Clinical outcome and occurrence of uveitis in children with idiopathic tubulointerstitial nephritis

An updated approach to the evaluation of the urinary sediment

Examination of the urinary sediment (U-sed) is an important non-invasive, rapid, and inexpensive tool for the diagnosis and surveillance over time of renal diseases. In this Educational Review, we describe first how to collect, prepare, and examine urine samples in order to obtain reliable results. Then, we describe the U-sed findings in isolated microscopic hematuria, glomerular diseases, acute interstitial nephritis, acute kidney injury, reactivation of the BK virus in kidney transplant recipients, and crystalluric genetic diseases.

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in this compartment (tubulointerstitial nephritis-TIN) can be acute and resolves if the offending factor is withdrawn or may enter a chronic process leading to irreversible kidney damage.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 in Pediatric Patients

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a disorder that was originally described in 1975. The syndrome, although diagnosed in all age ranges, is more frequently reported in pediatric patients. Diagnosis can be difficult, and its clinical spectrum is still being defined. In this article, we review the epidemiology, diagnosis, pathogenesis, clinical findings, prognosis, and treatment of both the ocular and renal disease. We comment on the current difficulties in diagnosis and study of the disease, its expanding clinical spectrum, and treatment strategies in pediatric patients.

Renal outcomes in tubulointerstitial nephritis and uveitis (TINU) syndrome: a systematic review and meta-analysis

BACKGROUND

Tubulointerstitial nephritis and uveitis syndrome (TINU) is a rare condition characterised by bilateral uveitis and interstitial nephritis. There is no nationally, or internationally agreed upon treatment regimen. A systematic review was undertaken to report the renal outcomes in TINU, and treatments used.

METHODS

Medline (1969-2021) and EMBASE (1988-2021) databases were searched for primary studies, clinical practice guidelines and case reports of adult and paediatric TINU cases, as defined by Mandeville criteria. Two reviewers identified articles meeting inclusion criteria (registered with PROSPERO). Data were extracted into a synthesis table and meta-analysis performed. Quality of case series was also assessed.

RESULTS

One hundred twenty-two articles were identified, totalling 257 cases included in the meta-analysis. Females were more commonly affected than males (2:1), and median age was 19 years. GFR at follow-up correlated with nadir GFR, and the proportion with GFR <90 ml/min/1.73 m² was statistically different between adult and paediatric groups. Of the entire cohort, 40% had GFR <90 ml/min/1.73 m² at follow-up. Glucocorticoid monotherapy was the most common treatment (70%); other strategies included no treatment (9%) and immunosuppressant drugs (e.g. azathioprine), mostly in steroid-resistant cases, or as 'steroid-sparing' alternatives.

CONCLUSIONS

The majority of literature regarding TINU is limited to case reports and case series. There are no prospective trials assessing the effects of different treatments on renal outcomes, and currently employed treatment strategies are physician-specific without a reliable evidence-base. Prospective data collection as part of multicentre trials should be a research focus to improve the evidence-base.

Tubulointerstitial nephritis and uveitis syndrome: a systematic review

BACKGROUND

Tubulointerstitial nephritis and uveitis (TINU) syndrome is defined as the occurrence of tubulointerstitial nephritis (TIN) and uveitis in the absence of other systemic diseases. The most comprehensive review on this condition was published in 2001.

METHODS

We conducted a systematic review of the literature for cases of TINU syndrome. MEDLINE and Embase databases were screened. Full-length articles or letters reporting cases with both TIN and uveitis were selected. We investigated differences between males and females and paediatric and adult cases. Multivariate analysis was performed to identify potential risk factors for chronic kidney disease (CKD) development.

RESULTS

A total of 233 articles reporting 592 TINU cases were retained for the analysis. The median age of the included subjects was 17 years (interquartile range 13-46) with a female predominance (65%). Uveitis most frequently (52%) followed renal disease and was mostly anterior (65%) and bilateral (88%). Children tended to have more ocular relapses, while they were slightly less likely than adults to suffer from acute kidney injury and to develop CKD. Adult age as well as posterior or panuveitis were associated with an increased risk of developing CKD.

CONCLUSIONS

TINU affects both children and adults, with some differences between these two categories. Adult age and the presence of a posterior uveitis or panuveitis appear to be associated with the development of CKD.

Renal Prognosis in Children With Tubulointerstitial Nephritis and Uveitis Syndrome

Introduction

Tubulointerstitial nephritis (TIN) and uveitis (TINU) syndrome is a rare disease. The renal prognosis is generally thought to be better in children with TINU syndrome than in adults. However, data are scarce. We aimed to investigate the long-term renal prognosis in a French cohort of children with TINU syndrome.

Methods

We performed a national retrospective study including 23 French pediatric nephrology centers enrolling patients with TINU syndrome diagnosed between January 2000 and December 2018.

Results

A total of 46 patients were included (52% female, median age 13.8 years). At diagnosis of TIN, the median estimated glomerular filtration rate (eGFR) was 30.6 ml/min per 1.73 m² (4.9–62.8). The median time between diagnosis of uveitis and TIN was 0.4 months (−4.1; +17.1). All patients had anterior uveitis, but 12 (29%) were asymptomatic. Nearly all patients (44 of 46) received steroid treatment, and 12 patients (26%) received a second-line therapy. At last follow-up (median 2.8 years), the median eGFR was 87.5 ml/min per 1.73 m² (60.3–152.7) and <90 ml/min per 1.73 m² in 20 patients.

Conclusion

In our study, nearly half of the patients had renal sequelae at last follow-up. Given the possible progression to chronic kidney disease, long-term monitoring of children with TINU syndrome is mandatory. Approximately a quarter of the children had asymptomatic uveitis suggesting all children presenting with TIN should undergo systematic ophthalmologic screening even in the absence of ocular signs.

Long-term clinical characteristics and renal prognosis of children with tubulointerstitial nephritis and uveitis syndrome

BACKGROUND

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disease, especially in children. Owing to the short-term observational period and the small number of patients analyzed in previous reports, the long-term clinical and laboratory characteristics and renal prognosis of children with TINU syndrome remain unclear.

METHODS

In this retrospective observational study, we enrolled 29 children with TINU syndrome from February 1990 to February 2019.

RESULTS

During the median follow-up duration of 38 months, the kidney function, urinary β2 microglobulin-creatinine ratio (U-β2MG/Cr), and uveitis in the patients had significantly improved at 24, 6, and 36 months after diagnosis. Higher U-β2MG/Cr was associated with longer duration of kidney function normalization. Half of the patients required uveitis treatment for 5 years after the diagnosis.

CONCLUSIONS

Patients with severe low-molecular weight proteinuria at diagnosis needed a longer duration to achieve improvements in kidney function. Uveitis has a much longer treatment period than tubulointerstitial nephritis. This study demonstrates the good prognosis of children with TINU syndrome in terms of their long-term clinical and laboratory characteristics.

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.

Long-term outcome of biopsy-proven idiopathic tubulointersitial nephritis with or without uveitis in children-a nationwide follow-up study

BACKGROUND

Only a few studies reporting the long-term outcome of children with idiopathic tubulointerstitial nephritis (TIN) and uveitis syndrome (TINU) are available. We studied the long-term kidney and ocular outcome in a nationwide cohort of children with TIN or TINU.

METHODS

All patients followed up for a minimum of 1 year by a paediatrician and an ophthalmologist were enrolled. The data on plasma creatinine (P-Cr), estimated glomerular filtration rate (eGFR), proteinuria, hypertension and uveitis were collected retrospectively.

RESULTS

Fifty-two patients were studied. Median age at time of diagnosis was 13.1 (1.8-16.9) years and median follow-up time was 5.7 (1.1-21.2) years. Forty-five (87%) patients were initially treated with glucocorticoids. The median of the maximum P-Cr was 162 μmol/l (47-1,016) and that of eGFR 47 ml/min/1.73m² (8-124). Uveitis was diagnosed in 33 patients (63%) and 21 (40%) patients developed chronic uveitis. P-Cr normalised in a median of 2 months. Eleven (21%) patients had nephritis recurrence during or after discontinuation of glucocorticoids. At the latest follow-up, 13 (25%) patients had eGFR < 90 ml/min/1.73m² (median 83; 61-89 ml/min/1.73m²). Six patients had tubular proteinuria; all presented with TIN without uveitis. Seven (13%) patients were hypertensive. Eleven (21%) patients had uveitis. One patient developed uraemia and was later transplanted.

CONCLUSIONS

Our study questions the previously reported good long-term kidney and ocular outcome of patients with TIN/TINU. Decreased kidney function and/or ocular co-morbidities may persist for several years; thus, both kidney and ocular follow-up for at least 1 year is warranted. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

Acute tubulointerstitial nephritis in children- a retrospective case series in a UK tertiary paediatric centre

BACKGROUND

Acute tubulointerstitial nephritis (AIN) is an uncommon cause of acute kidney injury in children, accounting for less than 10% of cases. There is limited information regarding the range of underlying diagnoses and how these may differ geographically. We undertook a retrospective case note review of consecutive cases of biopsy-proven AIN, presenting to a single UK tertiary paediatric centre, to describe the range of AIN in our caseload, define key characteristics and response to treatment, with the aim of informing paediatric nephrology practice.

METHODS

Cases were identified retrospectively from departmental records. Data extracted included demographics, presenting clinical and biochemical features, renal biopsy histology, treatment and follow-up.

RESULTS

Ten cases were identified over 8 years (2007-2014). Age range 6-16 years. Male:Female ratio 1:9. Final diagnoses included 6 tubulointerstitial nephritis and uveitis syndrome (TINU), 2 idiopathic, 1 sarcoidosis, 1 child with Streptococcal disease. Of the TINU cases, timing of eye symptoms varied in relation to AIN presentation. Cases had a varied investigative work-up. Median presenting plasma creatinine was 303 μmol/l (range 152-932 μmol/l). Renal function improved spontaneously in 1 idiopathic case and improved with antimicrobial treatment in a child with Streptococcal disease. Eight cases received immunosuppressive treatment with intravenous methylprednisolone (approximately 10 mg/kg for 3-5 days) and / or oral prednisolone (1-2 mg/kg initially, reducing over 7-28 days). At 1 month, median creatinine had fallen to 91 μmol/l (range 41-120 μmol/l) with median eGFR 61 ml/min/1.73m2 (range 51-103 ml/min/1.73m2). At last follow-up (median 18.5 months, range 2-70 months), median creatinine was 71 μmol/l (range 47-90 μmol/l) with median eGFR 80 ml/min/1.73m2, range 63 to 101 ml/min/1.73m2). Two patients received antihypertensives at diagnosis and 1 further patient at 1 month follow-up. Eight patients received electrolyte supplementation. Median time to discontinuing electrolyte supplementation was 3.5 months (range 1-12 months).

CONCLUSION

To our knowledge, this is the only contemporary UK case series of biopsy-proven AIN in children. Our population has a high proportion of TINU. Treatment was accompanied by improvement of renal function, however 7/10 patients had an eGFR < 90 ml/min/1.73m2 at last follow-up. We suggest a standardised investigative work-up and recommend long-term follow-up.

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.

Acute tubulointerstitial nephritis in children and chronic kidney disease

BACKGROUND

Acute tubulointerstitial nephritis (ATIN) is a rare condition in children. The etiology, treatment, and outcome of childhood ATIN remain poorly understood. The long-term prognosis seems to be favorable; however, chronic kidney disease has been reported. This article describes clinical outcomes in a series of children with biopsy-proven ATIN.

METHODS

All medical records with biopsy-proven ATIN between January 2006 and 2016 were retrospectively analyzed. The incidence, clinical features, etiology, treatment, and outcome were recorded for each patient.

RESULTS

Over 10 years, ATIN was diagnosed in 25 cases (8%) based on 306 renal needle biopsies. The most frequent clinical signs were abdominal pain, asthenia/weight loss, and fever. A median glomerular filtration rate estimated at 30.1mL/min/1.73 m² (16.5; 45.5). Drug-induced toxicity was the main etiology (eight patients). Other causes were TINU syndrome (tubulointerstitial nephritis and uveitis) (seven patients), infection (two patients), and toxic agents other than medication (one patient). No etiology was found in seven patients (idiopathic cases). Eighteen patients (72%) were treated with steroids. At the end of follow-up, eight patients presented chronic kidney disease, three hypertension, and three tubular dysfunction. Overall, renal function was highest in the idiopathic ATIN group and in children treated without delay.

CONCLUSIONS

In a single-center 10-year series of biopsy-confirmed ATIN in children, drugs and TINU syndrome were the main etiologies of ATIN. This study suggests that children with idiopathic ATIN and prompt treatment have a better prognosis. In this series, occurrence of chronic kidney disease justified long-term follow-up.

IL-10 polymorphisms +434T/C, +504G/T, and -2849C/T may predispose to tubulointersititial nephritis and uveitis in pediatric population

BACKGROUND

Tubulointerstitial nephritis (TIN) and uveitis syndrome (TINU) are likely to be autoimmune diseases. Based on previous studies, adults with isolated idiopathic uveitis have polymorphisms in interleukin 10 (IL-10) and tumor necrosis factor α (TNF-α) genes. We aimed to evaluate the presence of IL-10 and TNF-α polymorphisms in a nationwide cohort of pediatric TIN/TINU patients.

METHODS

Single nucleotide polymorphisms in IL-10 (+434T/C, +504G/T, -1082G/A, -2849C/T) and in TNFα (-308G/A, -238G/A, -857C/T) genes were genotyped in 30 well-defined pediatric patients with idiopathic TIN/TINU syndrome. Control group frequencies for these SNPs were obtained from 393 independent Finnish subjects.

RESULTS

The homozygous minor allele in IL-10 +434T (rs2222202) and IL-10+504G (rs3024490) was found in all patients with TIN or TINU syndrome while the frequency of these minor alleles in the control population was 44% and 23%, respectively (p <0.001). In IL-10 SNP -2849 (rs6703630) a significant difference was found with genotype TT in all patients (p = 0.004) and in subgroups with TINU syndrome (p = 0.017) and TINU syndrome with chronic uveitis (p = 0.01) compared to reference population. There were no statistical differences in any of the studied TNF-α genotypes between TIN/TINU patients and control population.

CONCLUSIONS

A significant difference in the frequency of IL-10+434T and +504G alleles was found between TIN/TINU patients and control population. Genotype -2849TT was more frequently present in patients with TINU syndrome than in the reference subjects. Genetic variation in the inflammatory mediators may predispose to autoimmune nephritis and uveitis.

Tubulointerstitial Nephritis

Tubulointerstitial nephritis (TIN) is a cause of acute kidney injury in children characterized histologically by an inflammatory cell infiltrate in the kidney interstitium. The most common causes of TIN in children include medications, infections, inflammatory disorders, and genetic conditions. TIN typically presents with nonoliguric acute kidney injury and may be associated with systemic symptoms, including fever, rash, and eosinophilia. The long-term prognosis is generally favorable, with full kidney recovery; however, some patients may develop progressive chronic kidney disease. Immunosuppressive therapy may be indicated for severe or prolonged disease.

Etiologic Spectrum and Follow-Up Results of Noninfectious Uveitis in Children: A Single Referral Center Experience

Objectives

This study aims to investigate the etiologic spectrum, demographic features, and long-term follow-up results of children with noninfectious uveitis (NIU).

Patients and methods

Files of patients with NIU were reviewed between May 2010 and September 2017. The cohort consisted of 54 juvenile uveitis patients (26 males, 28 females; mean age 7.7 years; interquartile range [IQR] 9.2 years) with 93 affected eyes. Location of uveitis, laterality, age at onset of uveitis, complications of uveitis, duration of follow-up, associated systemic diseases, pertinent laboratory tests, medications used, and status of uveitis at the time of enrollment were recorded from the files. All patients had final systemic and ocular examination at the last month of enrollment.

Results

Twenty-seven patients (50.0%) had juvenile idiopathic arthritis (JIA), 17 (31.4%) had idiopathic uveitis, six (11.1%) had Behçet disease (BD), and four (7.5%) had tubulointerstitial nephritis and uveitis (TINU) syndrome. Median duration of follow-up for uveitis was 16 (IQR: 15) months. Anterior uveitis was seen in 81.4% of the patients (65.9% had bilateral and 34.1% had unilateral anterior uveitis). Bilateral intermediate uveitis was observed in 11.2% and bilateral panuveitis in 7.4% of the patients. At the time of enrollment, 45 uveitis patients (83.3%) were under remission. Complications of uveitis were observed in 18.5% of the patients.

Conclusion

Patients with JIA and BD should be regularly checked for uveitis. It is challenging to find an etiology in uveitis patients referred from ophthalmologists if initial questioning and examination do not reveal an overt rheumatologic disease. However, a simple urine test may help in establishing the diagnosis of TINU syndrome.

The Invisible Threat of Non-steroidal Anti-inflammatory Drugs for Kidneys

Background: Non-steroidal anti-inflammatory drugs (NSAIDs) are often used as analgesic and antipyretic drugs. Nephrotoxicity is a common side effect and leads in 1-5% of pediatric cases to acute kidney injury (AKI). The nephrotoxic effects of NSAIDs arise mainly from two pathological mechanisms: (1) acute tubulo-interstitial nephritis (ATIN) following immune reaction and (2) prerenal failure because of reduced renal plasma flow. Histological examinations are required to confirm the pathomechanism of AKI after NSAID exposure. The aim of this study was to illustrate the risk of ATIN in children with AKI after NSAID exposure. Results: The medical records of all 100 pediatric patients with biopsy-proven AKI treated between January 2006 and 2016 at La Timone Hospital, Marseille, France, were analyzed retrospectively. Twenty-five of these patients had ATIN, four of which were healthy children who had been treated with NSAIDs. In other words, NSAID side effects accounted for 4% of all cases of biopsy-proven AKI and 16% of all cases of ATIN. None of the patients had hypovolemia when they received NSAIDs. Clinical symptoms were non-specific. All patients had abdominal pain and vomiting but normal urine volume output. Maximum serum creatinine levels ranged from 300 to 512 μmol/l, with estimated minimum creatinine clearances of 12-26 ml/min/1.73 m². None of the patients had significant proteinuria. One child had hyperechogenic enlarged kidneys. Three patients were treated with steroids, one of whom also received intravenous methylprednisolone. Renal function improved gradually in all patients, but the patient who received methylprednisolone developed moderate chronic kidney disease (CKD). Conclusions: Biopsy proven-AKI secondary to NSAID use can be severe and be associated with ATIN. Since NSAID-induced ATIN can lead to CKD, clinicians using NSAIDs should focus on preventing AKI.

Acute tubulointerstitial nephritis and polyclonal hypergammaglobulinaemia: Which is the culprit?

Proton pump inhibitors (PPIs) are among the most frequent implicated drugs in acute tubulointerstitial nephritis (ATIN), nevertheless it is important to report cases with atypical profiles. A 80-year-old female, exposed during 34 months to omeprazole, presented with polyclonal hypergammaglobulinaemia and renal failure. After stopping omeprazole there was a partial improvement in serum creatinine and IgG. Renal biopsy revealed ATIN; immunohistochemistry for IgG4 was negative. Treatment with steroids and mycophenolate sodium improved renal function and normalized immunoglobulins. The lack of data of other entities and the patient’s evolution strongly point omeprazole as the culprit. After 27 months of follow-up, she remains clinical and analytically stable. ATIN caused by PPIs may appear after a long period of exposure and may be accompanied by analytical anomalies that simulate a systemic disease.

The Syndrome of Tubulointerstitial Nephritis With Uveitis (TINU)

The syndrome of tubulointerstitial nephritis and uveitis (TINU) is a multisystemic autoimmune disorder that may occur in response to various environmental triggers, including drugs and microbial pathogens. Evidence exists of HLA antigen-related genetic predisposition to developing TINU. The resulting inflammation affects chiefly the ocular uvea and renal tubules, although other organs may be involved. TINU is uncommon; only about 200 cases are on record since its original description 40 years ago, although it is possible that new ones are no longer being reported. Although its incidence is highest in children and adolescents, all ages may be affected. Renal and ocular inflammation may be clinically severe and persistent, but the prognosis for the majority of patients with TINU is favorable. Owing to its low prevalence, no standard therapeutic protocols have been established, but most reported cases have been treated with corticosteroids or other immunomodulatory agents. TINU has many features in common with sarcoidosis, the main clinical entity from which it must be distinguished. This article begins with an illustrative case vignette, followed by an overview of the syndrome and current theories regarding its pathogenesis.

FOXP3+ T cells are present in kidney biopsy samples in children with tubulointerstitial nephritis and uveitis syndrome

BACKGROUND

Tubulointerstitial nephritis (TIN) is an inflammatory disease of unknown pathogenesis. To evaluate a possible role of regulatory T cells (Tregs) in the pathophysiology of TIN with (TINU) and without uveitis, we investigated the presence and quantity of FOXP3⁺ T regulatory lymphocytes in diagnostic kidney biopsies from pediatric patients.

METHODS

A total of 33 patients (14 TIN and 19 TINU) were enrolled. The quantity of CD4⁺, FOXP3⁺ and double-positive T cells in formalin-fixed kidney biopsies was determined using double label immunohistochemistry with anti-human CD4 and FOXP3 antibodies.

RESULTS

FOXP3 staining was successful in all 33 patients. In patients with chronic uveitis, the density of FOXP3⁺ cells was significantly lower (p = 0.046) than in TIN patients without uveitis or with uveitis lasting <3 months. CD4⁺ staining was successful in 23 patients. The density of all lymphocytes (CD4⁺, CD4⁺FOXP3⁺ and FOXP3⁺ cells) was significantly lower (p = 0.023) in patients with chronic uveitis than in other patients.

CONCLUSIONS

FOXP3⁺ T cells are present in kidney biopsy samples from TIN and TINU patients. In patients with chronic uveitis, the density of FOXP3⁺ T cells is significantly lower than in other patients, suggesting a different pathomechanism for these clinical conditions.

Clinical Profile, Ultra-Wide-Field Fluorescence Angiography Findings, and Long-Term Prognosis of Uveitis in Tubulointerstitial Nephritis and Uveitis Syndrome at One Tertiary Medical Institute in China

Purpose: To analyze the clinical features and long-term prognosis of uveitis in tubulointerstitial nephritis and uveitis (TINU) syndrome in a cohort of Chinese patients. Methods: A total of 32 patients with TINU syndrome between 2000 - 2016 were analyzed retrospectively. Results: Mild anterior inflammation was observed in all cases. Ultra-wide-field fluorescence angiography (UWFA) was conducted on 13 patients, and peripheral vascular leakage was observed in 22/26 eyes (84.62%) compared with active anterior chamber inflammation in 13/26 eyes (50%). Three patients received increased corticosteroid dosage therapy on their first episode of uveitis guided by UWFA had stopped steroids without recurrence. Conclusion: The uveitis in TINU syndrome was mild. Corticosteroids were efficient in most cases, but a slower tapering and long-term treatment were required. UWFA is sensitive in detecting the activity of uveitis and might be useful in monitoring disease progression. Complete withdrawal of medication was difficult to achieve in some cases.

Tubulointerstitial nephritis and uveitis (TINU) syndrome: a systematic review of its epidemiology, demographics and risk factors

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare oculorenal inflammatory condition that was first described in 1975. In 2001 a major review identified 133 cases in the world literature and proposed key diagnostic criteria for the condition. Although acknowledged as rare, the limited data available prevented reliable estimates of the prevalence of the condition, and hampered elucidation of the relationship between genetic and environmental factors that contribute to its pathogenesis.In this review we have performed a systematic search on the epidemiology, demographics and proposed risk factors for TINU. Estimates of prevalence based on studies that explicitly report TINU cases suggest that it is diagnosed in 0.2-2% of patients attending specialist uveitis services, with variation reflecting a number of factors including level of diagnostic certainty required. The prevalence of uveitis in patients with tubulointerstitial nephritis (TIN) may be higher than currently recognised, particularly in the paediatric population.The prevalence of TINU is higher in younger age groups and there is a female preponderance although this gender effect appears weaker than suggested by early studies. Although important genetic contributions have been proposed, the small size of studies and variation between reports currently preclude identification of a 'pro-TINU' haplotype. Drugs and infections have been proposed as the leading acquired risk factors for the development of TINU; whilst the small size of TINU cohorts and issues of study design limit interpretation of many studies. Larger datasets from the renal literature suggest that the majority of these cases are precipitated by a drug-induced hypersensitivity reaction; however in many ophthalmic cases no clear precipitant is identified.

Tubulointerstitial nephritis: diagnosis, treatment, and monitoring

Tubulointerstitial nephritis (TIN) is a frequent cause of acute kidney injury (AKI) that can lead to chronic kidney disease (CKD). TIN is associated with an immune-mediated infiltration of the kidney interstitium by inflammatory cells, which may progress to fibrosis. Patients often present with nonspecific symptoms, which can lead to delayed diagnosis and treatment of the disease. Etiology can be drug-induced, infectious, idiopathic, genetic, or related to a systemic inflammatory condition such as tubulointerstitial nephritis and uveitis (TINU) syndrome, inflammatory bowel disease, or immunoglobulin G4 (IgG4)-associated immune complex multiorgan autoimmune disease (MAD). It is imperative to have a high clinical suspicion for TIN in order to remove potential offending agents and treat any associated systemic diseases. Treatment is ultimately dependent on underlying etiology. While there are no randomized controlled clinical trials to assess treatment choice and efficacy in TIN, corticosteroids have been a mainstay of therapy, and recent studies have suggested a possible role for mycophenolate mofetil. Urinary biomarkers such as alpha1- and beta2-microglobulin may help diagnose and monitor disease activity in TIN. Screening for TIN should be implemented in children with inflammatory bowel disease, uveitis, or IgG4-associated MAD.

Biopsy-proven paediatric tubulointerstitial nephritis

BACKGROUND

Tubulointerstitial nephritis (TIN) is an uncommon condition in which the aetiology, treatment and outcome is not well defined. We describe a large series of children with biopsy-proven TIN.

METHODS

All children with biopsy-proven TIN presenting to our institution during a 23-year period were retrospectively reviewed for aetiology, symptoms, treatment, and long-term outcome.

RESULTS

A total of 27 children (16 girls) were described. Median age was 12 years (range 8 months to 15 years). A potentially adverse drug reaction was found in 12 (44 %) and infection in 8 (30 %). In 13 (48 %) no initiating factor was identified. All but 1 patient were treated with corticosteroids owing to worsening kidney function and 4 patients with other immunosuppressive agents. Fifteen children (56 %) had an estimated glomerular filtration rate (eGFR) of less than 80 ml/min/1.73 m(2) at last follow-up. Fifteen of the 23 children investigated (65 %) had coexistent uveitis.

CONCLUSION

This series represents a subset of paediatric TIN patients in whom there was a clinical indication for a renal biopsy, hence presenting with more severe disease than previously reported. This group were more likely to have no identifiable underlying cause and an increased requirement for corticosteroid treatment. Furthermore, more than half of the cases developed chronic kidney disease (CKD) with impaired kidney function.

Clinicopathologic characteristics, treatment, and outcomes of tubulointerstitial nephritis and uveitis syndrome in adults: A national retrospective strobe-compliant study

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disease, defined by the association of idiopathic acute TINU. The aim of our work was to determine the characteristics of adult TINU syndrome in France, and to assess factors (including treatment) influencing medium-term prognosis.We conducted a nationwide study including 20 French hospitals. Clinical, laboratory, and renal histopathologic data of 41 biopsy-proven TINU syndromes were retrospectively collected. The patients were diagnosed between January 1, 1999 and December 1, 2015.Twenty-five females and 16 males were included (F/M ratio: 1.6:1). The median age at disease onset was 46.8 years (range 16.8-77.4) with a median serum creatinine level at 207 μmol/L (range 100-1687) and a median estimated glomerular filtration rate (eGFR) at 27 mL/min per 1.73 m (range 2-73). Twenty-nine patients (71%) had a bilateral anterior uveitis and 24 (59%) had deterioration in general health at presentation. Moderate proteinuria was found in 32 patients (78%) (median proteinuria 0.52 g/24 h; range 0.10-2.10), aseptic leukocyturia in 25/36 patients (70%). The evaluation of renal biopsies revealed 41 patients (100%) with an acute tubulointerstitial nephritis, 19/39 patients (49%) with light to moderate fibrosis and 5 patients (12%) with an acute tubular necrosis. Thirty-six patients (88%) were treated with oral corticosteroids. After 1 year of follow-up, the median eGFR was 76 mL/min per 1.73 m (range 17-119) and 32% of the patients suffered from moderate to severe chronic kidney disease. Serum creatinine (P < 0.001, r = -0.54), serum bicarbonate and phosphate levels (respectively, P = 0.01, r = 0.53; and P = 0.04, r = 0.46), and age (P = 0.03, r = -0.37) at the 1st symptoms were associated with eGFR after 1 year. During the 1st year 40% of patients had uveitis relapses. The use of oral corticosteroids was not associated with a better kidney function but was associated with fewer uveitis relapses (P = 0.44 and 0.02, respectively).In our study, 32% of patients were suffering from moderate to severe chronic kidney disease after 1 year of follow-up, and 40% had uveitis relapses during this follow-up. This work also suggests that oral corticosteroids are effective for the treatment of TINU syndrome's uveitis.

[Acute tubulointerstitial nephritis following adenovirus and respiratory syncytial virus infection]

Acute tubulointerstitial nephritis (TIN) is responsible for nearly 10% of acute renal failure (ARF) cases in children. It is mostly drug-induced, but in a few cases viruses are involved, probably by an indirect mechanism. An immune-competent 13-month-old boy was admitted to the intensive care unit for severe ARF with anuria in a context of fever, cough, and rhinorrhea lasting 1 week. The kidney biopsy performed early brought out tubulointerstitial damage with mild infiltrate of lymphocytes, without any signs of necrosis. There were no virus inclusion bodies, no interstitial hemorrhage, and no glomerular or vascular damage. Other causes of TIN were excluded: there was no biological argument for an immunological, immune, or drug-induced cause. Adenovirus (ADV) and respiratory syncytial virus (RSV) were positive in respiratory multiplex polymerase chain reaction (PCR) in nasal aspirate but not in blood, urine, and renal tissue. The patient underwent dialysis for 10 days but the response to corticosteroid therapy was quickly observed within 48 h. The mechanism of TIN associated with virus infection is unknown. However, it may be immune-mediated to be able to link severe renal dysfunction and ADV and/or RSV invasion of the respiratory tract.

Kidney involvement in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy in a Finnish cohort

BACKGROUND

Autoimmune tubulo-interstitial nephritis (TIN) is a rare complication of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Previous data on TIN and other renal or urologic manifestations of APECED are sparse.

METHODS

We performed a retrospective study on the urinary and renal tract diseases in a cohort of 30 Finnish patients with APECED (mean age 40 years), with special emphasis on the clinical presentation and the immunologic characteristics of TIN. Clinical and laboratory findings, specific anticytokine and kidney-specific antibodies were analysed.

RESULTS

Five of the 30 (17%) patients had moderate-to-severe renal failure, including 3 (10%) with TIN, leading to either transplantation, haemodialysis or immunosuppressive treatment. No other cause other than APECED was found for the TIN. All three patients with TIN had circulating antibodies against the distal part of the nephron, as did 30% of all cohort cases. Two had nephrocalcinosis, and two had renal tubular acidosis type 1. Immunosuppressive therapy with mycophenolate mofetil or rituximab in one pediatric case did not revert the TIN, however.

CONCLUSIONS

Renal failure should raise concern for TIN in APECED. It discloses some specific features: no uveitis, no glycosuria and inconstant urinalysis anomalies. Regular renal monitoring for any APECED patient should be performed. Circulating antibodies against the distal part of the nephron are frequent and present in all TIN patients, but their pathologic significance is not yet known. Future studies will be needed to understand the triggers leading to overt clinical disease in these patients.

HLA-DR, DQ class II DNA typing in pediatric panuveitis and tubulointerstitial nephritis and uveitis

PURPOSE

To describe chorioretinal lesions in pediatric uveitis that are associated strongly with the HLA-DR, DQ class II type associated with tubulointerstitial nephritis and uveitis (TINU).

DESIGN

Retrospective, observational case series.

METHODS

SETTING

University-based clinic.

PATIENT POPULATION

Fifteen consecutive patients with onset of bilateral panuveitis at less than 16 years of age who were seen between September 2004 and October 2012 and 6 pediatric patients with confirmed TINU.

OBSERVATION PROCEDURE

HLA-DR, DQ class II DNA typing.

MAIN OUTCOME MEASURE

Detection of the HLA-DRB1*01 and HLA-DQB1*05 risk alleles for TINU.

RESULTS

Fourteen (93%) of the 15 patients with otherwise unexplained pediatric panuveitis typed HLA-DRB1*01-HLA-DQB1*05. Eleven (73.3%) of 15 patients had bilateral sharply demarcated, usually inferior, 200- to 300-μm spots of chorioretinal atrophy, and 4 (27.7%) of 15 patients had bilateral clusters of 500- to 750-μm poorly defined orange choroidal lesions without overlying atrophy of the retinal pigment epithelium. None had interstitial nephritis. Four of the 6 definite TINU cases had class II typing and TINU risk alleles; all 6 had bilateral panuveitis. The frequency of risk alleles was statistically higher in those with pediatric panuveitis than in the North American population and in nonpanuveitis pediatric uveitis patients assumed to have the North American HLA distribution (P < .0001, Fischer exact test). Positive likelihood ratios were 9.92 to 5.18, depending on assumptions regarding pretest probability of disease.

CONCLUSIONS

Recognition of characteristic chorioretinal lesions in otherwise unexplained pediatric panuveitis, supported by selective HLA class II DNA typing, is useful in narrowing diagnostic possibilities and directing further evaluations. Panuveitis is underappreciated as a manifestation of TINU.

The blind kidney: disorders affecting kidneys and eyes

There are many disorders that can affect both the kidneys and the eyes. Awareness of the ocular manifestations of kidney disorders is important as it can guide the diagnosis and facilitate the choice of a specific treatment. Conversely, ophthalmologists need to be aware of potential renal manifestations in disorders presenting initially with visual failure. We review disorders affecting both of these organ systems, based upon cases from our clinical practice to highlight the importance of interdisciplinary collaboration.

Tubulointerstitial nephritis with uveitis in Chinese adults

BACKGROUND AND OBJECTIVES

Tubulointerstitial nephritis and uveitis (TINU) syndrome is considered a rare cause of acute tubulointerstitial nephritis (ATIN) that is usually associated with renal recovery. This study sought to investigate the diagnosis, prognosis, and contributing factors of TINU syndrome using a large cohort of patients with prospective follow-up.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study included patients with TINU syndrome from a prospective cohort of patients with ATIN from 2007 to 2012. Clinical-pathologic data were collected at biopsy and autoantibodies against modified C-reactive protein (mCRP-Ab) were measured. Serum levels and renal tissue expression of Kreb von den Lunge-6 were also detected. Independent risk factors for poor renal outcome at 12 months and late-onset uveitis were analyzed.

RESULTS

Thirty-one patients (28%) with biopsy-proven ATIN were classified as having TINU syndrome. Of these patients, 18 (58%) developed late-onset uveitis and were misdiagnosed as having drug-induced ATIN at the time of biopsy. An abnormal level of mCRP-Ab was an independent risk factor for late-onset uveitis (odds ratio, 14.7; 95% confidence interval, 3.4 to 64.0). Patients with TINU syndrome and drug-induced ATIN had comparable levels of Kreb von den Lunge-6 in both serum and renal tissues. Ninety-two percent of patients developed stage 3-4 CKD and/or tubular dysfunction by 12 months postbiopsy. Age, serum creatine level, erythrocyte sedimentation rate, and the presence of concomitant thyroid disease or leukocyturia were related to poor renal outcome. Relapse was seen in 36% (11 of 31) of patients and potentiated poor renal outcome.

CONCLUSIONS

The diagnosis of TINU syndrome can be missed in a large fraction of patients with ATIN because uveitis can present well after the onset of tubulointerstitial nephritis. Elevated mCRP-Ab levels may be useful in predicting late-onset uveitis TINU syndrome. Unfortunately, patients with TINU tended to have frequent relapses and most patients had incomplete renal recovery. Long-term follow-up is needed to prevent misdiagnosis and properly manage TINU syndrome.

Prednisone in the treatment of tubulointerstitial nephritis in children

BACKGROUND

Patients with tubulointerstitial nephritis (TIN) may develop permanent renal impairment. However, there are no prospective studies available on the treatment of TIN.

METHODS

The effect of prednisone in the treatment of TIN was evaluated in a total of 17 patients who received prednisone or who were followed up without medication. The patient group was subdivided based on the initial plasma creatinine (PCr), below or above 150 μmol/l.

RESULTS

All prednisone-treated patients had normal plasma creatinine (PCr) after 1 month of treatment (median 59.1 [45-85] μmol/l) whereas only 50 % of patients in the non-treatment group had normal creatinine (median 81.0 [42-123] μmol/l) at the same time point (p = 0.025). During 6 months' follow-up, PCr decreased in all patient groups; however, it decreased significantly only in prednisone-treated patients with baseline PCr >150 μmol/l (p < 0.001). At the end of follow-up, no difference in PCr, glomerular filtration rate (GFR), or low molecular weight (LMW) proteinuria could be found between the study groups. A considerable number of patients in both groups had subnormal GFR and/or persistent LMW proteinuria at the 6-month follow-up visit. Eighty-two percent of the patients had uveitis.

CONCLUSIONS

Prednisone speeds up the recovery from renal symptoms of TIN, especially in patients with severe nephritis. The renal function did not differ significantly between prednisone and control patients after 6 months' follow-up.

HLA associations with tubulointerstitial nephritis with or without uveitis in Finnish pediatric population: a nation-wide study

The human leukocyte antigen (HLA) genotype has been shown to associate with tubulointerstitial nephritis (TIN) and tubulointerstitial nephritis with uveitis syndrome (TINU). The association of HLA genes with TIN was examined in this nation-wide study. HLA genotyping was performed in 31 pediatric patients with biopsy-proven TIN. All patients were examined by an ophthalmologist to diagnose possible uveitis. Class II HLA genotypes of TIN patients were compared with the Finnish reference population. We found a significant association between the HLA alleles DQA1*04:01 [risk ratio (RR) 5.0, 95% confidence interval (CI) 2.0-11.2], DQB1*04:02 (RR 2.7, 95% CI 1.4-5.3), and DRB1*08 (RR 3.8, 95% CI 1.5-8.4) and TIN. Uveitis was found in 20/31 (64.5%) patients. HLA genotyping of the TINU patients showed additional risk HLA alleles: DQA1*01:04 (RR 6.1, 95% CI 1.5-17.8), and DRB1*14 (RR 8.2, 95% CI 2.2-22.1). The alleles DQA1*01:04 (RR 8.8, 95% CI 2.2-26.5), DQA1*04:01 (RR 3.2, 95% CI 1.2-7.3), and DRB1*14 (RR 12.0, 95% CI 3.2-33.0) were more frequent in patients with TIN and chronic uveitis than in reference population. The HLA class II haplotype DQA1*04:01/DQB1:04:02/DRB1*08 was the most common combination in our study population (58.1%). None of the patients had haplotype DQA1*04:01/DQB1*06:02/DRB1*15, which is common in Finland. HLA genotype did not predict the renal outcome. We found a strong association between certain HLA genotypes both in TIN and TINU patients. The TIN/TINU-associated HLA alleles appear to vary depending on study population.

Tubulointerstitial nephritis and uveitis syndrome in a twelve-year-old girl

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disorder defined by the combination of biochemical abnormalities, tubulointerstitial nephritis, and uveitis. We describe a 12-year-old female, presented with a ten-day history of fever, characterized by sudden onset and rapid spontaneous resolution in few hours, accompanied by shivering, extreme fatigue, and loss of appetite. Laboratory values were consistent with renal failure of tubular origin. Renal biopsy confirmed a tubulointerstitial nephritis, with acute tubulitis, polymorphonuclear infiltration, and microabscesses. The renal interstitium was occupied by a dense inflammatory infiltrate, consisting of lymphocytes, plasma cells, and neutrophils. Glomerular structures were preserved. Ophthalmological examination that suggested a previous asymptomatic bilateral uveitis and HLA typing (HLA-DQA1∗0101/0201 and HLA-DQB1∗0303/0503) further supported the suspect of TINU syndrome. TINU syndrome is probably an underdiagnosed disorder, responsible for many cases of idiopathic anterior uveitis in young patients, especially in those who have asymptomatic renal disease and when proper diagnostic tests are not performed at the time of presentation.

Tubulointerstitial nephritis and uveitis syndrome in children: a prospective multicenter study

PURPOSE

To evaluate the occurrence and characteristics of uveitis related to tubulointerstitial nephritis (TIN) in children.

DESIGN

Prospective, observational, multicenter, partly placebo-controlled treatment trial.

PARTICIPANTS

Nineteen children with a biopsy-proven TIN.

METHODS

Patients were treated with prednisone or followed without treatment. In addition to the nephrologic evaluations, the prospective follow-up included structured ophthalmological examinations at the onset of TIN and at 3 and 6 months after the diagnosis.

MAIN OUTCOME MEASURES

Occurrence, clinical features, and outcome of uveitis.

RESULTS

Some 84% (16/19) of the patients had uveitis, 83% (5/6) in the nontreatment group and 82% (9/11) in the prednisone-treated group. The remaining 2 patients, originally in the nontreatment group, were switched to the prednisone group after 2 weeks. Both of them developed uveitis. Altogether, 3 patients developed uveitis during prednisone treatment and 2 patients showed worsening of uveitis despite the systemic corticosteroid. Some 50% (8/16) of the patients with uveitis presented with no ocular symptoms; 88% (14/16) of the patients had a chronic course of uveitis. Two patients were diagnosed with uveitis before nephritis; nephritis and uveitis were diagnosed within 1 week from each other in 7 patients, and uveitis developed 1 to 6 months after the diagnosis of TIN in 7 patients.

CONCLUSIONS

There was no statistically significant difference in the occurrence of uveitis in patients with TIN in the prednisone and nontreatment groups. In this study, the occurrence of uveitis associated with TIN was considerably higher than previously reported. Uveitis related to TIN may develop late and is often asymptomatic. The ophthalmological follow-up of all patients with TIN is warranted for at least 12 months starting with 3-month intervals.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any material discussed in this article.

Acute tubulointerstitial nephritis

Acute tubulointerstitial nephritis (TIN) is a frequent cause of acute renal failure, characterised by the presence of inflammatory cell infiltrate in the interstitium of the kidney. Immuno-allergic reaction to certain medications, mainly non-steroidal anti-inflammatory drugs and antibiotics are by far the most important etiology for TIN today, but other situations such as infections, toxins, and vasculitis are known to induce TIN. Incidence of TIN is increasing, probably due to prescription habits and NSAID overuse, representing 3-7% of acute kidney injury in biopsies in children. Avoidance of the causal substance and rapid steroid therapy are hallmarks for patient care, but spontaneous initial recovery is very frequent and the general prognosis seems satisfactory. However, development of chronic TIN, without response to steroid or other immunosuppressive treatment, is possible. As the largest part of TIN is secondary to certain drugs, clear indications in particular for NSAID or antibiotics should be respected to reduce the number of TIN cases.