Accelerated involution of germinal center in palatine tonsils in IgA nephropathy.

BACKGROUND: Altered immunological responses in the palatine tonsils may be involved in the pathogenesis of IgA nephropathy (IgAN). The germinal center serves as the site for antigen-specific humoral immune responses in the palatine tonsils. Germinal center involution is frequently observed in the palatine tonsils of IgAN (IgAN tonsils). However, the pathogenic significance of these characteristic changes remains unclear. This study aimed to investigate the morphological changes in secondary lymphoid follicles in IgAN tonsils and to evaluate the correlation between the morphometric results and the clinicopathological severity of IgAN. METHODS: The tonsils of age-matched patients with recurrent tonsillitis (RT tonsils) were used as controls. The correlation between the degree of lymphoid follicular involution and histopathological severities in clinical or kidney biopsy was evaluated. RESULTS: In total, 87 patients with IgAN were included (48% male, median age 35 years, median estimated glomerular filtration rate: 74 mL/min/1.73 m2). Compared to RT tonsils, IgAN tonsils showed smaller median sizes of lymphoid follicles and germinal centers (P < 0.001). The relative areas of lymphoid follicles (%LFA) and germinal centers (%GCA) in the total tonsillar tissue were smaller in the IgAN tonsils than in the RT tonsils (P < 0.001). In contrast, the median proportion of mantle zones in the total tonsillar tissue was comparable between the groups. A lower %LFA was associated with a longer period from the onset of urinary abnormalities to biopsy diagnosis and higher urinary protein excretion (P = 0.01). %LFA showed significant negative correlations with frequencies of glomeruli with both global and segmental sclerosis. CONCLUSIONS: The present study confirmed accelerated germinal center involution in the tonsils of patients with IgAN. This characteristic change in the IgAN tonsil correlates with heavy proteinuria and advanced chronic histopathological changes in the kidneys, thereby suggesting the involvement of repeated tonsillar immunoreactions during IgAN progression.

A 20-year follow-up study of identical twin sisters with immunoglobulin A nephropathy.

Immunoglobulin A nephropathy (IgAN) is characterized by diverse clinicopathological phenotypes. Herein we present a follow-up study of previously reported identical twin sisters with IgAN. The older sister exhibited more severe kidney histopathology and proteinuria and a lower birthweight than did her younger sister, and only the older sister experienced two childbirths. These raised concerns regarding her kidney outcomes. However, with timely multidisciplinary treatments, the older sister's kidney function remained preserved after 20 years of IgAN history. Our findings indicate the significant contribution of environmental/epigenetic factors to IgAN progression and the need for tailored medical care corresponding to life events.

Early growth response 1 as a podocyte injury marker in human glomerular diseases.

Background: In human glomerular diseases, visualizing podocyte injury is desirable since podocytes do not regenerate and podocyte injury leads to podocyte loss. Herein, we investigated the utility of immunostaining for early growth response 1 (EGR1), which is expressed in injured podocytes from the early stages of injury in animal experiments, as a podocyte injury marker in human glomerular diseases. Methods: This study included 102 patients with biopsy-proven glomerular diseases between 2018 and 2021. The proportion of EGR1 expression in podocytes (%EGR1pod) was analyzed in relation to clinical and histopathological features, including glomerular and urinary podocyte-specific markers. Results: %EGR1pod correlated significantly with the urinary protein:creatinine ratio, urinary nephrin and podocin mRNA levels, and glomerular podocin staining (rho = 0.361, 0.514, 0.487 and -0.417, respectively; adjusted P = .002, <.001, <.001 and <.001, respectively). Additionally, %EGR1pod correlated with cellular/fibrocellular crescents (rho = 0.479, adjusted P <.001). %EGR1pod was high in patients with glomerulonephritis, such as immunoglobulin A nephropathy (IgAN), lupus nephritis and antineutrophil cytoplasmic antibody-associated glomerulonephritis, and in those with podocytopathies, such as membranous nephropathy and primary focal segmental glomerulosclerosis, while %EGR1pod was low in patients with minimal change disease. In a subgroup analysis of IgAN, %EGR1pod was higher in Oxford C1 patients than in C0 patients. However, unexpectedly, patients with higher %EGR1pod were more prone to attain proteinuria remission, suggesting that EGR1 in the context of IgAN reflects reversible early injury. Conclusions: Our findings indicate that EGR1 is a promising potential marker for identifying active early podocyte injury in human glomerular diseases.

Active flare of IgA nephropathy during long-term therapy with anti-tumor necrosis factor-α antibody drugs for Crohn's disease: three case reports and literature review.

In recent years, increasing numbers of reports have described new onset or active disease flare of IgA nephropathy (IgAN) during administration of TNF-α inhibitor (TNFi) therapy for chronic inflammatory diseases. Crohn's disease (CD) is the most common indication for TNFi therapy in this clinical setting, but the underlying etiology of IgAN in such patients remains unclear. We report our experience with three patients who developed acute worsening of preexisting urinalysis abnormalities and kidney dysfunction approximately 2 to 6 years after TNFi administration for CD. Kidney biopsies at the time of kidney disease flare revealed IgAN in two patients and IgAN complicated by acute tubulointerstitial nephritis in one patient. The CD and IgAN in all three patients were successfully managed with additional corticosteroid therapy and tonsillectomy without discontinuing TNFi therapy. The clinical course of our patients and similar patients described in the literature suggests that TNFi therapy for CD is associated with a relatively high risk for new onset or disease flare of IgAN. This report discusses the possible involvement of Th1/Th2 imbalance on the immunological background of CD or IgAN.

Neural epidermal growth factor-like 1 protein (NELL1)-associated membranous nephropathy with heterogeneous underlying diseases: a case report.

Neural epidermal growth factor-like 1 protein (NELL1) is a target antigen of membranous nephropathy (MN). NELL1-associated MN (NELL1-MN) was originally described as a primary form but has subsequently been associated with other diseases, including malignancies, pre-exposure to certain drugs, hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, and rheumatoid arthritis (RA). We present a case of a 78-year-old woman with long-standing RA who developed persistent proteinuria and was diagnosed with MN. Evaluation of the underlying cause revealed chronic active HCV infection and past HBV infection. The underlying cause was less likely to be drug-related; however, there was no evidence of malignancy. The patient was diagnosed with HCV-associated MN. At 4 years after the diagnosis of MN, the patient died of breast cancer with multiple metastases. Subsequent immunohistological analysis revealed that she had NELL1-MN, and her breast cancer tissue stained positive for NELL1. Our case illustrates the difficulty in establishing the underlying cause of NELL1-MN, even after diagnosis. However, the incidence of malignancies, particularly breast and prostate cancers, is higher in NELL1-MN than in MN with other target antigens. Therefore, malignancies are considered a priority for investigation because of their frequency and prognosis among patients with NELL1-MN.

Gross Hematuria Following SARS-CoV-2 Infection in IgA Nephropathy: A Report of 5 Cases.

Gross hematuria after upper respiratory tract infections is a well-known characteristic symptom of immunoglobulin A nephropathy (IgAN). In recent years, there have been several reports of existing or newly diagnosed patients with IgAN susceptible to gross hematuria after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. However, reports of patients with IgAN and gross hematuria after SARS-CoV-2 infection are extremely rare despite a considerable number of patients with coronavirus disease 2019 (COVID-19) who preferentially present with upper respiratory symptoms. Here, we report the cases of 5 Japanese patients with IgAN who developed gross hematuria associated with SARS-CoV-2 infection. These patients presented with fever and other COVID-19-related symptoms, followed by the appearance of gross hematuria within 2 days, which lasted for 1-7 days. Acute kidney injury occurred after gross hematuria in 1 case. In all cases, microhematuria was identified before gross hematuria associated with SARS-CoV-2 infection, and it persisted after the gross hematuria episode. Because repeated gross hematuria and persistent microhematuria may lead to irreversible kidney injury, the clinical manifestations of patients with IgAN during the COVID-19 pandemic should be carefully monitored.

[RS3PE syndrome with angioimmunoblastic T-cell lymphoma early after the start of immunosuppressive therapy].

A 75-year-old man visited our Collagen Disease Department because of a fever, edema in the lower legs, and arthralgia. He presented with peripheral arthritis of the extremities and was negative for rheumatoid factor, leading to a diagnosis of RS3PE syndrome. A search for malignancy was performed, but no obvious malignant findings were found. After starting treatment with steroid, methotrexate, and tacrolimus, the patient's joint symptoms improved, but after five months, enlarged lymph nodes throughout the body were observed. A lymph node biopsy revealed a diagnosis of other iatrogenic immunodeficiency-associated lymphoproliferative disorders/angioimmunoblastic T-cell lymphoma (OI-LPD/AITL). After discontinuation of methotrexate and follow-up, no lymph node shrinkage was observed, and the patient had strong general malaise, so chemotherapy was started for AITL. After the start of chemotherapy, the patient's general symptoms improved quickly. RS3PE syndrome is a polyarticular, rheumatoid factor-negative, polyarticular synovitis with symmetric dorsolateral hand-palmar symmetric indentation edema that occurs mainly in elderly patients. It is also noted as a paraneoplastic syndrome, with 10%-40% of patients having malignant tumors. When our patient was diagnosed with RS3PE syndrome, a search for malignancy was performed, but there were no findings suggestive of malignant disease. However, after methotrexate and tacrolimus administration was started, the patient developed rapid lymph node enlargement, and the pathology showed AITL. The possibility of AITL as an underlying disease and RS3PE syndrome as a paraneoplastic syndrome, or conversely, OI-LPD/AITL associated with immunosuppressive therapy for RS3PE syndrome is considered. We herein report this case, as sufficient recognition is required for a proper diagnosis to be made and treatment of RS3PE syndrome to be performed.

Histiocytic Glomerulopathy With Noncrystalline Inclusion Associated With IgG-Kappa Plasma Cell Dyscrasia.

The kidney pathology of monoclonal gammopathy of renal significance varies greatly. In this report, we present a woman in her 20s with nephrotic syndrome and monoclonal immunoglobulin G kappa (serum and urine) without diabetes. She had a family history of nephrotic syndrome as well as hematologic and connective tissue disorders. A kidney biopsy showed nodular glomerulosclerosis, with the glomerular capillary full of histiocytes, which were strongly positive for kappa, not lambda. Immunoelectron microscopy revealed that histiocytes had infiltrated the glomerular subendothelial space, and enlarged lysosomes of histiocytes contained kappa light chains, without apparent crystalline formation. Bone marrow examination was negative for malignancy; thus, we diagnosed this case as histiocytic glomerulopathy with noncrystalline inclusion associated with immunoglobulin G-kappa plasma cell dyscrasia. Hematologic treatment with bortezomib and daratumumab decreased her level of serum kappa chain and proteinuria. Two years after diagnosis, her kidney function remained normal, urinary protein level decreased to 1 g/d, and free light-chain ratio decreased to 3.1.

Possible Use of Non-purine Selective Xanthine Oxidoreductase Inhibitors for Prevention of Exercise-induced Acute Kidney Injury Associated with Renal Hypouricemia.

Exercise-induced acute kidney injury (EIAKI) is frequently complicated with renal hypouricemia (RHUC). In patients with RHUC, limiting anaerobic exercise can prevent EIAKI. However, it is challenging to reduce exercise intensity in athletes. We herein report a 16-year-old Japanese football player with familial RHUC with compound heterozygous mutations in urate transporter 1 (URAT1) who presented with recurrent EIAKI. As prophylaxis (hydration during exercise) could not prevent EIAKI, febuxostat was initiated. EIAKI was not observed for 16 months despite exercising intensively. Hence, non-purine-selective xanthine oxidoreductase inhibitors may decrease the incidence of EIAKI in athletes with RHUC.

Different Clinical Courses of Nephronophthisis in Dizygotic Twins.

Siblings with nephronophthisis occasionally show different clinical courses; however, the reasons for this remain unclear. We herein report cases of nephronophthisis in a pair of dizygotic twins with different clinical courses. The brother developed end-stage kidney disease at 17 years old; however, his sister did not show kidney insufficiency. Kidney biopsies revealed severe tubulointerstitial damage at 14 and 22 years old in the brother and sister, respectively. Both had a homozygous NPHP1 deletion with different heterozygous mutations related to hereditary cystic kidney disease. Since the dizygotic twins were exposed to similar environmental factors, genetic factors may have influenced their clinical course more strongly than environmental factors.

Persistent SARS-CoV-2 Infection in a Patient with Nephrotic Syndrome under Rituximab Therapy: Successful Treatment with a Combination of Remdesivir and Monoclonal Antibodies.

Rituximab is an effective treatment for frequently relapsing/steroid-dependent nephrotic syndrome, but there is concern about infections caused by humoral immunodeficiency. We herein report a case of prolonged (>7 weeks) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. A 24-year-old man with minimal change disease treated with rituximab developed SARS-CoV-2 infection. The clinical response to remdesivir was soon transiently abolished. Treatment with casirivimab and imdevimab (REGEN-COV) monoclonal antibodies in combination with remdesivir resulted in complete clearance of the infection. The REGEN-COV antibody cocktail may improve the outcome of SARS-CoV-2 infection in patients with humoral immunodeficiency.

Podocytes are lost from glomeruli before completing apoptosis.

Although apoptosis of podocytes has been widely reported in in vitro studies, it has been less frequently and less definitively documented in in vivo situations. To investigate this discrepancy, we analyzed the dying process of podocytes in vitro and in vivo using LMB2, a human (h)CD25-directed immunotoxin. LMB2 induced cell death within 2 days in 56.8 ± 13.6% of cultured podocytes expressing hCD25 in a caspase-3, Bak1, and Bax-dependent manner. LMB2 induced typical apoptotic features, including TUNEL staining and fragmented nuclei without lactate dehydrogenase leakage. In vivo, LMB2 effectively eliminated hCD25-expressing podocytes in NEP25 mice. Podocytes injured by LMB2 were occasionally stained for cleaved caspase-3 and cleaved lamin A but never for TUNEL. Urinary sediment contained TUNEL-positive podocytes. To examine the effect of glomerular filtration, we performed unilateral ureteral obstruction in NEP25 mice treated with LMB2 1 day before euthanasia. In the obstructed kidney, glomeruli contained significantly more cleaved lamin A-positive podocytes than those in the contralateral kidney (50.1 ± 5.4% vs. 29.3 ± 4.1%, P < 0.001). To further examine the dying process without glomerular filtration, we treated kidney organoids generated from nephron progenitor cells of NEP25 mice with LMB2. Podocytes showed TUNEL staining and nuclear fragmentation. These results indicate that on activation of apoptotic caspases, podocytes are detached and lost in the urine before nuclear fragmentation and that the physical force of glomerular filtration facilitates detachment. This phenomenon may be the reason why definitive apoptosis is not observed in podocytes in vivo.NEW & NOTEWORTHY This report clarifies why morphologically definitive apoptosis is not observed in podocytes in vivo. When caspase-3 is activated in podocytes, these cells are immediately detached from the glomerulus and lost in the urine before DNA fragmentation occurs. Detachment is facilitated by glomerular filtration. This phenomenon explains why podocytes in vivo rarely show TUNEL staining and never apoptotic bodies.

Cholecystectomy in a patient with paroxysmal nocturnal haemoglobinuria undergoing ravulizumab maintenance treatment.

A 47-year-old male with paroxysmal nocturnal haemoglobinuria (PNH) controlled with routine ravulizumab administration suffered a massive haemolytic crisis due to choledocholithiasis. Laparoscopic cholecystectomy was performed 6 weeks after a regular ravulizumab infusion. After surgery, the patient presented with anaemia without marked elevation in lactate dehydrogenase and required two blood transfusions. Tumour necrosis factor-α increased more than twofold with reticulocyte suppression after surgery, suggesting the involvement of myelosuppressive cytokines. This case suggests that laparoscopic surgery may be safely performed in patients with PNH receiving ravulizumab maintenance treatment. However, attention should be paid to postoperative anaemia, regardless of breakthrough haemolysis.