Chronic Renal Inflammation Research Articles

Transgenic Sickle Mice Are Markedly Sensitive to Renal Ischemia-Reperfusion Injury

Ischemic injury is invoked as a mechanism contributing to end-organ damage and other complications of sickle cell disease (SCD). However, the intrinsic sensitivity of tissues in SCD to ischemic insults has never been addressed. We examined the effect of renal ischemia in a transgenic mouse expressing human sickle hemoglobin. Twenty-four hours after bilateral, total renal artery occlusion for 15 minutes, transgenic sickle mice exhibited worse renal function and more marked histological injury. With bilateral renal ischemia of greater duration (22.5 minutes), and after 6 hours, transgenic sickle mice exhibited massive vascular congestion, sickling of red blood cells, more marked histological injury in the kidney, and more prominent congestion in the capillary beds in the lungs and heart. Additionally, serum amyloid P-component, the murine homologue of C-reactive protein, was markedly increased in transgenic sickle mice as compared to wild-type mice. Twenty-four hours after bilateral renal ischemia for 22.5 minutes, transgenic sickle mice exhibited 28% mortality, with no mortality observed in any other group. With bilateral renal ischemia of short or long duration, renal expression of caspase-3 was most prominent in transgenic sickle mice subjected to ischemia. Thus, renal ischemia in this murine model induces more severe renal injury and extrarenal complications. We conclude that tissues in SCD exhibit heightened vascular congestion and sensitivity to ischemia and that clinically apparent or silent episodes of ischemia may contribute to the complications of SCD.

Activation and cellular localization of the p38 and JNK MAPK pathways in rat crescentic glomerulonephritis

The p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) are intracellular signal transduction pathways involved in the production of inflammatory mediators. Little, however, is known about the contribution of these pathways to renal inflammation, nor the cell types in which these pathways are activated within normal and inflamed kidneys. The aim of this study was therefore to delineate the pattern and cellular localization of p38 and JNK activation in normal rat kidney and rat acute and chronic inflammatory renal disease. Normal male Sprague-Dawley rats and groups of rats given accelerated anti-glomerular basement membrane (GBM) disease were killed at 3 hours, day 1, day 7, or day 28 and examined for p38 and JNK pathway activation by Western blotting and immunolocalization of the phosphorylated p38 (p-p38) and JNK (p-JNK) kinases. In terms of glomerular MAPK activation, Western blotting identified the presence of both p-p38 and p-JNK in normal glomeruli, localized by immunohistochemistry to podocytes and epithelial cells of Bowman's capsule. In anti-GBM disease, Western blotting showed that p38 activation peaked at 3 hours and remained elevated above normal throughout the disease time course. JNK activation (via the 54 kD isoform) likewise increased at 3 hours of anti-GBM disease and remained elevated throughout disease. At 3 hours, p-p38, but not p-JNK, was localized to neutrophils and glomerular endothelial cells. p-JNK was localized to glomerular endothelial cells at day 7. Macrophages, lymphocytes, activated podocytes, and myofibroblasts were positive for both p-p38 and p-JNK. In terms of tubular MAPK activation, Western blotting identified p38 and JNK activation in tubules of normal kidney. Immunostaining showed that most cortical tubules contained some p-p38 and p-JNK stained cells. There was a significant increase in tubular p38 activation at 3 hours of anti-GBM disease, followed by increased JNK activation of the 54 kD isoform from day 7 onward, and the 46 kD isoform at day 28. Immunostaining of diseased tissue localized p-p38 and p-JNK to virtually all cortical tubular cells. The p38 and JNK MAPK pathways are activated in glomeruli and tubules of normal kidney. In acute anti-GBM disease, there was an increase in p38 activation within glomerular endothelial cells and within infiltrating neutrophils, suggesting an important role for p38 MAPK in acute inflammation. In progressive anti-GBM disease, p38 and JNK activation in podocytes, glomerular endothelial cells, infiltrating macrophages, T cells, and myofibroblasts suggests that both the p38 and JNK MAPK pathways are important in chronic inflammation and fibrosis. Blockade of these pathways may therefore be potentially therapeutic in the treatment of acute and chronic renal inflammation.

A non-surgical rat model of foreign body-associated urinary tract infection with Pseudomonas aeruginosa.

This study established a rat model of foreign body-associated urinary tract infection. A spiral polyethylene tube (PT) was placed transurethrally into the bladder without surgical manipulation, followed by transurethral inoculation with Pseudomonas aeruginosa. The persistence of P. aeruginosa in the kidneys and bladder was significantly enhanced by placement of the PT, whereas the bacteria were eliminated rapidly from the urinary tract in the animals without the PT. Scanning electron microscopy revealed a thick biofilm on the surface of the PT from the early stage of infection. Histopathologically, acute pyelonephritis was followed by chronic renal inflammation as well as continuous and sporadic polymorphonuclear leukocyte accumulation and hemorrhage in the pelvis and adjacent tissues, suggesting continuous ascending introduction of the bacteria from the biofilm adhering to the PT. We believe our model simulates the pathophysiology of foreign body-associated urinary tract infection characterized by biofilm formation on the surface of a foreign body.

Heme protein-induced chronic renal inflammation: Suppressive effect of induced heme oxygenase-1

Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme; its inducible isozyme, HO-1, protects against acute heme protein-induced nephrotoxicity and other forms of acute tissue injury. This study examines the induction of HO-1 in the kidney chronically inflamed by heme proteins and the functional significance of such an induction of HO-1. Studies were undertaken in a patient with chronic tubulointerstitial disease in the setting of paroxysmal nocturnal hemoglobinuria (PNH), in a rat model of chronic tubulointerstitial nephropathy caused by repetitive exposure to heme proteins, and in genetically engineered mice deficient in HO-1 (HO-1 -/-) in which hemoglobin was repetitively administered. The kidney in PNH evinces robust induction of HO-1 in renal tubules in the setting of chronic inflammation. The heme protein-enriched urine from this patient, but not urine from a healthy control subject, induced expression of HO-1 in renal tubular epithelial cells (LLC-PK1 cells). A similar induction of HO-1 and related findings are recapitulated in a rat model of chronic inflammation induced by repetitive exposure to heme proteins. Additionally, in the rat, the administration of heme proteins induces monocyte chemoattractant protein (MCP-1). The functional significance of HO-1 so induced was uncovered in the HO-1 knockout mouse: Repeated administration of hemoglobin to HO-1 +/+ and HO-1 -/- mice led to intense interstitial cellular inflammation in HO-1 -/- mice accompanied by striking up-regulation of MCP-1 and activation of one of its stimulators, nuclear factor-kappaB (NF-kappaB). These findings were not observed in similarly treated HO-1 +/+ mice or in vehicle-treated HO-1 -/- and HO-1 +/+ mice. We conclude that up-regulation of HO-1 occurs in the kidney in humans and rats repetitively exposed to heme proteins. Such up-regulation represents an anti-inflammatory response since the genetic deficiency of HO-1 markedly increases activation of NF-kappaB, MCP-1 expression, and tubulointerstitial cellular inflammation.

Role of iron and iron chelation therapy in oxygen free radical mediated tissue injury in an ascending mouse model of chronic pyelonephritis

The contribution of iron towards the free radical generation leading to renal tissue damage was assessed using a non-obstructive ascending mouse model for chronic pyelonephritis. The parameters studied include luminol dependent chemiluminescence (LDCL), histopathology and some biochemical investigations. We found that iron enhanced the renal tissue damage and led to renal scarring, an end point in chronic renal inflammation, irrespective of the bacterial strain studied. In addition a role of iron chelation therapy as a treatment for chronic renal inflammation is also suggested.

CATHETER-ASSOCIATED URINARY TRACT INFECTIONS

The two most common indications for long-term catheterization are recalcitrant urinary incontinence and urinary obstruction that is not corrected by surgery. For incontinent patients, if behavioral changes, nursing care, special clothes, special bed clothes, and medications have not been successful, then a device to collect urine must be considered. For men such a device is a condom catheter; for women an analogous external collection device would be very useful. Suprapubic catheterization may offer an alternative but has been inadequately studied in this patient population. Long-term urinary catheterization has salutary effects for selected patients including patient comfort, family satisfaction, and nursing efficiency and effectiveness. To the patient for whom any physical movement is uncomfortable or painful, and indwelling catheter may be preferable to frequent changes of clothes. Similarly, the family of of severely impaired patients may want to accept the risks of urethral catheterization in order to keep the patient dry. Further, to the extent that the indwelling catheter is effective in decubitus ulcer prevention and/or management, long-term catheterization may diminish the risk of bacteremia or death from soft tissue infection. These benefits of long-term urethral catheterization, in addition to its risks, should be examined in future studies. Once a urethral catheter is in place, even with good catheter hygiene, bacterial entry can be postponed only temporarily; eventually all patients become bacteriuric. Indeed, as the catheter remains in place, organisms continue to enter, others leave or die, and the bacteriuria becomes complex, polymicrobial, and dynamic. Some organisms, particularly recognized uropathogens such as E. coli and K. pneumoniae, appear to reside in the urinary tract itself. Others, such as P. mirabilis, P. stuartii, and M. morganii, probably establish a niche within the urinary catheter, thus increasing their ability to cause subsequent bladder bacteriuria. The complications of long-term urinary catheterization include fevers, acute pyelonephritis, and bacteremias (such as seen in short-term catheterized patients), as well as catheter obstructions, urinary stones, chronic renal inflammation, local periurinary infections, vasicoureteral reflux, renal failure, and, for very long-term catheterized patients, bladder cancer. The thrust of catheter care for the long-term catheterized patient is to prevent complications of the omnipresent bacteriuria. Unfortunately, clinical opportunities for preventing complications are limited.(ABSTRACT TRUNCATED AT 400 WORDS)

GRO chemokines: a transduction, integration, and amplification mechanism in acute renal inflammation.

We recently observed that cytokine-induced neutrophil chemoattractant (CINC), a GRO chemokine, contributes to neutrophil migration into the inflamed glomerulus in rat. Therefore, we sought to clarify how expression of the GRO chemokines, CINC and macrophage inflammatory protein-2 (MIP-2), is regulated in mesangial cells in vitro and the kidney in vivo. Mesangial cells expressed both GRO chemokine mRNAs in response to mediators of acute renal inflammation [interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and lipopolysaccharides (LPS)], but not chronic renal inflammation (transforming growth factor-beta 1), with CINC mRNA expression predominating over MIP-2. The kinetics of GRO chemokine mRNA expression in response to both IL-1 beta and TNF-alpha (but not LPS) paralleled those defined for polymorphonuclear leukocyte (PMN) migration during nephritis in vivo. IL-1 beta and TNF-alpha displayed nonparallel concentration-response relationships for GRO chemokine mRNA expression, and together were synergistic together rather than additive. Expression of GRO chemokine mRNAs in response to both cytokine agonists, however, was inhibited by genistein, a tyrosine kinase inhibitor. GRO chemokine mRNAs were rapidly expressed in inflamed glomeruli during immune complex glomerulonephritis with MIP-2 predominating over CINC. Expression of both chemokines was substantially inhibited by complement, leukocyte, and PMN depletion. In sum, GRO chemokines are expressed coordinately by mesangial cells and inflamed glomeruli and appear both to transduce the response to mediators of acute inflammation into a chemotactic signal and to amplify this response both temporally and quantitatively.(ABSTRACT TRUNCATED AT 250 WORDS)

An ascending non-obstructive model for chronic pyelonephritis in BALB/c mice.

Chronic pyelonephritis was successfully produced in female BALB/c mice with Escherichia coli after introduction of the bacterial inoculum by the ascending route. E. coli strain 31-B, a nalidixic acid-resistant derivative of strain TN675 expressing type-1 pili, and E. coli strain BH-5, a mutant of 31-B, not expressing type-1 pili, were used in the model. Both the strains were able to induce chronic renal inflammation in the experimental animals. Whereas the initial colonisation was greater with strain 31-B, its non-pilate mutant BH-5 caused a significantly greater inflammatory response and also caused renal scarring observable 5 months after the infection.

Urethral obstruction of 6 hours or less causes bacteriuria, bacteremia, and pyelonephritis in mice challenged with "nonuropathogenic" Escherichia coli.

Urethral obstruction may be caused by prostatic hypertrophy, urethral stricture, or encrustation of a urethral-catheter lumen. Bacteriuria often complicates these obstructions. The sequelae include fever, acute pyelonephritis, chronic renal inflammation, and death. We hypothesized that even brief obstruction of the urinary tract containing a nonvirulent bacterium would result in these complications. Mice challenged transurethrally with Escherichia coli FN414, which is rapidly eliminated from normal mice without causing bacteriuria, bacteremia, or renal pathology, were subjected to reversible urethral obstruction by coating the urethral meatus with collodion for 1, 3, or 6 h. The majority of mice obstructed for 1 h demonstrated parenchymal renal inflammation 48 h later. At the end of 3 h of obstruction, 9 of 10 mice were bacteremic; some bacteremias were present at 48 h after removal of the obstruction. At that time, more severe renal inflammation was seen in these mice. As little as 6 h of obstruction resulted not only in the acute changes described above but also in chronic renal inflammation and fibrosis in the majority of animals sacrificed 3 and 6 weeks later. Additional studies demonstrated that urethral obstruction enhanced the uropathogenicity of another nonpathogenic E. coli strain (K-12 strain HB101) and caused more severe renal lesions in mice challenged with E. coli CFT073, isolated from a patient with symptoms of pyelonephritis. These findings demonstrate that brief urethral obstruction may (i) induce organisms which are cleared rapidly from the normal urinary tract to cause bacteriuria, bacteremia, and pyelonephritis and (ii) intensify the renal lesions caused by a uropathogen.

Catheter-associated Bacteriuria

Catheter-associated bacteriuria is the most common nosocomial infection in both acute and long-term care facilities. Complications include fever, bacteremia, acute pyelonephritis, urinary stones, chronic renal inflammation, and death. Catheter-associated bacteriuria can be postponed by maintaining the closed nature of the catheter system. Postponement may become prevention of bacteriuria if the catheter is removed as soon as possible.

Catheter-Associated Urinary Tract Infections

The two most common indications for long-term catheterization are recalcitrant urinary incontinence and urinary obstruction that is not corrected by surgery. For incontinent patients, if behavioral changes, nursing care, special clothes, special bed clothes, and medications have not been successful, then a device to collect urine must be considered. For men such a device is a condom catheter; for women an analogous external collection device would be very useful. Suprapubic catheterization may offer an alternative but has been in-adequately studied in this patient population. Long-term urinary catheterization has salutary effects for selected patients including patient comfort, family satisfaction, and nursing efficiency and effectiveness. To the patient for whom any physical movement is uncomfortable or painful, an indwelling catheter may be preferable to frequent changes of clothes. Similarly, the family of of severely impaired patients may want to accept the risks of urethral catheterization in order to keep the patient dry. Further, to the extent that the indwelling catheter is effective in decubitus ulcer prevention and/or management, long-term catheterization may diminish the risk of bacteremia or death from soft tissue infection. These benefits oflong-term urethral catheterization, in addition to its risks, should be examined in future studies. Once a urethral catheter is in place, even with good catheter hygiene, bacterial entry can be postponed only temporarily; eventually all patients become bacteriuric. Indeed, as the catheter remains in place, organisms continue to enter, others leave or die, and the bacteriuria becomes complex, polymicrobial, and dynamic. Some organisms, particularly recognized uropathogens such as E. coli and K. pneumoniae, appear to reside in the urinary tract itself. Others, such as P. mirabilis, p, stuartii, and M. morganii, probably establish a niche within the urinary catheter, thus increasing their ability to cause subsequent bladder bacteriuria. The complications of long-term urinary catheterization include fevers, acute pyelonephritis, and bacteremias (such as seen in short-term catheterized patients), as well as catheter obstructions, urinary stones, chronic renal inflammation, local periurinary infections, vasicoureteral reflux, renal failure, and, for very long-term catheterized patients, bladder cancer. The thrust of catheter care for the long-term catheterized patient is to prevent complications of the omnipresent bacteriuria. Unfortunately, clinical opportunities for preventing complications are limited. Patients with recurrent catheter obstruction can be managed with more frequent catheter changes and possibly with methenamine preparations. For patients who are febrile, catheter obstruction and local periurethral infection should be sought. In patients with high-grade fevers, bacteremia should be suspected and treated. Patients who have recurrent high fevers or bacteremias should be evaluated for urinary tract stones and vesicoureteral reflux. If stones can be implicated in the etiology of episodes, surgical, antibiotic, and other medical therapy may be indicated.

Evidence for pathogenicity of Ureaplasma urealyticum for the upper urinary tract derived from animal models.

In limited clinical studies ureaplasmas have been cultured from the upper urinary tracts of some patients with struvite renal calculi and interstitial renal diseases. Struvite calculi were also produced in rats by inoculation of human ureaplasmas. We found that a type 8 strain of Ureaplasma urealyticum survived for at least 21 days and replicated following inoculation into the experimentally obstructed canine upper urinary tract. Development of severe chronic interstitial renal inflammation was accompanied by 10-fold rises in systemic anti-urea-plasmal antibody titers. This animal model should prove to be useful for investigating the potential role of ureaplasmas as opportunistic pathogens of the upper urinary tract.

XANTHOGRANULOMATOUS PYELONEPHRITIS: A REAPPRAISAL

A survey was undertaken of the clinical, radiological, ultrasonic, and pathological features of 80 patients with xanthogranulomatous pyelonephritis (XPN). The condition is a progressive granulomatous reaction to chronic renal inflammation which is often suppurative and usually caused by calculous urinary tract obstruction. The characteristic pathological features are large numbers of foam cells containing lipid, and the presence of inflammatory destruction of neighbouring renal tissue. XPN, which is commoner than generally recognised, may often be diagnosed preoperatively—the patient is usually a middle-aged female who presents with severe toxaemia, tender loin mass, and mild lower urinary tract symptoms. The diagnosis is confirmed by radiology and ultrasonography. Nephrectomy is curative.

Studies on the carcinogenicity of pentachloroethane in rats and mice

The carcinogenicity of chronically administered (41 to 103 weeks) technical-grade pentachloroethane (PCE) was assessed in groups of 50 male and female Fischer 344 rats and B6C3F 1mice. The major contaminant in the PCE sample used for the chronic study was hexachloroethane (4.2%). Prechronic studies (two and 13 weeks repeated dose) employing gavage doses of from 5.0 to 1000 mg/kg/day of PCE failed to reveal specific target organ toxicity in these species. In the absence of treatment-related pathological changes during the prechronic tests, the doses for the chronic studies were set on the basis of survival and body weight gains during the 13-week repeated dose study. During the chronic studies dose levels of 75 and 150 mg/kg for rats and 250 and 500 mg/kg for mice were administered, by gavage, five days per week. The survival of high-dose rats (both sexes) was significantly reduced as compared to the survival of control animals and that of the low-dose males was slightly, but not significantly, reduced. Although the administration of PCE to rats did not increase the incidence of primary tumors, it did produce a significant dose-related increase in the incidence of chronic renal inflammation among males. The survival times of all treated groups of mice were significantly shortened by PCE administration. Despite this reduced survival time, the incidence of hepatocellular carcinoma was significantly increased in all treated groups. With the exception of a dose-related increase in the incidence of hepatocellular adenoma among females, there were no other significant increases in primary tumor incidence in mice. Neither renal lesions in rats nor hepatocellular carcinoma in mice were considered to be adequate explanations for the decreased survivals. Complete histopathological examinations failed to reveal the cause of decreased survival. The results of the study show that technical-grade PCE, like numerous other chlorinated ethanes, is an hepatocarcinogen for B6C3F 1mice. This interpretation for PCE per se, however, must be tempered because the major contaminant, hexachloroethane, has been shown to produce hepatocellular carcinoma in mice. While the results obtained in rats suggest a species difference in susceptibility, the reduced survival in this species may have contributed to the absence of a carcinogenic effect.

Studies on the Carcinogenicity of Pentachloroethane in Rats and Mice

Studies on the Carcinogenicity of Pentachloroethane in Rats and Mice. Mennear, J.H., Haseman, J.K., Sullivan, D.J., Bernal, E. and Hildebrandt, P.K. (1982). Fundam. Appl. Toxicol. 2:82–87. The carcinogenicity of chronically administered (41 to 103 weeks) technical-grade pentachloroethane (PCE) was assessed in groups of 50 male and female Fischer 344 rats and B6C3F1 mice. The major contaminant in the PCE sample used for the chronic study was hexachloroethane (4.2%). Prechronic studies (two and 13 weeks repeated dose) employing gavage doses of from 5.0 to 1000 mg/kg/day of PCE failed to reveal specific target organ toxicity in these species. In the absence of treatment-related pathological changes during the prechronic tests, the doses for the chronic studies were set on the basis of survival and body weight gains during the 13-week repeated dose study. During the chronic studies dose levels of 75 and 150 mg/kg for rats and 250 and 500 mg/kg for mice were administered, by gavage, five days per week. The survival of high-dose rats (both sexes) was significantly reduced as compared to the survival of control animals and that of the low-dose males was slightly, but not significantly, reduced. Although the administration of PCE to rats did not increase the incidence of primary tumors, it did produce a significant dose-related increase in the incidence of chronic renal inflammation among males. The survival times of all treated groups of mice were significantly shortened by PCE administration. Despite this reduced survival time, the incidence of hepato-cellular carcinoma was significantly increased in all treated groups. With the exception of a dose-related increase in the incidence of hepatocellular adenoma among females, there were no other significant increases in primary tumor incidence in mice. Neither renal lesions in rats nor hepatocellular carcinoma in mice were considered to be adequate explanations for the decreased survivals. Complete histopathological examinations failed to reveal the cause of decreased survival. The results of the study show that technical-grade PCE, like numerous other chlorinated ethanes, is an hepato-carcinogen for B6C3F1 mice. This interpretation for PCE per se, however, must be tempered because the major contaminant, hexachloroethane, has been shown to produce hepatocellular carcinoma in mice. While the results obtained in rats suggest a species difference in susceptibility, the reduced survival in this species may have contributed to the absence of a carcinogenic effect.

Tissue antibodies in malignant and benign urogenital disease

The presence of anti-tissue antibodies in sera from patients with genitourinary carcinomas and non-malignant genitourinary diseases was studied by indirect immunofluorescence. An increased incidence of various tissue antibodies was observed in carcinomas of the urinary bladder, prostate and kidney when compared to controls. There was a trend towards association between antinuclear antibodies and metastatic undifferentiated tumors. A low degree of malignancy was associated with antibodies against connective tissue "reticulin". A striking similarity between tissue antibody "patterns" in carcinoma patients and patients with chronic renal inflammation was seen. This points to inflammation as being an important factor in tissue antibody production.