Immune checkpoint inhibitors induce acute interstitial nephritis in mice with increased urinary MCP1 and PD-1 glomerular expression

INTRODUCTION

Immune checkpoint inhibitors (ICIs) induce acute interstitial nephritis (AIN) in 2-5% of patients, with a clearly higher incidence when they are combined with platinum derivatives. Unfortunately, suitable disease models and non-invasive biomarkers are lacking. To fill this gap in our understanding, we investigated the renal effects of cisplatin and anti-PD-L1 antibodies in mice, assessing PD-1 renal expression and cytokine levels in mice with AIN, and then we compared these findings with those in AIN-diagnosed cancer patients.

METHODS

Twenty C57BL6J mice received 200 µg of anti-PD-L1 antibody and 5 mg/kg cisplatin intraperitoneally and were compared with those receiving cisplatin (n = 6), anti-PD-L1 (n = 7), or saline (n = 6). After 7 days, the mice were euthanized. Serum and urinary concentrations of TNFα, CXCL10, IL-6, and MCP-1 were measured by Luminex. The kidney sections were stained to determine PD-1 tissue expression. Thirty-nine cancer patients with AKI were enrolled (AIN n = 33, acute tubular necrosis (ATN) n = 6), urine MCP-1 (uMCP-1) was measured, and kidney sections were stained to assess PD-1 expression.

RESULTS

Cisplatin and anti PD-L1 treatment led to 40% AIN development (p = 0.03) in mice, accompanied by elevated serum creatinine and uMCP1. AIN-diagnosed cancer patients also had higher uMCP1 levels than ATN-diagnosed patients, confirming our previous findings. Mice with AIN exhibited interstitial PD-1 staining and stronger glomerular PD-1 expression, especially with combination treatment. Conversely, human AIN patients only showed interstitial PD-1 positivity.

CONCLUSIONS

Only mice receiving cisplatin and anti-PDL1 concomitantly developed AIN, accompanied with a more severe kidney injury. AIN induced by this drug combination was linked to elevated uMCP1, consistently with human AIN, suggesting that uMCP1 can be potentially used as an AIN biomarker.

NSC828779 Alleviates Renal Tubulointerstitial Lesions Involving Interleukin-36 Signaling in Mice

Renal tubulointerstitial lesions (TILs), a common pathologic hallmark of chronic kidney disease that evolves to end-stage renal disease, is characterized by progressive inflammation and pronounced fibrosis of the kidney. However, current therapeutic approaches to treat these lesions remain largely ineffectual. Previously, we demonstrated that elevated IL-36α levels in human renal tissue and urine are implicated in impaired renal function, and IL-36 signaling enhances activation of NLRP3 inflammasome in a mouse model of TILs. Recently, we synthesized NSC828779, a salicylanilide derivative (protected by U.S. patents with US 8975255 B2 and US 9162993 B2), which inhibits activation of NF-κB signaling with high immunomodulatory potency and low IC50, and we hypothesized that it would be a potential drug candidate for renal TILs. The current study validated the therapeutic effects of NSC828779 on TILs using a mouse model of unilateral ureteral obstruction (UUO) and relevant cell models, including renal tubular epithelial cells under mechanically induced constant pressure. Treatment with NSC828779 improved renal lesions, as demonstrated by dramatically reduced severity of renal inflammation and fibrosis and decreased urinary cytokine levels in UUO mice. This small molecule specifically inhibits the IL-36α/NLRP3 inflammasome pathway. Based on these results, the beneficial outcome represents synergistic suppression of both the IL-36α-activated MAPK/NLRP3 inflammasome and STAT3- and Smad2/3-dependent fibrogenic signaling. NSC828779 appears justified as a new drug candidate to treat renal progressive inflammation and fibrosis.

New Biomarkers in Acute Tubulointerstitial Nephritis: A Novel Approach to a Classic Condition

Acute tubulointerstitial nephritis (ATIN) is an immunomediated cause of acute kidney injury. The prevalence of ATIN among the causes of acute kidney injury (AKI) is not negligible, especially those cases related to certain drugs. To date, there is a lack of reliable non-invasive diagnostic and follow-up markers. The gold standard for diagnosis is kidney biopsy, which shows a pattern of tubulointerstitial leukocyte infiltrate. The urinalysis findings can aid in the diagnosis but are no longer considered sensitive or specific. Atthe present time, there is a rising attentiveness tofinding trustworthy biomarkers of the disease, with special focus in urinary cytokines and chemokines that may reflect kidney local inflammation. Cell-based tests are of notable interest to identify the exact drug involved in hypersensitivity reactions to drugs, manifesting as ATIN. Certain single-nucleotide polymorphisms in HLA or cytokine genes may confer susceptibility to the disease according to pathophysiological basis. In this review, we aim to critically examine and summarize the available evidence on this topic.

Proteinuria in Dent disease: a review of the literature

BACKGROUND

Dent disease is a rare X-linked recessive proximal tubulopathy caused by mutations in CLCN5 (Dent-1) or OCRL (Dent-2). As a rule, total protein excretion (TPE) is low in tubular proteinuria compared with glomerular disease. Several authors have reported nephrotic-range proteinuria (NP) and glomerulosclerosis in Dent disease. Therefore, we aimed to analyze protein excretion in patients with documented CLCN5 or OCRL mutations in a systematic literature review.

DESIGN

PubMed and Embase were searched for cases with documented CLCN5 or OCRL mutations and (semi-)quantitative data on protein excretion. The most reliable data (i.e., TPE > protein-creatinine ratio > Albustix) was used for NP classification.

RESULTS

Data were available on 148 patients from 47 reports: 126 had a CLCN5 and 22 an OCRLmutation. TPE was not significantly different between both forms (p = 0.11). Fifty-five of 126 (43.7 %) Dent-1 vs 13/22 (59.1 %) Dent-2 patients met the definition of NP (p = 0.25). Serum albumin was normal in all reported cases (24/148). Glomerulosclerosis was noted in 20/32 kidney biopsies and was strongly related to tubulointerstitial fibrosis, but not to kidney function or proteinuria.

CONCLUSION

More than half of the patients with both forms of Dent disease have NP, and the presence of low molecular weight proteinuria in a patient with NP in the absence of edema and hypoalbuminemia should prompt genetic testing. Even with normal renal function, glomerulosclerosis and tubulointerstitial fibrosis are present in Dent disease. The role of proteinuria in the course of the disease needs to be examined further in longitudinal studies.

Pentraxin 3 Is Closely Associated With Tubulointerstitial Injury in Lupus Nephritis: A Large Multicenter Cross-Sectional Study

Lupus nephritis always elicits immune inflammatory tissue damages in kidney. Pentraxin 3 (PTX3), mainly produced at inflammatory sites, is known to be involved in the regulation of the innate immunity system. The aim of this study was to investigate the serum and urine levels of PTX3, and the expression of PTX3 in renal tissues in lupus nephritis patients from a large Chinese cohort.The study used cross-sectional survey and 288 active lupus nephritis patients, including discovery cohort and validation cohort, 115 systemic lupus erythematosus (SLE) patients without clinical renal involvement and 46 healthy controls were enrolled. Serum and urine PTX3 were screened by enzyme-linked immunosorbent assay (ELISA). The renal deposition of PTX3 was detected by immunohistochemistry and immunofluorescence.The average level of serum PTX3 in the discovery cohort of lupus nephritis was significantly higher than that in nonrenal involvement SLE group and normal controls (P < 0.001, P < 0.001, respectively), which was confirmed by the validation cohort. Serum PTX3 levels of 15 lupus nephritis patients in remission decreased significantly compared with that in active phase. Serum PTX3 levels were significantly higher in patients with hematuria (P = 0.014), leucocyturia (P = 0.002), acute renal failure (P = 0.001), and nephrotic syndrome (P = 0.036). There were significant correlations between serum PTX3 levels and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, serum creatinine value, renal pathological activity indices, and serum complement 3 (C3) in active lupus nephritis patients. The urinary PTX3 levels were significantly higher in active lupus nephritis patients compared with patients in remission and normal controls (P = 0.011, P = 0.008, respectively). There were significant associations between urinary PTX3 levels and multiple indices of tubulointerstitial lesions, including urinary KIM-1 (r = 0.368, P = 0.016), neutrophil gelatinase-associated lipocalin (NGAL) (r = 0.320, P = 0.039), microalbumin (r = 0.621, P = 0.003), transferring (r = 0.451, P = 0.040) levels and renal pathological indices scores, especially interstitial inflammation (r = 0.349, P = 0.025) in active lupus nephritis patients. A significant correlation was found between serum and urine PTX3 levels (r = 0.431, P = 0.006). PTX3 staining was mainly observed in tubulointerstitial areas of patients with lupus nephritis, and immunofluorescence study showed that PTX3 could colocalize with fibroblast in interstitium.Circulating and local PTX3 levels were significantly increased in patients with active lupus nephritis and might be a biomarker for the disease progression, especially of tubulointerstitial injury.

Simultaneous exposure to multiple heavy metals and glyphosate may contribute to Sri Lankan agricultural nephropathy

BACKGROUND

Sri Lankan Agricultural Nephropathy (SAN), a new form of chronic kidney disease among paddy farmers was first reported in 1994. It has now become the most debilitating public health issue in the dry zone of Sri Lanka. Previous studies showed SAN is a tubulo-interstitial type nephropathy and exposure to arsenic and cadmium may play a role in pathogenesis of the disease.

METHODS

Urine samples of patients with SAN (N = 10) from Padavi-Sripura, a disease endemic area, and from two sets of controls, one from healthy participants (N = 10) from the same endemic area and the other from a non-endemic area (N = 10; Colombo district) were analyzed for 19 heavy metals and for the presence of the pesticide- glyphosate.

RESULTS

In both cases and the controls who live in the endemic region, median concentrations of urinary Sb, As, Cd, Co, Pb, Mn, Ni, Ti and V exceed the reference range. With the exception of Mo in patients and Al, Cu, Mo, Se, Ti and Zn in endemic controls, creatinine adjusted values of urinary heavy metals and glyphosate were significantly higher when compared to non-endemic controls. Creatinine unadjusted values were significant higher for 14 of the 20 chemicals studied in endemic controls and 7 in patients, compared to non-endemic controls. The highest urinary glyphosate concentration was recorded in SAN patients (range 61.0-195.1 μg/g creatinine).

CONCLUSIONS

People in disease endemic area exposed to multiple heavy metals and glyphosate. Results are supportive of toxicological origin of SAN that is confined to specific geographical areas. Although we could not localize a single nephrotoxin as the culprit for SAN, multiple heavy metals and glyphosates may play a role in the pathogenesis. Heavy metals excessively present in the urine samples of patients with SAN are capable of causing damage to kidneys. Synergistic effects of multiple heavy metals and agrochemicals may be nephrotoxic.

[ROLE OF BIOMARKERS IN ESTIMATION OF RENAL TUBULOINTERSTITIAL TISSUE DAMAGE IN PATIENTS WITH CHRONIC GLOMERULONEPHRITIS]

AIM

to investigate the relationship between the levels of NGAL and IL-18 in.blood, urine and clinical, morphological parameters reflecting renal tubulointerstitial tissue damage (TTD) in patients with chronic glomerulonephritis (CGN).

MATERIALS AND METHODS

We examined 81 patients with CGN. Patients were divided into 2 groups according to the presence of arterial hypertension (AH). Levels of NGAL and IL-18 in blood and urine were determined by the immuno-enzymic method. Data of renal morphological study were used for the analysis of TTD.

RESULTS

In patients with CGN and AH we observed more pronounced morphological changes of renal TTD, what coincide with higher levels of NGAL and IL-18 in blood and urine. We found correlations between markers and morphological changes, what allow to use NGAL in blood and urine, IL-18 in blood to estimate renal TTD in CGN.

CONCLUSIONS

NGAL in blood most accurately reflects interstitial fibrosis (IF) and tubular basement membrane changes; NGAL in urine--tubular epithelium dystrophy. IL-18 in blood is an indicator of dystrophy and necrosis of the tubular epithelium, IF.

[Clinical value of the determination of markers for endothelial dysfunction (endothelin-1, microalbuminuria) and tubulointerstitial tissue lesion (β2-microglobulin, monocyte chemotactic protein-1) in hypertensive patients with uric acid metabolic disorders]

AIM

To identify the risk factors of kidney injuries in hypertensive patients with uric acid (UA) metabolic disorders in order to choose the optimal management tactics, by analyzing the changes in markers for endothelial dysfunction (endothelin-1 (ET-1), microalbuminuria (MAU), intima-media thickness (IMT)) and tubulointerstitial tissue lesion (beta2-microglobulin (beta2-MG, monocyte chemotactic protein-1 (MCP-1)).

SUBJECTS AND METHODS

Eighty-one patients with grade 1 hypertension without associated diseases, diabetes mellitus, or metabolic syndrome were examined. There were 3 study groups: 1) hyperuricosuria (n = 7); 2) hyperuricemia (n = 53); 3) hyperuricemia and renal failure (n = 6); and a control group of 15 hypertensive patients without UA metabolic disorders who were matched for age and gender with the patients of the study groups.

RESULTS

The hypertensive patients with hyperuricemia, as compared with those without UA metabolic disorders, showed higher plasma concentrations of ET-1 (p = 0.003) and MAU (p = 0.009) and more marked increases in common carotid IMT (p = 0.044), urinary excretion of beta2-MG (p = 0.010), and MCP-1 (p = 0.030). There were direct correlations between all the examined biomarkers and the degree of uricemia (Rs = 0.453; p < 0.001; Rs = 0.411; p < 0.001; Rs = 0.322; p = 0.067; Rs = 0.537; p < 0.001; and Rs = 0.318; p = 0.004, respectively) and between the markers of endothelial dysfunction and those of tubulointerstitial tissue lesion (Rs = 0.295 for ET-1 and MCP-1; p = 0.008; Rs = 0.399 for ET-1 and beta2-MG; p < 0.001; Rs = 0.462 for MAU and beta2-MG; p < 0.001; and Rs = 0.188 for MAU and MCP-1; p = 0.094). Multivariate analysis of the clinical and laboratory parameters under study confirmed the role of serum MCP-1, beta2-MG, MAU, creatinine levels as independent predictors for decreased relative urinary gravity, the clinical sign of tubulointerstitial tissue lesion/fibrosis, and that of a wider range of the indicators, such as MAU, ventricular septal thickness, glomerular filtration rate, relative urinary gravity, systolic blood pressure, MPC-1, low-density lipoproteins, as risk factors for renal filtrating dysfunction.

Urinary vitamin D binding protein: a potential novel marker of renal interstitial inflammation and fibrosis

Non-invasive tubulointerstitial damage markers may allow better titration and monitoring of renoprotective therapy. We investigated the value of urinary vitamin D binding protein excretion (uVDBP) as a tubulointerstitial inflammation and fibrosis marker in adriamycin rats, and tested whether uVDBP parallels renal damage and responds to therapy intensification in humans. In adriamycin (ADR) rats, uVDBP was strongly elevated vs controls (CON) already 6 wks after nephrosis induction (ADR: 727±674 [mean±SD] vs CON: 9±12 µg/d, p<0.01), i.e. before onset of pre-fibrotic and inflammatory tubulointerstitial damage, and at all following 6-wk time points until end of follow up at 30 wks (ADR: 1403±1026 vs CON: 206±132 µg/d, p<0.01). In multivariate regression analysis, uVDBP was associated with tubulointerstitial macrophage accumulation (standardized beta = 0.47, p = 0.01) and collagen III expression (standardized beta = 0.44, p = 0.02) independently of albuminuria. In humans, uVDBP was increased in 100 microalbuminuric subjects (44±93 µg/d) and in 47 CKD patients with overt proteinuria (9.2±13.0 mg/d) compared to 100 normoalbuminuric subjects (12±12 µg/d, p<0.001). In CKD patients, uVDBP responded to intensification of renoprotective therapy (ACEi+liberal sodium: 9.2±13.0 mg/d vs dual RAAS blockade+low sodium: 2747±4013, p<0.001), but remained still >100-fold increased during maximal therapy vs normoalbuminurics (p<0.001), consistent with persisting tubulointerstitial damage. UVDBP was associated with tubular and inflammatory damage markers KIM-1 (standardized beta = 0.52, p<0.001), beta-2-microglobuline (st.beta = 0.45, p<0.001), cystatin C (st.beta = 0.40, p<0.001), MCP-1 (st.beta = 0.31, p<0.001) and NGAL (st.beta = 0.20, p = 0.005), independently of albuminuria. UVDBP may be a novel urinary biomarker of tubulointerstitial damage. Prospectively designed studies are required to validate our findings and confirm its relevance in the clinical setting.

Interstitial nephritis with moderate-to-heavy proteinuria: an unusual combination

Interstitial nephritis with proteinuria >1 g/day is uncommon and almost always the result of drug-induced ATIN with an associated minimal change glomerulonephritis (GN). Here, we present a series of five unusual cases of interstitial nephritis without GN but with proteinuria >1 g/day, and they were identified from renal biopsies done from February 2008 to March 2009. Out of 236 patients who underwent renal biopsy, only five met the inclusion criteria. Three patients presented with edema and two with oliguria, while none had frank hematuria, fever, arthralgia, skin rash or history of exposure to nonsteroidal antiinflamatory drugs, analgesics, antibiotics, allopurinol, or Chinese herb before presentation. Urinalysis revealed hematuria in two patients, pyuria in three and nephrotic range proteinuria in two. All had normal complement levels and were negative for antinuclear antibodies, Anti-dsDNA antibody, and antineutrophil cyto-plasmic antibodies. Clinical diagnosis was nephrotic syndrome in two patients, the third had diagnosis of rapidly progressive GN, the fourth had HIV associated nephropathy, and the fifth had unexplained advanced renal failure. Though three patients had renal dysfunction only one required dialysis. Light microscopy of renal biopsies revealed granulomatous interstitial nephritis in three patients and small vessel vasculitis in two of them. One patient had nongranulomatous interstitial nephritis along with vasculitis. Acute interstitial nephritis was the only finding in one patient. In conclusion, patients with interstitial nephritis can present with moderate-to-heavy proteinuria probably due to cytokine-like permeability increasing factor secreted by inflammatory cells in the interstitium.

Diffuse tubulointerstitial nephritis accompanied by renal crystal formation in an HIV-infected patient undergoing highly active antiretroviral therapy

This report presents a human immunodeficiency virus (HIV) patient that developed a slowly progressive renal impairment over years under highly active antiretroviral therapy (HAART). The renal biopsy showed diffuse tubulointerstitial nephritis accompanied by crystal formations that were surrounded by multinuclear giant cells. Furthermore, rod-like crystals were detected in the urinary sediments. Tenofovir and Atazanavir were thought to be the causative drugs for the renal injury. Therefore, the possibility of HARRT-induced nephrotoxicity should be considered in HIV-infected patients, even though the activity of HIV is controlled by such therapies.

[Correlation between urinary biomarkers and pathological lesions in drug-induced tubulointerstitial nephritis]

OBJECTIVE

To find some urinary biomarkers for differential diagnosis in drug-induced tubulointerstitial nephritis (DTIN) by accessing the relationship between their changes and the pathological processes of DTIN.

METHODS

Forty patients biopsy-proven DTIN and 24 healthy controls were enrolled in this study. The urine samples of DTIN patients were collected on the day of biopsy and were measured for the following biomarkers: urinary TGF-β with enzyme-linked immunosorbent assay (ELISA); urinary IL-6 with radio-immunoassay; N-acetyl-β-D-glucosaminidase (NAG) with enzyme-substrate colorimetric assay; α1-microglobulin (α1-MG) with immune transmission turbidity method. Meanwhile, the pathological changes on renal biopsy were analyzed semi-quantitatively and scored. The relationship between these pathological changes and the urinary biomarkers were analyzed and receiver operating characteristic curve (ROC curve) of those biomarkers in distinguishing different pathological lesions were constructed.

RESULTS

Urinary α1-MG levels were positively correlated to interstitial edema, inflammatory cell infiltration and tubular atrophy, while urinary IL-6 were negatively correlated to the above parameters. Urinary NAG had positive relationship with inflammatory cell infiltration and tubular atrophy, while urinary TGF-β had positive relationship with tubular atrophy. ROC analysis results indicated that the area under curve (AUC) of α1-MG was larger than that of NAG (0.797 vs 0.734, P<0.05). Combined measurement of α1-MG and NAG could enhance the sensitivity of detecting interstitial inflammatory cell infiltration. For detecting interstitial edema and tubular atrophy, only α1-MG had statistical significance (AUC=0.723, P=0.027; AUC=0.774, P=0.008, respectively).

CONCLUSIONS

Urinary α1-MG and NAG levels can reflect the severity of interstitial inflammatory infiltration, combined measurement of both can enhance sensitivity. Urinary α1-MG level can also reflect the degree of interstitial edema and tubular atrophy.

[Significance of urinary biomarkers in differential diagnosis of acute tubulointerstitial nephritis]

OBJECTIVE

To find some urinary biomarkers with significance in the differentiation of drug-induced tubulointerstitial nephritis (DTIN).

METHODS

Forty patients with biopsy-proven DTIN were enrolled. The urine samples of DTIN patients were collected on the day of biopsy and all urine samples were measured for the following different biomarkers as indicated, respectively: urinary TGF-beta by ELISA; urinary IL-6 by radio-immunoassay; NAG by an enzyme-substrate colorimetric assay; alpha1-MG by immune transmission turbidity method. Receiver operating characteristic curves (ROC curve) were constructed to calculate the sensitivity and specificity of those biomarkers in distinguishing acute (A-DTIN) and chronic DTIN (C-DTIN).

RESULTS

Urinary NAG and alpha1-MG levels in patients with A-DTIN were as 2.5 and 2.1 times as those in C-DTIN (P<0.05), while urinary TGF-beta levels in the two groups had no statistical difference. The areas under ROC curve (AUC) of urinary NAG and alpha1-MG for differentiating A-DTIN were 0.720 (P=0.029) and 0.714 (P=0.034) respectively, while the AUCs for TGF-beta and IL-6 were 0.536 (P=0.767) and 0.150 (P=0.004) respectively. Combined measurement of NAG and alpha1-MG could make sensitivity and specificity reach 78.6% and 75.0 % respectively.

CONCLUSION

Urinary alpha1-MG and NAG levels can reflect the acute lesions of DTIN, and combined measurement of both could enhance efficiency in differentiating A-DTIN.

[Antihypertensive therapy optimization and endothelial function in patients with gout and chronic urate tubulointerstitial nephritis]

AIM

to characterize the markers of endothelial dysfunction and the effect of antihypertensive drugs on them in patients with chronic urate tubulointestinal nephritis (UTIN) and articular gout.

SUBJECTS AND METHODS

The study enrolled 81 patients aged 39 to 59 years with gout and urate nephropathy. All the patients were diagnosed as having grade 1-2 arterial hypertension. A lower glomerular filtration rate (GFR) was noted in 49.9%; microalbuminuria (MAU) and elevated serum endothelin-1 (ET-1) levels were recorded in all the patients. Combination antihypertensive therapy based on the use of angiotensin-converting enzyme (ACE) inhibitors and/or an angiotensin II receptor blocker (ARB) in combination with calcium channel blockers was performed during 12 months. The time course of changes in blood pressure, the parameters of target organ lesion, and the markers of endothelial dysfunction were monitored.

RESULTS

Before the study, all the examinees were found to have MAU and increased serum ET-1, which are regarded simultaneously as signs of renal lesion and as markers of endothelial function. A combination of an ACE inhibitor or an ARB could diminish albuminuria and reduce ET-1 concentrations, lower systolic and diastolic blood pressure significantly, and increase GFR.

CONCLUSION

The patients with articular gout and chronic UTIN are observed to have signs of endothelial dysfunction eliminated by combination antihypertensive therapy.

[Estimated methods of predicting risk of analgetic interstitial renal disease]

AIM

Screening of renal pathology and investigation of its dependence on intake of metamisol, the risk of nephritis associated with metamisol.

MATERIAL AND METHODS

The study included 1446 inpatients (mean age 49.63 +/- 0.43 years, 690 males--48%, 756 females--52%). Analysis of the urine, tests for urea, blood creatinine, estimation of glomerular filtration rate were made. Metamisol doses and duration of analgetic treatment were controlled in 658 patients. Statistical processing was made with Statistica 6.0 soft.

RESULTS

Of 1446 examinees, 346 (23.9%) patients took analgetics. Out of 98 patients treated with metamisol, 34 (34.7%) had pathology of urinary sediment, 18 (18.4%) had suppression of renal function (RF) while in patients untreated with analgetics this percentage was 7.4 and 16.1%, respectively, p < 0.05. In intake of metamisol from 0.5 to 5.0 kg and more changes in urine analysis parameters and regress of RF were more prominent than in intake up to 0.5 kg (p < 0.05). Application of nonlinear logistic regression analysis provided equations of logistic regression making it possible to assess probability of changes in urine analysis and renal function decline depending on the drug dose and duration of its intake.

CONCLUSION

Inpatients often take analgetic drugs, especially metamisol. Its high doses are associated with risk of renal function decline and pathology of urinary sediment. Equations of calculation of renal affection risk in administration of metamisol are presented.

Urinary excretion of monocyte chemoattractant protein-1: a biomarker of active tubulointerstitial damage in patients with glomerulopathies

BACKGROUND/AIMS

The urinary concentration of the monocyte chemoattractant protein-1 (uMCP-1) chemokine is increased in several proteinuric and/or inflammatory renal diseases. In the present study, we evaluated the association between uMCP-1 and renal function, proteinuria, glomerular and interstitial macrophage infiltration, and renal fibrosis in patients with primary and secondary glomerulopathies diagnosed by renal biopsy.

METHODS

Thirty-seven patients aged 32.6 +/- 7.7 years were studied. uMCP-1 was determined by ELISA. Renal macrophage expression (CD68 positive cells) is reported as number of macrophages/10(4) microm2 of the cortical tubulointerstitial (TI) area or of glomerular capillary tuft area. Cortical interstitial fibrosis was quantitated by PicroSirius red staining under polarized light by a computerized manner.

RESULTS

The uMCP-1 ratio (pg/ml/urinary creatinine mg/ml) was positively correlated (Spearman coefficient) with proteinuria (r = 0.4629; p < 0.005) and number of macrophages in the cortical TI area (r = 0.64; p = 0.0005), and negatively correlated with creatinine clearance (r = -0.4877; p < 0.001). The uMCP-1 ratio was not significantly correlated with number of macrophages/glomerular capillary tuft area (r = 0.27; p = 0.19) or with percent cortical interstitial fibrosis (r = 0.08; p = 0.62).

CONCLUSIONS

The uMCP-1 excretion is a biomarker of the inflammatory activity of the TI area, and does not reflect chronic interstitial damage.

Karyomegalic interstitial nephritis: a pitfall in urine cytology

A case of a 44-yr-old Maori female presenting with chronic renal failure due to karyomegalic interstitial nephritis is reported. To our knowledge, this is the first instance this disorder has been reported in a New Zealand Maori. Karyomegalic interstitial nephritis is a rare cause of progressive renal failure, which may be familial, and is frequently associated with a history of recurrent respiratory infections. The urine in this case contained large, pleomorphic cells, mimicking carcinoma. The case therefore illustrates a rare cause of chronic renal failure, and presents an important diagnostic pitfall in the practice of urine cytopathology.

Tubulointerstitial nephritis causes decreased renal expression and urinary excretion of cauxin, a major urinary protein of the domestic cat

Cauxin, a member of mammalian carboxylesterases (EC 3.1.1.1), is excreted as a major urinary protein in the domestic cat. Urinary cauxin is derived from the kidney proximal straight tubules. Here, we report changes in the renal expression and urinary excretion of cauxin in cats with tubulointerstitial nephritis (TIN). Immunohistochemistry using anti-cauxin antibody showed fewer cauxin-positive tubules in 15 TIN cases than in normal animals. In areas with tubulointerstitial damage, fibroblasts and inflammatory cells replaced renal tubules, and cauxin-positive tubules consequently disappeared. Urine was analysed in six of the 15 cases. In the two cases with mild tubulointerstitial changes, urinary cauxin was detected using SDS-PAGE with Coomassie staining. In the four cases with severe tubulointerstitial changes, urinary cauxin was below the detection limit using Western blotting. These results indicate that the renal expression and urinary excretion of cauxin decrease with the progression of TIN in cats.

Glomerular and tubular epithelial defects in kd/kd mice lead to progressive renal failure

BACKGROUND/AIM

The kd/kd mouse spontaneously develops severe and progressive nephritis leading to renal failure, characterized by cellular infiltration, tubular destruction and glomerular sclerosis. Recent identification of the mutant gene and the observation that podocytes are affected, led to the hypothesis that there are primary renal epithelial cell defects in this strain.

METHODS

Clinical and pathological signs of disease in a large cohort of kd/kd mice were studied by light microscopy, electron microscopy, and biochemical analyses of serum and urine at early stages of disease. Special attention was paid to mice under 140 days of age that had normal blood urea nitrogen (BUN) levels, but had developed albuminuria.

RESULTS

Although overt glomerular abnormalities are commonly observed either coincident with or after tubulointerstitial nephritis, we now report that albuminuria and visceral epithelial abnormalities, including hyperplasia and podocyte effacement may occur before the onset of either elevated BUN levels or severe interstitial nephritis, and this is accompanied by biochemical perturbations in serum typical of the nephrotic syndrome.

CONCLUSIONS

The results suggest that the defect in kd/kd mice primarily affects both the tubular and glomerular visceral epithelium. The tubular epithelial defect triggers autoimmune interstitial nephritis, whereas a defect in podocytes leads to proteinuria and glomerulosclerosis. Thus, a single mitochondrial abnormality may result in differences in disease expression that vary with the type of epithelial cells. It is likely that the mitochrondrial perturbations in glomerular and tubular epithelia act in concert, through activation of different pathologic pathways, to accelerate disease progression leading to renal failure.

Detection and quantitation of BK virus DNA by real-time polymerase chain reaction in the LT-ag gene in adult renal transplant recipients

Determination of polyomavirus BK (BKV) load in urine and plasma has been advocated for monitoring adult renal transplant recipients suffering from BKV-related nephropathy. An "in-house" real-time quantitative PCR assay was developed using the BKV-1/BKV-3 primers set in the large tumor antigen (LT-ag) region to quantitate BK virus loads in plasma and urine in renal transplant patients. This assay was adapted to routine virology laboratory by evaluating two extraction procedures of nucleic acids from urine and plasma, one manual and the other using an automatic extractor, and by evaluating the Light Cycler versus Taqman apparatus. Both the manual and automatic extraction procedures and real-time PCR apparatus were equivalent. The Light Cycler and Taqman instruments allow similarly rapid, accurate, reproducible and specific quantitative detection of the three major BKV subtypes, with a detection limit of 10 BKV DNA copies/ml, and a range from 10(0) to 10(7) copies/ml. Of 855 renal transplant patients, 128 (15%) had BKV DNA in both plasma and urine samples with a mean viral load of 5.1 log/ml in plasma and 6.8 log/ml in urine and in 5 (4%) BKV-associated tubulo-interstitial nephropathy; 332 (39%) BKV DNA was found only in the urine, not in the plasma, without further development of nephropathy and 395 patients had no BKV in plasma and urine. These observations emphasize the usefulness of real-time PCR to assess the BKV load by routine testing, and confirm the need to combine both plasma and urine determinations of the BKV DNA load in order to identify renal transplant patient at high risk for BKV-associated nephropathy.

A Case of Tubulointerstitial Nephritis and Uveitis in an Adult Male

We report a case of tubulointerstitial nephritis and uveitis (TINU) syndrome in an adult male. A 40-year-old man was found to have bilateral anterior uveitis and mild renal insufficiency with high urinary beta-2 microglobulin. Work up for connective tissue and infectious diseases were negative. His kidney function normalized spontaneously and remained normal at 1 year without intervention. Uveitis responded completely to local corticosteroid treatment and has not recurred.

Ochratoxin A and β2-microglobulinuria in healthy individuals and in chronic interstitial nephropathy patients in the Centre of Tunisia: a hot spot of Ochratoxin A exposure

Ochratoxin A (OTA) is a nephrotoxic mycotoxin considered to be the causal agent of the Balkan endemic nephropathy (BEN). In Tunisia, a chronic interstitial nephropathy (CIN) of unknown aetiology, resembling BEN, has been characterised wherein OTA seems to be implicated too. However, despite the considerable number of investigations conducted so far, the role of OTA in the outcome of this human nephropathy is still uncertain. In this study, an attempt is being made to consolidate the link between OTA and the Tunisian CIN of unknown aetiology. Blood OTA and beta(2)-microglobulinuria levels were measured in several groups of healthy individuals and patients having different renal diseases of known and unknown aetiologies (100 nephropathy patients and 40 healthy subjects). The high blood OTA and beta(2)-microglobulinuria levels seem to be strongly associated to the CIN of unknown aetiology. Our results support the involvement of this nephrotoxic agent in the outcome of this particular human nephropathy and underline furthermore the importance of beta(2)-microglobulinuria in the characterization of this disease.

Repeat renal biopsy in children with severe idiopathic tubulointerstitial nephritis

Idiopathic (primary) tubulointerstitial nephritis (TIN) of childhood is relatively rare. Four children, two with concomitant uveitis, aged 8-14 years, with idiopathic TIN who underwent repeat renal biopsy were retrospectively evaluated. At presentation, all had a significant elevation of the urinary beta(2)-microglobulin/creatinine ratio (beta2MG ratio), ranging from 10100 to 44550, with increased histological indices of tubulointerstitial scores (TI scores) in excess of 6 points. Three of the children received prednisolone (PSL) therapy following diagnosis, while the remaining child received the therapy 30 months after the first renal biopsy. In the children that received prompt PSL therapy, a rapid decrease in urinary beta2MG ratio was observed and the TI scores obtained at a mean interval of 16 months after the first biopsy decreased to less than 5, while preserving renal function. In the remaining child that received delayed PSL therapy, persistent elevations of urinary beta2MG ratio and TI scores were observed. He subsequently progressed to chronic renal insufficiency. These clinical findings suggest that persistent elevations of urinary beta2MG ratio and TI scores are indicators of progression of renal failure in TIN. For successful treatment, early therapeutic intervention should be deployed in selected patients with severe idiopathic TIN.

Characterization of renal damage in canine leptospirosis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting of the urinary proteins

Canine leptospirosis is a zoonotic disease that can cause interstitial nephritis. As a consequence of the renal damage, proteinuria may occur. To determine the urine protein pattern in the disease we performed sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) on the urine from 10 dogs with leptospirosis and 20 healthy dogs. Western blotting analysis of the urine samples with antibodies against canine IgG and IgA was also performed to identify these immunoglobulins in the urine. Urine electrophoresis showed three new bands in the dogs suffering from leptospirosis. Only two of the dogs with leptospirosis showed detectable concentrations of IgG and IgA in urine, while a third animal showed IgG alone. The study showed a 36.7% increase in the excretion of low molecular weight proteins in dogs with leptospirosis but almost no change in the high molecular weight protein pattern. These results, together with the low number of animal with detectable concentrations of IgG and IgA in the urine, support the view that canine leptospirosis is characterized by interstitial nephritis.

Urinary excretion of complement C3d in patients with renal diseases

INTRODUCTION

Complement-mediated tubular injury may play an important role in the progression of renal diseases. C3d is a presumed marker of complement activation. Its precursor C3dg has been detected in the urine of patients with membranous nephropathy. However, little is known of the renal handling of C3d or its excretion in other renal diseases.

METHODS

We measured the urinary excretion of albumin, IgG, beta2-microglobulin (beta2m), and of complement C3d in patients with tubulo-interstitial nephritis (TIN; n= 8), in patients with membranous nephropathy (n = 35) and in patients with nonmembranous glomerular diseases (23 nonproliferative and 21 proliferative). Fractional excretions (FE) were calculated using creatinine clearance as marker of GFR.

RESULTS

C3d was not measurable in the urine of the healthy controls, but was detectable in seven out of eight of the TIN patients (median excretion 0.11 mU min-1, range 0.006-2.4 mU min-1). In these patients the urinary excretion of beta2m was clearly elevated (median 26.6 micro g min-1, range 1.0-103 micro g min-1). The FE of C3d correlated with the FE of beta2microglobulin (r = 0.83, P = 0.01), and their ratio amounted to 0.03 (range 0.003-0.06), a value in agreement with the expected sieving coefficient. Urine C3d was detectable in all but three of the patients with glomerular diseases (median excretion 0.36 mU min-1, range 0.004-7.9 mU min-1); C3d-excretion did not differ between the three subgroups of patients with glomerular diseases. FEC3d correlated with FEIgG (r = 0.88, P < 0.01). The ratio FEC3d/FEbeta2m was 0.78 (range 0.04-9.99). Selected patients with membranous nephropathy were re-analyzed after (partial) remission of proteinuria. Reduction of proteinuria resulted in a decrease of C3d excretion.

CONCLUSION

Urinary excretion of C3d is elevated in patients with TIN, most likely as a mere consequence of decreased tubular reabsorption. In patients with glomerular diseases urinary excretion of C3d is increased and related to proteinuria, independent of the underlying glomerular disease. In these patients there is evidence of increased local formation of C3d.

Urinary retinol binding protein in Indo-Asian patients with idiopathic interstitial nephritis

BACKGROUND

Idiopathic interstitial nephritis (IIN) is common in the UK Indo-Asian population. Lack of systemic involvement and unremarkable urinalysis on stick testing suggest that it may underlie some cases of end-stage renal failure of undetermined cause. If IIN is diagnosed early, prompt initiation of treatment can improve long-term outcome.

AIMS

To investigate whether urinary retinol binding protein (RBP) is elevated more commonly than urinary albumin in IIN, and might be useful in the early detection of renal disease in Indo-Asian patients.

DESIGN

Preliminary observational study

METHODS

We measured urinary RBP and urinary albumin in 19 Indo-Asian patients in whom a renal biopsy had shown IIN, 10 of whom had already been treated with corticosteroids at the time of specimen collection. A further 28 Indo-Asian patients with glomerular disease, and six with normal light-microscopic renal biopsy, were assessed in parallel.

RESULTS

Urinary RBP/creatinine ratio (RCR) was elevated in all 19 cases of IIN, compared to 12/19 in whom the albumin/creatinine ratio (ACR) was elevated. Elevated urinary RBP was thus significantly more common than albuminuria in this group (p<0.01). Twelve of the 19 cases also satisfied the criteria for tubular proteinuria. RCR was elevated to >30 times the upper limit of normal in 7/9 who had not previously received corticosteroids, of whom four had normal ACR; none had ACR >5 times the upper limit of normal.

DISCUSSION

These data suggest that measurement of urinary RBP should be explored as an adjunct to albuminuria, if screening for renal disease in the Indo-Asian population is contemplated.

Urinary complement factor H in renal disease

BACKGROUND

Complement factor H (hCFH) plays a key inhibitory role in the control of the alternative complement pathway. We examined whether urinary hCFH (U-hCFH) levels is useful as an indirect indicator of renal damage.

METHODS

Urine samples were obtained from 104 patients with renal disease. Urine was collected with 10 mM EDTA and U-hCFH levels were measured using the BTA TRAK Assay Kit.

RESULTS

In the 62 patients with nephritis, the levels of U-hCFH were elevated (range 15-52,198 U/ml) over the normal range (0-14 U/ml). U-hCFH levels of patients with chronic renal failure, lupus nephritis, membranoproliferative glomerulonephritis, focal glomerulosclerosis were higher than that of IgA nephropathy patients (p < 0.05). In the patients with minimal change disease, showed high levels of U-hCFH during the nephrotic syndrome. U-hCFH was correlated significantly with urinary protein and urinary N-acetyl-beta-D-glucosaminidase.

CONCLUSIONS

We demonstrated that U-hCFH was detected in the urine of nephritis patients.

Cellulose acetate membrane electrophoresis in the analysis of urinary proteins in patients with tubulointerstitial nephritis

Urinary proteins from 14 patients with tubulointerstitial nephritis were analyzed by cellulose acetate membrane electrophoresis. Urinary total protein concentrations were measured, and urinary 15 proteins (prealbumin, albumin, alpha(1)-microglobulin, alpha(1)-antitrypsin, alpha(2)-macroglobulin, haptoglobin, retinol binding protein, transferrin, beta(2)-microglobulin, IgA, IgG, kappa- and lambda-light chains, cystatin C, and lysozyme) were identified by the use of a rapid and highly sensitive colloidal silver staining reagent suited for use with cellulose acetate membranes, as reported previously by Matsuda et al. (J Clin Lab Anal 15:171-174, 2001; Clin Chem47:763-766, 2001) and Hiratsuka et al. (J Clin Lab Anal 10:403-406, 1996). We also analyzed urinary total protein concentration and urinary protein fractions according to the presence of acute or nonacute interstitial nephritis. In addition, the relationship between urinary protein fraction and complications of interstitial nephritis was analyzed. The goal of this work was to find a useful index for the diagnosis of tubulointerstitial nephritis.

Proteinuria inducing tubulointerstitial damage

Introduction Glomerular basal membrane represents a mechanical and electric barrier for plasma proteins. In physiological conditions only plasma proteins of low molecular weight are completely filtered through basal membrane. Due to damages of glomerular basal membrane there is an increase in filtration of plasma proteins of moderate and high molecular weight. Proteinuria In regard to its etiology proteinuria can be prerenal, renal and postrenal. By analyzing albumin, 1-microglobulin, immunoglobulin G and 2-macroglobulin, together with total protein in urine, it is possible to detect and differentiate causes of prerenal, glomerular, tubular and postrenal proteinuria. Abnormal glomerular permeability to macromolecules results in excessive protein delivery and reabsorption in proximal tubules. Excessive reabsorption in turn may cause congestion of intracellular endocytic and biosynthetic compartments leading to NFkB-dependent and -independent gene upregulation. Among those genes, monocyte chemoattractant protein-1 (MCP-1), cytokines, osteopontin and endothelin stimulate processes of interstitial inflammation and fibroblast proliferation and are ultimately responsible for enhanced extracellular matrix deposition and renal scarring. Human tubular cells exposed to albumin and HDL increase production of endothelin-1. Endothelin-1 affects microcirculation and fibroblasts and is a monocyte chemoattractant. Specific proteins that are cytotoxic are transferrin/iron, low-density lipoprotein, and complement components, all of which appear in urine in proteinuric states. Adequate and early diagnosis and differentiation of proteinuria are of immense therapeutic importance.

Drug-induced acute tubulointerstitial nephritis: a case with elevated urinary cadmium

Acute tubulointerstitial nephritis (ATIN) has many different causes, but is most frequently caused by drugs. We report a 13-year-old vegetarian girl with drug-induced ATIN, confirmed by renal biopsy, and simultaneous occurrence of elevated urinary cadmium. Four weeks prior to admission she had been treated with antibiotics and acetaminophen for respiratory infection, and remaining febrile, was treated with different "home-made" herbal mixtures. She presented with acute non-oliguric renal failure, tubular dysfunction, and sterile pyuria, but without skin rash or edema. Laboratory data showed a raised erythrocyte sedimentation rate, normal white blood count with eosinophilia, and a serum creatinine of 245 micromol/l. Urinalysis was remarkable for glycosuria, tubular proteinuria, and elevated beta(2)-microglobulin and N-acetyl-beta-D-glucosaminidase excretion. Immunoserological tests characteristic of acute glomerulonephritis and systemic diseases were negative. She was treated with steroids and her renal function improved. Follow-up analyses disclosed normal urinary cadmium and enzyme excretion within 6 months. Heavy metal analysis of herbal preparations that she had taken confirmed the presence of cadmium, but within approved concentrations. In conclusion, elevated urinary cadmium in the case of drug-induced ATIN may be assumed to be an accidental finding. However, consumption of different herbs containing cadmium and cadmium-induced nephro-toxicity could be the reason for such serious renal damage.

Urine laminin and kallikrein, markers of tubulointerstitial damage in experimental protein overload on pre-existing renal damage

We studied the response of urinary protein overload on preexisting tubulointerstitial nephritis (TIN), which was induced in male Sprague Dawley rats by hexachloro-1,3-butadiene (HCBD). Five days after the development of TIN, puromycin aminonucleoside (PAN) was administered to induce urinary protein overload. Urinary laminin and kallikrein were measured. Urine specimens were collected daily for 14 days and on day 21; and tissue specimens were collected on days 1, 4, 7, 10, 14 and 21. Urinalysis was correlated with the renal pathology at the light microscopic level. Laminin excretion was increased on day 4; one day before total protein, indicating damage to the basement membrane. Kallikrein levels also fell early indicating distal tubular damage. There is clear evidence that urine protein overload in a previously damaged kidney with tubulointerstitial injury leads to accelerated and more severe renal damage. Laminin and kallikrein are early and sensitive markers of renal injury.

Up-regulation of monocyte chemoattractant protein-1 in tubulointerstitial lesions of human diabetic nephropathy

BACKGROUND

We previously described that monocyte chemoattractant protein-1 (MCP-1) plays an important role in progressive glomerular and interstitial damage in inflammatory renal diseases. However, the expression of MCP-1 in diabetic nephropathy remains to be investigated.

METHODS

We examined whether locally expressed MCP-1 participates in human diabetic nephropathy via recruiting and activating monocytes/macrophages (Mphi). Urinary and serum MCP-1 levels were measured by enzyme-linked immunosorbent assay in 45 patients with diabetic nephropathy. The presence of MCP-1 in diseased kidneys was determined by immunohistochemical and in situ hybridization analyses.

RESULTS

Urinary MCP-1 levels were significantly elevated in patients with diabetic nephrotic syndrome and advanced tubulointerstitial lesions. Moreover, urinary levels of MCP-1 were well correlated with the number of CD68-positive infiltrating cells in the interstitium. In contrast, serum MCP-1 levels remained similar to those of healthy volunteers. Furthermore, we detected the MCP-1-positive cells in the interstitium of diabetic nephropathy via both immunohistochemical and in situ hybridization analyses.

CONCLUSION

These observations suggest that locally produced MCP-1 may be involved in the development of advanced diabetic nephropathy, especially in the formation of tubulointerstitial lesions possibly through Mphi recruitment and activation. Moreover, up-regulation of MCP-1 may be a common pathway involved in the progressive tubulointerstitial damage in diabetic nephropathy as well as inflammatory renal diseases.

[Functional loading tests in nephropathy examination in patients recovering from hemorrhagic fever with renal syndrome]

AIM

To characterize nephropathy in patients recovering after hemorrhagic fever with renal syndrome (HFRS) using functional loading tests.

MATERIALS AND METHODS

In 65 HFRS convalescents we examined renal function under water deprivation, exercises and studied intraglomerular hemodynamics.

RESULTS

After 2-month follow-up renal functional reserve was absent in 34% of the convalescents indicating intraglomerular hypertension. Under water deprivation most of the patients showed persistent tubulointerstitial disorders. Submaximal muscular exercises aggravated glomerular and tubular dysfunction manifesting with microalbuminuria, increased excretory beta 2-microglobulin fraction, low concentration reserve.

CONCLUSION

Functional loading tests provide more detailed characterization of renal function in HFRS convalescents.

Oxidant stress in hyperlipidemia-induced renal damage

Hyperlipoproteinemia can aggravate glomerulosclerosis and chronic tubulointerstitial (ti) damage in kidneys without primary immunologic disease. We evaluated whether the effect of hyperlipidemia on progression of renal damage differed between kidneys without preexisting glomerular disease and kidneys with mesangioproliferative glomerulonephritis and whether the renal actions of hyperlipidemia were dependent on oxidant-antioxidant balance. Hyperlipidemia was induced by high-fat and high-cholesterol diet in uninephrectomized rats. In rats without glomerulonephritis, hyperlipidemia led to a rise in glomerular and ti generation of reactive oxygen species (ROS). Oxygen radicals were mainly generated by enhanced xanthine oxidoreductase (XO), which rose with protein concentration and activity during hyperlipidemia; concurrently, glomerulosclerosis and chronic ti injury were noticed during hyperlipidemia [ti damage (% of total tubulointerstitium (TI) after 150 days): normolipidemia 0.1 +/- 0% vs. hyperlipidemia 3.4 +/- 0. 9%; P < 0.05]. In mesangioproliferative Thy-1 nephritis, ti injury was significantly accelerated by hyperlipidemia (ti damage after 150 days: normolipidemic Thy-1 nephritis 2.5 +/- 0.6% vs. hyperlipidemic Thy-1 nephritis 12.5 +/- 3.1%; P < 0.05). Antioxidant enzyme activities decreased and XO activity rose markedly in the TI (XO activity in TI after 150 days: normolipidemic Thy-1 nephritis 2.2 +/- 0.5 vs. hyperlipidemic Thy-1 nephritis 4.5 +/- 0.7 cpm/microg protein; P < 0.05). In hyperlipidemic Thy-1 nephritis rats, which had a higher urinary protein excretion than normolipidemic rats, hypochlorite-modified proteins, an indirect measure for enhanced myeloperoxidase activity, were detected in renal tissue and in urine, respectively. During hyperlipidemia, chronic damage increased in renal TI. Enhanced generation of ROS, rise in oxidant enzyme activity, and generation of hypochlorite-modified proteins in renal tissue and urine were noticed. These data suggest that oxidant stress contributed to the deleterious effects of hyperlipidemia on the renal TI.

Composition of the sugar moiety of Tamm-Horsfall protein in patients with urinary diseases

The sugar moiety of Tamm-Horsfall protein (THP) is altered by pathological conditions. The aim of this study was to investigate the composition of THP glycans in urinary diseases. THP was isolated from the urine of patients with urinary tract infection (group A), glomerulonephritis or interstitial nephritis (group B), and Bartter's syndrome (BS) (group C). Monosaccharides, N-glycan profile, THP reactivity with specific lectins and some other proteins were analyzed. THP of patients from groups A, B, and C showed lower amounts of N-acetylgalactosamine (P<0.05, P<0.005, and P<0.05, respectively) than controls; this was reflected in lower reactivity with Phaseolus vulgaris lectin (P<0.005, P<0.05, and P<0.005). Reduced amounts of N-acetylglucosamine were noticed in groups A (P<0. 05) and B (P<0.05). In group A lower amounts of galactose and alpha2, 6-linked sialic acid, as determined by reactivity with Datura stramonium lectin (P<0.005) and Sambucus nigra lectin (P<0.005), were observed. In patients with BS there was a shift from tetrasialylated glycans towards less-sialylated chains. We found also that THP of all patients binds more strongly to IgG(1) (P<0.005, for all patient groups). Our results indicate that the urinary diseases examined affect the THP sugar moiety and the binding of THP to IgG(1).

Tubular function and tubulointerstitial disease

Tubular transport determined by the fractional excretion (FE) of filtered solutes was studied in 129 nephrotic patients; 72 patients with mesangial proliferation (MesP-NS) and intact tubulointerstitium (group 1), 13 patients with MesP-NS and superimposed tubulointerstitial fibrosis (TIF; group 2), 27 patients with mild focal segmental glomerulosclerosis (FSGS; group 3), and 17 patients with severe FSGS (group 4). In the 72 nephrotic patients with MesP-NS and normal tubulointerstitium (no TIF), tubular transport was intact (FE of sodium [FENa], 0.5 +/- 0.5; FE of calcium [FECa], 0.3 +/- 0.3; FE of phosphate [FEPO4], 14 +/- 13; FE of uric acid [FEUA], 9.8 +/- 5; FE of magnesium [FEMg], 1.3 +/- 0.5). In the 13 nephrotic patients with MesP-NS and superimposed TIF (4.9% +/- 2%), there was no difference in FE solutes from those in group 1 except for FEMg (3.3 +/- 0.9; P < 0.001). In the 27 nephrotic patients with mild FSGS (TIF, 28% +/- 9%), four of five variables of FE solutes (FENa, 1.2 +/- 0.7; P < 0.001; FECa, 0.9 +/- 0.8; P < 0.001; FEPO4, 17 +/- 12; P, not significant; FEUA, 16.5 +/- 8; P < 0.001; FEMg, 4. 1 +/-1; P < 0.001) were significantly different from those of patients with MesP-NS without TIF, and two of five variables (FECa, FEMg) were statistically different from those of patients with MesP-NS with TIF. In the severe category of FSGS (TIF, 69% +/-19%), all FE solutes were statistically different from the other groups (FENa, 4.8 +/- 3; FECa, 2 +/- 1; FEPO4, 47 +/- 24; FEUA, 37 +/- 18; FEMg, 12 +/- 6). Thus, the results imply that (1) normal tubular transport reflects an underlying intact tubulointerstitial structure, whereas tubular dysfunction indicates an underlying tubulointerstitial disease, and (2) FEMg is the most sensitive index to detect an early abnormality of tubular structure and function.

Eotaxin contributes to renal interstitial eosinophilia

BACKGROUND

A potent eosinophil chemotactic cytokine, human eotaxin, is directly chemotactic for eosinophils. Therefore, the specific expression of eotaxin in tissue might play a crucial role in tissue eosinophilia. However, the precise molecular mechanism of the recruitment and activation of eosinophils in human renal diseases remains to be investigated. We evaluated the role of eotaxin in the pathogenesis of human diffuse interstitial nephritis with marked infiltration of eosinophils.

METHODS

In this study, we examined 20 healthy volunteers. 56 patients with primary or secondary glomerular diseases and two hypereosinophilic syndrome patients without renal involvement. Urinary and serum eotaxin levels were determined by an enzyme-linked immunosorbent assay. We also detected the presence of eotaxin protein immunohistochemically.

RESULTS

On the one hand, urinary levels of eotaxin were significantly higher before the initiation of glucocorticoid administration in the patient with interstitial nephritis with marked infiltration of eosinophils. On the other hand, urinary eotaxin levels were not detected in any patients with nephrotic syndrome, interstitial nephritis without eosinophils, hypereosinophilic syndrome without renal involvement or other renal diseases. Serum eotaxin levels were not detected in any of the patients. Therefore, the detection of eotaxin in the urine was specific for renal interstitial eosinophilia. Moreover, endothelial cells, infiltrating mononuclear cells and renal epithelial cells in the tubulointerstitial lesions were immunostained with specific anti-eotaxin antibodies. Furthermore, the elevated urinary levels of eotaxin decreased dramatically during glucocorticoid-induced convalescence.

HYPOTHESIS

We hypothesize that in situ expression of eotaxin may provide a new mechanism to explain the renal interstitial eosinophil infiltration.

Acute interstitial nephritis following treatment with anorectic agents phentermine and phendimetrazine

A 47-year-old mildly obese female began a weight reduction program that included anorectic therapy with phentermine and phendimetrazine. A normal urinalysis and serum creatinine were documented at the start of therapy. After three weeks of treatment, the patient felt ill and discontinued her treatment. Subsequently she was found to have leukocyturia, a rash on her face and chest, and a rise in her serum creatinine from 0.8 mg/dl to 2.1 mg/dl. A renal biopsy confirmed the diagnosis of acute interstitial nephritis. The patient was treated with corticosteroids and her renal function returned to normal. Despite the recent withdrawal of two anorectic agents due to data linking them to severe cardiac and pulmonary disease, the appetite suppressants phentermine and phendimetrazine remain in widespread usage for the treatment of obesity. This case represents the first report of acute interstitial nephritis associated with phentermine or phendimetrazine.

A mathematical equation to differentiate overload proteinuria from tubulo-interstitial involvement in glomerular diseases

Determination of marker proteins like albumin and alpha 1-microglobulin allows to differentiate various types of proteinuria in kidney diseases. In the present communication we calculate the degree of tubulointerstitial involvement by quantitation of the tubular marker alpha 1-microglobulin in urine in relation to albuminuria. A mathematical relation between minimal tubular proteinuria with the degree of albumin excretion was observed. Cases forming this line did not exhibit interstitial fibrosis when analyzed histologically. In contrast most cases exhibiting higher excretion rates of the tubular marker showed various degrees of tubulointerstitial involvement. In order to differentiate interstitial contribution from overload tubular proteinuria in patients with an albumin excretion rate above 3000 mg/g creatinine alpha 1-microglobulin (measured) is suggested to be corrected by the "glomerular" component of alpha 1-microglobulin using the following equation: "tubulo-interstitial alpha 1-microglobulin" = alpha 1-microglobulin (measured) -4.7 exp (2.2 x 10(-4)) [albumin]. Alternatively the correction can be performed graphically. This procedure may be of considerable help in preventing misinterpretations of urinary protein patterns in patients with nephrotic proteinuria.

Tubulointerstitial nephritis in a patient with eosinophilic fasciitis and IgA nephropathy

We report a tubulointerstitial nephritis in a patient with eosinophilic fasciitis and IgA nephropathy. Urinalysis revealed mild proteinuria and microscopic hematuria, and renal biopsy disclosed diffuse interstitial infiltrations of lymphocytes and plasma cells with few eosinophils in spite of mild mesangial proliferation with IgA deposits, indistinguishable from those of primary tubulointerstitial nephritis. Immunohistochemical examination showed a predominance of helper/inducer T cells infiltrating the renal interstitium and the fascia. Corticosteroid treatment led to a decrease of infiltrating cells in both tissues. Therefore, eosinophilic fasciitis and tubulointerstitial nephritis in our patient seemed to be interdependent phenomena.