Hyperlipidemia in stable renal transplant recipients.

Hyperlipidemia is a major risk factor for atherosclerosis and probably contributes to the increased cardiovascular mortality following renal transplantation. We studied the lipid profiles of 62 adults (29 males) with stable renal function (mean plasma creatinine 0.14 mmol/l, SD 0.07), 7 months to 21 years after renal transplantation. Fifteen patients (24%) were above the age- and sex-adjusted 95th percentile for total triglyceride and 10 (16%) for total cholesterol concentrations when compared with a local reference population. The most common lipoprotein abnormalities were type IIa (19%) and type IIb (13%). Multiple regression analysis demonstrated that the use of diuretics and angiotensin-converting enzyme inhibitors were significant factors determining plasma triglyceride concentrations. There were significant bivariate associations between plasma triglyceride concentration and duration since transplantation, plasma creatinine concentration and the use of ciclosporin and diuretics. Duration since transplantation and ciclosporin use were significant factors determining lower plasma cholesterol concentrations. The use of ciclosporin and diuretics was associated with a significantly higher apolipoprotein (apo) B concentration. The cholesterol/HDL cholesterol risk ratio correlated poorly with the apo B/apo A-1 ratio. The value of these ratios as predictors of coronary artery disease need to be established in renal transplant recipients.     

All-trans-retinoic acid aggravates cryoglobulin-associated membranoproliferative glomerulonephritis in mice.

BACKGROUND: Transgenic (tg) mice overexpressing thymic stromal lymphopoietin (TSLP) develop mixed cryoglobulinaemia with renal disease closely resembling human cryoglobulinaemic membranoproliferative glomerulonephritis (MPGN), as well as systemic inflammation involving lung, liver and skin as a result of cryoglobulin deposits. We assessed the effect of all-trans-retinoic acid (ATRA), a powerful anti-inflammatory agent, on this model of cryoglobulinaemic MPGN. METHODS: Groups of male TSLP tg mice and wild-type controls were treated with either ATRA (20 mg/kg) or vehicle 3 times weekly by intraperitoneal injection for 4 or 8 weeks, when mice were then sacrificed. Routine histology and immunohistochemistry for collagen IV, alpha-smooth muscle actin, Mac-2 and Ki67 were performed. Immunoglobulin levels were measured by enzyme-linked immunosorbent assay. RESULTS: ATRA unexpectedly exacerbated renal injury in TSLP tg mice with increased glomerular extracellular matrix, mesangial cell activation, glomerular cell proliferation, glomerular macrophage influx and immune complex deposition. Systemic injuries involving liver and lung, and the amount of circulating cryoglobulins were all worsened by ATRA treatment. Furthermore, ATRA resulted in increased IgG1 and IgM levels, the main components of the cryoglobulins in TSLP tg mice, and a manifestation of an enhanced Th2 immune response. CONCLUSIONS: ATRA is not protective but instead aggravates cryoglobulinaemic MPGN and its systemic manifestations in TSLP tg mice. We speculate these findings may be due to augmented production of pathogenic immunoglobulins and/or an enhanced systemic Th2 response. Although disappointing, our results also suggest caution in the application of retinoid therapy to human disease based on the largely positive animal data reported to date.     

Earlier renal fibrosis aggravates acute kidney injury induced by ischemia reperfusion in mice

Objective To investigate the influence of earlier renal fibrosis on ischemia and reperfusion induced acute kidney injury. Methods Male C57BL/6 mice at eight to twelve weeks old age were divided into 4 groups randomly: (1)Sham (n=3); (2)Unilateral ureter obstruction (UUO, n=6): UUO for 3 days (UUO3d, n=3) and UUO for 5 days (UUO5d, n=3);(3)Ischemia and reperfusion (IR, n=7): bilateral kidney ischemia for 40 minutes followed by 24 hours of reperfusion; (4)UUO for 3 days plus IR (UUO3d+IR, n=6): bilateral kidney ischemia after UUO 2 days for 40 minutes followed by 24 hours of reperfusion, and the real time for UUO was 3 days. Pathologic analysis for acute or chronic injury was performed on paraffin embedded kidney sections with hematoxylin and eosin (HE) or Masson staining. Apoptosis was detected by immunohistochemistry(IHC) and Western blotting with anti-caspase-3 antibody, and proliferation was observed by IHC with anti-ki67 antibody. Results On kidney sections with HE or Masson staining, it showed that the chronic kidney lesions and fibrosis got more severe as time of UUO prolonged from 3 days to 5 days; the area of matrix deposition increased in UUO5d and UUO3d mice significantly compared to Sham mice (P＜0.05) and was smaller in UUO3d mice compared with UUO5d mice obviously (P＜0.05). Acute kidney injury could be observed in UUO3d+IR mice, such as massive inflammatory cells infiltration, tubules dilation, brush border disappearance, tubular epithelial cells vacuolar degeneration, necrosis, casting formation, coexisting with chronic lesions: thinner cortex, broadened interstitial space, and increased blue stained matrix. Acute kidney injury score in UUO3d+IR mice was higher than that in IR mice significantly (P＜0.05), and serum creatinine level increased significantly in UUO3d+IR mice compared to Sham mice (P＜0.05). Caspase-3 expression increased and ki67 positive tubular cells decreased in UUO3d+IR mice than those in IR mice obviously (P＜0.05). Conclusion Earlier renal fibrosis aggravates acute kidney injury induced by ischemia reperfusion in mice through increasing apoptosis and decreasing proliferation of tubular epithelial cells.     

Hyperlipidemia in peripheral atherosclerotic arterial disease.

One hundred and ten patients with radiologically established peripheral atherosclerotic arterial disease were studied. None of them suffered from diabetes, endocrine disorders or renal disease. Their serum cholesterol and triglyceride values were compared with those of a reference group consisting of 548 individuals. When the 95th percentile of the reference values was used for cut-off, the frequency of hyperlipidemias in the patients with peripheral arterial atherosclerosis was about 52%. Combined hyperlipidemia was slightly more common (21%) than isolated increase of either cholesterol (17.9%) or triglycerides (12.6%). Using other cut-off limits for the definition of hyperlipidemia, a striking change in the distribution between these three types of hyperlipidemia occurred. In our patients, the frequencies of different blood groups were not significantly different from those of a comparable population. The serum lipids were at the same level in the different blood groups.     

Cigarette smoke condensate aggravates renal injury in the renal ablation model

BACKGROUND: Cigarette smoking increases the risk of progression of diabetic and non-diabetic renal diseases. The mechanisms underlying the adverse effects of smoking are largely unknown. We examined the subtotally nephrectomized rat (i) to investigate whether components of cigarette smoke dissolved in acetone (cigarette smoke condensate) aggravate structural renal damage and (ii) to establish whether this provides an animal model that can be used to investigate potential pathomechanisms of cigarette smoke-induced renal damage. Since nicotine activates the sympathetic nerve system in humans, we investigated whether interference with this system modulates the effects of cigarette smoke condensate on the damaged kidney. METHODS: One group of Sprague-Dawley rats was subtotally nephrectomized (SNX). Acetone (SNX + solvent) or cigarette smoke condensate (SNX + cigarette) was applied daily to the oral mucosa. Another group of Sprague-Dawley rats was sham-operated and received the same treatments (sham + solvent, sham + cigarette). To investigate whether increased activity of the sympathetic nerve system is involved, the remnant kidney was denervated by microsurgical technique in one SNX + cigarette group. The control group for this intervention was a solvent-treated SNX group with denervated remnant kidney. Blood pressure (BP) was measured weekly by tail plethysmography. The experiment was terminated after 12 weeks. Structural renal damage was assessed by morphometric techniques (indices of glomerulosclerosis, tubulointerstitial and vascular damage) and urinary albumin and endothelin-1 excretion were measured. RESULTS: Indices of structural renal damage were increased in all SNX-groups. Treatment with cigarette smoke condensate further increased the indices of glomerulosclerosis and tubulointerstitial damage in SNX, but not sham-operated rats. This increase was completely prevented by renal denervation. No differences in systemic blood pressure were observed in the different SNX groups. Urinary albumin excretion went in parallel with the indices of glomerulosclerosis and tubulointerstitial damage and urinary endothelin-1 excretion was significantly increased in SNX + cigarette animals. CONCLUSION: These findings document that acetone soluble components in cigarette smoke aggravate glomerulosclerosis and tubulointerstitial damage in the renal ablation model. Renal injury induced by cigarette smoke condensate in this model is reversed by renal denervation. We conclude that cigarette smoke-induced renal damage is due, at least in part, to activation of the sympathetic nerve system.     

Inhibition of neprilysin with sacubitril without RAS blockage aggravates renal disease in Dahl SS rats

Salt-sensitive (SS) hypertension is accompanied with severe cardiorenal complications. In this condition, elevated blood pressure (BP) resulting from salt retention is associated with counterintuitively lower levels of atrial natriuretic peptide (ANP). In plasma, ANP is degraded by the neprilysin; therefore, pharmacological inhibition of this metalloprotease (i.e., with sacubitril) can be employed to increase ANP level. We have shown earlier that sacubitril in combination with valsartan (75 μg/day each) had beneficial effects on renal function in Dahl SS rats. The goal of this study was to evaluate the effects of a higher dose of sacubitril on renal damage in this model. To induce hypertension, male Dahl SS rats were fed a 4% NaCl diet (HS) for 21 days, and were administered sacubitril (125 μg/day) or vehicle via s.c. osmotic pumps. At the end of the HS challenge, both groups exhibited similar outcomes for GFR, heart weight, plasma electrolytes, BUN, and creatinine. Sacubitril exacerbated kidney hypertrophy, but did not affect levels of renal fibrosis. We also observed aggravated glomerular lesions and increased formation of protein casts in the sacubitril-treated animals compared to controls. Thus, in Dahl SS rats, administration of sacubitril without renin-angiotensin-system blockage had adverse effects on renal disease progression, particularly in regards to glomerular damage and protein cast formation. We can speculate that while ANP levels are increased because of neprilysin inhibition, there are off-target effects of sacubitril, which are detrimental to renal function in the SS hypertensive state.     

Vitamin B6 requirements in chronic renal failure

According to our results the long-term daily oral supplementation of 6 mg vitamin B₆ was sufficient for prevention of vitamin B₆ deficiency in chronic renal failure, regular dialysis treatment and CAPD groups of patients. Haemodialysis and charcoal haemoperfusion have led to non-significant decrease of erythrocyte vitamin B₆. A favourable effect was found of daily oral administration of 50 mg pyridoxine on electrophoretic mobility of peripheral blood lymphocytes and cellular immunity.     

Aging aggravates long-term renal ischemia-reperfusion injury in a rat model

Aim

Ischemia-reperfusion injury (IRI) has been considered as the major cause of acute kidney injury and can result in poor long-term graft function. Functional recovery after IRI is impaired in the elderly. In the present study, we aimed to compare kidney morphology, function, oxidative stress, inflammation, and development of renal fibrosis in young and aged rats after renal IRI.

Materials and methods

Rat models of warm renal IRI were established by clamping left pedicles for 45 min after right nephrectomy, then the clamp was removed, and kidneys were reperfused for up to 12 wk. Biochemical and histologic renal damage were assessed at 12 wk after reperfusion. The immunohistochemical staining of monocyte macrophage antigen-1 (ED-1) and transforming growth factor beta 1 (TGF-β1) and messenger RNA level of TGF-β1 in the kidney were analyzed.

Results

Renal IRI caused significant increases of malondialdehyde and 8-hydroxydeoxyguanosine levels and a decrease of superoxide dismutase activity in young and aged IRI rats; however, these changes were more obvious in the aged rats. IRI resulted in severe inflammation and tubulointerstitial fibrosis with decreased creatinine (Cr) clearance and increased histologic damage in aged rats compared with young rats. Moreover, we measured the ratio of Cr clearance between young and aged IRI rats. It demonstrated that aged IRI rats did have poor Cr clearance compared with the young IRI rats. ED-1 and TGF-β1 expression levels in the kidney were significantly higher in aged rats than in young rats after IRI.

Conclusion

Aged rats are more susceptible to IRI-induced renal failure, which may associate with the increased oxidative stress, increased histologic damage, and increased inflammation and tubulointerstitial fibrosis. Targeting oxidative stress and inflammatory response should improve the kidney recovery after IRI.     

Fluorofenidone reduces renal fibrosis in diabetic kidney disease mice

Objective To investigate the effects of fluorofenidone (AKF-PD) on diabetic kidney disease in db/db mice and its possible mechanisms. Methods (1) Fifty-six mice aged 8 weeks (half male and half female), including 42 db/db mice and 14 wild-type mice were studied. Forty-two db/db mice randomly were divided into model group (mock-treated diabetic db/db mice), AKF-PD (250 mg?kg-1?d-1) treatment group and losartan (20 mg?kg-1?d-1) treatment group. Wild-type mice and model mice were treated with vehicle (0.5% sodium carboxymethylcellulose), while the treatment groups received either AKF-PD or losartan. After 18 weeks, the blood glucose and urinary albumin were measured, the pathological changes of kidney were observed by PAS staining. The protein expressions of type Ⅳ collagen and fibronectin (FN) in kidney tissue were detected by immunohistochemistry. (2) Mouse glomerular mesangial cells (MES-13 cells) were divided into six groups: normal glucose group (5.5 mmol/L glucose), hypertonic group (5.5 mmol/L glucose+19.5 mmol/L mannitol), high glucose group (25.0 mmol/L glucose), AKF-PD group (25.0 mmol/L glucose+400 mg/L AKF-PD) and losartan group (25.0 mmol/L glucose+2 μmol/L losartan). After 72 h treatment, the expressions of type Ⅰ collagen, type Ⅳ collagen and transforming growth factor-β1 (TGF-β1) mRNA were detected by real-time PCR, and the content of TGF-β1 protein in the culture supernatant was detected by ELISA. Results (1) Compared with the wild type mice, model mice had increased weight, blood glucose and glomerulosclerosis index (all P＜0.01), accompanied with heavy albuminuria, glomerular hypertrophy, mesangial area expansion and deposition of collagen type Ⅳ and FN (all P＜0.01). Compared with model mice, in AKF-PD and losartan groups 24 h urinary albumin and glomerulosclerosis index decreased (all P＜0.01), glomerular hypertrophy and mesangial area expansion alleviated, and the protein expressions of collagen type Ⅳ and FN were inhibited (all P＜0.01). (2) Compared with the normal glucose group, the mRNA expressions of type Ⅰ collagen and type Ⅳ collagen increased in high glucose group, meanwhile the mRNA and protein expressions of TGF-β1 increased (all P＜0.01). In AKF-PD and losartan groups the expressions of type Ⅰ collagen, type Ⅳ collagen and TGF-β1 were inhibited as compared with high glucose group (all P＜0.05). Conclusion Fluorofenidone may play an anti-fibrotic effect in db/db mice by reducing the expression of TGF-β1 and inhibiting collagen synthesis in glomerular mesangial cells.     

Obesity-induced renal impairment is exacerbated in interleukin-6-knockout mice

Aim: Interleukin‐6 (IL‐6) is secreted from adipose tissue and thought to contribute to obesity‐related disorders. The aim of this study was to assess if IL‐6‐knockout (IL‐6‐/‐) mice would develop obesity‐induced renal impairment. Methods: Wild‐type (WT) and IL‐6‐/‐ mice were high‐fat fed (HFF) for 16 weeks to induce obesity. At the end of the study, renal function was measured via albumin/creatinine ratio and serum creatinine levels, using enzyme‐linked immunosorbent assay (ELISA) and high‐performance liquid chromatography (HPLC). Glomerulosclerotic index (GSI) was scored in periodic acid Schiff‐stained sections and collagen IV accumulation was assessed by immunohistochemistry. Renal cortical tumour growth factor beta (TGF‐β₁) activity and monocyte chemotactic protein‐1 (MCP‐1) levels were measured via ELISA. Results: Renal IL‐6 concentrations were increased with obesity. Although both WT HFF and IL‐6‐/‐ HFF mice exhibited renal impairment as measured by increased serum creatinine and urinary albumin/creatinine ratios, this was exacerbated in IL‐6‐/‐ mice. Obese mice had renal activation of cortical TGF‐β₁, which was also higher in IL‐6‐/‐ mice. Collagen IV staining was not affected by obesity. GSI was increased with obesity in both WT and IL‐6‐/‐ mice. Conclusion: Obese IL‐6‐/‐ mice demonstrated renal functional and structural abnormalities above that seen in obese WT mice. We suggest that absence or low IL‐6 levels may be an important accelerating factor implicated in the development and progression of obesity‐induced renal disease.     

Chronic kidney disease aggravates arteriovenous fistula damage in rats

Neointimal hyperplasia (NIH) and impaired dilatation are important contributors to arteriovenous fistula (AVF) failure. It is unclear whether chronic kidney disease (CKD) itself causes adverse remodeling in arterialized veins. Here we determined if CKD specifically triggers adverse effects on vascular remodeling and assessed whether these changes affect the function of AVFs. For this purpose, we used rats on a normal diet or on an adenine-rich diet to induce CKD and created a fistula between the right femoral artery and vein. Fistula maturation was followed noninvasively by high-resolution ultrasound (US), and groups of rats were killed on 42 and 84 days after surgery for histological and immunohistochemical analyses of the AVFs and contralateral femoral vessels. In vivo US and ex vivo morphometric analyses confirmed a significant increase in NIH in the AVFs of both groups with CKD compared to those receiving a normal diet. Furthermore, we found using histological evaluation of the fistula veins in the rats with CKD that the media shrank and their calcification increased significantly. Afferent artery dilatation was significantly impaired in CKD and the downstream fistula vein had delayed dilation after surgery. These changes were accompanied by significantly increased peak systolic velocity at the site of the anastomosis, implying stenosis. Thus, CKD triggers adverse effects on vascular remodeling in AVFs, all of which contribute to anatomical and/or functional stenosis.     

Hepatitis B liver disease in cyclosporine-treated renal allograft recipients

To establish the impact of cyclosporine on the development of chronic hepatitis in hepatitis B surface antigen (HBsAg)-positive renal allograft recipients, the incidence and outcome of chronic hepatitis in 20 cyclosporine-treated patients (CsA group) were compared with 13 azathioprine-treated patients (AZA group). All 33 patients had a functioning graft for 2 years or longer. Twenty-nine of the 33 patients were HBsAg-positive prior to the initiation of hemodialysis. The difference in the incidence of chronic hepatitis between these 2 groups was not statistically significant (78.6% in the AZA group vs. 52.4% in the CsA group, P = 0.12). In the CsA group, 3 patients (15%) developed liver cirrhosis, and there was a 5% mortality. The AZA group had a 7.7% mortality, and 4 patients (30.8%) developed liver cirrhosis. Serial serum samples obtained from these 33 HBsAg-positive renal allograft recipients were analyzed for antibody to hepatitis D virus (anti-HD). Anti-HD was found in 3 patients. Two of them developed anti-HD seroconversion after renal transplantation during a mean follow-up of 4 years. All 3 patients developed chronic hepatitis and 2 of them have subsequently developed liver cirrhosis. There was a mortality of 6.1% in 33 HBsAg-positive patients compared with a 5.3% mortality in 57 HBsAg-negative renal allograft recipients. The difference was not statistically significant. We conclude from this study that (1) CsA-treated HBsAg-positive renal allograft recipients have a tendency to develop chronic hepatitis like AZA-treated patients; (2) HBsAg-positive patients have an increased risk of HDV superinfection after renal transplantation, and this may result in rapid progression to liver cirrhosis; (3) HBsAg-positive patients who acquire HBsAg prior to renal transplantation have a low overall mortality, including death due to liver disease, for a mean follow-up of 4 years.     

Genetic deletion of JNK1 and JNK2 aggravates the DSS-induced colitis in mice.

The c-Jun N-terminal kinases (JNKs) are considered as novel targets for therapy of inflammatory bowel diseases (IBD). However, the relevant JNK isoforms have to be elucidated. Here, we analyze the individual contribution of the JNK1 and JNK2 isoforms in a dextran sulfate sodium (DSS) model of experimental colitis. JNK1 and JNK2 knockout mice (JNK1 ko, JNK2 ko) and their wild-type controls (WT1, WT2) received three cycles of DSS treatment, each consisting of 1.7% DSS for 5 days, followed by 5 days with water. Animals were daily evaluated by a disease activity index (DAI) comprising measurement of body weight, estimation of stool consistency, and test for occult blood/gross rectal bleeding. After 30 days all animals were sacrificed, and the inflamed intestine was histologically evaluated by a crypt damage score. Unexpectedly, neither JNK1 ko nor JNK2 ko prevented mice from developing a chronic colitis when compared to wild-type controls WT1 and WT2, respectively. On the contrary, DAI and mortality were aggravated in JNK2 ko compared to WT2. DAI and mortality did not differ between JNK1 ko and WT1, but the histological crypt damage score was significantly enhanced in the cecum of JNK1 ko mice. Genetic deletion of JNK2 worsens the disease outcome in an experimental model of murine colitis. We hypothesize that the functional deletion of the otherwise proapoptotic JNK2 prolongs the activity of proinflammatory immune cells with deterioration of disease activity.     

Hyperlipidemia in kidney disease: causes and consequences

Dyslipidemias are common in patients with chronic kidney disease. The causes vary with the stage of kidney disease, the degree of proteinuria, and the modality of end-stage renal disease treatment. Dyslipidemias have been associated with kidney disease progression, and a number of small, randomized, controlled trials of lipid-lowering agents have been conducted. Unfortunately, the results of these trials, although encouraging, have been inconclusive because of the small numbers of patients enrolled. Dyslipidemias may also contribute to the high incidence of cardiovascular disease in patients with chronic kidney disease. This is most likely for patients with chronic renal insufficiency and for kidney transplant recipients. Less certain is the role of dyslipidemias in the pathogenesis of cardiovascular disease among dialysis patients.     

Immunoglobulin E in renal disease.

Samples of renal tissue from 373 patients were examined for the presence of immunoglobulin E (IgE) by immunofluorescent techniques. Only trace to ++ amounts ( on a scale of ++++) were found in 20 patients: 4/9 with post-streptococcal acute glomerulonephritis (GN), 5/30 with GN associated with systemic lupus erythematosus, 3/20 with membranous GN, 1/4 with Goodpasture's syndrome, 2/18 with recurrent microhematuria and focal GN, 1/5 with hemolytic anemia and uremia, 3/73 with renal homografts, and 1/5 with dermatomyositis. No IgE was found in 18 patients with lipoid nephrosis, 8 of whom were being treated with prednisone, nor in 5 patients with focal glomerular sclerosis and the nephrotic syndrome. Serum IgE was measured in 9 of the 20 patients with glomerular deposits of this globulin. With one exception, levels of IgE were within the range generally considered to be normal. However, they were greater than the mean of this range in all but two and near the highest limits of normal in most. Neither the amounts of serum IgE nor the degree of proteinuria could be related to the intensity of stain for IgE in the glomeruli of these patients.