, lowering blood pressure has no effect on the development of hypertensive renal disease.

Anti-TGF-ß1 Antibody Therapy in Patients with Diabetic Nephropathy.

TGF-ß has been implicated as a major pathogenic factor in diabetic nephropathy. This randomized, double-blind, phase 2 study assessed whether modulating TGF-ß1 activity with a TGF-ß1-specific, humanized, neutralizing monoclonal antibody (TGF-ß1 mAb) is safe and more effective than placebo in slowing renal function loss in patients with diabetic nephropathy on chronic stable renin-angiotensin system inhibitor treatment. We randomized 416 patients aged ≥25 years with type 1 or type 2 diabetes, a serum creatinine (SCr) level of 1.3-3.3 mg/dl for women and 1.5-3.5 mg/dl for men (or eGFR of 20-60 ml/min per 1.73 m2), and a 24-hour urine protein-to-creatinine ratio ≥800 mg/g to TGF-ß1 mAb (2-, 10-, or 50-mg monthly subcutaneous dosing for 12 months) or placebo. We assessed a change in SCr from baseline to 12 months as the primary efficacy variable. Although the Data Monitoring Committee did not identify safety issues, we terminated the trial 4 months early for futility on the basis of their recommendation. The placebo group had a mean±SD change in SCr from baseline to end of treatment of 0.33±0.67 mg/dl. Least squares mean percentage change in SCr from baseline to end of treatment did not differ between placebo (14%; 95% confidence interval [95% CI], 9.7% to 18.2%) and TGF-ß1 mAb treatments (20% [95% CI, 15.3% to 24.3%], 19% [95% CI, 14.2% to 23.0%], and 19% [95% CI, 14.0% to 23.3%] for 2-, 10-, and 50-mg doses, respectively). Thus, TGF-ß1 mAb added to renin-angiotensin system inhibitors did not slow progression of diabetic nephropathy.

Three interacting genomic loci incorporating two novel mutations underlie the evolution of diet-induced diabetes.

We investigated the pathophysiology of diet-induced diabetes in the Cohen diabetic rat (CDs/y) from its induction to its chronic phase, using a multi-layered integrated genomic approach. We identified by linkage analysis two diabetes-related quantitative trait loci on RNO4 and RNO13. We determined their functional contribution to diabetes by chromosomal substitution, using congenic and consomic strains. To identify within these loci genes of relevance to diabetes, we sequenced the genome of CDs/y and compared it to 25 other rat strains. Within the RNO4 locus, we detected a novel high impact deletion in the Ndufa4 gene that was unique to CDs/y. Within the RNO13 locus, we found multiple SNPs and INDELs that were unique to CDs/y but were unable to prioritize any of the genes. Genome wide screening identified a novel third locus not detected by linkage analysis that consisted of a novel high impact deletion on RNO11 that was unique to CDs/y and that involved the Sdf2l1 gene. Using co-segregation analysis, we investigated in silico the relative contribution to the diabetic phenotype and the interaction between the three genomic loci on RNO4, RNO11 and RNO13. We found that the RNO4 locus plays a major role during the induction of diabetes, whereas the genomic loci on RNO13 and RNO11, while interacting with the RNO4 locus, contribute more significantly to the diabetic phenotype during the chronic phase of the disease. The mechanisms whereby the mutations on RNO4 and 11 and the RNO13 locus contribute to the development of diabetes are under continuing investigation.

[Medical research improves quality of care].

INTRODUCTION: The Barzilai Medical Center has recently been designated as an Academic Medical Center. The challenge to become an academic center arose from the realization that the level and quality of care provided to patients are necessarily improved when clinical medicine is practiced in a teaching and research environment. Indeed, after years of close working ties between the Barzilai Medical Center in Ashkelon and the Ben-Gurion University of the Negev, the center officially became an Academic Medical Center and was recognized as one of the two leading clinical campuses of the Faculty of Health Sciences. The academic status of a medical center incorporates the necessity for the medical staff to become actively involved and excel in medical service, educational activities and research. In this issue of Harefuah, we publish original research and review articles that reflect, in part, the clinical and research interests and activities of the medical staff of the Barzilai University Medical Center during the past few years.

[THE ISRAELI RAT GENOME CENTER].

INTRODUCTION: The Israeli Rat Genome Center, which is located at the Barzilai Medical Center Campus of the Faculty of Health Sciences of the Ben-Gurion University of the Negev in Ashkelon, was established to provide a repository of unique genetic strains of rats that were created in Israel and that simulate complex diseases. The Center incorporates models of: salt-sensitive hypertension (SBN/y and SBH/y rats), type 2 diabetes (CDr and CDs rats), combined hypertension and diabetes (CRDH) and additional genetic strains (transgenics, consomics, congenics). All these strains are available to researchers who are interested in the study of complex diseases, on the basis of collaboration. The Laboratory for Molecular Medicine within the Center also performs independent research on the genetic basis of complex diseases, including hypertension, diabetes, kidney disease and target organ involvement in cardiovascular and metabolic diseases. The Center collaborates with researchers from research centers in other medical centers and universities in Israel and worldwide.

Unmasking of proteinuria in the course of genetic dissection of nonproteinuric diabetic nephropathy.

We previously described the development of nonproteinuric diabetic nephropathy (NPDN) in the Cohen diabetic rat (CDs), a model that simulates Type 2 diabetes in humans. Using linkage analysis in an F2 cross, we currently set out to investigate the mechanisms underlying NPDN. We crossbred between CDs and SBN/y, a nondiabetic rat strain, generated F1 and F2 progenies, fed them diabetogenic diet that elicits diabetes and NPDN in CDs but not in SBN/y, and determined metabolic and renal phenotypes. Over 5 mo, ∼75% of F2 developed a diabetic phenotype. In parallel, a nephropathy developed in F2, with glomerular filtration rate (GFR) declining in ∼25% and, unexpectedly, significant proteinuria appearing in ∼75%. We scanned the F2 genome with microsatellite markers and used linkage analysis to identify quantitative trait loci (QTLs). We detected diabetes-related QTLs on RNO4 and 13. We also detected two QTLs for the decline in GFR on RNO4 and 13 and another QTL for proteinuria on RNO13. The metabolic and renal-related QTLs overlapped. These results suggest that the mechanisms underlying the nephropathy in F2 are related to genes that map to RNO4 and 13, as well as a common genetic background for the development of diabetes and the renal disease. Our findings further indicate that proteinuria is inhibited in parental diabetic CDs, thus accounting for the nonproteinuric phenotype, but "unmasked" in diabetic F2 whose genome has been modified. Identifying the nature of the factor inhibiting proteinuria in diabetic CDs but not in F2 may provide a clue to treatment and prevention of proteinuria in diabetes.

Pyridorin in type 2 diabetic nephropathy.

Pyridoxamine dihydrochloride (Pyridorin, NephroGenex) inhibits formation of advanced glycation end products and scavenges reactive oxygen species and toxic carbonyls, but whether these actions translate into renoprotective effects is unknown. In this double-blind, randomized, placebo-controlled trial, we randomly assigned 317 patients with proteinuric type 2 diabetic nephropathy to twice-daily placebo; Pyridorin, 150 mg twice daily; or Pyridorin, 300 mg twice daily, for 52 weeks. At baseline, the mean age ± SD was 63.9±9.5 years, and the mean duration of diabetes was 17.6±8.5 years; the mean serum creatinine level was 2.2±0.6 mg/dl, and the mean protein-to-creatinine ratio was 2973±1932 mg/g. Regarding the primary end point, a statistically significant change in serum creatinine from baseline to 52 weeks was not evident in either Pyridorin group compared with placebo. However, analysis of covariance suggested that the magnitude of the treatment effect differed by baseline renal function. Among patients in the lowest tertile of baseline serum creatinine concentration, treatment with Pyridorin associated with a lower average change in serum creatinine concentration at 52 weeks (0.28, 0.07, and 0.14 mg/dl for placebo, Pyridorin 150 mg, and Pyridorin 300 mg, respectively; P=0.05 for either Pyridorin dose versus placebo); there was no evidence of a significant treatment effect in the middle or upper tertiles. In conclusion, this trial failed to detect an effect of Pyridorin on the progression of serum creatinine at 1 year, although it suggests that patients with less renal impairment might benefit.

Oral lixivaptan effectively increases serum sodium concentrations in outpatients with euvolemic hyponatremia.

Hyponatremia is the most common electrolyte disorder in clinical practice. Its incidence increases with age and it is associated with increased morbidity and mortality. Recently, the vaptans, antagonists of the arginine vasopressin pathway, have shown promise for safe treatment of hyponatremia. Here we evaluated the efficacy, safety, and tolerability of oral lixivaptan, a selective vasopressin V2-receptor antagonist, for treatment of nonhospitalized individuals with euvolemic hyponatremia (sodium less than 135 mmol/l) in a multicenter, randomized, double-blind, placebo-controlled, phase III study. About half of the 206 patients were elderly in a chronic care setting. Of these patients, 52 were given a placebo and 154 were given 25-100 mg per day lixivaptan, titrated based on the daily serum sodium measurements. Compared with placebo (0.8 mmol/l), the serum sodium concentration significantly increased by 3.2 mmol/l from baseline to day 7 (primary efficacy endpoint) with lixivaptan treatment. A significantly greater proportion of patients that received lixivaptan achieved normal serum sodium (39.4%) by day 7 relative to placebo (12.2%). Overall, lixivaptan was considered safe and well-tolerated. Thus, oral lixivaptan can be safely initiated in the outpatient setting and effectively increases serum sodium concentrations in outpatients with euvolemic hyponatremia.

Diminished and waning immunity to COVID-19 vaccination among hemodialysis patients in Israel: the case for a third vaccine dose.

BACKGROUND: Humoral responses to coronavirus disease 2019 (COVID-19) vaccines in hemodialysis (HD) patients can direct vaccination policy. METHODS: We compared 409 COVID-19-naïve HD patients from 13 HD units in Israel to 148 non-dialysis-dependent COVID-19-naïve controls. Twenty-four previously infected (antinucleocapsid positive) HD patients were analysed separately. Blood samples were obtained ≥14 days post-vaccination (BNT162b2, Pfizer/BioNTech) to assess seroconversion rates and titers of anti-spike (anti-S) and neutralizing antibodies. RESULTS: The median time from vaccination to blood sample collection was 82 days [interquartile range (IAR) 64-87] and 89 days (IQR 68-96) for HD patients and controls, respectively. Seroconversion rates were lower in HD patients compared with controls for both anti-S and neutralizing antibodies (89% and 77% versus 99.3%, respectively; P < 0.0001). Antibody titers were also significantly lower in HD patients compared with controls {median 69.6 [IQR 33.2-120] versus 196.5 [IQR 118.5-246], P < 0.0001; geometric mean titer [GMT] 23.3 [95% confidence interval (CI) 18.7-29.1] versus 222.7 [95% CI 174-284], P < 0.0001, for anti-S and neutralizing antibodies, respectively}. Multivariate analysis demonstrated dialysis dependence to be strongly associated with lower antibody responses and antibody titers waning with time. Age, low serum albumin and low lymphocyte count were also associated with lower seroconversion rates and antibody titers. HD patients previously infected with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had no difference in their seroconversion rates or antibody titers compared with COVID-19-naïve patients. CONCLUSION: This study demonstrates diminished and waning humoral responses following COVID-19 vaccination in a large and diverse cohort of HD patients, including those previously infected with SARS-CoV-2. Considering these results and reduced vaccine effectiveness against variants of concern, in addition to continued social distancing precautions, a third booster dose should be considered in this population.

Sex-specific genetic dissection of diabetes in a rodent model identifies Ica1 and Ndufa4 as major candidate genes.

The aim of the study was to initiate a sex-specific investigation of the molecular basis of diabetes, using a genomic approach in the Cohen Diabetic rat model of diet-induced Type 2 diabetes. We used an F2 population resulting from a cross between Cohen Diabetic susceptible (CDs) and resistant (CDr) and consisting of 132 males and 159 females to detect relevant QTLs by linkage and cosegregation analyses. To confirm the functional relevance of the QTL, we applied the "chromosome substitution" strategy. We identified candidate genes within the quantitative trait locus (QTL) and studied their differential expression. We sequenced the differentially expressed candidate genes to account for differences in their expression. We confirmed in this new cross in males a previously detected major QTL on rat chromosome 4 (RNO4); we identified in females this major QTL as well. We found three additional diabetes-related QTLs on RNO11, 13, and 20 in females only. We pursued the investigation of the QTL on RNO4 and generated a CDs.4(CDr) consomic strain, which provided us with functional confirmation for the contribution of the QTL to the diabetic phenotype in both sexes. We successfully narrowed the QTL span to 2.6 cM and identified within it six candidate genes, but only two of which, Ica1 (islet cell autoantigen 1) and Ndufa4 (NADH dehydrogenase ubiquinone) were differentially expressed between CDs and CDr. We sequenced the exons and promoter regions of Ica1 and Ndufa4 but did not identify sequence variations between the strains. The detection of the QTL on RNO4 in both sexes suggests involvement of Ica1, Ndufa4, the Golgi apparatus, the mitochondria and genetic susceptibility to dietary-environmental factors in the pathophysiology of diabetes in our model. The additional sex-specific QTLs are likely to account for differences in the diabetic phenotype between the sexes.

Geno-transcriptomic dissection of proteinuria in the uninephrectomized rat uncovers a molecular complexity with sexual dimorphism.

Investigation of proteinuria, whose pathophysiology remains incompletely understood, is confounded by differences in the phenotype between males and females. We initiated a sex-specific geno-transcriptomic dissection of proteinuria in uninephrectomized male and female Sabra rats that spontaneously develop focal and segmental glomerulosclerosis, testing the hypothesis that different mechanisms might underlie the pathophysiology of proteinuria between the sexes. In the genomic arm, we scanned the genome of 136 male and 111 female uninephrectomized F2 populations derived from crosses between SBH/y and SBN/y. In males, we identified proteinuria-related quantitative trait loci (QTLs) on RNO2 and 20 and protective QTLs on RNO6 and 9. In females, we detected proteinuria-related QTLs on RNO11, 13, and 20. The only QTL overlap between the sexes was on RNO20. Using consomic strains, we confirmed the functional significance of this QTL in both sexes. In the transcriptomic arm, we searched on a genomewide scale for genes that were differentially expressed in kidneys of SBH/y and SBN/y with and without uninephrectomy. These studies identified within each sex differentially expressed genes of relevance to proteinuria. Integrating genomics with transcriptomics, we identified differentially expressed genes that mapped within the boundaries of the proteinuria-related QTLs, singling out 24 transcripts in males and 30 in females, only 4 of which (Tubb5, Ubd, Psmb8, and C2) were common to both sexes. Data mining revealed that these transcripts are involved in multiple molecular mechanisms, including immunity, inflammation, apoptosis, matrix deposition, and protease activity, with no single molecular pathway predominating in either sex. These results suggest that the pathophysiology of proteinuria is highly complex and that some of the underlying mechanisms are shared between the sexes, while others are sex specific and may account for the difference in the proteinuric phenotype between males and females.