Acute interstitial nephritis superimposed on glomerulonephritis: report of a case

A case of acetaminophen-induced acute tubulointerstitial nephritis in adult

We report a case of allergic acute tubulointerstitial nephritis (TIN) induced by acetaminophen in a 48-year-old Japanese man with no past medical history. Two days after receiving the non-steroidal anti-inflammatory drug (NSAID) loxoprofen for left shoulder pain, he developed cold symptoms such as fever and sore throat. He then took a 300 mg dose of acetaminophen three times a day and a 100 mg dose of minocycline hydrochloride twice a day for 7 days. Because there was no improvement in his symptoms, he consulted a local clinic again, where blood tests revealed renal insufficiency, and he was, then, referred to our hospital for evaluation of kidney function. Renal biopsy revealed acute TIN, and Ga-67 scintigraphy showed diffuse uptake in bilateral kidneys. A drug-induced lymphocyte stimulation test (DLST) was positive for acetaminophen and negative for loxoprofen and minocycline. Based on these findings, we made a diagnosis of acetaminophen-induced TIN. We treated the patient with three courses of semi-pulse steroid therapy, after which his fever went down, and his serum creatinine level recovered from 2.09 to 1.43 mg/dL. Although we medical doctors think that therapeutic dose of acetaminophen retains high safety, it is important to keep in mind that acetaminophen can cause allergic acute TIN.

The role of molecular genetics in diagnosing familial hematuria(s)

Familial microscopic hematuria (MH) of glomerular origin represents a heterogeneous group of monogenic conditions involving several genes, some of which remain unknown. Recent advances have increased our understanding and our ability to use molecular genetics for diagnosing such patients, enabling us to study their clinical characteristics over time. Three collagen IV genes, COL4A3, COL4A4, and COL4A5 explain the autosomal and X-linked forms of Alport syndrome (AS), and a subset of thin basement membrane nephropathy (TBMN). A number of X-linked AS patients follow a milder course reminiscent of that of patients with heterozygous COL4A3/COL4A4 mutations and TBMN, while at the same time a significant subset of patients with TBMN and familial MH progress to chronic kidney disease (CKD) or end-stage kidney disease (ESKD). A mutation in CFHR5, a member of the complement factor H family of genes that regulate complement activation, was recently shown to cause isolated C3 glomerulopathy, presenting with MH in childhood and demonstrating a significant risk for CKD/ESKD after 40 years old. Through these results molecular genetics emerges as a powerful tool for a definite diagnosis when all the above conditions enter the differential diagnosis, while in many at-risk related family members, a molecular diagnosis may obviate the need for another renal biopsy.

Familial C3 glomerulopathy associated with CFHR5 mutations: clinical characteristics of 91 patients in 16 pedigrees

BACKGROUND AND OBJECTIVES

Complement factor H and related proteins (CFHR) are key regulators of the alternative complement pathway, where loss of function mutations lead to a glomerulopathy with isolated mesangial C3 deposits without immunoglobulins. Gale et al. (12) reported on 26 patients with the first familial, hematuric glomerulopathy caused by a founder mutation in the CFHR5 gene in patients of Cypriot descent living in the United Kingdom. CFHR5 nephropathy is clinically characterized by continuous microscopic hematuria whereas some patients present with additional episodes of synpharyngitic macrohematuria, associated with infection and pyrexia. A subgroup of patients, particularly men, develop additional proteinuria, hypertension, and chronic renal disease or ESRD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We herewith expand significantly on the study by Gale et al., reporting on histologic, molecular, and clinical findings in 91 patients from 16 families with the same founder mutation.

RESULTS

Eighty-two patients (90%) exhibited microscopic hematuria; 51 (62%), exhibited only microscopic hematuria, whereas the remaining 31 additionally had proteinuria (38%); 28 proteinuric patients developed chronic renal failure (CRF). Among carriers of CFHR5 mutation aged >50 years, 80% of the men and 21% of the women developed CRF; 18 developed ESRD (14 men [78%], 4 women [22%]).

CONCLUSIONS

The diagnosis of CFHR5-related, isolated C3 glomerulopathy was established in 2009 using newly described mutation analysis after decades of follow-up with unclear diagnoses, occasionally confused with IgA nephropathy. This larger patient cohort establishes the clinical course, significant variable expressivity, and marked gender difference regarding the development of CRF and ESRD.

Acute glomerulonephritis superimposed on focal segmental glomerulosclerosis: a case report

A 9-year-old boy was referred to our hospital because of significant hematuria and proteinuria associated with hypocomplementemia. Although he had had a 3-year history of asymptomatic persistent proteinuria detected by urine screening of school children, he did not visit a physician. Finally, he visited a regional hospital, and hypocomplementemia was noted there. A percutaneous renal biopsy performed hospital day 4 revealed diffuse endocapillary proliferative glomerulonephritis with severe tubulointerstitial changes. Although his hematuria and hypocomplementemia spontaneously subsided within a month, proteinuria remained. A renal biopsy performed 4 months after the first renal biopsy revealed the lesion suggesting advanced focal segmental glomerulosclerosis (FSGS). Despite corticosteroid treatment, his proteinuria persisted, and he developed end stage renal failure. These clinical observation indicated that he had acute glomerulonephritis (AGN) superimposed on non-nephrotic FSGS, and that the episode of AGN might cause exacerbation of the FSGS.

Acute tubulointerstitial nephritis: phenotype of infiltrating cells and prognostic impact of tubulitis

The prognostic impact of tubulitis and the phenotype of the infiltrating cells in the tubules were studied in ten percutaneous renal biopsies from six patients with acute tubulointerstitial nephritis (ATIN). The inflammatory cell subsets in the tubules and interstitium (CD3+, CD4+, CD8+, CD20+, CD45RO+, CD56+, CD57+, CD68+ and TIA-1+ cells), the expression of vimentin and the proliferation-associated antigen Ki-67 by cortical tubular cells, and the grade of tubulitis, interstitial infiltration and fibrosis were analysed. Cytotoxic injury to tubular cells in the vicinity of tubular-wall-localized lymphocytes was studied ultrastructurally. ATIN was drug-induced in three patients, related to Legionella infection in two and idiopathic in one patient. Four patients recovered, one with reduced renal function. Two patients developed end-stage renal disease. CD8+ and CD4+ lymphocytes, and a smaller number of macrophages, infiltrated the tubules. The predominant lymphocyte subset in the tubules was the same as in the interstitium. Cytotoxic injury to tubular cells was not seen electron microscopically. The tubular cells exhibited increased proliferative activity and expressed vimentin, indicating non-specific tubular damage. The cell subset, the severity of tubulitis, and the tubular expression of vimentin were not related to outcome. The main prognostic factor was the severity of the interstitial fibrosis. Tubulitis in ATIN may be a harmless non-immune reaction, mediated by tubular expression of cytokines, together with adhesion and other molecules.

Tubulointerstitial nephritis

Tubulointerstitial nephritis (TIN) describes a range of pathological processes that are at least partly responsible for the progression of renal disease of nearly all aetiologies. TIN is frequently the most important pathological manifestation of progressive glomerulonephritis, obstructive uropathy, reflux nephropathy and cystic diseases, although it may also present as a primary disease process associated with infection, drug use or other immunologically mediated disease. Recent clinical and laboratory research has increased our knowledge of tubulointerstitial structure, physiological function and tubulointerstitial response to injury. This review presents a classification of TIN in which acute and chronic tubulointerstitial diseases are recognized as forming a continuum. Primary TIN and TIN associated with glomerulonephritis, obstructive nephropathy and chronic progressive renal disease are discussed from both clinical and pathogenic aspects. It is argued that chronic TIN is a disease process in which inflammation is accompanied by a destructive tubulopathy and fibrogenesis. In acute TIN there is a cessation and reversal of this process. It is suggested that most forms of TIN have an immunological basis because of the presence of immune cell infiltrates, the occurrence of TIN in several immune diseases and immunological animal models of TIN. However, to date TIN has not been convincingly modified in patients by immune manipulation. Experimental evidence suggesting an important pathogenic role for proteinuria and antigenuria, and the renal tubule cell acting as an antigen-presenting cell is discussed.