Renal Prognosis in Children With Tubulointerstitial Nephritis and Uveitis Syndrome

Tubulointerstitial nephritis and uveitis post COVID-19 infection in an adult

A woman in her 50s contracted COVID-19 and initially presented a few weeks afterwards with left eye pain and redness. She was diagnosed with uveitis and treated with glucocorticoid eye drops. Renal impairment was found on laboratory investigations performed following the diagnosis of uveitis, and urine testing showed proteinuria. Serological testing showed no cause for the new findings, and renal imaging was unremarkable. A renal biopsy was conducted and histology was consistent with tubulointerstitial nephritis. A diagnosis of tubulointerstitial nephritis with uveitis (TINU) was established, and she was given prednisolone, with resolution of proteinuria and improvement in renal function. While TINU is rare but well described in children, it can also uncommonly be a cause of renal impairment in adults post COVID-19 infection, similar to cases in children.

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.

Acute neuroretinitis as a delayed manifestation of tubulointerstitial nephritis and uveitis syndrome

Purpose

Tubulointerstitial nephritis syndrome with uveitis (TINU) is a rare, acquired syndrome characterized by interstitial nephritis with bilateral uveitis. We report a case of TINU with typical bilateral anterior uveitis complicated by an atypical, delayed-onset neuroretinitis in a 12-year old patient.

Observation

A 12-year-old female with a 21-month history of TINU featuring chronic bilateral anterior uveitis presented with one week of blurred vision in her left eye. On exam she was found to have new-onset disc edema in the right eye and neuroretinitis in the left eye. After a negative infectious disease workup, the patient was treated with a course of intravenous (IV) solumedrol with prednisone taper and advancement of her systemic immunosuppression. In follow up she demonstrated resolution of her disc edema and neuroretinitis with improved visual acuity and clinical exam.

Conclusion

This case stresses the importance of monitoring for additional ocular manifestations including neuroretinitis years after the onset of anterior uveitis in TINU. In comparison to the two published cases of TINU with neuroretinitis, this case shares features of uveitis progression, and thus highlights the value of further description of TINU-associated neuroretinitis.

Tubulointerstitial Nephritis and Uveitis Syndrome: A Report of 6 Cases with Renal Biopsy and Electron Microscopy Evaluation

Tubulointerstitial nephritis with uveitis syndrome is a rare, immune-mediated entity, characterized by oculo-renal inflammation. Diagnosis requires the exclusion of all other causes of tubulointerstitial nephritis (TIN). We present 6 patients with clinical, laboratory, and renal biopsy findings denotative of tubulointerstitial nephritis with uveitis syndrome. All our patients experienced ocular and renal manifestations, defined by bilateral uveitis and photosensitivity, along with a decline of renal function. In some patients, increased serum creatinine was accompanied by non-nephrotic range proteinuria, glucosuria or "full-blown" Fanconi syndrome. The rest of the laboratory evaluation was normal apart from the presence of elevated erythrocyte sedimentation rate and increased urine β2-microglobulin, as well as normochromic, normocytic anemia in some cases. All patients underwent renal biopsy. Histochemical (PAS, Masson, silver, Congo-red) and immunohistochemical stains for immune cell populations (CD3, CD20, CD4, CD8, PGM1, CD138) and for the assessment of β2-microglobulin were conducted. Electron microscopy examination of the biopsies was also performed. Follow-up, ranging from 18 months to 10 years, was available for 4 patients. Histological evaluation revealed interstitial inflammatory infiltration consisting mainly of lymphocytes, with a T-cell predominance, along with several macrophages. Inflammation severity varied among different patients, with some showing scarce foci of immune cell clusters, while others demonstrated a dense, diffuse interstitial infiltration. Interestingly, in 2 cases, a granulomatous pattern, characterized by non-necrotic, ill-defined granulomas was detected. Tubulitis was also encountered in some patients. A divergence was noted regarding the chronicity index, with different levels of tubular atrophy, interstitial fibrosis, and global glomerulosclerosis among different cases. β2-Microglobulin immunohistochemical evaluation revealed a substantial diminishment of cytoplasmic staining in tubular epithelial cells compared to control kidneys. The most notable finding derived from electron microscopy examination was the presence, in 1 patient, of scattered granular electron-dense deposits along some tubular basement membranes. First-line treatment included steroids, supplemented in some cases by additional immunosuppressive agents. Three patients experienced a partial or complete response, while progressive renal damage was observed in a case with severe chronic lesions and persistence of inflammation-triggering factor. Our cases seem to represent progressive stages within the continuum of disease evolution. Patients with more prominent inflammation might represent a more initial state, while those with a more severe chronicity index, probably depict more advanced stages. While the predominance of T-cells predicates a cell-mediated autoimmune mechanism, as the driving force of the disease occurrence, the presence of immune complexes in more advanced stages might indicate the involvement of humoral immunity as a late event during the disease course.