Icodextrin-induced acute generalized exanthematous pustulosis in a patient with peritoneal dialysis.

Icodextrin has been widely prescribed for peritoneal dialysis (PD) patients with inadequate ultrafiltration, but icodextrin induced acute generalized exanthematous pustulosis (AGEP) has been not well recognized in clinical practice. We described a young-aged female with IgA nephropathy and end stage kidney disease under continuous automated peritoneal dialysis. She developed skin erythema with exfoliation over the groin 7th day after initiation of icodextrin based PD dialysate. Initially, her scaling skin lesion with pinhead-sized pustules affected the bilateral inguinal folds, and then it extended to general trunk accompanied by pruritus. She was admitted because of deterioration of skin lesion on 14th day of icodextrin exposure. She was afebrile and physical examination was notable for widespread erythematous papules with pruritus extending over her groins and trunk. Pertinent laboratory examination showed leukocytosis of 18 970 cells/µL with neutrophile count of 17 642 cells/µL (92.3%), and c-reactive-protein: 3.39 mg/dL. Skin biopsy revealed multifocal sub corneal abscess with papillary dermal edema, and upper-dermal neutrophilia with perivascular accentuation, consistent with the diagnosis of AGEP. After discontinuation of PD, she underwent temporary high-flux haemodialysis with treatment of steroid and antihistamine. Her dermatologic lesion resolved without any skin sequalae completely within 4 days, and she underwent icodextrin-free peritoneal dialysis at 17th day. This case highlighted the fact that icodextrin-induced AGEP should be early recognized to avoid inappropriate management.

Identification and characterization of a novel CASR mutation causing familial hypocalciuric hypercalcemia.

Context: Although a monoallelic mutation in the calcium-sensing receptor (CASR) gene causes familial hypocalciuric hypercalcemia (FHH), the functional characterization of the identified CASR mutation linked to the clinical response to calcimimetics therapy is still limited. Objective: A 45-year-old male presenting with moderate hypercalcemia, hypocalciuria, and inappropriately high parathyroid hormone (PTH) had a good response to cinacalcet (total serum calcium (Ca2+) from 12.5 to 10.1 mg/dl). We identified the genetic mutation and characterized the functional and pathophysiological mechanisms, and then linked the mutation to calcimimetics treatment in vitro. Design: Sanger sequencing of the CASR, GNA11, and AP2S1 genes was performed in his family. The simulation model was used to predict the function of the identified mutant. In vitro studies, including immunoblotting, immunofluorescence, a cycloheximide chase study, Calbryte™ 520 Ca2+ detection, and half-maximal effective concentration (EC50), were examined. Results: This proband was found to carry a de novo heterozygous missense I554N in the cysteine-rich domain of CASR, which was pathogenic based on the different software prediction models and ACGME criteria. The simulation model showed that CASR I554N mutation decreased its binding energy with Ca2+. Human CASR I554N mutation attenuated the stability of CASR protein, reduced the expression of p-ERK 1/2, and blunted the intracellular Ca2+ response to gradient extracellular Ca2+ (eCa2+) concentration. The EC50 study also demonstrated the correctable effect of calcimimetics on the function of the CASR I554N mutation. Conclusion: This novel CASR I554N mutation causing FHH attenuates CASR stability, its binding affinity with Ca2+, and the response to eCa2+ corrected by therapeutic calcimimetics.

Acute kidney disease following COVID-19 vaccination: a single-center retrospective study.

Background: Rare cases of de novo or relapsed kidney diseases associated with vaccination against coronavirus disease 2019 (COVID-19) have been increasingly reported. The aim of this study was to report the incidence, etiologies, and outcomes of acute kidney disease (AKD) following COVID-19 vaccination. Methods: This retrospective study extracted cases from renal registry of a single medical center from 1 March 2021 to 30 April 2022, prior to the significant surge in cases of the Omicron variant of COVID-19 infection in Taiwan. Adult patients who developed AKD after COVID-19 vaccination were included. We utilized the Naranjo score as a causality assessment tool for adverse vaccination reactions and charts review by peer nephrologists to exclude other causes. The etiologies, characteristics, and outcomes of AKD were examined. Results: Twenty-seven patients (aged 23 to 80 years) with AKD were identified from 1,897 vaccines (estimated rate of 13.6 per 1000 patient-years within the renal registry). A majority (77.8%) of vaccine received messenger RNA-based regimens. Their median (IQR) Naranjo score was 8 (6-9) points, while 14 of them (51.9%) had a definite probability (Naranjo score ≥ 9). The etiologies of AKD included glomerular disease (n = 16) consisting of seven IgA nephropathy, four anti-neutrophil cytoplasmic antibodies-associated glomerulonephritis (AAN), three membranous glomerulonephritis, two minimal change diseases, and chronic kidney disease (CKD) with acute deterioration (n = 11). Extra-renal manifestations were found in four patients. Over a median (IQR) follow-up period of 42 (36.5-49.5) weeks, six patients progressed to end-stage kidney disease (ESKD). Conclusion: Besides glomerulonephritis (GN), the occurrence of AKD following COVID-19 vaccination may be more concerning in high-risk CKD patients receiving multiple doses. Patients with the development of de novo AAN, concurrent extra-renal manifestations, or pre-existing moderate to severe CKD may exhibit poorer kidney prognosis.

'Aquaporin-omics': mechanisms of aquaporin-2 loss in polyuric disorders.

Animal models of a variety of acquired nephrogenic diabetes insipidus (NDI) disorders have identified a common feature: all such models are associated with the loss of aquaporin-2 (AQP2) from collecting duct principal cells, explaining the associated polyuria. To discover mechanisms of AQP2 loss, previous investigators have carried out either transcriptomics (lithium-induced NDI, unilateral ureteral obstruction, endotoxin-induced NDI) or proteomics (hypokalaemia-associated NDI, hypercalcaemia-associated NDI, bilateral ureteral obstruction), yielding contrasting views. Here, to address whether there may be common mechanisms underlying loss of AQP2 in acquired NDI disorders, we have used bioinformatic data integration techniques to combine information from all transcriptomic and proteomic data sets. The analysis reveals roles for autophagy/apoptosis, oxidative stress and inflammatory signalling as key elements of the mechanism that results in loss of AQP2. These processes can cause AQP2 loss through the combined effects of repression of Aqp2 gene transcription, generalized translational repression, and increased autophagic degradation of proteins including AQP2. Two possible types of stress-sensor proteins, namely death receptors and stress-sensitive protein kinases of the EIF2AK family, are discussed as potential triggers for signalling processes that result in loss of AQP2. KEY POINTS: Prior studies have shown in a variety of animal models of acquired nephrogenic diabetes insipidus (NDI) that loss of the aquaporin-2 (AQP2) protein is a common feature. Investigations of acquired NDI using transcriptomics (RNA-seq) and proteomics (protein mass spectrometry) have led to differing conclusions regarding mechanisms of AQP2 loss. Bioinformatic integration of transcriptomic and proteomic data from these prior studies now reveals that acquired NDI models map to three core processes: oxidative stress, apoptosis/autophagy and inflammatory signalling. These processes cause loss of AQP2 through translational repression, accelerated degradation of proteins, and transcriptional repression.

Machine Learning to Identify Genetic Salt-Losing Tubulopathies in Hypokalemic Patients.

Introduction: Clinically distinguishing patients with the inherited salt-losing tubulopathies (SLTs), Gitelman or Bartter syndrome (GS or BS) from other causes of hypokalemia (LK) patients is difficult, and genotyping is costly. We decided to identify clinical characteristics that differentiate SLTs from LK. Methods: A total of 66 hypokalemic patients with possible SLTs were recruited to a prospective observational cohort study at the University College London Renal Tubular Clinic, London. All patients were genotyped for pathogenic variants in genes which cause SLTs; 39 patients had pathogenic variants in genes causing SLTs. We obtained similar data sets from cohorts in Taipei and Kobe, as follows: the combined data set comprised 419 patients; 291 had genetically confirmed SLT. London and Taipei data sets were combined to train machine learning (ML) algorithms, which were then tested on the Kobe data set. Results: Single biochemical variables (e.g., plasma renin) were significantly, but inconsistently, different between SLTs and LK in all cohorts. A decision table algorithm using serum bicarbonate and urinary sodium excretion (FENa) achieved a classification accuracy of 74%. This was superior to all the single biochemical variables identified previously. Conclusion: ML algorithms can differentiate true SLT in the context of a specialist clinic with some accuracy. However, based on routine biochemistry, the accuracy is insufficient to make genotyping redundant.

Early Molecular Events Mediating Loss of Aquaporin-2 during Ureteral Obstruction in Rats.

BACKGROUND: Ureteral obstruction is marked by disappearance of the vasopressin-dependent water channel aquaporin-2 (AQP2) in the renal collecting duct and polyuria upon reversal. Most studies of unilateral ureteral obstruction (UUO) models have examined late time points, obscuring the early signals that trigger loss of AQP2. METHODS: We performed RNA-Seq on microdissected rat cortical collecting ducts (CCDs) to identify early signaling pathways after establishment of UUO. RESULTS: Vasopressin V2 receptor (AVPR2) mRNA was decreased 3 hours after UUO, identifying one cause of AQP2 loss. Collecting duct principal cell differentiation markers were lost, including many not regulated by vasopressin. Immediate early genes in CCDs were widely induced 3 hours after UUO, including Myc, Atf3, and Fos (confirmed at the protein level). Simultaneously, expression of NF-κB signaling response genes known to repress Aqp2 increased. RNA-Seq for CCDs at an even earlier time point (30 minutes) showed widespread mRNA loss, indicating a "stunned" profile. Immunocytochemical labeling of markers of mRNA-degrading P-bodies DDX6 and 4E-T indicated an increase in P-body formation within 30 minutes. CONCLUSIONS: Immediately after establishment of UUO, collecting ducts manifest a stunned state with broad disappearance of mRNAs. Within 3 hours, there is upregulation of immediate early and inflammatory genes and disappearance of the V2 vasopressin receptor, resulting in loss of AQP2 (confirmed by lipopolysaccharide administration). The inflammatory response seen rapidly after UUO establishment may be relevant to both UUO-induced polyuria and long-term development of fibrosis in UUO kidneys.

Novel CNNM2 Mutation Responsible for Autosomal-Dominant Hypomagnesemia With Seizure.

CNNM2 is primarily expressed in the brain and distal convoluted tubule (DCT) of the kidney. Mutations in CNNM2 have been reported to cause hypomagnesemia, seizure, and intellectual disability (HSMR) syndrome. However, the clinical and functional effect of CNNM2 mutations remains incompletely understood. We report our clinical encounter with a 1-year-old infant with HSMR features. Mutation screening for this trio family was performed using next-generation sequencing (NGS)-based whole exome sequencing (WES) with the identified mutation verified by Sanger sequencing. We identified a de novo heterozygous mutation c.G1439T (R480L) in the essential cystathionine ß-synthase (CBS) domain of CNNM2 encoding CNNM2 (cyclin M2) without any other gene mutations related to hypomagnesemia. The amino acid involved in this missense mutation was conserved in different species. It was also found to be pathogenic based on the different software prediction models and ACGME criteria. In vitro studies revealed a higher expression of the CNNM2-R480L mutant protein compared to that of the wild-type CNNM2. Like the CNNM2-wild type, proper localization of CNNM2-R480L was shown on immunocytochemistry images. The Mg2+ efflux assay in murine DCT (mDCT) cells revealed a significant increase in intracellular Mg2+ green in CNNM2-R480L compared to that in CNNM2-WT. By using a simulation model, we illustrate that the R480L mutation impaired the interaction between CNNM2 and ATP-Mg2+. We propose that this novel R480L mutation in the CNNM2 gene led to impaired binding between Mg2+-ATP and CNNM2 and diminished Mg2+ efflux, manifesting clinically as refractory hypomagnesemia.

Generation and analysis of pseudohypoaldosteronism type II knock-in mice caused by a nonsense KLHL3 mutation in the Kelch domain.

Mutations in the Kelch-like 3 (KLHL3) gene are the most common cause of inherited pseudohypoaldosteronism type II (PHAII) featuring thiazide-sensitive hypertension and hyperkalemic metabolic acidosis. Although Klhl3R528H/+ knock-in (KI) mice carrying a missense mutation in the Kelch repeat domain have been reported, nonsense KLHL3 mutations in the same domain that cause PHAII have not been fully investigated in vivo. We generated and analyzed Klhl3 KI mice harboring a nonsense W523X mutation (corresponding to the human KLHL3 W470X mutation). Both heterozygous and homozygous Klhl3W523X/+ KI mice exhibited typical PHAII with low-renin hypertension, hyperkalemia with reduced renal potassium excretion, and hyperchloremic metabolic acidosis. Their kidney tissues showed the presence of Klhl3 mRNA and increased Klhl3 protein levels along with enhanced downstream Wnk1/4-Spak/Osr1-N(k)cc phosphorylation. Increased protein expression of total Spak, phosphor(p-)Spak, total Ncc, and p-Ncc from urinary extracellular vesicles (uEVs) also confirmed the activation of the Wnk-mediated Ncc pathway. In vitro studies showed that the human KLHL3 W470X mutation resulted in increased KLHL3 protein stability and disrupted its binding affinity for WNK1/4, leading to the attenuated degradation and increased abundance of total WNKs. In conclusion, nonsense Klhl3W523X/+ mice recapitulating PHAII phenotypes exhibit Klhl3 protein stability, abrogating its binding to Wnks, with enhanced Ncc expression in the kidney tissue and even in uEVs. Activation of the WNK-mediated Na+ -Cl- co-transporter reiterated the in vivo pathogenic role of nonsense KLHL3 mutations in PHAII.

A young man with secondary adrenal insufficiency due to empty sella syndrome.

BACKGROUND: Empty sella syndrome is characterized by a constellation of symptoms that encompass various systems, and includes endocrine, neurologic, ophthalmologic, and psychiatric presentations. We here report a case of a young man presenting with severe hyponatremia due to empty sella syndrome and focus on changes in electrolytes during corticosteroid supplementation. CASE REPORT: A 36-year-old man presented with general weakness, poor appetite, and dizziness for 4 days. Physical assessment revealed lower limbs nonpitting oedema. Pertinent laboratory data showed severe hyponatremia (sodium 108 mmol/L). Endocrine work-up revealed low cortisol levels at 1.17 µg/dL (reference: 4.82-19.5 µg/dL) and inappropriately normal adrenocorticotropic hormone levels at 12.4 pg/mL (reference: 0.1-46.0 pg/mL), indicating secondary adrenal insufficiency. Brain magnetic resonance imaging confirmed the diagnosis of empty sella syndrome. He developed delirium and agitation one day after cortisol supplementation with a sodium correction rate of 10 mmol/L/day, while hypokalaemia (potassium 3.4 mmol/L) also developed. The symptoms improved after lowering the serum sodium level. This patient was eventually discharged after 12 days of hospitalization when the serum sodium and potassium levels were 139 mmol/L and 3.5 mmol/L, respectively. CONCLUSION: Herein, we address the importance of timely diagnosis of empty sella syndrome in patients with hyponatremia and highlight the close monitoring of the changes in electrolytes during corticosteroid replacement.

NSC828779 Alleviates Renal Tubulointerstitial Lesions Involving Interleukin-36 Signaling in Mice.

Renal tubulointerstitial lesions (TILs), a common pathologic hallmark of chronic kidney disease that evolves to end-stage renal disease, is characterized by progressive inflammation and pronounced fibrosis of the kidney. However, current therapeutic approaches to treat these lesions remain largely ineffectual. Previously, we demonstrated that elevated IL-36α levels in human renal tissue and urine are implicated in impaired renal function, and IL-36 signaling enhances activation of NLRP3 inflammasome in a mouse model of TILs. Recently, we synthesized NSC828779, a salicylanilide derivative (protected by U.S. patents with US 8975255 B2 and US 9162993 B2), which inhibits activation of NF-κB signaling with high immunomodulatory potency and low IC50, and we hypothesized that it would be a potential drug candidate for renal TILs. The current study validated the therapeutic effects of NSC828779 on TILs using a mouse model of unilateral ureteral obstruction (UUO) and relevant cell models, including renal tubular epithelial cells under mechanically induced constant pressure. Treatment with NSC828779 improved renal lesions, as demonstrated by dramatically reduced severity of renal inflammation and fibrosis and decreased urinary cytokine levels in UUO mice. This small molecule specifically inhibits the IL-36α/NLRP3 inflammasome pathway. Based on these results, the beneficial outcome represents synergistic suppression of both the IL-36α-activated MAPK/NLRP3 inflammasome and STAT3- and Smad2/3-dependent fibrogenic signaling. NSC828779 appears justified as a new drug candidate to treat renal progressive inflammation and fibrosis.

Association of Serum Phosphate with Low Handgrip Strength in Patients with Advanced Chronic Kidney Disease.

Muscle wasting and hyperphosphatemia are becoming increasingly prevalent in patients who exhibit a progressive decline in kidney function. However, the association between serum phosphate (Pi) level and sarcopenia in advanced chronic kidney disease (CKD) patients remains unclear. We compared the serum Pi levels between advanced CKD patients with (n = 51) and those without sarcopenia indicators (n = 83). Low appendicular skeletal muscle mass index (ASMI), low handgrip strength, and low gait speed were defined per the standards of the Asian Working Group for Sarcopenia. Mean serum Pi level was significantly higher in advanced CKD patients with sarcopenia indicators than those without sarcopenia indicators (3.88 ± 0.86 vs. 3.54 ± 0.73 mg/dL; p = 0.016). Univariate analysis indicated that serum Pi was negatively correlated with ASMI, handgrip strength, and gait speed. Multivariable analysis revealed that serum Pi was significantly associated with handgrip strength (standardized ß = -0.168; p = 0.022) and this association persisted even after adjustments for potential confounders. The optimal serum Pi cutoff for predicting low handgrip strength was 3.65 mg/dL, with a sensitivity of 82.1% and specificity of 56.6%. In summary, low handgrip strength is common in advanced CKD patients and serum Pi level is negatively associated with handgrip strength.

Allele-specific RT-PCR for the rapid detection of recurrent SLC12A3 mutations for Gitelman syndrome.

Recurrent mutations in the SLC12A3 gene responsible for autosomal recessive Gitelman syndrome (GS) are frequently reported, but the exact prevalence is unknown. The rapid detection of recurrent SLC12A3 mutations may help in the early diagnosis of GS. This study was aimed to investigate the prevalence of recurrent SLC12A3 mutations in a Taiwan cohort of GS families and develop a simple and rapid method to detect recurrent SLC12A3 mutations. One hundred and thirty independent Taiwan families with genetically confirmed GS were consecutively enrolled to define recurrent SLC12A3 mutations and determine their prevalence. Using TaqMan probe-based real-time polymerase chain reaction, we designed a mutation detection plate with all recurrent mutations. We validated this mutation detection plate and tested its feasibility in newly diagnosed GS patients. A total of 57 mutations in the SLC12A3 gene were identified and 22 including 2 deep intronic mutations were recurrent mutations consisting of 87.1% (242/278, 18 triple) of all allelic mutations. The recurrent mutation-based TaqMan assays were fully validated with excellent sensitivity and specificity in genetically diagnosed GS patients and healthy subjects. In clinical validation, recurrent mutations were recognized in 92.0% of allelic mutations from 12 GS patients within 4 h and all were confirmed by direct sequencing. Recurrent SLC12A3 mutations are very common in Taiwan GS patients and can be rapidly identified by this recurrent mutation-based SLC12A3 mutation plate.

Independent Determinants of Appetite Impairment among Patients with Stage 3 or Higher Chronic Kidney Disease: A Prospective Study.

Protein-energy wasting (PEW) is an important complication resulting from chronic kidney disease (CKD). Appetite impairment contributes significantly to PEW in these patients, but risk factors associated with having appetite impairment in patients with CKD remain elusive. Patients with an estimated glomerular filtration rate <60 mL/min/1.73 m2 for ≥2 times at least three months apart were prospectively enrolled during 2017, with their demographic features, comorbidities, anthropometric parameters, physical and performance indices, functional status, frailty, sensory organ integrity, and laboratory data collected. Their appetite status was measured using the Council on Nutrition Appetite Questionnaire (CNAQ). We examined independent determinants of appetite impairment in these CKD patients using multiple regression analyses. Among 78 patients with CKD, 42.3% had CNAQ-identified impaired appetite. Those with an impaired appetite also had poorer physical performance, a higher degree of functional impairment, higher frail severities, lower serum sodium levels, less intact oral cavity, and a trend toward having less intact nasal structures than those without. Multiple regression analyses revealed that a higher frail severity, in the forms of increasing Study of Osteoporotic Fractures (SOF) scores (odds ratio (OR), 2.74; 95% confidence interval (CI), 1.15-6.57) and a less intact nasal structure (OR, 0.96; 95% CI, 0.92-0.995) were associated with a higher probability of having an impaired appetite, while higher serum sodium (OR, 0.76; 95% CI, 0.6-0.97) correlated with a lower probability. Based on our findings, in patients with CKD, the severity of frailty, serum sodium, and nasal structural integrity might modify appetite status. Therapies targeting these factors might be beneficial for appetite restoration in patients with CKD.

Urinary Extracellular Vesicles for Renal Tubular Transporters Expression in Patients With Gitelman Syndrome.

Background: The utility of urinary extracellular vesicles (uEVs) to faithfully represent the changes of renal tubular protein expression remains unclear. We aimed to evaluate renal tubular sodium (Na+) or potassium (K+) associated transporters expression from uEVs and kidney tissues in patients with Gitelman syndrome (GS) caused by inactivating mutations in SLC12A3. Methods: uEVs were isolated by ultracentrifugation from 10 genetically-confirmed GS patients. Membrane transporters including Na+-hydrogen exchanger 3 (NHE3), Na+/K+/2Cl- cotransporter (NKCC2), NaCl cotransporter (NCC), phosphorylated NCC (p-NCC), epithelial Na+ channel ß (ENaCß), pendrin, renal outer medullary K1 channel (ROMK), and large-conductance, voltage-activated and Ca2+-sensitive K+ channel (Maxi-K) were examined by immunoblotting of uEVs and immunofluorescence of biopsied kidney tissues. Healthy and disease (bulimic patients) controls were also enrolled. Results: Characterization of uEVs was confirmed by nanoparticle tracking analysis, transmission electron microscopy, and immunoblotting. Compared with healthy controls, uEVs from GS patients showed NCC and p-NCC abundance were markedly attenuated but NHE3, ENaCß, and pendrin abundance significantly increased. ROMK and Maxi-K abundance were also significantly accentuated. Immunofluorescence of the representative kidney tissues from GS patients also demonstrated the similar findings to uEVs. uEVs from bulimic patients showed an increased abundance of NCC and p-NCC as well as NHE3, NKCC2, ENaCß, pendrin, ROMK and Maxi-K, akin to that in immunofluorescence of their kidney tissues. Conclusion: uEVs could be a non-invasive tool to diagnose and evaluate renal tubular transporter adaptation in patients with GS and may be applied to other renal tubular diseases.

Phytobezoar-induced small bowel obstruction in an elderly patient undergoing dialysis: a case report.

A phytobezoar is defined as an accumulation of poorly digested fruit and vegetable fibers in the gastrointestinal tract. Phytobezoar-induced small bowel obstruction is an uncommon entity and is usually removed surgically. We herein describe an elderly man undergoing dialysis who developed a phytobezoar because of excessive consumption of high-fiber fruits and inappropriate chewing. His potential predisposing factors were dialysis-related lifestyle changes, reduced activity levels, fluid restriction, and gastrointestinal motility dysfunction; however, he had no history of gastric surgery. The patient's clinical history and characteristic imaging features aided in the diagnosis. He underwent medical treatment, and his recovery was uneventful. This case highlights the importance of an awareness of phytobezoar-induced small bowel obstruction in patients at increased risk of developing bezoars and demonstrates that this condition can occur in the absence of previous gastric surgery. We believe that elderly patients undergoing dialysis are at increased risk of developing bezoars. Excessive consumption of a strictly fibrous diet and insufficient chewing exacerbate the risk. A detailed dietary history and imaging features can aid in early diagnosis, leading to appropriate medical or surgical care. Surgical treatment is not inevitable in all cases. Individualized dietary suggestions in these patients are important for effective preventive control.

RNA-Seq and protein mass spectrometry in microdissected kidney tubules reveal signaling processes initiating lithium-induced nephrogenic diabetes insipidus.

Lithium salts, used for treating bipolar disorder, frequently induce nephrogenic diabetes insipidus (NDI) thereby limiting therapeutic success. NDI is associated with loss of expression of the gene coding for the molecular water channel, aquaporin-2, in the renal collecting duct (CD). Here, we use systems biology methods in a well-established rat model of lithium-induced NDI to identify signaling pathways activated at the onset of polyuria. Using single-tubule RNA-Seq, full transcriptomes were determined in microdissected cortical collecting ducts (CCDs) of rats after 72 hours without or with initiation of lithium chloride administration. Transcriptome-wide changes in mRNA abundances were mapped to gene sets associated with curated canonical signaling pathways, showing evidence for activation of NF-κB signaling with induction of genes coding for multiple chemokines and most components of the Major Histocompatibility Complex Class I antigen-presenting complex. Administration of anti-inflammatory doses of dexamethasone to lithium chloride-treated rats countered the loss of aquaporin-2. RNA-Seq also confirmed prior evidence of a shift from quiescence into the cell cycle with arrest. Time course studies demonstrated an early (12 hour) increase in multiple immediate early response genes including several transcription factors. Protein mass spectrometry in microdissected CCDs provided corroborative evidence and identified decreased abundance of several anti-oxidant proteins. Thus, in the context of prior observations, our study can be best explained by a model in which lithium increases ERK activation leading to induction of NF-κB signaling and an inflammatory-like response that represses Aqp2 transcription.

Generation and analysis of a mouse model of pseudohypoaldosteronism type II caused by KLHL3 mutation in BTB domain.

The Kelch-like 3 ( KLHL3) mutations contributed to the most common causative genes in patients with pseudohypoaldosteronism type II (PHAII); however, the molecular mechanisms of PHAII-causing mutations in BTB domain of KLHL3 in vivo have not been investigated. We generated and analyzed Klhl3 knock-in (KI) mice carrying a missense M131V mutation in the BTB domain (corresponding to human KLHL3 M78V mutation). Klhl3M131V/+ KI mice exhibited typical PHAII phenotype with an exaggerated diuretic response to hydrochlorothiazide. Their kidney tissues showed an unchanged KLHL3, decreased cullin 3 (Cul3), and increased with-no-lysine kinases (WNKs) WNK1 and WNK4 along with an enhanced downstream ste20-related proline/alanine-rich kinase/oxidative stress response kinase 1-N(K)CC phosphorylation. Their Cul3 protein in the cytosol of distal convoluted tubule cells was also significantly attenuated on immunogold-labeling electron microscopy. In microdissected renal tubules, Klhl3M131V/+ KI mice expressed high levels of Wnk4 mRNA in the distal nephron. In vitro coimmunoprecipitation showed the KLHL3 BTB domain mutation retained intact interaction with WNKs but reduced binding to Cul3, thus leading to the increased abundance of total WNKs. In summary, Klhl3M131V/+ KI mice feature typical PHAII with a simultaneous increase of WNK1 and WNK4 through the impaired KLHL3 BTB domain binding to Cul3.-Lin, C.-M., Cheng, C.-J., Yang, S.-S., Tseng, M.-H., Yen, M.-T., Sung, C.-C., Lin, S.-H. Generation and analysis of a mouse model of pseudohypoaldosteronism type II caused by KLHL3 mutation in BTB domain.

Hypoparathyroidism concomitant with macrothrombocytopenia in an elderly woman with 22q11.2 deletion syndrome.

We describe the case of a 62-year-old woman with schizophrenia and intellectual disability, who presented with intermittent muscle cramping for 2 weeks. A dysmorphic face and a positive Trousseau's sign, but without ecchymosis or petechial lesion were noted. Laboratory data revealed impaired renal function (creatinine level = 1.6 mg/dL), severe hypocalcaemia (total calcium level = 5.7 mg/dL) with low urinary calcium excretion (13.2 mg/day), hyperphosphatemia (phosphate level = 7.3 mg/dL), and low intact parathyroid hormone level (52.5 pg/mL)-indicating primary hypoparathyroidism. A blood smear revealed thrombocytopenia (30,000 thrombocytes/µL) and giant platelets-indicating macrothrombocytopenia. Chromosome 22q11.2 deletion syndrome (22q11.2DS) in the deficient chromosome 22 was confirmed using multiplex ligation-dependent probe amplification showing haploinsufficiency in GP1BB and TBX-1. Cooccurrence of hypoparathyroidism and macrothrombocytopenia in 22q11.2DS is rare and can easily be misdiagnosed as idiopathic thrombocytopenia purpura and inappropriate splenectomy or chemotherapy can aggravate hypoparathyroidism. Early diagnosis of 22q11.2DS, characterized by hypoparathyroidism and macrothrombocytopenia, in elderly patients with schizophrenia can facilitate in avoiding circuitous diagnosis and inappropriate management.