Case Report: A Rare Presentation of NSAID-Induced Secondary Membranous Nephropathy in a Pediatric Patient.

Background: Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults, but it is responsible for <5% of nephrotic syndrome cases in children. MN has primary and secondary forms. Secondary MN is caused by viral infections, autoimmune diseases like lupus, or drugs. Non-steroid anti-inflammatory drug (NSAID)-induced secondary MN is rarely described in the pediatric population. Thus, the clinical presentation and time to recovery are vastly unknown in the pediatric subgroup. Clinical Presentation: We report a case of a 15-year-old female who presented with acute onset of nephrotic range proteinuria, significant hypoalbuminemia, hyperlipidemia, and lower extremity edema related to the presence of nephrotic syndrome. She had a history of ibuprofen use periodically for 6 months before presentation because of menstrual cramps and intermittent lower abdominal pain. After the presentation, we performed a renal biopsy that reported stage 1-2 MN, likely secondary. The phospholipase A2 receptor (PLA2R) antibody on the blood test and PLA2R immune stain on the renal biopsy sample were negative. We performed a comprehensive evaluation of the viral and immune causes of secondary MN, which was non-revealing. She had stopped ibuprofen use subsequent to the initial presentation. She was prescribed ACE inhibitor therapy. After 6 months of ACE inhibitor treatment, the proteinuria had resolved. Conclusion: Proteinuria can last for several weeks when NSAID induces secondary MN and nephrotic syndrome. With the widespread use of NSAIDs prevalent in the pediatric community, further studies are needed to evaluate and study the role of NSAIDs in this condition.

A Rare and Severe Presentation of Henoch-Schönlein Purpura in an Adolescent With Crescentic Glomerulonephritis, Arrhythmia, Acute Gastrointestinal Bleed, and Neurological Complications.

Henoch-Schönlein purpura (HSP) is a childhood vasculitis disorder that involves the skin, joints, gastrointestinal (GI) tract, and kidneys. It is related to immunoglobulin A (IgA) antibody deposition in small blood vessels. HSP is a self-limiting disorder, but its morbidity is primarily associated with renal involvement. GI pathologies like intussusception, gastritis, duodenitis, ileitis, or ulcer have been reported to be associated with this disease. However, cardiac and neurological complications are rarely reported. We present the case of a 16-year-old, previously healthy male who was diagnosed with HSP after presenting with a non-blanching purpuric rash in the lower extremities. The patient also had joint and abdominal pain, and swelling in the extremities. There was renal dysfunction at presentation with blood urea nitrogen (BUN) of 67 mg/dL and serum creatinine of 1.9 mg/dL. The serum albumin was low at 2 g/dL, and the patient had nephrotic range proteinuria. Urine microscopy showed red blood cell casts. A renal biopsy was performed, which showed IgA deposition in glomeruli. He was started on intravenous (IV) pulse methylprednisolone and was later prescribed oral steroids. Four weeks after the treatment initiation, he presented with syncope and acute anemia (hemoglobin of 3.5 g/dL). The fecal occult blood was positive. Esophagogastroduodenoscopy (EGD) was not suggestive of gastritis, duodenitis, or ulcer. The pill-cam capsule endoscopy revealed GI bleeding from the terminal ileum near Meckel's diverticulum. He subsequently required blood transfusions, and the bleeding eventually improved with symptomatic management. Six weeks after treatment initiation, he presented with dizziness and palpitations. The EKG showed the presence of atrial fibrillation, and he had an episode of non-sustained ventricular tachycardia on telemetry. Arrhythmia was diagnosed secondary to HSP cardiac vasculitis, and we initiated treatment with metoprolol and amiodarone. Seven weeks after the initial treatment, he had neurological clinical findings of proximal muscle weakness, tremors, and upper and lower extremity clonus. A second renal biopsy was then performed due to the presence of persistently elevated serum creatinine, which showed 75% of glomeruli with cellular crescents. He was treated with IV cyclophosphamide. Subsequently, the renal function improved. There were no other GI, cardiac, or neurological complications after six months of follow-up. The presentation of HSP can be more severe in adolescents, and they need to be closely monitored for GI, cardiac, renal, and neurological complications after the disease occurrence. Bleeding from Meckel's diverticulum or an episode of non-sustained ventricular tachycardia with HSP has not been previously reported to our knowledge. Arrhythmia is an exceptionally unusual occurrence in HSP, and it is usually treated with anti-arrhythmic drugs and intensification of the immunosuppressive regimen.

Patients with Proliferative Lupus Nephritis Have Autoantibodies That React to Moesin and Demonstrate Increased Glomerular Moesin Expression.

Kidney involvement in systemic lupus erythematosus (SLE)-termed lupus nephritis (LN)-is a severe manifestation of SLE that can lead to end-stage kidney disease (ESKD). LN is characterized by immune complex deposition and inflammation in the glomerulus. We tested the hypothesis that autoantibodies targeting podocyte and glomerular cell proteins contribute to the development of immune complex formation in LN. We used Western blotting with SLE sera from patients with and without LN to identify target antigens in human glomerular and cultured human-derived podocyte membrane proteins. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identified the proteins in the gel regions corresponding to reactive bands observed with sera from LN patients. We identified 102 proteins that were present in both the podocyte and glomerular samples. We identified 10 high-probability candidates, including moesin, using bioinformatic analysis. Confirmation of moesin as a target antigen was conducted using immunohistochemical analysis (IHC) of kidney biopsy tissue and enzyme-linked immunosorbent assay (ELISA) to detect circulating antibodies. By IHC, biopsies from patients with proliferative lupus nephritis (PLN, class III/IV) demonstrated significantly increased glomerular expression of moesin (p < 0.01). By ELISA, patients with proliferative LN demonstrated significantly increased antibodies against moesin (p < 0.01). This suggests that moesin is a target glomerular antigen in lupus nephritis.

NHERF1 Loss Upregulates Enzymes of the Pentose Phosphate Pathway in Kidney Cortex.

(1) Background: We previously showed Na/H exchange regulatory factor 1 (NHERF1) loss resulted in increased susceptibility to cisplatin nephrotoxicity. NHERF1-deficient cultured proximal tubule cells and proximal tubules from NHERF1 knockout (KO) mice exhibit altered mitochondrial protein expression and poor survival. We hypothesized that NHERF1 loss results in changes in metabolic pathways and/or mitochondrial dysfunction, leading to increased sensitivity to cisplatin nephrotoxicity. (2) Methods: Two to 4-month-old male wildtype (WT) and KO mice were treated with vehicle or cisplatin (20 mg/kg dose IP). After 72 h, kidney cortex homogenates were utilized for metabolic enzyme activities. Non-treated kidneys were used to isolate mitochondria for mitochondrial respiration via the Seahorse XF24 analyzer. Non-treated kidneys were also used for LC-MS analysis to evaluate kidney ATP abundance, and electron microscopy (EM) was utilized to evaluate mitochondrial morphology and number. (3) Results: KO mouse kidneys exhibit significant increases in malic enzyme and glucose-6 phosphate dehydrogenase activity under baseline conditions but in no other gluconeogenic or glycolytic enzymes. NHERF1 loss does not decrease kidney ATP content. Mitochondrial morphology, number, and area appeared normal. Isolated mitochondria function was similar between WT and KO. Conclusions: KO kidneys experience a shift in metabolism to the pentose phosphate pathway, which may sensitize them to the oxidative stress imposed by cisplatin.

Proteomic Analysis Identifies Distinct Glomerular Extracellular Matrix in Collapsing Focal Segmental Glomerulosclerosis.

BACKGROUND: The mechanisms leading to extracellular matrix (ECM) replacement of areas of glomerular capillaries in histologic variants of FSGS are unknown. This study used proteomics to test the hypothesis that glomerular ECM composition in collapsing FSGS (cFSGS) differs from that of other variants. METHODS: ECM proteins in glomeruli from biopsy specimens of patients with FSGS not otherwise specified (FSGS-NOS) or cFSGS and from normal controls were distinguished and quantified using mass spectrometry, verified and localized using immunohistochemistry (IHC) and confocal microscopy, and assessed for gene expression. The analysis also quantified urinary excretion of ECM proteins and peptides. RESULTS: Of 58 ECM proteins that differed in abundance between cFSGS and FSGS-NOS, 41 were more abundant in cFSGS and 17 in FSGS-NOS. IHC showed that glomerular tuft staining for cathepsin B, cathepsin C, and annexin A3 in cFSGS was significantly greater than in other FSGS variants, in minimal change disease, or in membranous nephropathy. Annexin A3 colocalized with cathepsin B and C, claudin-1, phosphorylated ERK1/2, and CD44, but not with synaptopodin, in parietal epithelial cells (PECs) infiltrating cFSGS glomeruli. Transcripts for cathepsins B and C were increased in FSGS glomeruli compared with normal controls, and urinary excretion of both cathepsins was significantly greater in cFSGS compared with FSGS-NOS. Urinary excretion of ECM-derived peptides was enhanced in cFSGS, although in silico analysis did not identify enhanced excretion of peptides derived from cathepsin B or C. CONCLUSIONS: ECM differences suggest that glomerular sclerosis in cFSGS differs from that in other FSGS variants. Infiltration of activated PECs may disrupt ECM remodeling in cFSGS. These cells and their cathepsins may be therapeutic targets.

Platelet Electron Microscopy: Utilizing LEAN Methodology to Optimize Laboratory Workflow.

BACKGROUND: Platelet electron microscopy (PEM) is the gold standard methodology for diagnosing storage pool disorder, defined as a paucity of delta granules, alpha granules, or both. PEM literature is limited with few published resources and without well-developed interlaboratory standardization for the preparation and examination of platelet samples. METHODS: Whole mount (WM) dense body (DB) counts for 300 pediatric cases were reviewed to determine whether counting fewer platelets could yield the same results. For 6 cases, DB average was determined on the day of WM preparation and on 2 consecutive days. Both WM and thin section (TS) preparations were examined for all cases. RESULTS: Employing LEAN methodology, an algorithm was developed to markedly decrease the number of platelets counted and still ensure accurate results. WMs decay with time; a statistically significant difference in DB counts was noted between day 0 and day 1 (p < .1). Twelve of 300 cases required both WM and TS preparations for a complete diagnosis. CONCLUSION: It is possible to maintain accuracy and decrease 100 platelet DB counts by >75%. WMs must be counted on the day they are prepared to avoid false paucity of DB secondary to sample decay. An accurate evaluation of platelet morphology requires both the WM and TS techniques.

Neutrophil exocytosis induces podocyte cytoskeletal reorganization and proteinuria in experimental glomerulonephritis.

Acute glomerulonephritis is characterized by rapid glomerular neutrophil recruitment, proteinuria, and glomerular hypercellularity. The current study tested the hypothesis that the release of neutrophil granule contents plays a role in both the loss of filtration barrier leading to proteinuria and the increase in glomerular cells. Inhibition of neutrophil exocytosis with a peptide inhibitor prevented proteinuria and attenuated podocyte and endothelial cell injury but had no effect on glomerular hypercellularity in an experimental acute glomerulonephritis model in mice. Cultivation of podocytes with neutrophil granule contents disrupted cytoskeletal organization, an in vitro model for podocyte effacement and loss of filtration barrier. Activated, cultured podocytes released cytokines that stimulated neutrophil chemotaxis, primed respiratory burst activity, and stimulated neutrophil exocytosis. We conclude that crosstalk between podocytes and neutrophils contributes to disruption of the glomerular filtration barrier in acute glomerulonephritis. Neutrophil granule products induce podocyte injury but do not participate in the proliferative response of intrinsic glomerular cells.

Sphenoid Dysplasia: A Rare Presentation of Infantile Myofibroma.

The authors report a case of isolated congenital orbital myofibroma causing sphenoid dysplasia and presenting as global restriction of extraocular motility and ptosis in a neonate. Sphenoid wing dysplasia is most commonly associated neurofibromatosis 1 but this patient had no evidence of neurofibromatosis on clinical examination and genetic testing. Congenital orbital myofibroma can have secondary effects on bone and likely the lesion was present early in development leading to aplasia of the sphenoid bone. To the best of the authors' knowledge, this is the first reported case of sphenoid wing aplasia secondary to congenital orbital myofibroma independent of neurofibromatosis 1.

Neonatal multiorgan failure due to ACAD9 mutation and complex I deficiency with mitochondrial hyperplasia in liver, cardiac myocytes, skeletal muscle, and renal tubules.

Complex I deficiency causes Leigh syndrome, fatal infant lactic acidosis, and neonatal cardiomyopathy. Mutations in more than 100 nuclear DNA and mitochondrial DNA genes miscode for complex I subunits or assembly factors. ACAD9 is an acyl-CoA dehydrogenase with a novel function in assembly of complex I; biallelic mutations cause progressive encephalomyopathy, recurrent Reye syndrome, and fatal cardiomyopathy. We describe the first autopsy in fatal neonatal lethal lactic acidosis due to mutations in ACAD9 that reduced complex I activity. We identified mitochondrial hyperplasia in cardiac myocytes, diaphragm muscle, and liver and renal tubules in formalin-fixed, paraffin-embedded tissue using immunohistochemistry for mitochondrial antigens. Whole-exome sequencing revealed compound heterozygous variants in the ACAD9 gene: c.187G>T (p.E63*) and c.941T>C (p.L314P). The nonsense mutation causes late infantile lethality; the missense variant is novel. Autopsy-derived fibroblasts had reduced complex I activity (53% of control) with normal activity in complexes II to IV, similar to reported cases of ACAD9 deficiency.

Diagnostic utility of PHOX2B in primary and treated neuroblastoma and in neuroblastoma metastatic to the bone marrow.

CONTEXT: Neuroblastoma (NB) is the most common extracranial tumor of childhood. Although most cases have a distinctive histology, a subset of primitive cases require immunohistochemical studies to distinguish them from other small round blue cell tumors of childhood. Immunohistochemistry is also used to detect small amounts of tumor metastatic to the bone marrow and in posttreatment samples with obscuring fibrosis, calcification, or inflammation. The transcription factor PHOX2B is essential for the differentiation and survival of sympathetic neurons and chromaffin cells, and therefore is highly specific for the peripheral autonomic nervous system. OBJECTIVE: To determine the diagnostic utility of PHOX2B immunohistochemistry as a marker of primary, treated, and metastatic NB. DESIGN: Neuroblastoma tissue microarrays were stained with PHOX2B, CD57, and synaptophysin. Arrays containing rhabdomyosarcoma, Ewing sarcoma, and Wilms tumor were stained with PHOX2B, and negative bone marrow samples were stained with PHOX2B and CD57. RESULTS: PHOX2B and CD57 were similar to synaptophysin in their ability to detect NB. PHOX2B and CD57 similarly showed robust staining in posttreatment NB and NB metastatic to the bone marrow. In contrast to the cytoplasmic staining pattern seen with synaptophysin and CD57, clear and strong nuclear PHOX2B permitted identification of individual tumor cells. PHOX2B staining was absent in all cases of rhabdomyosarcoma, Ewing sarcoma, and Wilms tumor, and in the negative bone marrow. CONCLUSIONS: PHOX2B and CD57 are useful markers of NB. PHOX2B is specific for NB in its differential diagnosis with other small round cell tumors, and its nuclear staining may be helpful for accurate bone marrow tumor quantification.

Fatal antimalarial-induced cardiomyopathy: report of 2 cases.

Chloroquine and hydroxychloroquine are used to chronically treat certain rheumatologic diseases and are generally considered safe. We describe 2 patients with skeletal myopathy and fatal cardiomyopathy-uncommon and underrecognized adverse effects of these agents. Both patients developed arrhythmias and heart failure, and 1 patient had documented diaphragmatic involvement. Muscle specimens showed typical vacuolar myopathy (indicative of impaired autophagy) with myeloid bodies in both patients and curvilinear bodies in 1 patient. Antimalarial-induced cardiomyopathy should be considered in patients receiving these medications with otherwise unexplained muscle weakness or cardiac symptoms. Whether autophagy enhancers can be used to manage such myopathies merits investigation.

Linking conformation change to hemoglobin activation via chain-selective time-resolved resonance Raman spectroscopy of protoheme/mesoheme hybrids.

Time-resolved resonance Raman (RR) spectra are reported for hemoglobin (Hb) tetramers, in which the alpha and beta chains are selectively substituted with mesoheme. The Soret absorption band shift in mesoheme relative to protoheme permits chain-selective recording of heme RR spectra. The evolution of these spectra following HbCO photolysis shows that the geminate recombination rates and the yields are the same for the two chains, consistent with recent results on (15)N-heme isotopomer hybrids. The spectra also reveal systematic shifts in the deoxyheme nu (4) and nu (Fe-His) RR bands, which are anticorrelated. These shifts are resolved for the successive intermediates in the protein structure, which have previously been determined from time-resolved UV RR spectra. Both chains show Fe-His bond compression in the immediate photoproduct, which relaxes during the formation of the first intermediate, R(deoxy) (0.07 micros), in which the proximal F-helix is proposed to move away from the heme. Subsequently, the Fe-His bond weakens, more so for the alpha chains than for the beta chains. The weakening is gradual for the beta chains, but is abrupt for the alpha chains, coinciding with completion of the R-T quaternary transition, at 20 micros. Since the transition from fast- to slow-rebinding Hb also occurs at 20 micros, the drop in the alpha chain nu (Fe-His) supports the localization of ligation restraint to tension in the Fe-His bond, at least in the alpha chains. The mechanism is more complex in the beta chains.