Recurrent acute interstitial nephritis: what lies beneath

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

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

Management of corticosteroid-dependent eosinophilic interstitial nephritis: A case report

INTRODUCTION

Drug-induced acute interstitial nephritis (DI-AIN) is an important cause of acute kidney injury. In renal biopsy specimens, tubulitis with eosinophilic infiltration is suggestive of DI-AIN. Although corticosteroid therapy and discontinuation of the offending drug can improve renal dysfunction in most cases of DI-AIN, some patients experience AIN recurrence, leading to corticosteroid dependency. Corticosteroid-dependent eosinophilic interstitial nephritis presents a difficult dilemma in diagnosis and information regarding optimum management is limited.

PATIENT CONCERNS

A 25-year-old man, who received treatment with carbamazepine, zonisamide, valproate, and lacosamide for temporal lobe epilepsy, showed an increase in serum creatinine level from 0.98 to 1.29 mg/dL over a period of 6 months. Although he exhibited no symptoms, his serum creatinine level continued to increase to 1.74 mg/dL.

DIAGNOSIS

Renal biopsy revealed tubulitis and interstitial inflammatory infiltrates with eosinophils. Immunological and ophthalmological examinations showed no abnormal findings, and thus, his renal dysfunction was presumed to be caused by DI-AIN. Although oral prednisolone (PSL) administration (40 mg/d) and discontinuation of zonisamide immediately improved his renal function, AIN recurred 10 months later. The increase in PSL dose along with discontinuation of valproate and lacosamide improved renal function. However, 10 months later, recurrent AIN with eosinophilic infiltration was confirmed by further biopsy. The patient was therefore diagnosed with corticosteroid-dependent eosinophilic interstitial nephritis.

INTERVENTIONS

To prevent life-threatening epilepsy, carbamazepine could not be discontinued; hence, he was treated with an increased dose of PSL (60 mg/d) and 1500 mg/d of mycophenolate mofetil (MMF).

OUTCOMES

MMF was well tolerated and PSL was successfully tapered to 5 mg/d; renal function stabilized over a 20-month period.

LESSONS

The presence of underdetermined autoimmune processes and difficulties in discontinuing the putative offending drug discontinuation are contributing factors to corticosteroid dependency in patients with eosinophilic interstitial nephritis. MMF may be beneficial in the management of corticosteroid-dependent eosinophilic interstitial nephritis by reducing the adverse effects related to high-dose and long-term corticosteroid use.

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

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