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

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in this compartment (tubulointerstitial nephritis-TIN) can be acute and resolves if the offending factor is withdrawn or may enter a chronic process leading to irreversible kidney damage.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

A Comprehensive Review of Tubulointerstitial Nephritis and Uveitis (TINU) Syndrome

Background: Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare autoimmune disorder, characterized by acute tubulointerstitial nephritis and uveitis. It poses diagnostic challenges due to the mostly asynchronous onset of renal and ocular manifestations, as well as the variety of differential diagnoses. This review provides an overview of the epidemiology, pathogenesis, clinical features, diagnostic criteria, and management strategies. Methods: A comprehensive review of the peer-reviewed literature, including studies and case reports, was conducted. Results: The etiology of TINU syndrome involves an autoimmune reaction to renal and ocular antigens, leading to interstitial inflammation and tubular damage in the kidneys, and anterior uveitis with acute onset of flares. Diagnostic criteria based on ocular examination, laboratory parameters, and renal biopsy emphasize the need to exclude other systemic diseases. TINU syndrome accounts for approximately 2% of all uveitis cases. Primary treatment consists of corticosteroids, while immunomodulatory therapies (methotrexate, azathioprine, mycophenolate mofetil, or biologic agents) are reserved for refractory cases. Recurrence of uveitis appears to be more common than that of nephritis. Conclusions: TINU syndrome is rare and requires clinical suspicion for accurate diagnosis. Early diagnosis and initiation of treatment are crucial for achieving favorable outcomes. Advances in the understanding of its pathogenesis and treatment have improved patient outcomes. Further research is needed to investigate the underlying triggers and mechanisms in order to develop targeted therapies.

Clinical outcomes in paediatric tubulointerstitial nephritis and uveitis syndrome (TINU)

PURPOSE

To evaluate the clinical presentation, course, and outcomes of uveitis in paediatric patients with tubulointerstitial nephritis and uveitis syndrome (TINU).

METHODS

Multicentric Retrospective Cohort Study 110 patients ≤21 years of age diagnosed with TINU from 10 sites across the United States and Canada. Clinical diagnosis of TINU required uveitis diagnosed by an ophthalmologist, elevated serum creatinine (SCr) and elevated urine β2-microglobulin (β2M) or abnormal urinalysis. Renal biopsy and systemic illness were not mandatory. Univariate and multivariate analysis was performed to analyse risk factors and treatment modalities.

RESULTS

Median age was 13 years (Range (5.9-18.4); 52% male); median follow-up, 1.6 years (IQR 0.98-4.02). Uveitis was symptomatic in 90%, with bilateral anterior uveitis in 94%. Ninety-two (84%) patients required immunomodulatory treatment (IMT). Methotrexate (n = 44) and mycophenolate mofetil (n = 39) were the first agents after oral corticosteroids. 45% required addition of biologic agents (Adalimumab [n = 33], Infliximab [n = 8]). Younger age (p = 0.018), male sex (p = 0.011), and higher uveitis grade at presentation (p = 0.031) were associated with greater IMT ( ≥ 2) requirement. 53% had uveitis recurrence compared to 16% with nephritis recurrence. At the most recent visit, nephritis was controlled in 90%, while uveitis in 74%. Four (4%) patients required glaucoma surgery. Nine (8%) patients had renal complications.

CONCLUSIONS

Most patients with TINU require steroid-sparing IMT for control of uveitis, with nearly half requiring addition of biologic agents. Urinalysis, urine β2M and SCr testing should be considered in children presenting with uveitis, especially when the disease is bilateral and anterior.

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.

Diagnostic and Management Strategies of Tubulointerstitial Nephritis and Uveitis Syndrome (TINU): Current Perspectives

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare autoimmune disease with unclear pathogenesis but probably related to a combination of genetic predisposition and environmental triggers. Diagnosis is challenging due to the asynchronous onset of renal and ocular symptoms, and it is necessary to exclude other causes of nephritis and uveitis. It affects both sexes, with an overall predominance of females and a median age of onset of 15 years. TINU syndrome is characterized by bilateral, non-granulomatous anterior uveitis and tubulointerstitial nephritis, which can cause acute renal failure in severe cases. Several triggers have been identified including concurrent infections, medications, or endocrine diseases. The diagnosis of TINU is mainly based on clinical and analytical findings, and although urinary β2-microglobulin is a useful parameter no specific diagnostic test is available. Current perspectives intend to facilitate its diagnosis identifying susceptibility HLA genotypes, serologic markers and imaging tools to avoid renal biopsy. Treatment options for TINU syndrome include corticosteroids, immunosuppressive agents, and intravenous immunoglobulins, but relapses are frequent, and management can be challenging. The purpose of this review is to provide an updated summary of the diagnostic and treatment strategies of TINU syndrome, helping clinicians recognize and manage this rare autoimmune disorder.

Ocular images-based artificial intelligence on systemic diseases

PURPOSE

To provide a summary of the research advances on ocular images-based artificial intelligence on systemic diseases.

METHODS

Narrative literature review.

RESULTS

Ocular images-based artificial intelligence has been used in a variety of systemic diseases, including endocrine, cardiovascular, neurological, renal, autoimmune, and hematological diseases, and many others. However, the studies are still at an early stage. The majority of studies have used AI only for diseases diagnosis, and the specific mechanisms linking systemic diseases to ocular images are still unclear. In addition, there are many limitations to the research, such as the number of images, the interpretability of artificial intelligence, rare diseases, and ethical and legal issues.

CONCLUSION

While ocular images-based artificial intelligence is widely used, the relationship between the eye and the whole body should be more clearly elucidated.

Clinical Features and Outcomes of Tubulointerstitial Nephritis and Uveitis Syndrome in Spain and Portugal: The IBERTINU Project

PURPOSE

To assess the clinical features, management and prognosis of patients diagnosed with tubulointerstitial nephritis and uveitis (TINU) syndrome in Spain and Portugal.

METHODS

Retrospective multicenter study, which included all patients diagnosed with TINU syndrome managed in 15 uveitis referral centers from Spain and Portugal.

RESULTS

Forty-eight subjects with a mean age at diagnosis of 25.0 [14.8; 49.5] years were included. Both eyes were affected in 43 patients (89.6%). The visual outcome was favorable, but immunosuppressive systemic therapy (IST) was needed in 26 (54.16%) due to relapses. Renal function normalized in 35 patients (72.9%). HLA-DQB1*05 was the most common genetic typing (57.1%). The mean follow-up time was 22.5 [11.0; 48.0] months.

CONCLUSIONS

Both visual and renal outcomes were favorable, although IST was frequently used. TINU is under- diagnosed, so further prospective studies would provide more knowledge about its recognition and management.

EXPERT OPINION

TINU Syndrome is underdiagnosed because ocular and renal disease are asynchronous. Outcomes are favorable so it has to be highly suspected in cases of bilateral anterior uveitis. According to literature and our experience, systemic immunosuppressive therapy is often required because of ocular relapses.This study adds to the previous knowledge that HLA-DQB1*05 could be an important HLA type amongst the TINU Syndrome Iberian population. HLA typing should be assessed in these patients in order to describe its phenotype-genotype relationship better. A considerable number of patients in our series were diagnosed in their sixties, so TINU Syndrome should also be suspected in elderly patients.

Acute Interstitial Nephritis in the Pediatric Population: A Review of Etiologic Associations, Histologic Findings, and Clinical Outcome

BACKGROUND

Acute interstitial nephritis (AIN) is an infrequent cause of acute kidney injury in the pediatric population with a broad range of etiologies. This retrospective review attempts to characterize AIN in the pediatric population, delineate etiologic factors, histologic features, and clinical outcome.

MATERIALS AND METHODS

Institutional pathology reports were queried for a diagnosis of AIN between 1/2010 and 10/2021. Archived slides and reports and clinical records were reviewed.

RESULTS

Twenty-four patients were identified whose ages ranged from 5 to 20 years. A 8 cases (37.5%) were characterized as tubulointerstitial nephritis and uveitis (TINU), 4 cases (16.7%) were associated with an autoimmune disease, 4 cases (16.7%) were likely drug induced, and 8 cases (37.5%) had unclear etiology.

DISCUSSION

Although all cases of drug induced interstitial nephritis contained eosinophils they were not exclusive to drug induced interstitial nephritis. A prominent plasma cell infiltrate was seen in both cases of Sjögren's associated interstitial nephritis. The vast majority (n = 18, 75%) showed an improved serum creatinine (<1 mg/dL) 1 year post diagnosis/at last follow-up. In this pediatric series of AIN, TINU contributed to a large subset of cases with known etiologies. On follow up, majority of the cases demonstrated recovery of renal function.

Bilateral Granulomatous Iridocyclitis Associated with Early-Onset Juvenile Psoriatic Arthritis

PURPOSE

The purpose of this study is to report on a case of bilateral granulomatous iridocyclitis in a patient with early-onset juvenile psoriatic arthritis (JPsA).

METHODS

The method used is an observational case report. Observations. A 3-year-old Hispanic girl was sent to our uveitis service for further evaluation of her granulomatous uveitis. The initial ophthalmologic examination revealed bilateral band keratopathy, large mutton-fat keratic precipitates, multiple posterior synechiae, and 4+ anterior chamber cells. The physical exam was notable for left knee edema and right axillary rash. Laboratory testing was remarkable for an erythrocyte sedimentation rate of 80 mm/h, positive antinuclear antibodies (1 : 1, 280), and negative human leukocyte antigen B27. A cutaneous biopsy was obtained, which confirmed the diagnosis of a psoriatic rash. Treatment with oral prednisolone and topical prednisolone acetate with atropine sulfate resulted in the complete resolution of the uveitis. Conclusion and Importance. Bilateral granulomatous iridocyclitis may be a rare presentation of ocular involvement in patients with early-onset JPsA.

Tubulointerstitial Nephritis and Uveitis Syndrome (TINU): A Case Series in a Tertiary Care Uveitis Setting

Background: Tubulointerstitial nephritis and uveitis syndrome (TINU) is a rare disorder typically characterized by sudden-onset non-granulomatous anterior uveitis associated with tubulointerstitial nephritis (TIN). However, the prevalence and clinical features of TINU are still a matter of debate. To add information about TINU, we describe here the clinical features of a series of patients affected by TINU in a retrospective study. Methods: A total of 9358 clinical records of both adult and pediatric patients up to 21 years of age, referred to the Uveitis Center of the Sapienza University of Rome, were examined. The medical records covered a period from 1990 to 2020. Various demographic and clinical features were analyzed in patients who met the criteria for TINU. Results: Twenty-one patients with TINU were identified. TINU was classified as definite, possible, or probable by the currently recognized international criteria. The median age at diagnosis was 14 years (interquartile range 12–35). Females were predominant (15/21, 71.4%). In most cases (14/21, 66.6%), patients developed ocular disease concurrently with renal disease. The most frequent type of ocular involvement was bilateral anterior uveitis (9/21, 42.8%). In two cases, patients presented with bilateral intermediate uveitis; in three cases, they presented with bilateral or unilateral alternating posterior uveitis; and in four cases, they presented with bilateral panuveitis. In one case, the uveitis was anterior in the right eye (OD) and posterior in the left eye (OS), and two cases presented with bilateral asynchronous or unilateral alternating anterior uveitis. All patients received treatment with systemic corticosteroids and topical ocular therapy. At the end of the follow-up, a significant improvement in ocular signs and symptoms with a return to normal visual acuity was generally observed. In all patients, acute kidney injury (AKI) reverted completely and none progressed to chronic kidney disease (CKD). Conclusions: Patients with TINU may often present with atypical uveitis. We suggest that patients with sudden-onset uveitis, even if not bilateral anterior, should be referred to a nephologist for an assessment of the possible presence of renal disease.

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.

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.

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.

Tubulointerstitial nephritis and uveitis: The first report from the ophthalmology perspective in India

A 16-year-old boy presented with uveitis in both eyes with recurrent febrile illness and renal ailments. The patient was referred to a nephrologist. Subsequent investigations revealed acute tubulointerstitial nephritis in a renal biopsy and raised urinary beta-2 microglobulin (B2M). Based on his clinical findings and laboratory investigations, a diagnosis of tubulointerstitial nephritis and uveitis (TINU) syndrome was made. Since, the literature on TINU through India is sparse, the two available case reports were published through nephrology setup. Our case illustrates how ophthalmologist can aid in the diagnosis of such a rare clinical entity using interdisciplinary approach.

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.

Paediatric autoimmune and autoinflammatory conditions associated with uveitis

Childhood uveitis comprises a collection of heterogenous ocular phenotypes which are associated with a diverse range of childhood autoimmune and autoinflammatory disorders. Of these genetic and/or acquired disorders, juvenile idiopathic arthritis is the most common, affecting 30-80% of children with uveitis. Up to a third of children with uveitis have 'isolated' idiopathic disease and do not have an associated systemic disease which manifests in childhood. However, uveitis may be the presenting manifestation of disease; thus, the apparently well child who presents with uveitis may have isolated idiopathic disease, but they may have an evolving systemic disorder. The diagnosis of most of the associated disorders is reliant on clinical features rather than serological or genetic investigations, necessitating detailed medical history taking and systemic examination. Adequate control of inflammation is key to good visual outcomes, and multidisciplinary care is key to good broader health outcomes.

Acute Kidney Injury Relevant to Tubulointerstitial Nephritis with Late-Onset Uveitis Superimposed by Thrombotic Microangiopathy: A Case Report and Review of the Literature

Background

The syndrome of tubulointerstitial nephritis and uveitis (TINU) is an uncommon and multisystemic autoimmune disorder. This review reports a rare case of TINU being superimposed on thrombotic microangiopathy (TMA) and, by comparing with the available literature, also summarizes the clinical features, associated conditions, treatment, and outcome of patients with TINU.

Summary

Herein, we report the case of a 37-year-old male patient with acute kidney injury (AKI) clinicopathologically identified as malignant hypertension-induced TMA superimposed by acute tubulointerstitial nephritis, which was suspected to be related to drug hypersensitivity. After treatment with oral prednisone combined with a renin-angiotensin system inhibitor, the patient achieved partial renal recovery and was withdrawn from hemodialysis. Recurrent AKI concomitant with new-onset asymptomatic uveitis was detected during routine clinical follow-up after cessation of prednisone. TINU was then diagnosed, and prednisone followed by cyclophosphamide was prescribed. The patient achieved better renal recovery than in the first round of treatment and maintained stable renal function afterward. By reviewing the literature, 36 cases were reported as TINU superimposed on other conditions, including thyroiditis, osteoarthropathy, and sarcoid-like noncaseating granulomas.

Key messages

TINU could be complicated by many other conditions, among which TMA is very rare. When presented as AKI, kidney biopsy is important for differential diagnosis. The case also shows that recurrent AKI with concomitant uveitis after prednisone withdrawal strongly suggested the need for long-term follow-up and elongated prednisone therapy for TINU syndrome.

Tubulointerstitial nephritis and uveitis (TINU) syndrome and recent Streptococcus infection in a 9-year-old girl

A 9-year-old girl presented to hospital with a 6-week history of non-specific constitutional symptoms and weight loss. She initially underwent extensive medical investigation without diagnosis being achieved. Although raised inflammatory markers and impaired renal function were noted during her initial admission to hospital, it was her subsequent presentation 2 weeks later with sudden-onset bilateral anterior uveitis that prompted a renal biopsy that indicated acute tubulointerstitial nephritis. A diagnosis of tubulointerstitial nephritis and uveitis (TINU) syndrome was made and systemic glucocorticoid treatment initiated to prevent visual loss and preserve renal function. She has subsequently been reviewed in multidisciplinary outpatient clinics and treated with a tapering regimen of immunosuppressive therapy. Her treatment has been complicated by the side effects of glucocorticoids and by persistent relapses in ocular disease and abnormalities on urinalysis. Recent clinical investigations indicate that her uveitis is controlled and that renal function remains well preserved.

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.

Glucosuria Predicts the Severity of Puumala Hantavirus Infection

Introduction

Puumala hantavirus (PUUV) causes a mild type of hemorrhagic fever with renal syndrome characterized by acute kidney injury (AKI), increased capillary leakage, and thrombocytopenia. Albuminuria and hematuria in dipstick urine test at hospital admission are known to predict the severity of upcoming AKI.

Methods

We analyzed dipstick urine glucose in 195 patients with acute PUUV infection at hospital admission, and divided them into 2 categories according to the presence or absence of glucose in the dipstick urine test. Determinants of disease severity were analyzed in glucosuric and nonglucosuric patients.

Results

Altogether, 24 of 195 patients (12%) had glucosuria. The patients with glucosuria had more severe AKI than patients without glucosuria (median maximum creatinine concentration 459 μmol/l, range 78-1041 μmol/l vs. 166 μmol/l, range 51-1499 μmol/l; P < 0.001). The glucosuric patients had more severe thrombocytopenia (median minimum platelet count 41 × 10⁹/l, range 5-102 × 10⁹/l vs. 62 × 10⁹/l, range 3-249 × 10⁹/l; P = 0.006), and more pronounced signs of increased capillary leakage (change in weight, maximum plasma hematocrit, minimum plasma albumin). The glucosuric patients were more often in clinical shock at admission (20.8% vs. 1.2%; P < 0.001) and the length of hospital stay was longer (median 7.5 days, range 4-22 days vs. 6 days, range 2-30 days; P = 0.009).

Conclusion

Glucosuria is relatively rare, but when present it predicts a more severe disease course in patients with acute PUUV infection.

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.

Tubulointerstitial nephritis and uveitis (TINU) with granulomatosis: a novel report of simultaneous TINU and sarcoidosis in a pediatric patient

We report the case of a 7-year-old girl who presented with bilateral anterior uveitis, acute interstitial nephritis, and asymptomatic pulmonary granulomas and provide novel clinical evidence of an association between tubulointerstitial nephritis and uveitis syndrome and sarcoidosis.

Clinical and Genetic Features of Tubulointerstitial Nephritis and Uveitis Syndrome with Long-Term Follow-Up

Purpose

To investigate the clinical manifestations, prognosis, and HLA-type of tubulointerstitial nephritis and uveitis syndrome (TINU) with long-term follow-up.

Methods

Clinical data of five patients with TINU were retrospectively reviewed.

Results

The mean age was 15.8 years. The mean follow-up periods were 54.0 months. The initial subjective symptoms were bulbar injection (100%), ocular pain (80%), and blurred vision (60%). The medical department that the patients visited first was ophthalmology in 4 (80%) cases. Urinalysis showed the characteristic increase of the β2 microglobulin in all (100%) patients. Uveitis and nephritis were diagnosed within 1 week from each other. Although two showed recurrences, the topical and systemic steroid treatment with mean duration of 14.1 months brought the resolution of nephritis and uveitis in all patients. Recurrence-free periods ranged from 12 to 71 months. The final visual outcome was 20/20 or better in all cases. HLA-DR4 or the allele of DRB1^∗04 was present in all (100%) patients.

Conclusions

TINU should be considered in the differential diagnosis in young patients with uveitis of unknown origin and renal dysfunction. Urinary β2 microglobulin level and HLA typing may help in the diagnosis of TINU. The prognosis for patients with TINU is generally good with steroid treatment.

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.

The ratio of urinary α1-microglobulin to microalbumin can be used as a diagnostic criterion for tubuloproteinuria

Low-molecular-weight proteinuria is one of the characteristic clinical manifestations of renal tubular and interstitial diseases. Low-molecular-weight proteinuria is defined as excessive urinary loss of α1-microglobulin, β2-microglobulin, or other low-molecular-weight plasma proteins. The current study examined the ratio of urinary α1-microglobulin to microalbumin in 24 Chinese pediatric patients with renal tubular and interstitial diseases, including 10 patients with Dent disease, 2 patients with Lowe syndrome, 6 patients with acute tubulointerstitial nephritis (ATIN), 4 patients with acute tubulointerstitial nephritis with uveitis syndrome (TINU), and 2 patients with nephronophthisis (NPHP). Patients with steroid-sensitive nephrotic syndrome, IgA nephropathy, Henoch-Schonlein purpura nephritis, or lupus nephritis served as control groups. In all of the patients with tubular and interstitial disease, urinary α1-microglobin increased 10-300-fold above the upper limit of the normal range, the ratio of urinary α1-microglobulin to microalbumin was greater than 1, and the percentage of low-molecular-weight plasma proteins (LMWP) in urine was greater than 50% according to urine protein electrophoresis. There was close correlation between the ratio of urinary α1-microglobulin to microalbumin and the percentage of LMWP in urine according to urine protein electrophoresis (r = 0.797, p = 0.000). We suggested firstly that the ratio of urinary α1-microglobulin to microalbumin, greater than 1, can be used as a diagnostic criterion for tubuloproteinuria.

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

PURPOSE OF REVIEW

Tubulointerstitial nephritis and uveitis (TINU) is an important yet underrecognized ocular inflammatory syndrome. This review summarizes key historical publications that identified and defined the syndrome, and more recent literature that reveal the importance of urinary β2-microglobulin testing and kidney biopsy in the diagnostic evaluation of patients with TINU. Additionally, research studies providing new insights into disease pathogenesis are highlighted.

RECENT FINDINGS

In contrast with initial reports of TINU manifesting exclusively as an anterior uveitis in pediatric patients, more recent reports have identified TINU in patients of all ages with a wide range of ocular manifestations. Urinary β2-microglobulin has emerged as a sensitive and specific laboratory screening test, and the role of kidney biopsy in differentiating TINU from sarcoidosis continues to evolve. Genetic studies have identified HLA-DQA101, HLA-DQB105, and HLA-DRB101 as high-risk alleles and the identification of antimonomeric C-reactive protein antibodies suggests a role for humoral immunity in disease pathogenesis. Management strategies have evolved to include systemic anti-inflammatory treatment as a result of important outcome studies in patients with significant renal and ocular disease.

SUMMARY

With greater recognition, understanding, and treatment of this syndrome, both ocular inflammation and renal disease can be better addressed.

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 and uveitis syndrome (TINU). Treatment with immunosuppressive therapy

CASE REPORT

Two cases of tubulointerstitial nephritis and uveitis are presented. Immunosuppressive therapy was required to control the uveitis. Contrary to that usually described, uveitis became chronic, which made immunosuppressive therapy necessary. Nephritis was successfully treated with steroids.

DISCUSSION

Tubulointerstitial nephritis and uveitis syndrome is an under-diagnosed disorder and requires clinical suspicion due to there being no specific laboratory study available. Recurrences and relapses of ocular inflammation are common. Immunosuppressive therapy is not often needed.

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.

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.