The changing profile of acute tubulointerstitial nephritis

Clinicopathological findings of tubulointerstitial nephritis: a cross-sectional analysis of the Japan Renal Biopsy Registry (J-RBR)

INTRODUCTION

Tubulointerstitial nephritis (TIN) is an important disease involving a diverse set of factors that can cause both acute kidney injury and chronic kidney disease. The purpose of this cross-sectional study was to clarify the causative diseases and clinicopathological characteristics of TIN using the Japan Renal Biopsy Registry (J-RBR).

METHODS

This cross-sectional study analyzed data from 22,049 cases registered in the J-RBR between 2018 and 2022. Clinicopathological findings at diagnosis were investigated.

RESULTS

Of the enrolled cases, 913 were diagnosed with TIN. "Drug-induced" was the most common (232 cases, 25.7%), followed by "IgG4-related kidney disease" (124 cases, 13.7%). Of "Drug-induced" TIN cases, "Chemotherapy-related" was the most common cause (63 cases, 27.2%), including 47 cases of "immune checkpoint inhibitor (ICI)-associated" TIN. IgM-positive plasma cell-rich TIN (IgMPC-TIN), which has been the focus of much attention in recent years, was also included, with 9 cases.

CONCLUSION

This is the first report of the clinicopathological findings of TIN patients in a large-scale, nationwide registry of renal biopsies. It was possible to identify recent trends in causative diseases, including an increase in chemotherapy-related TIN and IgMPC-TIN.

Unusual course of glyphosate-induced acute kidney injury: a case report of tubulointerstitial nephritis treated with steroids

Glyphosate is a widely used herbicide that is generally considered safe; however, acute kidney injury (AKI) caused by glyphosate ingestion can be severe and require hemodialysis. We present a unique case of a 68-year-old Japanese man who developed AKI after accidental ingestion of glyphosate and required hemodialysis. Based on the clinical presentation and findings, the patient was diagnosed with renal AKI with severe tubulointerstitial damage. However, the precise pathogenesis of the tubulointerstitial damage remained unclear. An elevated beta-2 microglobulin level discovered by the urinalysis during admission raised the suspicion of tubulointerstitial nephritis caused by glyphosate. Gallium scintigraphy revealed accumulation in both kidneys. A renal biopsy revealed acute tubulointerstitial nephritis rather than acute tubular necrosis, which is commonly observed with glyphosate-induced renal injury. After initiating steroid therapy, his kidney function gradually improved and he was weaned from hemodialysis. This report is the first to describe glyphosate-induced acute tubulointerstitial nephritis that was successfully treated with immunosuppressive therapy. Furthermore, this report highlights the importance of steroid therapy for cases of persistent kidney injury after the discontinuation of agents associated with acute tubulointerstitial nephritis.

Tubulointerstitial nephritis in children and adolescents

The tubulointerstitial compartment comprises most of the kidney parenchyma. Inflammation in this compartment (tubulointerstitial nephritis-TIN) can be acute and resolves if the offending factor is withdrawn or may enter a chronic process leading to irreversible kidney damage. Etiologic factors differ, including different exposures, infections, and autoimmune and genetic tendency, and the initial damage can be acute, recurrent, or permanent, determining whether the acute inflammatory process will lead to complete healing or to a chronic course of inflammation leading to fibrosis. Clinical and laboratory findings of TIN are often nonspecific, which may lead to delayed diagnosis and a poorer clinical outcome. We provide a general review of TIN, with special mention of the molecular pathophysiological mechanisms of the associated kidney damage.

Tubulointerstitial Nephritis and Uveitis Syndrome Presenting with Scleritis

PURPOSE

To report two patients who presented with scleritis associated with tubulointerstitial nephritis and uveitis syndrome (TINU).

RESULTS

A 13-year-old male initially presenting with unilateral panuveitis with scleritis in the fellow eye was ultimately diagnosed with TINU. A 33-year-old male previously diagnosed with TINU presented with recurrent bilateral episcleritis as well as bilateral scleritis eight years after his first episode of bilateral anterior uveitis. Both patients' scleritis responded to local corticosteroids and systemic immunosuppression.

CONCLUSIONS

Scleritis should be considered among the ocular manifestations of TINU.

Tissue-resident memory T cells break tolerance to renal autoantigens and orchestrate immune-mediated nephritis

Immune-mediated nephritis is a leading cause of acute kidney injury and chronic kidney disease. While the role of B cells and antibodies has been extensively investigated in the past, the advent of immune-checkpoint inhibitors has led to a reappraisal of the role of T cells in renal immunology. However, it remains elusive how T cells with specificity for renal autoantigens are activated and participate in immune-mediated nephritis. Here, we followed the fate and function of pathogen-activated autoreactive CD8 T cells that are specific for a renal autoantigen. We demonstrate that recently activated splenic CD8 T cells developed a hybrid phenotype in the context of renal autoantigen cross-presentation, combining hallmarks of activation and T cell dysfunction. While circulating memory T cells rapidly disappeared, tissue-resident memory T cells emerged and persisted within the kidney, orchestrating immune-mediated nephritis. Notably, T cells infiltrating kidneys of patients with interstitial nephritis also expressed key markers of tissue residency. This study unveils how a tissue-specific immune response can dissociate from its systemic counterpart driving a compartmentalized immune response in the kidneys of mice and man. Consequently, targeting tissue-resident memory T cells emerges as a promising strategy to control immune-mediated kidney disease.

The Road to Precision Medicine for Acute Kidney Injury

OBJECTIVES

Acute kidney injury (AKI) is a common form of organ dysfunction in the ICU. AKI is associated with adverse short- and long-term outcomes, including high mortality rates, which have not measurably improved over the past decade. This review summarizes the available literature examining the evidence of the need for precision medicine in AKI in critical illness, highlights the current evidence for heterogeneity in the field of AKI, discusses the progress made in advancing precision in AKI, and provides a roadmap for studying precision-guided care in AKI.

DATA SOURCES

Medical literature regarding topics relevant to precision medicine in AKI, including AKI definitions, epidemiology, and outcomes, novel AKI biomarkers, studies of electronic health records (EHRs), clinical trial design, and observational studies of kidney biopsies in patients with AKI.

STUDY SELECTION

English language observational studies, randomized clinical trials, reviews, professional society recommendations, and guidelines on areas related to precision medicine in AKI.

DATA EXTRACTION

Relevant study results, statements, and guidelines were qualitatively assessed and narratively synthesized.

DATA SYNTHESIS

We synthesized relevant study results, professional society recommendations, and guidelines in this discussion.

CONCLUSIONS

AKI is a syndrome that encompasses a wide range of underlying pathologies, and this heterogeneity has hindered the development of novel therapeutics for AKI. Wide-ranging efforts to improve precision in AKI have included the validation of novel biomarkers of AKI, leveraging EHRs for disease classification, and phenotyping of tubular secretory clearance. Ongoing efforts such as the Kidney Precision Medicine Project, identifying subphenotypes in AKI, and optimizing clinical trials and endpoints all have great promise in advancing precision medicine in AKI.

Association between Tubulointerstitial Nephritis and Uveitis Syndrome and Small-Vessel CNS Vasculitis: A Case of Polyautoimmunity

INTRODUCTION

 We report a case study of two male pediatric patients presenting with anterior uveitis and elevated renal function parameters. Both were diagnosed with tubulointerstitial nephritis and uveitis syndrome and subsequently developed diffuse cerebral symptoms such as headache, fatigue, and diziness.

METHODS

 Magnetic resonance images (MRIs) of the brain showed T2-hyperintense lesions with and without gadolinium enhancement leading to brain biopsy and diagnosis of small-vessel central nervous system (CNS) vasculitis in both cases. Both patients were treated according to BrainWorks small-vessel vasculitis protocol and symptoms vanished over the course of treatment. Follow-up MRIs up to 12 months after initiation of therapy showed no signs of recurrence indicating a monophasic disease.

CONCLUSION

 Small-vessel CNS vasculitis can occur simultaneously to other autoimmune diseases (ADs) in the scope of polyautoimmunity. As clinical findings of CNS vasculitis are often unspecific, neurological symptoms in nonneurological ADs should be adressed thoroughly. Under suspicion of small-vessel CNS vasculitis brain biopsy is still the gold standard and only secure way of definitive diagnosis.

The diagnosis of acute interstitial nephritis caused by infection versus antibiotic-induced interstitial nephritis: a narrative review

Acute interstitial nephritis (AIN) is a significant contributor to acute kidney injury and can be attributed to a variety of factors, including but not limited to allergens or drugs, infections, autoimmune or systemic diseases, and idiopathic forms of the disease. In some cases, AIN requires a therapeutic action according to a single specific etiology by handling the offending agent and applying an immunosuppressant. Although AIN can be diagnosed through renal biopsy, it is not able to pinpoint the precise cause when multiple causes are suspected to be present simultaneously. Such situations arise when a patient suffering from infection develops AIN during antibiotic therapy, the exact causative factor of which becomes a challenge for the clinicians to determine. This is attributed to the different approaches employed in different etiologies, wherein clinicians are required to maintain the current antibiotic therapy or augment the dose in cases of infection as AIN etiology, without resorting to immunosuppressant therapy as the primary objective is infection killing. In contrast, antibiotics as an etiology for AIN require an alternative drug from the antibiotics group, along with an immunosuppressant. In the interim, delaying the identification of the precise cause may result in interstitial fibrosis and chronic kidney disease. This narrative review highlights certain findings that can be typical of infection-associated ATIN compared with antibiotic-associated ATIN based on clinical history and physical examination, clinical presentation of different antibiotic drug classes, histopathological features, classical and novel biomarkers, serum and urine cytokines and chemokines, cellular biomarkers, and genetic biomarkers. Although these findings cannot provide conclusive and clear recommendations that can be useful in the clinical practice, they can entice researchers to conduct original research on these features to discover clear recommendations.

Sulfamethoxazole-induced crystal nephropathy: characterization and prognosis in a case series

Cotrimoxazole (Trimethoprim/Sulfamethoxazole-SMX) is frequently used in critically ill and immunocompromised patients. SMX is converted to N-acetyl-sulfamethoxazole (NASM) and excreted by the kidneys. NASM may form crystals in urine, especially in acid urine, that may induce a crystalline nephropathy. However, the imputability of crystals in acute kidney injury (AKI) has not been proven. We aimed to assess whether NASM crystals may promote AKI and to investigate risk factors associated with NASM crystalline nephropathy. Patients from Ile-de-France, France who developed AKI under SMX treatment introduced during hospitalization and had a crystalluria positive for NASM crystals were selected. Patients with excessive preanalytical delay for crystalluria or missing data regarding SMX treatment were excluded. We used the Naranjo score to assess the causal relationship between SMX and the development of AKI in patients with positive NASM crystalluria. Fourteen patients were included. SMX was the probable cause of AKI for 11 patients and a possible cause for 3 patients according to Naranjo score. Patients were exposed to high doses of SMX (but within recommended ranges), and most of them had a preexisting chronic kidney disease and were hypoalbuminemic. Urine pH was mildly acid (median 5.9). AKI occured more rapidly than expected after introduction of SMX (median 4 days) and recovered rapidly after drug discontinuation in most, but not all, cases. SMX is a probable cause of crystalline nephropathy. Monitoring of crystalluria in patients exposed to SMX may be of interest to prevent the development of crystalline nephropathy. Approval number of the study: BPD-2018-DIAG-008.

[Acute interstitial nephritis and hantavirus infection]

Acute interstitial nephritis (AIN) is a cause of acute kidney injury and characterized by an inflammation of the tubulointerstitial space, leading to a decline in kidney function. Multiple etiologies can cause AIN including medications, autoimmune diseases and infections. A multiplicity of drugs is associated with AIN, while antibiotics (especially beta-lactams), proton-pump inhibitors (PPI) and non-steroidal anti-inflammatory agents (NSAIDs) are the most common. The pathognomonic triad of exanthema, fever and eosinophilia is rarely present in AIN patients. Treatment of medication-associated AIN is based upon the discontinuation of the provoking drug. Glucocorticoids can be considered in severe cases.Nephropathia epidemica (NE) is a disease caused by an infection with the Puumula-virus (PUUV) in northern and central Europe. Small rodents (mostly mice) are the host of the virus accountable for a rising number of infections during spring and summer. It is causing a syndrome consisting of AIN, fever and often thrombocytopenia. There is a good chance of complete recovery of kidney function following NE.

Changing Tides of Acute Interstitial Nephritis: A Retrospective Observational Study from South India

Introduction

The incidence of acute interstitial nephritis (AIN) has been increasing in recent years. The causes and outcomes of AIN have been changing with time and vary widely based on geographical region.

Methods

A retrospective observational study was conducted in a tertiary care center. All (n = 6234) native kidney biopsies were reviewed from January 2016 to December 2021. All biopsy-proven AIN cases were included in the study. AIN associated with systemic diseases (such as SLE, Sjogren's, sarcoidosis, plasma cell dyscrasias), proliferative glomerulonephritis, and allograft biopsies were excluded.

Results

Among 6234 biopsies analyzed, there were 156 biopsy-proven AIN cases. The majority were in the 6th decade of life (24.4%) and males (80.8%). 50% of the patients had a history of drug intake, the most common being tenofovir (12.3%) followed by alternate forms of medications (10.3%). The majority (96.2%) presented with acute kidney injury (AKI). At the end of six months, 79.5% recovered completely, 19.2% progressed to chronic kidney disease. The presence of nephrotic range proteinuria at presentation was associated with progression to chronic kidney disease.

Conclusion

AIN is an important cause of AKI, especially in the elderly population. Drugs are the most common cause, especially HAART follwed by alternate forms of medication. The presence of nephrotic range proteinuria was associated with increased risk of progression to chronic kidney disease.

The Spectrum of Biopsy-Proven Kidney Diseases, Causes, and Renal Outcomes in Acute Kidney Injury Patients

INTRODUCTION

Acute kidney injury (AKI) is a group of highly heterogeneous, complicated clinical syndromes. Although kidney biopsy plays an irreplaceable role in evaluating complex AKI, a few studies have focused on the clinicopathology of AKI biopsies. This study analyzed the pathological disease spectrum, causes, and renal outcomes of biopsied AKI patients.

METHODS

We retrospectively included 2,027 AKI patients who underwent kidney biopsies at a national clinical research center of kidney diseases from 2013 through 2018. To compare the biopsied AKI cases without and with coexisting glomerulopathy, patients were classified into acute tubular/tubulointerstitial nephropathy-associated AKI (ATIN-AKI) and glomerular disease-associated AKI (GD-AKI) groups.

RESULTS

Of 2,027 biopsied AKI patients, 65.1% were male, with a median age of 43 years. A total of 1,590 (78.4%) patients had coexisting GD, while only 437 (21.6%) patients had ATIN alone. The AKI patients with GD mainly (53.5%) manifested as stage 1 AKI, while most ATIN-AKI patients (74.8%) had stage 3 AKI. In the ATIN-AKI group, 256 (58.6%) patients had acute interstitial nephritis (AIN), and 77 (17.6%) had acute tubular injury (ATI). ATIN-AKI was mainly caused by drugs in 85.5% of AIN and 63.6% of ATI cases, respectively. In AKI patients with coexisting GD, the leading pathological diagnoses in over 80% of patients were IgA nephropathy (IgAN, 22.5%), minimal change disease (MCD, 17.5%), focal segmental glomerulosclerosis (FSGS, 15.3%), lupus nephritis (LN, 11.9%), membranous nephropathy (MN, 10.2%), and ANCA-associated vasculitis (AAV, 4.7%). A total of 775 patients were followed up within 3 months after renal biopsy; ATIN-AKI patients achieved statistically higher complete renal recovery than the GD-AKI patients (83.5% vs. 70.5%, p < 0.001).

CONCLUSIONS

Most biopsied AKI patients have coexisting GD, while ATIN alone is seen less frequently. ATIN-AKI is mainly caused by drugs. In GD-AKI patients, IgAN, MCD, FSGS, LN, MN, and AAV are the leading diagnoses. Compared to AKI patients without GD, patients with GD suffer from worse renal function recovery.

A low BUN/creatinine ratio predicts histologically confirmed acute interstitial nephritis

INTRODUCTION

In hospitalized patients with acute renal injury (AKI), acute tubulointerstitial nephritis (AIN) constitutes one of the leading etiologies. The objective of this study was to identify clinical and biochemical variables in patients with AKI associated with kidney biopsy-confirmed AIN.

METHODS

For our prospective study, we recruited hospitalized patients aged 18 years and older who were diagnosed with AKI based on biochemical criteria. Prior to enrollment, each patient was assessed with a complete metabolic panel and a kidney biopsy.

RESULTS

The study consisted of 42 patients (with a mean age of 45 years) and equal numbers of male and female patients. Diabetes and hypertension were the main comorbidities. Nineteen patients had histological findings consistent with AIN. There was a correlation between histology and the BUN/creatinine ratio (BCR) (r = -0.57, p = 0.001). The optimal Youden point for classifying AIN via a receiver operating characteristic (ROC) curve analysis was a BCR ≤ 12 (AUC = 0.73, p = 0.024). Additionally, in diagnosing AIN, BCR had a sensitivity of 76%, a specificity of 81%, a positive predictive value of 81%, a negative predictive value of 76%, and OR of 14 (95% CI = 2.6 to 75.7, p = 0.021). In the multivariable analysis, BCR was the sole variable associated with AIN.

CONCLUSION

A BCR ≤ 12 identifies AIN in patients with AKI. This study is the first to prospectively assess the relationship between renal biopsy results and BCR.

Therapeutics in rheumatology and the kidney

The field of rheumatology has advanced significantly in recent years to provide rheumatologists with an extensive array of medications to combat rheumatic joint conditions. In contrast to an older era, when NSAIDs and other nephrotoxic agents were the mainstay of treatment, modern DMARDs vary considerably in their nephrotoxic potential and their use is not always precluded in populations with pre-existing chronic kidney disease (CKD). This review will explore in detail the safety and efficacy profiles of medications used to treat rheumatologic disease, specifically in the setting of CKD. Specifically, we discuss both traditional agents used, i.e. NSAIDs, CSs and conventional synthetic DMARDs, as well as novel biologic DMARDs and targeted synthetic DMARDs. Anti-gout prescribing in CKD is also reviewed. We aim to provide practical guidance to rheumatologists, nephrologists and general physicians when prescribing these medications in the setting of CKD.

Ten Cases of Biopsy-Proven Acute Tubulointerstitial Nephritis: Report from a Single Center in a Rural Area from 2008 to 2021

Acute tubulointerstitial nephritis (ATIN) can be caused by any number of factors, and it accounts for several percent of renal biopsy cases. In Japan, case reports exist, but there are few single-center series of ATIN cases. Case 1. A teenage male patient developed fever and cough on day X-61 and was found to have normal renal function and positive C-reactive protein (CRP) by his primary care physician. On day X-20, he presented with cough and nasal discharge in addition to low-grade fever, and his doctor noted renal dysfunction with serum creatinine of 2.12 mg/dL, negative urine occult blood, and positive urine glucose. Renal biopsy results showed diffuse interstitial nephritis with scarce glomerular involvement. There was no concurrent uveitis. Renal function normalized after 4 months of treatment with moderate-dose prednisolone. Cases 2–10. Of the 422 cases for which renal biopsies were performed at our institution from 2008 to 2021, acute tubulointerstitial nephritis was confirmed clinically and pathologically in 9 cases in addition to case 1, accounting for 2.4% of all biopsy cases. In the analysis of the 10 patients, the median age was 40 years old, eGFR at diagnosis was 19.4 (3.2–49.1) mL/min/1.73 m², and 2 of them underwent hemodialysis, but both were weaned from dialysis, and the eGFR after treatment was 53.6 (20.8–110.0) mL/min/1.73 m²; all patients showed improvement (P < 0.001). Treatment consisted of steroids in 8 patients and no steroids in 2 patients, the latter being treated by discontinuation of the suspect drugs and treatment of infection; 7 of the 10 patients were examined for ocular uveitis, and uveitis was diagnosed in 5 patients. The causes and clinical course of ATIN are diverse, but it is treated according to individual judgment in addition to standard treatment, and it generally has a good renal prognosis.

Assessment of renal microcirculation in biopsy-proven tubulointerstitial nephritis in patients with and without glomerular disease: the role of resistive index

BACKGROUND

Renal resistive index (RRI) measured by Doppler sonography is a marker of microvascular status and it is associated with changes in renal function. Aim of the study was to assess RRI in biopsy-proven tubulointerstitial nephritis (TIN) in patients with and without glomerular disease.

METHODS

132 consecutive patients underwent to native renal biopsy with diagnosis of isolated TIN or in association with glomerulonephritis. Estimated glomerular filtration rate (eGFR), 24-hour urinary protein excretion and renal ecocolorDoppler ultrasonography with RRI assessment were performed at time of enrollment.

RESULTS

Patients with isolated-TIN had significantly higher RRI than both patients with non-immunoglobulin A glomerulonephritis (non-IgA-TIN) [0.73 (0.68-0.77) vs 0.64 (0.60-0.67), p < 0.001] and patients with IgA nephropathy (IgAN) [0.73 (0.68-0.77) vs 0.66 (0.60-0.71), p < 0.01]. Patients with isolated-TIN had mainly RRI ≥ 0.70 (n = 15, 65.2%) with the respect to patients with non-IgA-TIN (n = 7, 12.3%) and patients with IgAN (n = 17, 32.7%). A negative linear correlation was found between RRI and hemoglobin (r = 0.233, p < 0.01) and between RRI and eGFR (r = 0.537, p < 0.001).

CONCLUSION

Tubulointerstitial damage is the most accurate histological lesion that correlates with eGFR and renal impairment. RRI can be a useful parameter to detect tubulointerstitial lesions.

5-ASA induced interstitial nephritis in patients with inflammatory bowel disease: a systematic review

Background

Acute interstitial nephritis (AIN) is an important cause of kidney injury accounting for up to 27% of unexplained renal impairment. In up to 70% of cases, drugs, including aminosalicylates, are reported as the underlying cause. Following two recent paediatric cases of suspected mesalazine induced AIN within our own department, we performed a systematic review of the literature to address the following question: In patients with inflammatory bowel disease (IBD), is interstitial nephritis associated with 5-aminosalicylate (5-ASA) treatment? Our primary objective was to identify the number of cases reported in the literature of biopsy-proven 5-ASA induced interstitial nephritis, in children and adults with IBD. We also aimed to identify which variables influence the onset, severity and recovery of 5-ASA interstitial nephritis.

Methods

Embase and PubMed databases were searched from inception to 07/10/20. Search terms had three main themes: “inflammatory bowel disease”, “interstitial nephritis” and “aminosalicylates”. Studies were included if they reported an outcome of AIN, confirmed on biopsy, suspected to be secondary to a 5-ASA drug in those with IBD. A narrative synthesis was performed.

Results

Forty-one case reports were identified. Mesalazine was the most frequently reported aminosalicylate associated with AIN (95%). The median duration of treatment before AIN was diagnosed was 2.3 years (Interquartile Range (IQR) 12–48 months). The median rise in creatinine was 3.3 times the baseline measurement (IQR 2.5–5.5). Aminosalicylate withdrawal and steroids were the most frequently used treatments. Despite treatment, 15% of patients developed end-stage renal failure.

Conclusions

AIN is a serious adverse drug reaction associated with aminosalicylates, with mesalazine accounting for most reports. The current guidance of annual monitoring of renal function may not be sufficient to identify cases early. Given the severity of AIN and reports in the literature that early treatment with steroids may be beneficial, we would recommend at least 6 monthly monitoring of renal function.

PROSPERO registration number CRD42020205387.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00687-y.

Non-diabetic Kidney Disease in Diabetic Population: A Single-Center Study From South India

Introduction: Diabetic kidney disease (DKD) is the commonest cause of chronic kidney disease and end-stage kidney disease worldwide, consequently it has become an important productive implication to the healthcare system. This study was conducted to assess the prevalence of non-DKD (NDKD) in diabetic patients from south India.

Objective: To assess the prevalence of NDKD in type 2 diabetes mellitus patients presenting to a tertiary care hospital from south India and also to analyze clinical clues to establish a diagnosis of NDKD.

Patient and methods: It is a retrospective observational study of analyzing patient characteristics and renal biopsies. All Diabetic patients with a clinical suspicion of non-diabetic kidney disease who underwent renal biopsy during the study period between January 2012 and June 2017 were included. Based on the biopsy findings, the patients were classified into three groups (isolated diabetic nephropathy, isolated NDKD, and NDKD with underlying diabetic nephropathy) and patients’ characteristics were compared between the groups for analysis.

Results: A total of 236 renal biopsies were analyzed for the study. Of that, 114 had features of DKD, 78 NDKD with diabetic nephropathy (DN) and 44 had isolated NDKD. Acute interstitial nephritis was the most common cause of NDKD.

Conclusion: From the current study, the long duration of diabetes mellitus beyond five years and hypertension beyond two years reasonably predict DKD.

Serum anti-CRP antibodies differentiate etiology and predict relapse in acute tubulointerstitial nephritis

INTRODUCTION

Acute tubulointerstitial nephritis (ATIN) is a common cause of acute kidney injury with various etiologies. It has been shown that autoimmune-related ATIN (AI-ATIN) has a higher recurrence rate and a greater likelihood of developing into chronic kidney disease compared with drug-induced ATIN, yet misdiagnosis at renal biopsy is not uncommon.

METHODS

Patients who were clinicopathologically diagnosed as ATIN from January 2006 to December 2015 in Peking University First Hospital were enrolled. Clinical, pathological and follow-up data were collected. Serum samples on the day of renal biopsy were collected and tested for anti-C-reactive protein (CRP) antibodies. CRP and its linear peptides were used as coating antigens to detect antibodies. Statistical analysis was used to assess the diagnostic value of the antibodies.

RESULTS

Altogether 146 patients were enrolled. The receiver operating characteristic-area under the curve of the anti-CRP antibody for the identification of late-onset AI-ATIN was 0.750 (95% confidence interval 0.641-0.860, P < 0.001) and the positivity was associated with ATIN relapse (adjusted hazard ratio = 4.321, 95% confidence interval 2.402-7.775, P < 0.001). Antibodies detected by CRP linear peptide 6 (PT6) were superior with regard to differentiating patients with AI-ATIN, while antibodies detected by peptide 17 (PT17) could predict ATIN relapse. Antibodies detected by these two peptides were positively correlated with the severity of tubular dysfunction and pathological injury.

CONCLUSIONS

Serum anti-CRP antibody could be used to differentiate late-onset AI-ATIN and predict relapse of ATIN at the time of renal biopsy. The CRP linear peptides PT6 and PT17 could be used as coating antigens to detect anti-CRP antibodies, which may provide more information for the clinical assessment of ATIN.

Renal replacement therapy-requiring acute kidney injury due to tubulointerstitial nephritis and uveitis syndrome: case report

BACKGROUND

Acute kidney injury is a major challenge for today's healthcare systems around the globe. Renal replacement therapy has been shown to be beneficial in acute kidney injury, but treatment highly depends on the cause of the acute kidney injury. One less common cause is tubulointerstitial nephritis, which comes in different entities. A very rare type of tubulointerstitial nephritis is tubulointerstitial nephritis and uveitis syndrome, in which the patient presents with additional uveitis.

CASE PRESENTATION

A 19-year-old caucasian male presented with mild dyspnea, lack of appetite, weight loss, and moderate itchiness. Lab results showed an acute kidney injury with marked increase of serum creatinine. The patient was started on prednisolone immediately after admission. As the patient in this case showed symptoms of uremia on admission, we decided to establish renal replacement therapy, which is unusual in tubulointerstitial nephritis and uveitis syndrome. During his course of dialysis, the patient developed symptoms of sepsis probably due to a catheter-related infection requiring intensive care and antibiotic treatment, which had to be terminated early as the patient developed a rash. Intensified immunosuppression, combined with antibiotics, significantly resolved excretory kidney dysfunction.

CONCLUSIONS

Since both the primary inflammatory process and the secondary infectious complication significantly impaired excretory kidney function, kidney function of younger individuals with new-onset anterior uveitis should be monitored over time and during follow-up.

Dismal Prognosis of Acute Allergic Tubulointerstitial Nephritis in Patients with AA Amyloidosis

INTRODUCTION

Patients with AA amyloidosis may present with acute kidney injury that progresses to end-stage kidney disease in a short period of time. Acute allergic tubulointerstitial nephritis (aTIN) is a frequent cause of acute kidney injury in patients with AA amyloidosis. Although aTIN has a favorable prognosis in the general population, the course of aTIN in patients with AA amyloidosis was not previously reported. In this retrospective study, we determined the prognosis of aTIN superimposed on AA amyloidosis.

METHODS

Thirty-two patients with combined pathological diagnosis of AA amyloidosis + aTIN and 32 patients with isolated aTIN were compared in terms of 1-year renal functions after the biopsies were performed with an indication of acute kidney injury. Baseline renal functions and number of patients requiring hemodialysis at the time of biopsy was similar in both groups.

RESULTS

At the end of the 12-month follow-up period, 29 of 32 patients in the amyloidosis + aTIN group and 1 of 32 patients in the isolated aTIN group required dialysis. Most of these patients with AA amyloidosis had completely normal renal function before the episode of acute kidney injury and had clear exposures to drugs associated with aTIN.

CONCLUSION

In contrary to the patients without AA amyloidosis, patients with AA amyloidosis have extremely high risk of permanent renal failure in case of development of aTIN. Great caution should be exercised in prescribing drugs that are associated with aTIN, in patients with AA amyloidosis.

Tubulointerstitial nephritis and uveitis syndrome following meningitis and systemic lymphadenopathy with persistent Toxoplasma immunoglobulin M: a case report

Background

Tubulointerstitial nephritis and uveitis syndrome is a rare lymphocyte-related oculorenal inflammatory disease presumed to be associated with drug use and infectious agents. Toxoplasma gondii is one of such pathogens that could exhibit encephalitis, meningitis, and uveitis in immunocompromised or in some immunocompetent individuals. If the immunoglobulin M of Toxoplasma is positive on screening, the interpretation of the result is not simple, especially when immunoglobulin M stays positive persistently.

Case presentation

A 34-year-old Asian male developed fever, headache, and lymphadenopathy with tenderness, which was initially diagnosed as meningitis. Antibiotics were started, and diclofenac sodium was used for the fever. Although his symptoms were alleviated in a week by the treatment, gradual decline in renal function was noted, prompting a renal biopsy that indicated acute granulomatous interstitial nephritis. A week later, tenderness in both eyes with blurred vision appeared and revealed iritis and keratic precipitations in both eyes; hence, the diagnosis of acute tubulointerstitial nephritis and bilateral uveitis syndrome was made. Toxoplasma gondii-specific immunoglobulin G and immunoglobulin M titers were both positive. Although we could not rule out recent infection of Toxoplasma gondii, which may cause uveitis initially, Toxoplasma immunoglobulin G avidity test indicated a distant infection, which allowed us to rule out meningitis and uveitis as responsible for the complication of recent Toxoplasma gondii infection. Drug-induced lymphocyte stimulation test, or lymphocyte transformation test of diclofenac sodium, was solely positive among the tested drugs. Uveitis was alleviated only with ophthalmic steroid, and renal function returned to normal without administration of systemic steroid.

Conclusions

We experienced a case of diclofenac-induced tubulointerstitial nephritis and uveitis syndrome. In ruling out infections, Toxoplasma immunoglobulin M was persistently positive, and Toxoplasma immunoglobulin G avidity test indicated a “distant” infection. From these two results, we ruled out recent infection. However, it should be noted that “distant” infection indicated by commercial immunoglobulin G avidity is still a multiplex profile consisting of reinfection, reactivation, and latent infection. Narrowing down the infection profile of Toxoplasma is challenging in some cases. Therefore, careful diagnosis and extended follow-up of such patients are needed.

Tubulointerstitial nephritis and uveitis syndrome in an adolescent female: a case report

BACKGROUND

Tubulointerstitial nephritis with uveitis syndrome is a rare disease affecting mainly children and young women. Tubulointerstitial nephritis with uveitis is a diagnosis of exclusion, requiring a high degree of clinical suspicion. Studies report recent infections or certain drugs as precipitating factors of a lymphocytic oculorenal immune response. The prognosis is usually favorable with topical and systemic corticosteroid therapy.

CASE PRESENTATION

We report a literature review and the case of a 14-year-old white girl, who presented to the ophthalmology department with features of one-sided uveitis. Upon transfer of patient to nephrological care, diagnostic work-up revealed renal involvement. Renal biopsy showed a mixed-cell and granulomatous tubulointerstitial nephritis with some noncaseating granulomas, leading to a diagnosis of tubulointerstitial nephritis with uveitis syndrome. With topical ocular and systemic corticosteroid therapy, the patients' condition improved over several weeks.

CONCLUSIONS

Our case highlights the importance of early recognition and treatment of this syndrome, where cross-specialty care typically leads to a favorable outcome.

Acute interstitial nephritis associated with ingesting a Momordica charantia extract: A case report

RATIONALE

Momordica charantia is often used to treat type 2 diabetes mellitus in Korea. Drug-induced acute interstitial nephritis (AIN) accounts for 60% to 70% of AIN cases. However, only 1 case of AIN associated with ingesting M charantia has been reported in the English literature. We report an extremely rare case of AIN that occurred after a patient ingested a pure M charantia extract over 7 months.

PATIENT CONCERNS

A 60-year-old Korean woman was admitted to our hospital for a renal biopsy. Her renal function had decreased gradually over the last 9 months without symptoms or signs.

DIAGNOSIS

Her blood urea nitrogen and serum creatinine levels were 29.7 mg/dL (range: 8.0-20.0 mg/dL) and 1.45 mg/dL (range: 0.51-0.95 mg/dL) on admission. Renal histology indicated AIN; there was immune cell infiltration into the interstitium, tubulitis, and epithelial casts, although the glomeruli were largely intact.

INTERVENTIONS

M charantia was discontinued and prednisolone was prescribed.

OUTCOMES

The value of serum creatinine has almost been restored to the baseline level after 3 months.

CONCLUSION

s: This is the first case report of AIN associated with the ingestion of a pure M charantia extract. Recognition of the possible adverse effects of these agents by physicians is very important for early diagnosis and appropriate management.

Prognosis of severe drug-induced acute interstitial nephritis requiring renal replacement therapy

Objective

Drug-induced acute interstitial nephritis (DAIN) is often associated with improved outcomes, whereas some patients may still progress to chronic kidney disease (CKD). The aim of this study was to evaluate the prognosis of patients with severe DAIN requiring renal replacement therapy (RRT) at baseline, and to explore the risk factors of progression to CKD.

Methods

We performed a retrospective study of patients with severe DAIN confirmed by renal biopsies in our center over a 10 years period, all the patients received RRT at presentation. The clinical and pathological characteristics at baseline were recorded, and the outcomes (renal function recovered or progressed to CKD) during follow-ups were also evaluated. Univariate and multivariate logistic regression analysis were performed to identify the independent risk factors of progression to CKD.

Results

Seventy-two patients who met the inclusion criteria were enrolled, 13 patients (18.0%) progressed to CKD (GFR < 60 ml/min/1.73 m²) after at least 6 months of follow-up, the remaining 59 patients achieved a favorable renal function recovery. Compared with patients who achieved renal function recovery (recovery group), the patients progressed to CKD (progression group) were older and had longer interval from symptom onset to treatment with steroids. The peak serum cystatin C concentration was higher in progression group than recovery group. Higher score of interstitial fibrosis/tubular atrophy (IFTA) and more interstitial inflammatory cells infiltration were detected in renal tissue in progression group. According to multivariable analysis, higher peak cystatin C concentration (OR = 2.443, 95% CI 1.257, 4.746, p = 0.008), longer interval to treatment with corticosteroids (OR = 1.183, 95% CI 1.035, 1.352, p = 0.014) were independent risk factors of progression to CKD. The cutoff value of cystatin C concentration was 4.34 mg/L, at which the sensitivity and specificity were 76.9% and 89.3%, respectively; the cutoff value of interval to treatment with corticosteroids was 22.5 days, at which the sensitivity and specificity were 81.8% and 79.5%, respectively.

Conclusion

Renal function was reversible in majority of patients with severe DAIN requiring RRT when early identification and treatment. Higher peak cystatin C concentration and longer interval to treatment with corticosteroids associated with worse renal prognosis.

Cocaine-Induced Acute Interstitial Nephritis: A Comparative Review of 7 Cases

Acute interstitial nephritis is a well-known cause of acute kidney injury, but its association with cocaine use is extremely rare. In this article, we chronicle the case of a patient who developed acute interstitial nephritis secondary to cocaine insufflation. Furthermore, we conducted a systematic literature search of MEDLINE, Cochrane, Embase, and Scopus databases regarding cocaine-induced acute interstitial nephritis. A comprehensive review of the search results yielded a total of 7 case reports only. The data on patient characteristics, clinical features, biochemical profiles, treatment, and outcomes were collected and analyzed. This paper illustrates that acute interstitial nephritis may be added to the list of differentials in patients with acute kidney injury and a history of cocaine use. The therapeutic approach for cocaine-related kidney disease may be different than other etiologies responsible for acute renal insult. Prompt recognition of this entity is crucial because such patients may ultimately develop severe deterioration in renal function.

Clinical characteristics of childhood acute tubulointerstitial nephritis

BACKGROUND

Acute tubulointerstitial nephritis (ATIN) is a rare cause of acute kidney injury in children that can lead to chronic kidney disease. The aim of this study was to describe the presenting features, etiology, and clinical characteristics of childhood ATIN, and to evaluate treatment modalities and renal outcomes.

METHODS

The study included 38 patients who had been diagnosed with ATIN, were younger than 18 years old, and were admitted for at least 6 months of follow up.

RESULTS

The median age at diagnosis was 13.1 years (range 1.2-16.6 years). The female / male ratio was 1.37. The most common symptoms were abdominal pain (65.7%) and nausea / vomiting (55.2%). Twenty-three of the patients had a history of drug intake (60.5%), and the most active drugs in the etiology were non-steroidal anti-inflammatory drugs (56.5%). Eleven patients were given steroid therapy due to severe kidney involvement and rapid increases in serum creatinine values, and ten of those patients were drug-related ATIN cases. Other patients were given symptomatic treatment. Four patients needed several sessions of dialysis due to the severity of their acute renal failure. The follow-up creatinine and estimated glomerular filtration rate levels were not statistically different between the symptomatic and corticosteroid treated groups (P > 0.05).

CONCLUSIONS

Although our study was unable to show the beneficial effect of corticosteroid therapy on the extent of renal recovery, the use of steroids may be preferable in severe nephritis because of the rapid recovery of estimated glomerular filtration rate with corticosteroid therapy.

A Systematic Review of Renal Pathology in Chronic Kidney Disease of Uncertain Etiology

INTRODUCTION

Despite much research on chronic kidney disease of uncertain etiology (CKDu) in Sri Lanka and the Mesoamerican nephropathy, the etiology and pathogenesis of this disease remains elusive. The pathology has broadly been described as chronic tubulointerstitial nephritis and no specific signature lesions have been identified.

METHODS

A scoping review was conducted through MEDLINE and Google Scholar databases for peer-reviewed publications on biopsy studies related to CKDu - Sri Lanka and Mesoamerican nephropathy to develop a comparative and critical analysis of the renal pathology found in these patients.

RESULTS

Thirteen studies met the selection criteria. Interstitial fibrosis was the predominant lesion in all the studies. Tubulointerstitial and glomerular abnormalities showed a more variable distribution. No characteristic histopathological feature was reported other than a proximal tubular lysosomal inclusion body which was claimed to indicate a toxic etiology. Three main pathogenetic mechanisms were postulated: repeated acute insults leading to scarring, low-grade chronic insults leading to non-inflammatory fibrosis, and tubulointerstitial damage in combination with glomerular injury. The main limitations in the interpretation and comparative analysis of these studies were the heterogeneity in case selection and biopsy reporting.

CONCLUSIONS

Although no characteristic histopathological feature could be found in CKDu-Sri Lanka or Mesoamerican nephropathy, there are noticeable differences between these two groups in the frequency and severity of the glomerular and tubulointerstitial changes which warrant more explorative studies preferably on kidneys in early stages of the disease. Future strategies should ensure that more uniform selection criteria and reporting methods are used.

Aetiology, course and treatment of acute tubulointerstitial nephritis in paediatric patients: a cross-sectional web-based survey

BACKGROUND

Acute tubulointerstitial nephritis (TIN) is a significant cause of acute renal failure in paediatric and adult patients. There are no large paediatric series focusing on the aetiology, treatment and courses of acute TIN.

PATIENTS, DESIGN AND SETTING

We collected retrospective clinical data from paediatric patients with acute biopsy-proven TIN by means of an online survey. Members of four professional societies were invited to participate.

RESULTS

Thirty-nine physicians from 18 countries responded. 171 patients with acute TIN were included (54% female, median age 12 years). The most frequent causes were tubulointerstitial nephritis and uveitis syndrome in 31% and drug-induced TIN in 30% (the majority of these caused by non-steroidal anti-inflammatory drugs). In 28% of patients, no initiating noxae were identified (idiopathic TIN). Median estimated glomerular filtration rate (eGFR) rose significantly from 31 at time of renal biopsy to 86 mL/min/1.73 m² 3-6 months later (p<0.001). After 3-6 months, eGFR normalised in 41% of patients (eGFR ≥90 mL/min/1.73 m²), with only 3% having severe or end-stage impairment of renal function (<30 mL/min/1.73 m²). 80% of patients received corticosteroid therapy. Median eGFR after 3-6 months did not differ between steroid-treated and steroid-untreated patients. Other immunosuppressants were used in 18% (n=31) of patients, 21 of whom received mycophenolate mofetil.

CONCLUSIONS

Despite different aetiologies, acute paediatric TIN had a favourable outcome overall with 88% of patients showing no or mild impairment of eGFR after 3-6 months. Prospective randomised controlled trials are needed to evaluate the efficacy of glucocorticoid treatment in paediatric patients with acute TIN.

Clinical pearls in hospital nephrology

Hospitalized patients who have established kidney disease and those who have acute kidney injury in the hospital, along with patients with electrolyte disturbances tend to be some of the most complex to care for. Through working closely in nephrology consultation in the hospital with patients and providers, in both private and academic settings, we have come to encounter certain common presentations and recurrent themes that are worthy of emphasis, and of which a good understanding can translate into improved patient care. For the provider who works closely with such patients, many of these aspects are important to recognize and understand. In this review, we present 10 questions that address some of the highly relevant aspects of nephrology for the provider in the hospital. Through a MEDLINE database search, we reviewed the most pertinent studies as we then go through the explanation of management decisions in an evidence-based methodology with an up-to-date approach based on the current literature on the subject.

Tolerability of Cefazolin in Nafcillin-Intolerant Patients for the Treatment of Methicillin-Susceptible Staphylococcus aureus Infections

BACKGROUND

Non-IgE-mediated hypersensitivity reactions (HSRs) to nafcillin are commonly reported, but scarce data are available to guide appropriate antibiotic change following these reactions. While cefazolin is an attractive therapeutic alternative in methicillin-susceptible Staphylococcus aureus (MSSA) infections when patients experience an HSR to nafcillin, more data are needed to evaluate the tolerability of cefazolin after switching from nafcillin. The purpose of this study was to describe the tolerability of cefazolin in patients who develop a suspected non-IgE-mediated HSR to nafcillin.

METHODS

This was a retrospective, descriptive case series of patients who received nafcillin for an MSSA infection, experienced a suspected non-IgE-mediated HSR, and were switched to cefazolin between October 2015 and November 2019 at a single academic medical center. The primary objective was to identify the percentage of patients who completed cefazolin after experiencing a suspected non-IgE-mediated HSR to nafcillin.

RESULTS

There were 80 patients with 87 pre-specified non-IgE-mediated HSRs during the study period. Seventy-one (89%) patients completed cefazolin, with 53 (75%) of these patients completing at least 2 weeks of therapy. One patient was ultimately switched from cefazolin to daptomycin due to concern for treatment failure. Eight patients (10%) did not tolerate cefazolin after switching from nafcillin. Of these, 3 patients experienced an unrelated HSR, while 5 patients experienced the same non-IgE-mediated HSR that was attributed to nafcillin and discontinued cefazolin within 7 days. The most common HSR cited was immune-mediated nephritis; however, the majority were clinically presumed but did not meet objective diagnostic criteria.

CONCLUSIONS

Treatment with cefazolin after experiencing a suspected non-IgE-mediated HSR to nafcillin appears to be safe, even for patients requiring a prolonged duration of cefazolin.

Acute interstitial nephritis associated with ingestion of Achyranthes japonica extract: a case report

BACKGROUND

The Japanese chaff flower, Achyranthes japonica, is used as complementary medicine to control degenerative arthritis. Although commonly used in South Korea, there has been no report of side effects. We report the first case of acute interstitial nephritis (AIN) that occurred in a woman who ingested A. japonica extract for 4 months.

CASE PRESENTATION

A 56-year-old Korean woman was admitted for deterioration of renal function. She had general weakness and nausea for 1 month. Her initial blood urea nitrogen and serum creatinine levels were 26.3 mg/dL and 3.2 mg/dL, respectively. She acknowledged ingesting A. japonica extract for the past 4 months. Renal histology demonstrated AIN represented by immune cell infiltration into the interstitium, tubulitis, and tubular atrophy, but the glomeruli were intact. A. japonica was discontinued immediately and conservative management was started. Renal function was nearly restored to the baseline level without medication after 13 months.

CONCLUSION

This is a rare case report of AIN associated with a pure A. japonica extract. In the case of unknown etiology of AIN, physicians should ask about the use of herbal medicines, nutraceuticals, and traditional folk medicines including A. japonica.

Frequency and etiology of tubulo-interstitial nephritis in an adult renal biopsies in a tertiary renal care hospital: A single-center study

Tubulo-interstitial nephritis (TIN) is an important cause of acute renal failure which may progresses to chronic kidney disease (CKD). TIN is often under diagnosed with there are no specific signs and symptoms. As this entity has paramount importance, so we evaluated the frequency and etiological of TIN both acute TIN (ATIN) and chronic tububulo-interstitial nephritis (CTIN) in renal biopsies. This is a retrospective observational, descriptive study carried out in the Department of Nephrology at The Kidney Centre Post Graduate Training Institute from 2004 to 2016. A total of 1560 adult renal biopsies were done during this period with 125 biopsies of TIN, of which 70 (56%) cases were ATIN and 55 (44%), were CTIN. Thirty-eight (30%) patients had a history of taking proton-pump inhibitors, use of various antibiotics in 21 (16%) cases, and 11 (8%) patients had a history of taking Hakeemi (traditional healer using herbs and sometimes trace amounts of heavy metals) medications. The incidence of TIN is higher than suspected and can be caused by variety of etiological agents. Therefore, clinical awareness will help in the diagnosis and early identification of the disease.

Combined protective effects of icariin and selenomethionine on novel chronic tubulointerstitial nephropathy models in vivo and in vitro

Chronic tubulointerstitial nephropathy (CTIN) is one of the most common kidney diseases. However, treatment for CTIN has multiple limits. Adjuvant therapy through nutritional regulation has become a hot research topic at present. Icariin (ICA), an extraction of Chinese herbal medicine epimedium, has many pharmacological functions including anti-inflammation and tonifying kidney. Selenomethionine (SeMet) possesses the effects of antioxidant and lightening nephrotoxicity. However, little is known about the combined nephroprotection of them. This study was investigated to evaluate the joint effects of ICA and SeMet on CTIN and explore the mechanism. Based on a novel CTIN model developed in our previous study, mice were randomly divided into five groups (a: control; b: model; c: model + ICA; d: model + SeMet; e: model + ICA + SeMet). Renal tubule epithelial cells were treated with cyclosporine A and ochratoxin A without/with ICA or/and SeMet. The results showed that ICA or/and SeMet ameliorated CTIN by inhibiting the uptrends of blood urine nitrogen, serum creatinine, urine protein, urine gravity, histopathological damage degree and collagen I deposition. ICA or/and SeMet also increased cell proliferation and decreased apoptosis and the expression of transforming growth factor-beta 1 and α-smooth muscle actin. Emphatically, ICA and SeMet joint had better nephroprotection than alone in most indexes including fibrosis. Furthermore, ICA and SeMet joint decreased the activation of toll-like receptor 4 (TLR4)/NFκB pathway induced by CTIN. TLR4 overexpression counteracted the joint protection of ICA and SeMet. Therefore, ICA and SeMet in combination could protect against CTIN through blocking TLR4/NFκB pathway. The study will provide novel insights to explore an adjuvant therapeutic orientation.

The clinicopathological features of drug-induced acute kidney injury-a single-center retrospective analysis

Background

This study aimed to analyze changes to the drug spectrum and clinicopathological features of drug-induced acute kidney injury (AKI) with recent medication habits changes.

Methods

A retrospective analysis of the characteristics of patients diagnosed with drug-induced AKI from January 2012 to October 2016 period at the First Affiliated Hospital of the Medical College of Zhejiang University was conducted.

Results

Between January 2012 and October 2016, 909 patients were diagnosed with AKI. Of these, 228 were diagnosed with drug-related AKI were engaged in this study, including 51 who underwent renal biopsies, 74 treated with antibacterial and antiviral drugs, and 63 who received nonsteroidal anti-inflammatory drugs (NSAIDs), and 17 who were treated with Chinese herbal medicine. AKI was most frequently associated with antibiotics and antiviral drugs, including cephalosporins, acyclovir, azithromycin, clindamycin, and levofloxacin. In those who underwent renal biopsy, 12 patients were diagnosed with allergic interstitial nephritis, 19 with interstitial nephritis, 8 with renal tubular epithelial cell injury, 2 with minimal change nephropathy, 2 with IgA nephropathy, and 2 with mild mesangial hyperplasia with glomerulosclerosis. The mean follow-up time was 437 days, ranging from 3 to 2,756 days. Among 228 patients, 165 recovered completely, 4 recovered partially, 8 did not recover, and 51 were lost to follow-up after discharge.

Conclusions

The three main contributors to drug-induced AKI were antimicrobial agents, NSAIDs, and Chinese herbal medicines. The age distribution of the three different drug-induced AKI groups was significantly different. Allergic interstitial nephritis, interstitial nephritis, and tubular epithelial cell injury were the main pathological manifestations of drug-induced AKI. The novel predictive nomogram achieved a good performance of prediction recovery within 2 weeks in drug-induced AKI patients.

Infliximab for the treatment of patients with checkpoint inhibitor-associated acute tubular interstitial nephritis

Acute tubular interstitial nephritis (ATIN) is the most frequently reported pathology in patients with checkpoint inhibitor (CPI) induced acute kidney injury (AKI). Glucocorticoid (GC) therapy and discontinuation of CPI are the mainstay of treatment to prevent permanent renal dysfunction and dialysis. However, less than 50% of patients have complete kidney recovery and relapse of ATIN can occur. Infliximab is effective in treating other immune-related adverse events but its use for the treatment of CPI-ATIN is not well established. We report the first retrospective study examining the steroid-sparing potential of infliximab in achieving durable and complete renal recovery for patients with CPI-ATIN. Data were collected from medical records of patients diagnosed with CPI-AKI with a kidney biopsy or clinical diagnosis of ATIN that was managed with GC and infliximab. Infliximab-containing regimens were used to treat 10 patients with CPI-ATIN. Four patients relapsing after GC therapy achieved durable and complete renal recovery, four patients experienced partial renal recovery, and two patients showed no improvement in kidney function. This is the first study evaluating clinical outcomes using an infliximab-containing regimen for treatment of relapsed CPI-ATIN in patients or patients failing to achieve complete response after primary therapy. Our data suggest that infliximab may be a treatment option for achieving durable and complete renal recovery in this patient population and represents a potential steroid-sparing strategy in challenging cases of CPI-ATIN. Rigorous clinical studies are warranted to evaluate the risk-benefit analysis for infliximab usage in CPI-ATIN patients.

Drug-Induced Acute Kidney Injury: A Study from the French Medical Administrative and the French National Pharmacovigilance Databases Using Capture-Recapture Method

BACKGROUND

Acute kidney injury (AKI) is a public health concern. Among the pathological situations leading to AKI, drugs are preventable factors but are still under-notified. We aimed to provide an overview of drug-induced AKI (DIAKI) using pharmacovigilance and medical administrative databases Methods: A query of the PMSI database (French Medical Information System Program) of adult inpatient hospital stays between 1 January 2017 and 31 December 2018 was performed using ICD-10 (International Classification of Diseases 10th revision) codes to identify AKI cases which were reviewed by a nephrologist and a pharmacovigilance expert to identify DIAKI cases. In parallel, DIAKIs notified in the French Pharmacovigilance Database (FPVDB) were collected. A capture-recapture method was performed to estimate the total number of DIAKIs.

RESULTS

The estimated total number of DIAKIs was 521 (95%CI 480; 563), representing 20.0% of all AKIs. The notification was at a rate of 12.9% (95%CI 10.0; 15.8). According to the KDIGO classification, 50.2% of the DIAKI cases were stage 1 and 49.8% stage 2 and 3. The mortality rate was 11.1% and 9.6% required hemodialysis.

CONCLUSION

This study showed that drugs are involved in a significant proportion of patients developing AKI during a hospital stay and emphasizes the severity of DIAKI cases.

Glycosuria and Acute Kidney Injury: A Rare Presentation of Acute Interstitial Nephritis

Acute interstitial nephritis (AIN) is often induced by drugs and is a common cause of acute kidney injury. Clinically diagnosing AIN can often be challenging because these signs and symptoms rarely present in concert. The inflammatory pathology of AIN leads to renal tubule dysregulation, which can be clinically observed as glycosuria, eosinophilia, leukocytes or white blood cell casts, and proteinuria. We present a case of an otherwise healthy woman in her 30s with AIN presenting with acute kidney injury and glycosuria without pyuria. This patient had an atypical presentation of AIN that lacked classic diagnostic laboratory features and has been rarely reported. She had profound glycosuria in the setting of normoglycemia, which resolved following a course of corticosteroids. Glycosuria was most likely due to proximal tubule damage from AIN. This case supports previous hypotheses that drug-induced AIN can cause proximal tubule dysfunction resulting in glycosuria in the absence of other identifiable proximal tubule dysregulations. We hypothesize that resolution of AIN involves the repair and restoration of sodium-dependent glucose cotransporter function.

Epidemiology and Risk Factors for Severe Delayed Drug Hypersensitivity Reactions

Severe delayed drug hypersensitivity reactions comprise different clinical entities and can involve different immune-mediated mechanisms. Common examples are severe cutaneous adverse reactions and druginduced internal organ injuries. The incidence of such reactions is overall low but seems to be on the rise reaching numbers as high as 9 per million individuals-years in the case of SJS/TEN and DRESS. Such conditions carry an important associated morbidity, and mortality can attain 40% in SJS/TEN patients, making these hypersensitivity reactions important targets when implementing preventive measures. Several risk factors have been identified for reaction severity; some are transverse, such as older age and underlying chronic diseases. The recent advances in pharmacogenetics allowed the identification of specific populations with higher risk and permitted strategic avoidance of certain drugs being HLA-B*57:01 screening in patients initiating abacavir the best successful example. In this work, we reviewed the epidemiology of SCARs and liver/kidney/lung drug-induced immune-mediated reactions. We focus on particular aspects such as prevalence and incidence, drugs involved, mortality and risk factors.

Drug-induced tubulointerstitial nephritis: hypersensitivity and necroinflammatory pathways

More than 250 drugs carry a small but important dose-independent risk of initiating a delayed-type hypersensitivity reaction that leads to acute tubulointerstitial nephritis (TIN). Clinical manifestations are often non-specific, making epidemiological studies challenging. In severe cases, if cessation of the offending drug is not followed by a prompt improvement in renal function, corticosteroid therapy appears to enhance renal recovery rates. Other drugs, classified as potential nephrotoxins, may induce dose-dependent acute tubular necrosis. Studies over the past decade have identified a unique form of tubular cell death called "necroptosis" that is accompanied by a specific and significant interstitial inflammatory response to certain insults, including some nephrotoxins. Insights into the molecular basis of this necroinflammatory pathway have emerged. There is still a paucity of pediatric data on these two distinct types of drug-induced TIN. Early recognition is essential to minimize the risk of chronic kidney damage.

Nefritis tubulointersticial aguda. Revisión bibliográfica

La nefritis tubulointersticial aguda hace referencia a un tipo de daño renal que afecta principalmente el intersticio y ocasiona la lesión renal aguda, potencialmente reversible. Su curso puede ser subclínico, con deterioro progresivo hasta evolucionar hacia la insuficiencia renal crónica. La nefritis tubulointersticial aguda tiene múltiples etiologías, las más frecuentes son los medicamentos, productos herbales, las infecciones y las enfermedades autoinmunes. Las principales manifestaciones clínicas son la poliuria, polaquiuria, nocturia, dolor lumbar, microhematuria y leucocituria, aunque puede ser totalmente asintomática. El tratamiento depende de la causa de base y los esteroides juegan un papel importante cuando la condición es de origen medicamentoso o autoinmune. El pronóstico generalmente es bueno, si el problema se identifica de forma oportuna y se trata adecuadamente.

Mechanisms of antimicrobial-induced nephrotoxicity in children

Drug-induced nephrotoxicity is responsible for 20% to 60% of cases of acute kidney injury in hospitalized patients and is associated with increased morbidity and mortality in both children and adults. Antimicrobials are one of the most common classes of medications prescribed globally and also among the most common causes of nephrotoxicity. A broad range of antimicrobial agents have been associated with nephrotoxicity, but the features of kidney injury vary based on the agent, its mechanism of injury and the site of toxicity within the kidney. Distinguishing nephrotoxicity caused by an antimicrobial agent from other potential inciting factors is important to facilitate both early recognition of drug toxicity and prompt cessation of an offending drug, as well as to avoid unnecessary discontinuation of an innocuous therapy. This review will detail the different types of antimicrobial-induced nephrotoxicity: acute tubular necrosis, acute interstitial nephritis and obstructive nephropathy. It will also describe the mechanism of injury caused by specific antimicrobial agents and classes (vancomycin, aminoglycosides, polymyxins, antivirals, amphotericin B), highlight the toxicodynamics of these drugs and provide guidance on administration or monitoring practices that can mitigate toxicity, when known. Particular attention will be paid to paediatric patients, when applicable, in whom nephrotoxin exposure is an often-underappreciated cause of kidney injury.

Carboplatin-related acute interstitial nephritis in a patient with pancreatic neuroendocrine tumor

Carboplatin is characterized by low nephrotoxicity, including acute tubular necrosis (ATN), compared to a conventional platinum complex due to its low accumulative property in the renal tubules. Therefore, there are extremely few reports of carboplatin-induced kidney injury and only one case has been histologically examined. Herein, we describe the case of a 53-year-old man who presented with acute kidney injury (AKI) that occurred after carboplatin administration and was diagnosed with biopsy-proven acute interstitial nephritis (AIN). To our knowledge, this is the second case report of carboplatin-related AIN. The patient was diagnosed with a pancreatic neuroendocrine tumor, and chemotherapy consisting of cisplatin and irinotecan was initiated. However, 1 week later, he was admitted to our institution with fever, fatigue and an increase in C-reactive protein (CRP) level. The chemotherapy regimen was altered to carboplatin and etoposide, but high fever occurred on the first day, and CRP re-elevation and AKI became apparent 9 days later. Renal biopsy revealed prominent inflammatory cell infiltration into the interstitium, which lead to the pathological diagnosis of AIN. On immunostaining for surface markers, CD3- and CD68-positive cells were found to be predominant, and CD20-positive cells were relatively few. Although the serum creatinine level increased to 6.81 mg/dL, it decreased to 1.43 mg/dL 15 days after steroid therapy. This case demonstrated that carboplatin-related kidney injury includes not only ATN but also AIN. Appropriate pathological diagnosis including renal biopsy and indications for steroid treatment should be carefully considered.

Tubulointerstitial nephritis and uveitis (TINU) syndrome: a review

Inflammation of renal interstitium and uveal tissue establishes the two components of tubulointerstitial nephritis and uveitis (TINU) syndrome. Although believed to occur more frequently in young females, a broad spectrum of patients can be affected. Both renal and eye disease can be asymptomatic and may not manifest simultaneously, having independent progressions. Renal disease manifests as acute kidney injury and may cause permanent renal impairment. Eye inflammation can manifest in different anatomical forms, most commonly as bilateral anterior uveitis and may progress to a chronic course. TINU syndrome accounts for approximately 1%–2% of uveitis in tertiary referral centres. A literature review covering the clinical features, pathogenesis, diagnosis and treatment is presented.