Acute Interstitial Nephritis and Oxalate Nephropathy After Rapid Pasireotide Response in Treatment-resistant Acromegaly

We report a case of interstitial nephritis, likely secondary to oxalate nephropathy, due to the development of pancreatic exocrine dysfunction after commencement of pasireotide for acromegaly. Pasireotide is known to impair insulin secretion but can also impair pancreatic exocrine function, hypothezised to result from high-affinity binding of somatostatin receptors 1, 2, 3, and 5. This has been an advantage in postoperative tissue anastomoses after pancreatic surgery, but exocrine insufficiency has not been reported when used for the treatment of acromegaly. A 73-year-old woman, diagnosed with acromegaly, was unable to achieve biochemical control despite 2 surgical resections of an invasive mammosomatotroph pituitary tumor and treatment with cabergoline and maximal-dose lanreotide. The tumor expressed somatostatin receptor type 5 but not somatostatin receptor type 2, predicting good response from pasireotide, which was commenced at 40 mg every 4 weeks. IGF-1 rapidly normalized, but the patient presented with nausea, anorexia, and acute kidney injury. Renal biopsy revealed acute-on-chronic interstitial nephritis, with numerous oxalate crystals. Increased fecal fat globules were noted on fat stain (3+), supporting malabsorption as an etiology of secondary enteric hyperoxaluria. Renal function recovered to near baseline over months following pasireotide withdrawal and high-dose glucocorticoids.

Toxic Nephropathies of the Tubulointerstitium: Core Curriculum 2024

Toxic nephropathies are a clinically common group of disorders characterized by toxin-induced renal injury that can affect the glomerulus, vasculature, or tubulointerstitium. Various endogenous (eg, myoglobin, hemoglobin, monoclonal light chains, and lysozymes) and exogenous toxins (eg, therapeutic drugs, herbal medications, heavy metals, radiocontrast, intoxicants, and environmental exposures) have been implicated. The kidney's primary role of metabolism and excretion of substances via glomerular filtration and tubular secretion increases its susceptibility to their adverse effects. The structure, dose, metabolic handling, and excretory pathway of the drug/toxin through the kidney determines its nephrotoxic risk. Patient characteristics that impact risk include genetic determinants of drug metabolism, transport and excretion, immune response genes, and comorbid conditions. Clinical manifestations depend on site and severity of renal injury. Toxin-induced tubulointerstitial injury often presents as a decline in renal function and/or solute transport defects and renal solute wasting. Injury is often reversible with limited toxin exposure; however, irreversible renal injury can occur with prolonged exposure. In this Core Curriculum, we will focus on discussing mechanisms of common toxin-induced tubulointerstitial renal injury and review their causes, clinical presentations, diagnosis, and management.

Exudative glomerulonephritis associated with acute leptospirosis in dogs

In the past 20 years in Switzerland, dogs with suspect acute leptospirosis frequently showed severe glomerular changes that had not been previously reported. These features were characterized by abundant extravasated erythrocytes and fewer neutrophils accompanied by marked fibrin exudation into the urinary space that was interpreted as an exudative glomerulonephritis (GN). This retrospective study describes this significant glomerular pathological change and investigates the association with leptospirosis. Tissues from 50 dogs with exudative GN, retrieved from 2 pathology archives in Switzerland were reviewed using hematoxylin and eosin, periodic acid-Schiff, phosphotungstic acid-hematoxylin, and Warthin and Starry stains. Clinical and postmortem data were collected for each case. Immunohistochemistry (IHC) and/or polymerase chain reactions were used as confirmatory tests for leptospirosis. While all 50 cases had clinical and pathological features supporting a diagnosis of leptospirosis, 37 cases were confirmed for the disease. Using a LipL32 antibody in addition to the OMV2177 antibody raised against the lipopolysaccharide of Leptospira interrogans serovar Copenhageni increased the detection rate of Leptospira by IHC in exudative GN from 24% to 62%. Signalment, seasonality, clinical signs, blood results, and pathological changes in dogs with exudative GN were similar to those reported for dogs without GN and confirmed infection by Leptospira spp.. Exudative GN was common among Swiss dogs with leptospirosis where it caused acute severe disease. Leptospirosis should be considered as a cause of this new pathologic feature by the pathologist. The pathogenesis remains unclear, but involvement of a geographic-specific serovar with unique virulence factors is suspected and warrants further investigation.

Evidence of tosufloxacin deposition in the kidneys of a patient presenting with crystal nephropathy

Tosufloxacin tosilate is classified as a new quinolone antibacterial agent, which has been reported to cause crystal nephropathy. However, the origin of these crystal deposits has not yet been elucidated. We encountered a case of renal failure that progressed slowly owing to crystal-forming interstitial nephritis after long-term exposure to tosufloxacin. Mass spectrometry of the renal specimens revealed that tosufloxacin was deposited in the kidneys. The patient's renal function improved slowly with the withdrawal of tosufloxacin and steroid therapy. This is the first case to demonstrate the presence of crystal deposits consisting of tosufloxacin.

Karyomegalic Interstitial Nephritis in the Allograft Kidney - A Case Report

Karyomegalic interstitial nephritis is a rare progressive renal disease. We report a 36-year-old male patient who developed kidney failure due to this condition, underwent kidney transplantation from his sister, and developed the same condition in the graft. Genetic testing of the donor revealed autosomal recessive compound heterozygous mutation of Fanconi anemia-associated nuclease1 (FAN1) gene. Karyomegalic interstitial nephritis is most probably donor derived in our patient. It should not be mislabeled as viral nephropathy.

Development of microscopic polyangiitis following idiopathic pleuroparenchymal l fibroelastosis: A case report

Idiopathic pleuroparenchymal fibroelastosis (PPFE) is a rare type of idiopathic interstitial pneumonia, which is characterised by pleural fibrosis and subjacent parenchymal fibroelastosis of the upper lobes. Herein, we present a case of microscopic polyangiitis (MPA) following PPFE. The patient had abnormal shadows on chest radiographs 15 years before the onset of MPA, and the patient was diagnosed with PPFE. Four years after the PPFE diagnosis, the patient was diagnosed with MPA based on persistent fever, purpura, mononeuritis multiplex, myeloperoxidase-antineutrophil cytoplasmic antibody positivity, and pathological findings of peritubular capillaritis on kidney biopsy. The patient was treated with glucocorticoids, including methylprednisolone pulse therapy and rituximab, followed by maintenance therapy with rituximab. One year after treatment, the PPFE had not worsened. PPFE occasionally occurs secondary to connective tissue disease, including MPA; however, to the best of our knowledge, this is the first report of PPFE preceding MPA. Our case suggests that PPFE, as other interstitial lung diseases, may be associated with MPA and precede the onset of MPA. The accumulation of more cases is needed to clarify the characteristics of MPA-associated PPFE.

Immune checkpoint inhibitors and their interaction with proton pump inhibitors-related interstitial nephritis

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy and outcomes, leading to an expanding use in millions of patients worldwide. However, they can cause a spectrum of immune-related adverse events (irAEs). Essentially, any organs can be affected by irAEs, which have emerged as therapy-limiting side effects. In the kidneys, ICI-associated acute interstitial nephritis (ICI-AIN) leads to acute kidney injury (AKI) in 2%-5% of patients on ICI therapy. AKI associated with ICI therapy pathologically presents with AIN in nearly 90% of the cases, but the pathophysiology of ICI-AIN remains to be defined. The generation of autoreactive T cells in patients receiving AIN-inducible drugs, such as proton pump inhibitors (PPIs), is one of the leading theories, supported by a higher incidence of ICI-AIN in patients on these AIN-inducible drugs. In this review, we will discuss our understanding of the incidence, potential pathophysiological mechanisms, clinical presentations, risk factors, diagnosis, and management of PPI-related AIN and its interaction with ICI therapy.

Renal histopathological predictors of end-stage kidney disease in ANCA-associated vasculitis with glomerulonephritis: a single-centre study in Korea

This study investigated whether histopathological classification and histologic lesion scores could significantly and independently predict the progression to end-stage kidney disease (ESKD) in Korean patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis-glomerulonephritis (AAV-GN). This study included 113 patients with AAV-GN confirmed by kidney biopsy. The glomerular, tubulointerstitial, and vascular lesions were systematically assessed using a scoring system. The scoring system was adopted from the Banff scoring system but also the Oxford study and the revision of the ISN/RPS. For comparison, the scores were classified into two groups; the low, and the high, and the difference was investigated between ESKD and non-ESKD groups using Cox proportional analysis. At diagnosis, the median age was 59.0 years and 33.6% were males. Of 113 patients, 44.2% had ESKD progression during follow-up. There were significant differences in several kidney-, inflammation-, and AAV-pathogenesis-related variables between AAV-GN patients with ESKD and those without. The sclerotic class exhibited the worst renal prognosis among the four histopathological classes. Among histopathological features, high interstitial fibrosis, tubular atrophy and global glomerulitis scores were significantly associated with ESKD progression. Whereas multivariable Cox analysis revealed only a high global glomerulitis score which means global endocapillary hypercellularity in a larger number of glomeruli is an independent predictor of ESKD progression. Moreover, among clinical and histopathological features, a high global glomerulitis score could also predict ESKD progression in addition to serum blood urea nitrogen and creatinine. This study demonstrated the worst renal prognosis for the sclerotic class and first discovered that a high global glomerulitis score was an independent predictor of ESKD in patients with AAV-GN.

Chronic kidney disease of unknown aetiology: A comprehensive review of a global public health problem

The term chronic kidney disease of unknown aetiology (CKDu) refers to chronic kidney disease (CKD) in the absence of diabetes, long-standing hypertension, glomerulonephritis, obstructive uropathy or other apparent causes. An increasing number of CKDu cases have been reported from Latin America, Sri Lanka, India and others over the last two decades. These regional nephropathies share the following common attributes: (a) they affect low-to-middle income countries with tropical climates, (b) involve predominantly rural agricultural communities, (c) male predilection, (d) absence of significant proteinuria and hypertension, and (e) chronic tubulointerstitial nephritis on kidney biopsy. The current body of literature suggests that CKDu may be caused by heat stress, agrochemicals, contaminated drinking water or heavy metals; however, considerable regional disparities in CKDu research make it difficult to establish a common causal link. In the absence of a definite aetiology, specific preventive and therapeutic interventions are lacking. Improvement of working conditions of farmers and labourers, provision of safe drinking water and changes in agricultural practices are some of the measures that have been implemented; however, there is lack of data to assess their impact on the incidence and progression of CKDu. There is a need for a concerted global effort to address the current knowledge gaps, and to develop effective and sustainable strategies to tackle this devastating disease.

Sarcoid-Like Reaction in the Kidney Following Rituximab for Mantle Lymphoma in a 60-Year-Old Man

The sarcoid-like reaction is a rare autoinflammatory disease that can affect lymph nodes or organs but does not meet the diagnostic criteria for systemic sarcoidosis. Several drug classes have been associated with the development of a systemic sarcoid-like reaction, which defines drug-induced sarcoidosis-like reactions and can affect a single organ. Anti-CD20 antibodies (rituximab) have rarely been reported as responsible for this reaction and this adverse effect has mainly been described during the treatment of Hodgkin's lymphoma. We report a unique case of a sarcoid-like reaction complicating rituximab following the treatment of a mantle cell lymphoma and interesting only the kidney. The 60-year-old patient presented with severe acute renal failure 6 months after the end of his r-CHOP protocol and the urgent renal biopsy revealed acute interstitial nephritis rich in granulomas without caseous necrosis. After ruling out other causes of granulomatous nephritis, a sarcoid-like reaction was retained since infiltration was limited to the kidney. The temporal relationship between rituximab administration and the sarcoid-like reaction onset in our patient supported the diagnosis of a rituximab-induced sarcoidosis-like reaction. Oral corticosteroid treatment led to rapid and lasting improvement in renal function. Clinicians should be warned of this adverse effect and regular and prolonged monitoring of renal function should be recommended during the follow-up of patients after the end of treatment with rituximab.

Sodium benzoate attenuates 2,8-dihydroxyadenine nephropathy by inhibiting monocyte/macrophage TNF-α expression

Sodium benzoate (SB), a known D-amino acid oxidase (DAO) enzyme inhibitor, has an anti-inflammatory effect, although its role in renal damage has not been explored. 2,8-dihydroxyadenine crystal induced chronic kidney disease, in which TNF-α is involved in the pathogenesis, was established by oral adenine administration in C57BL/6JJcl mice (AdCKD) with or without SB to investigate its renal protective effects. SB significantly attenuated AdCKD by decreasing serum creatinine and urea nitrogen levels, and kidney interstitial fibrosis and tubular atrophy scores. The survival of AdCKD mice improved 2.6-fold by SB administration. SB significantly decreased the number of infiltrating macrophages observed in the positive F4/80 immunohistochemistry area and reduced the expression of macrophage markers and inflammatory genes, including TNF-α, in the kidneys of AdCKD. Human THP-1 cells stimulated with either lipopolysaccharide or TNF-α showed increased expression of inflammatory genes, although this was significantly reduced by SB, confirming the anti-inflammatory effects of SB. SB exhibited renal protective effects in AdCKD in DAO enzyme deficient mice, suggesting that anti-inflammatory effect of SB was independent of DAO enzyme activity. Moreover, binding to motif DNA sequence, protein level, and mRNA level of NF-κB RelB were significantly inhibited by SB in AdCKD kidneys and lipopolysaccharide treated THP-1 cells, respectively. We report that anti-inflammatory property of SB is independent of DAO enzymatic activity and is associated with down regulated NF-κB RelB as well as its downstream inflammatory genes such as TNF-α in AdCKD.

Serious Multiorgan Toxicity Caused by Mixed Herbal Tea Ingestion: A Case Report

Recent years have witnessed a growing trend in the use of complementary and alternative herbal products. However, the ingestion of some herbal products may cause a wide spectrum of adverse effects. We report a case of multiorgan toxicity following the ingestion of mixed herbal tea. A 41-year-old woman presented to the nephrology clinic with complaints of nausea, vomiting, vaginal bleeding, and anuria. She had consumed a glass of mixed herbal tea three times a day after meals for three days, to lose weight. Initial clinical and laboratory findings showed serious multiorgan toxicity including hepatotoxicity, bone marrow toxicity, and nephrotoxicity. Although herbal preparations are marketed as natural products, they may cause various toxic effects. There should more efforts to raise public awareness about the possible toxic effects of herbal preparations. Clinicians should consider the ingestion of herbal remedies as an etiology when encountering patients with unexplained organ dysfunctions.

Matrix protein Tenascin-C promotes kidney fibrosis via STAT3 activation in response to tubular injury

Accumulating evidence indicates that the extracellular matrix (ECM) is not only a consequence of fibrosis, but also contributes to the progression of fibrosis, by creating a profibrotic microenvironment. Tenascin-C (TNC) is an ECM glycoprotein that contains multiple functional domains. We showed that following kidney injury, TNC was markedly induced in fibrotic areas in the kidney from both mouse models and humans with kidney diseases. Genetically deletion of TNC in mice significantly attenuated unilateral ureteral obstruction-induced kidney fibrosis. Further studies showed that TNC promoted the proliferation of kidney interstitial cells via STAT3 activation. TNC-expressing cells in fibrotic kidney were activated fibroblast 2 (Act.Fib2) subpopulation, according to a previously generated single nucleus RNA-seq dataset profiling kidney of mouse UUO model at day 14. To identify and characterize TNC-expressing cells, we generated a TNC-promoter-driven CreER2-IRES-eGFP knock-in mouse line and found that the TNC reporter eGFP was markedly induced in cells around injured tubules that had lost epithelial markers, suggesting TNC was induced in response to epithelium injury. Most of the eGFP-positive cells were both NG2 and PDGFRβ positive. These cells did not carry markers of progenitor cells or macrophages. In conclusion, this study provides strong evidence that matrix protein TNC contributes to kidney fibrosis. TNC pathway may serve as a potential therapeutic target for interstitial fibrosis and the progression of chronic kidney disease.

Skin reaction with Eosinophilia and Systemic Symptoms after lenalidomide in peritoneal Dialysis

The Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome is a fatal and immune-mediated idiosyncratic drug reaction, with symptoms of fever, skin eruptions (that involves more than half of the body surface), facial oedema and hematological disorders, all presenting within the latent period following drug intake. Effects can also be seen on multiple organs, most notably hepatitis in liver and acute interstitial nephritis in kidney, generally post-administration of allopurinol. The European Registry of Severe Cutaneous Adverse Reactions (RegiSCAR) classifies the DRESS Syndrome cases as "definite", "probable" or "possible", based on clinical and laboratory features. Different pathogenetic mechanisms have been involved in this disease, including immunological reactions and HHV-6 reactivation. In our experience, a 72-year-old male, affected by myeloma in peritoneal dialysis, developed a rare case of DRESS syndrome after lenalidomide administration (less than ten cases are known) with HHV-6 reactivation. According to literature, we withdrew the drug and gave methylprednisolone 0,8 mg/kg orally and IVIG 1 gr/kg for two days. Despite this therapy, DRESS syndrome relapsed during steroid taper with rash, thrombocytopenia, hepatitis and high troponin level. A single cycle of intravenous immunoglobulin 0,5 g/kg for four days was enough for syndrome remission. Only few cases are reported in literature, but because of the increasing use of lenalidomide and the autoimmune sequelae of DRESS syndrome, a broad workup and a multidisciplinar careful approach could help in diagnosis, treatment and follow-up.

Development and external validation of a diagnostic model for biopsy-proven acute interstitial nephritis using electronic health record data

BACKGROUND

Patients with acute interstitial nephritis (AIN) can present without typical clinical features, leading to a delay in diagnosis and treatment. We therefore developed and validated a diagnostic model to identify patients at risk of AIN using variables from the electronic health record.

METHODS

In patients who underwent a kidney biopsy at Yale University between 2013 and 2018, we tested the association of >150 variables with AIN, including demographics, comorbidities, vital signs and laboratory tests (training set 70%). We used least absolute shrinkage and selection operator methodology to select prebiopsy features associated with AIN. We performed area under the receiver operating characteristics curve (AUC) analysis with internal (held-out test set 30%) and external validation (Biopsy Biobank Cohort of Indiana). We tested the change in model performance after the addition of urine biomarkers in the Yale AIN study.

RESULTS

We included 393 patients (AIN 22%) in the training set, 158 patients (AIN 27%) in the test set, 1118 patients (AIN 11%) in the validation set and 265 patients (AIN 11%) in the Yale AIN study. Variables in the selected model included serum creatinine {adjusted odds ratio [aOR] 2.31 [95% confidence interval (CI) 1.42-3.76]}, blood urea nitrogen:creatinine ratio [aOR 0.40 (95% CI 0.20-0.78)] and urine dipstick specific gravity [aOR 0.95 (95% CI 0.91-0.99)] and protein [aOR 0.39 (95% CI 0.23-0.68)]. This model showed an AUC of 0.73 (95% CI 0.64-0.81) in the test set, which was similar to the AUC in the external validation cohort [0.74 (95% CI 0.69-0.79)]. The AUC improved to 0.84 (95% CI 0.76-0.91) upon the addition of urine interleukin-9 and tumor necrosis factor-α.

CONCLUSIONS

We developed and validated a statistical model that showed a modest AUC for AIN diagnosis, which improved upon the addition of urine biomarkers. Future studies could evaluate this model and biomarkers to identify unrecognized cases of AIN.

Truth or dare: switching BRAF/MEK inhibitors after acute interstitial nephritis in a patient with metastatic melanoma - A case report and review of the literature

INTRODUCTION

The introduction of BRAF/MEK inhibitors has significantly improved overall survival of patients with BRAF V600-mutant advanced or metastatic melanoma. Most patients treated with BRAF/MEK inhibitors will experience adverse events during the course of their treatment. Kidney impairment, however, was rarely reported in the pivotal trials. To date, there are only three cases of biopsy-proven acute interstitial nephritis associated with dabrafenib and trametinib reported in the literature.

CASE REPORT

A 50-year-old man diagnosed with metastatic melanoma was hospitalized in August 2021, 5 months after treatment initiation with dabrafenib and trametinib. He presented with acute kidney injury, with serum creatinine of 3.34 mg/dL and eGFR of 20.3 mL/min/m². Kidney biopsy revealed acute interstitial nephritis.

MANAGEMENT & OUTCOME

He was treated with methylprednisolone 16 mg qd, and both dabrafenib and trametinib were permanently discontinued, with recuperation of his kidney function. Another BRAF/MEK inhibitor combination, encorafenib and binimetinib, was introduced, with preserved kidney function and excellent disease control.

DISCUSSION

We report the first case of biopsy-proven interstitial nephritis in a patient treated with dabrafenib and trametinib, with successful introduction of another BRAF/MEK inhibitor combination. Although rare, clinicians should be aware of the risk of renal adverse events associated with BRAF/MEK inhibitors. Renal biopsy is mandatory in the absence of a clear explanation or rapid recovery of renal failure. In case of proven interstitial nephritis, corticosteroids should be initiated. Switching to another BRAF/MEK inhibitor combination can be considered for patients with complete recovery of renal function and limited treatment options.

A case of simultaneous onset of highly active systemic lupus erythematosus and IgG4-related renal disease

The patient was a 73-year-old woman who had hair loss, purpura, and numbness of the soles for past 1 year. Three months prior, she was diagnosed with interstitial lung disease (ILD) and was admitted to our department. She was diagnosed with systemic lupus erythematosus (SLE) based on positive antinuclear antibodies 1280× (speckled type), hair loss, low white blood cell count, positive anti-cardiolipin and anti-ds-DNA antibodies, and lupus retinopathy. In addition, the patient was also diagnosed with immunoglobulin G (IgG)4-related disease (IgG4RD) based on high serum IgG4 levels, ILD, urine occult blood, protein, and cast, and renal histological findings showed endocapillary proliferative glomerulonephritis, increased IgG4 positive plasma cells, and characteristic storiform fibrosis. High-dose glucocorticoid therapy, hydroxychloroquine, and belimumab were administered, which improved the SLE symptoms of lupus retinopathy and peripheral neuropathy, as well as the IgG4RD symptoms of ILD and urinary findings. Herein, we report a rare case of simultaneous onset of IgG4-related nephropathy with active glomerular lesions and SLE, in which renal histology, including fluorescent antibodies, was crucial for diagnosis.

Membranous Nephropathy With Extensive Tubular Basement Membrane Deposits Following Allogeneic Hematopoietic Cell Transplant: A Report of 5 Cases

Tubular basement membrane (TBM) deposits are very uncommon in non-lupus membranous nephropathy. We report 5 patients with membranous nephropathy and extensive TBM deposits following allogeneic hematopoietic cell transplant. Patients presented with nephrotic syndrome (3 also had acute kidney injury) late post-transplant in association with chronic graft-versus-host disease (cGVHD). Kidney biopsies revealed global subepithelial and extensive TBM immune complex deposits, accompanied by acute tubular injury (n = 4) and tubulointerstitial inflammation (n = 4). Proteomic analysis of glomeruli in 4 cases identified PLA2R in 1, with no significant protein spectra for PLA2R, THSD7A, EX1/2, NELL-1, PCDH7, NCAM1, or SEMA3B detected in the remaining 3. On follow-up (for a mean 42 months), 4 patients had complete and 1 partial remission following prednisone and/or rituximab therapy. We propose that membranous nephropathy with extensive TBM deposits is a distinctive clinicopathologic lesion associated with allogeneic hematopoietic cell transplant. Pathogenesis likely involves cGVHD-driven antibodies against glomerular and TBM components, the identity of which remains to be elucidated.

Serum IL-6 as a marker of disease progression in interstitial nephritis

OBJECTIVE

To investigate the mechanism of serum interleukin-6 (IL-6) change in disease progression of interstitial nephritis.

METHODS

This is a retrospective study. From November 2017 to November 2019, 87 patients with interstitial nephritis treated in our hospital were enrolled and divided into an acute group (n=42) and a chronic group (n=45) based on pathological results of renal biopsies. Forty healthy individuals after physical examination during the same period were enrolled into the reference group. Serum IL-6 levels were determined using the enzyme-linked immunosorbent assay (ELISA).

RESULTS

Among the three groups, patients in the acute group showed the highest IL-6 level (P<0.001). The acute group obtained higher serum advanced oxidation protein products (AOPP) levels and glomerular filtration rate (GFR) than the other two groups (P<0.05). The acute group showed lower levels of CD34⁺ [number of positive microvessels (MVs)/HP], a smaller type III collagen positive area, and a larger type IV collagen positive area than the chronic group (P<0.05). The acute group obtained higher levels of IL-27 and tumor necrosis factor-α (TNF-α) than the chronic group (P<0.001). The acute group had higher levels of serum creatinine (SCr), erythrocyte sedimentation rate (ESR), estimated glomerular filtration rate (eGFR), and 24-hour urine protein quantity (24 h UPQ) than the other groups (P<0.001). The combined detection of serum IL-6, TNF-α, and micro-albumin (mALB) outperformed the stand-alone approach (P<0.05). Serum IL-32 and kidney injury molecule-1 (KIM-1) levels in the acute and chronic group were positively correlated with SCr and 24 h UPQ (P<0.05).

CONCLUSIONS

Serum IL-6 shows a great potential as an important marker of disease progression in interstitial nephritis.

Manifestations of renal involvement in sarcoidosis - case series

Renal involvement is observed in 30% of sarcoidosis cases, but the exact occurrence is unknown, and the current numbers are estimated to be underestimated. The most common manifestation of renal sarcoidosis is interstitial nephritis, but other presentations are also possible, with specific histopathological and laboratory findings. Glomerulopathies, nephrocalcinosis and nephrolithiasis are among the most commonly seen types of renal involvement.

CASE REPORTS

We would like to show a case series describing four patients with varying renal manifestations of sarcoidosis: membranous nephropathy, granulomatous interstitial nephritis, IgA nephropathy and chronic kidney disease. The diagnosis of sarcoidosis can precede, present simultaneously with or follow the onset of renal manifestations. Our patients also showcase varying clinical pictures of renal sarcoidosis with different changes in renal parameters.

CONCLUSIONS

The involvement of kidneys in sarcoidosis is multifaceted and may pose a diagnostic difficulty, and a diagnostic kidney biopsy is often needed. Chronic sarcoidosis patients should undergo regular screening for renal involvement to introduce proper management quickly and effectively.

Predominant mesangial IgM, C3, and λ light chain depositions and interstitial nephritis in a patient with overlap syndrome and positivity for anti-mitochondrial M2 antibody: a case report

Overlap syndrome refers to a group of conditions that have clinical features of more than one well-characterised rheumatic disease and meet the respective classification criteria. There are no typical renal histological findings in overlap syndrome. When patients with overlap syndrome develop renal dysfunction, various potential causes, including lupus nephritis (LN), renal crisis by systemic sclerosis, interstitial nephritis, and so on, need to be distinguished. Here, we report a 44-year-old woman with overlap syndrome involving systemic lupus erythematosus (SLE), diffuse cutaneous systemic scleroderma, and Sjogren's syndrome, who was also positive for anti-mitochondrial M2 antibody. She developed glomerular haematuria, proteinuria, and increase in creatinine appeared gradually. Suspecting LN, renal biopsy was performed. However, in the interstitium, mild infiltration of lymphocytes and plasma cells and very partial fibrosis were observed. Immunofluorescence microscopy revealed predominant mesangial immunoglobulin M, C3, and λ light chain staining. Overall, LN was not diagnosed based on these findings. Renal dysfunction was normalised by glucocorticoid treatment for 3 months. This case suggests the importance of a renal diagnosis based on renal pathological findings, especially in a case of overlap syndrome including SLE.

Evidence For and Against Direct Kidney Infection by SARS-CoV-2 in Patients with COVID-19

Despite evidence of multiorgan tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in patients with coronavirus disease 2019 (COVID-19), direct viral kidney invasion has been difficult to demonstrate. The question of whether SARS-CoV2 can directly infect the kidney is relevant to the understanding of pathogenesis of AKI and collapsing glomerulopathy in patients with COVID-19. Methodologies to document SARS-CoV-2 infection that have been used include immunohistochemistry, immunofluorescence, RT-PCR, in situ hybridization, and electron microscopy. In our review of studies to date, we found that SARS-CoV-2 in the kidneys of patients with COVID-19 was detected in 18 of 94 (19%) by immunohistochemistry, 71 of 144 (49%) by RT-PCR, and 11 of 84 (13%) by in situ hybridization. In a smaller number of patients with COVID-19 examined by immunofluorescence, SARS-CoV-2 was detected in 10 of 13 (77%). In total, in kidneys from 102 of 235 patients (43%), the presence of SARS-CoV-2 was suggested by at least one of the methods used. Despite these positive findings, caution is needed because many other studies have been negative for SARS-CoV-2 and it should be noted that when detected, it was only in kidneys obtained at autopsy. There is a clear need for studies from kidney biopsies, including those performed at early stages of the COVID-19-associated kidney disease. Development of tests to detect kidney viral infection in urine samples would be more practical as a noninvasive way to evaluate SARS-CoV-2 infection during the evolution of COVID-19-associated kidney disease.

[Immunotherapy in kidney cancer: how it has changed and what are the challenges for the nephrologist - focus on pembrolizumab]

Kidney cancer accounts for about 3.5% of all malignant neoplasms; in 85% of cases the tumor arises from cells of the renal parenchyma, with an incidence of 70% of the clear cells subtype. Surgery, at present, is the treatment of choice for most renal cancers; medical therapy, on the other hand, has only palliative purposes and is used only in the relapsed or metastatic patients. The therapeutic toolbox available in the fight against renal cancer is continuously renewed due to the approval of new drugs. In particular, in the 2000s, antiangiogenic drugs were introduced and showed good efficacy in terms of increased survival in patients with advanced renal carcinoma. Immunotherapy was a treatment strategy for renal cancer in the 1980s, when cytokines such as Interleukin-2 and Interferon were administered. The advent of antiangiogenic drugs had bound immunotherapy to a secondary role until the discovery of immune check-point inhibitors (ICIs), which have been approved in the various lines of treatment, in monotherapy or in combination with other drugs, as they have shown to increase the oncological outcome. In this review we analyze the evolution of immunotherapy for the treatment of kidney tumor from the viewpoint of nephrologists, with a special focus on renal adverse events, pembrolizumab and its recent approval as first line therapy in association with axitinib.

Idiopathic granulomatous interstitial nephritis and isolated renal sarcoidosis: Two diagnoses of exclusion

Granulomatous interstitial nephritis is a rare finding in renal biopsy caused by drugs, infections, and inflammatory or autoimmune diseases. Idiopathic cases account for 18% of granulomatous interstitial nephritis in native kidneys. Sarcoidosis and drugs are the most common causes of granulomatous interstitial nephritis in Western countries, while in India tuberculosis prevails. Few cases of renal sarcoidosis without extrarenal involvement, that is, isolated renal sarcoidosis, have been reported. The diagnostic criteria of isolated renal sarcoidosis remain, however, unclear. Extrarenal sarcoidosis and other etiologies of granulomatous interstitial nephritis, in particular drug-related, have to be excluded. Some of these patients may develop extrarenal manifestations during follow-up. Changes in calcium and vitamin D metabolism are frequently observed in renal sarcoidosis and support its diagnosis. While non-necrotizing granulomas are a feature of sarcoidosis and drug-induced granulomatous interstitial nephritis, they also prevail in tuberculosis-associated granulomatous interstitial nephritis. Granulomatous interstitial nephritis caused by sarcoidosis and drugs usually responds to steroid therapy. A poor response to steroids may indicate an infectious etiology such as tuberculosis and should lead to a review of the initial diagnosis. This article gives an overview of the various etiologies of granulomatous interstitial nephritis, their frequency and histopathological characteristics, as well as potential biomarkers associated with renal sarcoidosis.

Light chain cast nephropathy caused by plasmablastic lymphoma of the bladder

Introduction: Plasmablastic lymphoma (PBL) is a rare form of B-cell lymphoma typically seen in patients with underlying immunosuppression such as HIV, autoimmune disease, and organ transplantation. PBL in HIV-positive patients usually originates from the gastrointestinal tract, with a predilection for the oral cavity. Bladder involvement by PBL is exceedingly rare, and cast nephropathy due to κ light chain-secreting PBL has not been reported previously. Case report: We report a patient who presented with acute kidney injury (AKI) in the setting of HIV, and was found to have a bladder tumor. Bladder pathology revealed a high-grade PBL with κ light chain restriction. Renal biopsy showed κ light chain cast nephropathy, presumably secondary to κ light chain-secreting PBL. Conclusion: Although the prognosis of PBL is poor, our patient recovered from AKI, achieved complete hematologic remission with chemotherapy, and underwent successful autologous stem cell transplant.

Population Kidney Health. A New Paradigm for Chronic Kidney Disease Management

Statistical data extracted from national databases demonstrate a continuous growth in the incidence and prevalence of chronic kidney disease (CKD) and the ineffectiveness of current policies and strategies based on individual risk factors to reduce them, as well as their mortality and costs. Some innovative programs, telemedicine and government interest in the prevention of CKD did not facilitate timely access to care, continuing the increased demand for dialysis and transplants, high morbidity and long-term disability. In contrast, new forms of kidney disease of unknown etiology affected populations in developing countries and underrepresented minorities, who face socioeconomic and cultural disadvantages. With this background, our objective was to analyze in the existing literature the effects of social determinants in CKD, concluding that it is necessary to strengthen current kidney health strategies, designing in a transdisciplinary way, a model that considers demographic characteristics integrated into individual risk factors and risk factors population, incorporating the population health perspective in public health policies to improve results in kidney health care, since CKD continues to be an important and growing contributor to chronic diseases.

The Mechanism of Drug Nephrotoxicity and the Methods for Preventing Kidney Damage

Acute kidney injury (AKI) is a global health challenge of vast proportions, as approx. 13.3% of people worldwide are affected annually. The pathophysiology of AKI is very complex, but its main causes are sepsis, ischemia, and nephrotoxicity. Nephrotoxicity is mainly associated with the use of drugs. Drug-induced AKI accounts for 19-26% of all hospitalized cases. Drug-induced nephrotoxicity develops according to one of the three mechanisms: (1) proximal tubular injury and acute tubular necrosis (ATN) (a dose-dependent mechanism), where the cause is related to apical contact with drugs or their metabolites, the transport of drugs and their metabolites from the apical surface, and the secretion of drugs from the basolateral surface into the tubular lumen; (2) tubular obstruction by crystals or casts containing drugs and their metabolites (a dose-dependent mechanism); (3) interstitial nephritis induced by drugs and their metabolites (a dose-independent mechanism). In this article, the mechanisms of the individual types of injury will be described. Specific groups of drugs will be linked to specific injuries. Additionally, the risk factors for the development of AKI and the methods for preventing and/or treating the condition will be discussed.

Caprine Arthritis Encephalitis Virus Is Associated with Renal Lesions

Caprine arthritis encephalitis virus (CAEV) is a monocyte/macrophage-tropic lentivirus that primarily infects goats resulting in a well-recognized set of chronic inflammatory syndromes focused on the joint synovium, tissues of the central nervous system, pulmonary interstitium and mammary gland. Clinically affected animals generally manifest with one or more of these classic CAEV-associated tissue lesions; however, CAEV-associated renal inflammation in goats has not been reported in the peer-reviewed literature. Here we describe six goats with chronic, multisystemic CAEV infections in conjunction with CAEV-associated renal lesions. One of the animals had CAEV antigen-associated thrombotic arteritis resulting in infarction of both the kidney and heart. These goats had microscopic evidence of inflammatory renal injury (interstitial nephritis) with detectable renal immunolabeling for CAEV antigen in three of six animals and amplifiable proviral sequences consistent with CAEV in all six animals. Cardiac lesions (vascular, myocardial or endocardial) were also identified in four of six animals. Within the viral promoter (U3) region, known transcription factor binding sites (TFBSs) were generally conserved, although one viral isolate had a duplication of the U3 A region encoding a second gamma-activated site (GAS). Despite the TFBS conservation, the isolates demonstrated a degree of phylogenetic diversity. At present, the clinical consequence of CAEV-associated renal injury is not clear.

Biomarkers, Clinical Features, and Rechallenge for Immune Checkpoint Inhibitor Renal Immune-Related Adverse Events

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are effective in treating several cancers; however, acute kidney injury (AKI) can occur as part as an immune-related adverse event (iRAE). Biomarkers at the time of AKI diagnosis may help determine whether they are ICI- related and guide therapeutic strategies.

METHODS

In this retrospective study, we reviewed patients with cancer treated with ICI therapy between 2014 and 2020 who developed AKI (defined as a ≥1.5-fold increase in serum creatinine [SCr]) that was attributed to ICI (ICI-AKI) and compared them with an adjudicated non-ICI-AKI group. Clinical and laboratory features, including SCr, serum C-reactive protein (CRP), and urine retinol binding protein/urine creatinine (uRBP/Cr) levels at AKI event were evaluated.

RESULTS

There were 37 patients with ICI-AKI and 13 non-ICI-AKI referents in the cohort for analysis. At time of AKI, SCr, CRP, and uRBP/Cr were significantly higher in the ICI-AKI compared with the non-ICI-AKI patients (median [interquartile range (IQR)] SCr 2.0 [1.7, 2.9] vs. 1.5 [1.3, 1.6] mg/dl, serum CRP 54.0 [33.7, 90.0] vs. 3.5 [3.0, 7.9] mg/l, and uRBP/Cr 1927 [1174, 46,522] vs. 233 [127, 989] μg/g Cr, respectively, P < 0.05 for all). Compared with the referent group, time from ICI initiation to AKI was shorter in the ICI-AKI patients. Among the ICI-AKI group, complete renal recovery occurred in 39% of patients by 3 months; rechallenge occurred in 16 (43%) of patients, of whom 3 (19%) had recurrence of AKI.

CONCLUSION

Our findings suggest that serum CRP and uRBP/Cr may help to differentiate AKI due to ICI from other causes.

Incidence and Prediction of Immune Checkpoint Inhibitor-related Nephrotoxicity

Immune checkpoint inhibitors (ICIs) may cause immune-related adverse events that can affect any organ system, including the kidneys. Our study aimed to better characterize the incidence of and predictive factors for immune-related acute kidney injury (irAKI) and evaluate steroid responsiveness. An institutional database (Carolina Data Warehouse) was queried for patients who received ICIs and subsequently had substantial AKI, defined as a doubling of baseline creatinine. A retrospective chart review was performed to determine the cause of AKI. AKI events determined to be immune-related were further analyzed. A total of 1766 patients received an ICI between April 2014 and December 2018. A total of 123 (7%) patients had an AKI within 1 year of the administration of the first ICI dose. 14 (0.8% of all patients who received ICIs) of the AKI events were immune-related. History of an autoimmune disease (N=2, 14%, P=0.04) or history of other immune-related adverse events (irAEs) (N=8, 57%, P=0.01) was a significant predictor of irAKI. Of 14 irAKI patients, 9 received steroids with renal function improving to baseline in 5 patients, improving but not to baseline in 2, and 2 without improvement in renal function, including 1 becoming dialysis-dependent. Age, sex, urinalysis findings, and primary tumor site were not associated with irAKI. irAKI is relatively uncommon but likely under-recognized. Underlying autoimmune disease and history of nonrenal ICI-related irAEs are associated with irAKI. Early recognition and steroid administration are important for a positive outcome.

Association of Acute Interstitial Nephritis with Nivolumab in Renal Cell Carcinoma: A Case Report

Recently, a number of innovative anticancer agents such us the programmed death 1 (PD-1) immune checkpoint inhibitors have been developed. Nevertheless, this type of immunotherapy may be associated with immune-related adverse events whose pathophysiology is considered similar to those found in autoimmune diseases such as nephritis. We report the case of a 71-year-old female with metastatic renal carcinoma who underwent nephrectomy. After three lines of other chemotherapies (VEGF and mTOR inhibitors), the patient was treated by nivolumab (3 mg/kg) for 4 months and developed acute kidney injury 16 weeks after initiating this immunotherapy. Kidney biopsy displayed a diffuse extensive interstitial inflammation associated with moderate interstitial edema. The discontinuation of nivolumab and the administration of prednisone (at 1 mg/kg and tapered over 3 months) was an effective treatment of the interstitial edema and led to the recovery of the kidney function.

Balkan Endemic Nephropathy: An Autopsy Case Report

Balkan endemic nephropathy (BEN) is a form of interstitial nephritis seen only in certain geographical areas in the Balkan peninsula. Herein we describe the gross and histological changes in a diseased 42-year-old male Caucasian patient with BEN. All the changes fit the classically described alterations, with copper hue discoloration of the skin of the torso and orange discoloration of the soles and palms. Grossly, the kidneys were atrophic, with the left one weighing 31 grams and the right one 32 grams. Their surface was predominantly smooth with areas of fine granulations and cystic transformations. Histology revealed hyalinization of the glomeruli, predominantly in the external part of the cortex, severe vascular changes, interstitial fibrosis, and scant inflammatory cell infiltrate. The renal pelvis and ureters revealed multiple urothelial papillomas and atypical urothelial hyperplasia. BEN is only one geographical variant of interstitial nephritis caused by exposure to aristolochic acid. Other forms of this condition include Chinese herb nephropathy/aristolochic acid nephropathy, as well as several similar endemic conditions with a yet unestablished link to aristolochic acid.

[INTERSTITIAL NEPHRITIS CAUSED BY IPILIMUMAB AND NIVOLUMAB COMBINATION THERAPY FOR ADVANCED RENAL CELL CARCINOMA: A CASE REPORT]

The patient was 74-year-old woman. She underwent open nephrectomy for right kidney cancer with multiple lung metastasis in June X, and was diagnosed as clear cell renal cell carcinoma, pT3bN0M1. Combination therapy with ipilimumab and nivolumab was started in July X. In September X, she presented our hospital with the chief complaint of anorexia. The renal function deteriorated remarkably with serum Cr of 8.58 mg/dL and BUN of 71 mg/dL. CT scan revealed an enlarged left kidney at that time. She was clinically diagnosed as Grade 3 interstitial nephritis caused by immune checkpoint inhibitor, and treatment was initiated immediately. She was treated with steroid therapy and discontinuation of the drugs she was taking, which gradually improved her renal function, and brought it back to baseline in three weeks. After that, the steroid was carefully tapered, and turned off on day 52, and nivolumab monotherapy was resumed on day 60. After five cycles of nivolumab monotherapy, there has been no recurrence of interstitial nephritis, and the disease remains stable. In Japan, 38 cases of interstitial nephritis due to immune checkpoint inhibitors have been reported. In most cases, the diagnosis was made by histological examination; however, we believe that the diagnosis should be made clinically and treatment should be started immediately, since the early treatment is important for immune-related adverse events.

Granulomatous interstitial nephritis in granulomatosis with polyangiitis mimicking leprosy: A case report

Granulomatous polyangiitis (GPA) is a small vessel vasculitis commonly affecting the upper and lower respiratory tracts and kidneys. About 90% of the cases are associated with ANCA, namely, PR3-ANCA and MPO-ANCA. Herein, we describe a patient of GPA who presented with anasarca, sensory neuropathy, recurrent upper airway congestion, epistaxis, and rapidly progressive glomerulonephritis. Granulomatous interstitial nephritis and necrotizing granulomatous inflammation of the nasal septum were found on biopsy of the kidney and nasal septum, respectively both of which are rare findings. PR3-ANCA and MPO-ANCA were negative. Fulfilling the ACR criteria, this case of GPA proves that biopsy is still the gold standard of diagnosis.

Novel Homozygous FAN1 Mutation in a Familial Case of Karyomegalic Interstitial Nephritis

Karyomegalic interstitial nephritis (KIN) is a rare genetic kidney disease associated with a mutation in FAN1 gene and is often underdiagnosed. The histomorphology demonstrates chronic interstitial nephritis with tubular epithelial cells showing bizarre enlarged nuclei. We present a case report of a 47-year-old multiparous South-Indian woman presenting with bilateral pitting pedal oedema and mild hypertension. At the time of presentation, her serum creatinine was 1.52 mg/dL and urine analysis showed mild proteinuria. Kidney biopsy showed features of tubular injury with bizarre enlarged nuclei and focal mild chronic tubulointerstitial nephritis. Immunohistochemistry was negative for cytomegalovirus (CMV) Ag and SV40 Ag. Real-time polymerase chain reaction (PCR) done for CMV and BK virus genomes was negative. Relevant family history was that her older brother was also diagnosed with kidney failure and is on renal replacement therapy. Genetic analysis for FAN1 gene of the proband and her sibling showed two rare mutations of the FAN1 gene in the exon 4, of which, one is non-synonymous mutation and the other is a stop-gain mutation in the proband. This case illustrates a rare presentation of karyomegalic interstitial nephritis in siblings with previous unknown FAN1 gene mutations.

Late-onset interstitial nephritis in a patient with drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms

Drug-induced hypersensitivity syndrome (DIHS), also referred to as drug reaction with eosinophilia and systemic symptoms (DRESS), is a severe hypersensitivity drug reaction affecting the skin and multiple internal organ systems. We report a 47-year-old man with DIHS/DRESS and comorbidities (fulminant type 1 diabetes mellitus, valsartan-induced photosensitivity, vitiligo and acute interstitial nephritis). Although acute interstitial nephritis usually appears in the early phase, his is a rare case of acute interstitial nephritis more than 2 years after the onset of DIHS/DRESS.

Co-occurrence of bilateral nodular anterior scleritis and large-vessel arteritis in a patient with TINU syndrome

We present a case of tubulointerstitial nephritis and uveitis (TINU) with nodular anterior scleritis and large-vessel arteritis. A 67-year-old patient was admitted to the hospital with high fever, thoracic pain, and weakness. Bilateral anterior uveitis was seen at that time. Laboratory examination showed acute renal failure. A renal biopsy was performed and showed pathognomonic signs of tubulointerstitial nephritis (TIN). Six months later, she developed ocular inflammation suggestive of nodular scleritis. One year after hospital admission, she presented with large-vessel arteritis. We describe a case of TINU with co-occurrence of scleritis and large-vessel arteritis.

ANCA vasculitis presenting with acute interstitial nephritis without glomerular involvement

ANCA-associated vasculitis (AAV) with renal involvement typically causes pauci-immune glomerulonephritis. We present a case of acute interstitial nephritis (AIN) as the sole renal lesion without glomerulonephritis with myeloperoxidase (MPO) AAV. A 45-year-old female with history of Crohn’s disease, gastroesophageal reflux disease (GERD) with Barrett’s esophagus, pulmonary embolism, and polyarthralgias was evaluated in nephrology clinic in 2018. AIN without glomerulonephritis was first diagnosed in 2011 on renal biopsy. p-ANCA was positive with MPO titer of > 100 U/mL. Serum creatinine improved from 2.1 to 0.9 mg/dL with prednisone and azathioprine. Repeat biopsy in 2013 for worsening renal function showed AIN without glomerular involvement. Serum creatinine improved from 1.9 to 1.2 mg/dL with prednisone and cyclosporine. Crohn’s disease was diagnosed in 2014. AIN was attributed to Crohn’s, and cyclosporine was stopped in 2016. Adalimumab was started in 2016, without improvement in renal function or urine sediment. Attempt was made to switch proton pump inhibitor (PPI) to H2-blocker, but the latter was not tolerated. Repeat biopsy in 2/2018 showed AIN with severe fibrosis and tubular atrophy and glomerulosclerosis but no active glomerular disease. MPO titers remained high at 132 U/mL. Mycophenolic acid and prednisone were started without response, followed by rituximab for AAV-associated AIN. Serum creatinine worsened to 6.0 mg/dL in 9/2018, with plan to start peritoneal dialysis. AAV may present with isolated AIN without glomerular involvement. The rarity of this presentation may contribute to delay in appropriate management. Alternative explanations for AIN, such as Crohn’s disease or PPI use should be considered with caution in the setting of high-titer ANCA positivity.

Kidney Complications of Immune Checkpoint Inhibitors: A Review

Immunologic control of malignancy has long been recognized as an important determinant of disease progression. Recent advances in immunology have led to the focus on several mechanisms that can be targeted to achieve tumor suppression. In particular, checkpoint inhibition has evolved in less than a decade to become one of the most important strategies in cancer therapy, with a meaningful improvement in patient survival. Six agents have been approved for clinical use to date and many more are in the industry pipeline. The spectrum of malignancies responsive to immunotherapy ranges from advanced melanoma, for which the first immune checkpoint inhibitor ipilimumab was approved, to Hodgkin lymphoma, non-small cell lung cancer, renal cell carcinoma, and others. Notwithstanding its clinical benefits, checkpoint inhibition carries a risk for significant off-target toxicity stemming from the immune system activation. In this review, we discuss general principles of checkpoint inhibition, mechanisms of toxicity, and kidney complications of the treatment and propose diagnostic and treatment strategies when kidney injury occurs.

Clozapine-induced interstitial nephritis in a patient with schizoaffective disorder in the forensic setting: a case report and review of the literature

We present a rare case of Acute Interstitial Nephritis (AIN) that occurred following a re-trial of clozapine in a 56-year-old lady with schizoaffective disorder. On initial trial of clozapine, this patient felt generally unwell with respiratory symptoms. Her inflammatory markers were raised and her renal function showed a mild, transient deterioration which normalised on the day of cessation of clozapine. Two years later, clozapine was re-trialled due the refractory nature of her psychiatric symptoms. She subsequently developed renal failure and AIN was confirmed by renal biopsy. Renal function improved after cessation of clozapine; however, she never fully regained normal renal function.

Anti-PD-1 Immunotherapy May Induce Interstitial Nephritis With Increased Tubular Epithelial Expression of PD-L1

Introduction

Novel anticancer therapies include anti–programmed cell death protein-1 (PD-1) and anti–programmed death ligand-1 (PD-L1) drugs. These novel medications have side effects in different organs, including the kidney. The most common adverse effect in the kidney is acute interstitial nephritis (AIN). No diagnostic criteria are available to distinguish AIN associated with anti–PD-1 therapy from other AINs.

Methods

Kidney biopsy specimens from patients on anti–PD-1 therapy were stained with antibodies to PD-1 and PD-L1. Herein we report morphologic and immunohistochemical findings in 15 patients who received anti–PD-1 therapy and developed acute kidney injury requiring a kidney biopsy.

Results

Among these patients, 9 had AIN and 6 had no AIN but showed acute tubular necrosis (ATN). Immunohistochemistry with antibodies to PD-1 and PD-L1 was performed on all of these biopsy specimens and on 9 randomly selected biopsy specimens with AIN from patients who did not receive anti–PD-1 medications, as well as 9 patients with lupus nephritis and active-appearing interstitial inflammation. There was weak staining for PD-1 in T cells in all patients with AIN and lupus; however, tubular epithelial cell membrane staining for PD-L1 was seen only in patients with anti–PD-1 therapy−associated AIN, and not in patients with anti–PD-1 therapy−associated ATN, and not in those with AIN secondary to other medications, or patients with lupus nephritis.

Conclusion

We propose that immunohistochemistry with PD-L1 could be a useful tool to differentiate AIN associated with anti–PD-1 therapy from other AINs.

Alogliptin-Induced Minimal Change Nephrotic Syndrome and Interstitial Nephritis

Alogliptin is one of the dipeptidyl peptidase-4 inhibitors used to treat patients with type 2 diabetes. Little is known about the nephrotoxicity associated with alogliptin, such as nephrotic syndrome or interstitial nephritis. We report a biopsy-proven rare case of minimal change nephrotic syndrome and interstitial nephritis induced by alogliptin. A 68-year-old man who had been prescribed alogliptin was hospitalized for nephrotic syndrome. On admission, serum creatinine level was elevated with increased urinary β₂-microglobulin and N-acetyl-β-d-glucosaminidase excretion. Kidney biopsy revealed minor glomerular abnormalities and interstitial nephritis, and gallium-67 scintigraphy showed uptake in both kidneys. A drug lymphocyte stimulation test for alogliptin was positive. With discontinuation of alogliptin treatment alone, serum creatinine level normalized in parallel with urine β₂-microglobulin and N-acetyl-β-d-glucosaminidase levels. In addition, complete remission of nephrotic syndrome was observed. Drug-induced dual pathology has not been previously reported with alogliptin. In summary, clinicians should keep in mind that alogliptin can induce minimal change nephrotic syndrome and interstitial nephritis.

Non-steroidal Anti-inflammatory Drugs (NSAIDs) Systemic Use: The Risk of Renal Failure

For the pediatric nephrologist, the over-the-counter status for non-steroidal anti-inflammatory drugs (NSAIDs) is surprising due to their possible harmful side effects. These can include acute renal failure due mainly to glomerular hypoperfusion which may lead to acute tubular necrosis; more rarely in children, medullary ischemic injury and cardiovascular diseases; acute or chronic interstitial nephritis which may cause chronic renal failure. All of them may create electrolyte abnormalities: hyponatremia, hyperkaliemia, renal tubular acidosis, fluid retention causing hypertension.

Eosinophilia and Kidney Disease: More than Just an Incidental Finding?

Peripheral blood eosinophilia (PBE), defined as 500 eosinophils or above per microliter (µL) blood, is a condition that is not uncommon but often neglected in the management of patients with chronic kidney disease (CKD), acute kidney injury (AKI), or patients on renal replacement therapy (RRT). The nature of PBE in the context of kidney diseases is predominantly secondary or reactive and has to be distinguished from primary eosinophilic disorders. Nonetheless, the finding of persistent PBE can be a useful clue for the differential diagnosis of underdiagnosed entities and overlapping syndromes, such as eosinophilic granulomatosis with polyangiitis (EGPA), IgG4-related disease (IgG4-RD), acute interstitial nephritis (AIN), or the hypereosinophilic syndrome (HES). For patients on RRT, PBE may be an indicator for bio-incompatibility of the dialysis material, acute allograft rejection, or Strongyloides hyperinfection. In a subset of patients with EGPA, eosinophils might even be the driving force in disease pathogenesis. This improved understanding is already being used to facilitate novel therapeutic options. Mepolizumab has been licensed for the management of EGPA and is applied with the aim to abrogate the underlying immunologic process by blocking interleukin-5. The current article provides an overview of different renal pathologies that are associated with PBE. Further scientific effort is required to understand the exact role and function of eosinophils in these disorders which may pave the way to improved interdisciplinary management of such patients.