Effects of 20 mg rosuvastatin on VLDL1-, VLDL2-, IDL- and LDL-ApoB kinetics in type 2 diabetes

AIMS/HYPOTHESIS

In addition to its efficacy in reducing LDL-cholesterol, rosuvastatin has been shown to significantly decrease plasma triacylglycerol. The use of rosuvastatin may be beneficial in patients with type 2 diabetes, who usually have increased triacylglycerol levels. However, its effects on the metabolism of triacylglycerol-rich lipoproteins in type 2 diabetic patients remains unknown.

METHODS

We performed a randomised double-blind crossover trial of 6-week treatment with placebo or rosuvastatin 20 mg in eight patients with type 2 diabetes who were being treated with oral glucose-lowering agents. In each patient, an in vivo kinetic study of apolipoprotein B (ApoB)-containing lipoproteins with [13C]leucine was performed at the end of each treatment period. A central randomisation centre used computer-generated tables to allocate treatments. Participants, caregivers and those assessing the outcomes were blinded to group assignment.

RESULTS

Rosuvastatin 20 mg significantly reduced plasma LDL-cholesterol, triacylglycerol and total ApoB. It also significantly reduced ApoB pool sizes of larger triacylglycerol-rich VLDL particles (VLDL1; p = 0.011), smaller VLDL particles (VLDL2; p = 0.011), intermediate density lipoprotein (IDL; p = 0.011) and LDL (p = 0.011). This reduction was associated with a significant increase in the total fractional catabolic rate of VLDL1-ApoB (6.70 +/- 3.24 vs 4.52 +/- 2.34 pool/day, p = 0.049), VLDL2-ApoB (8.72 +/- 3.37 vs 5.36 +/- 2.64, p = 0.011), IDL-ApoB (7.06 +/- 1.68 vs 4.21 +/- 1.51, p = 0.011) and LDL-ApoB (1.02 +/- 0.27 vs 0.59 +/- 0.13, p = 0.011). Rosuvastatin did not change the production rates of VLDL2-, IDL- or LDL-, but did reduce VLDL1-ApoB production rate (12.4 +/- 4.5 vs 19.5 +/- 8.4 mg kg(-1) day(-1), p = 0.035). No side effects of rosuvastatin were observed during the study.

CONCLUSIONS/INTERPRETATION

In type 2 diabetic patients rosuvastatin 20 mg not only induces a significant increase of LDL-ApoB catabolism (73%), but also has favourable effects on the catabolism of triacylglycerol-rich lipoproteins, e.g. a significant increase in the catabolism of VLDL1-ApoB (48%), VLDL2-ApoB (63%) and IDL-ApoB (68%), and a reduction in the production rate of VLDL1-ApoB (-36%). The effects of rosuvastatin on the metabolism of triacylglycerol-rich lipoproteins may be beneficial for prevention of atherosclerosis in type 2 diabetic patients.

Expression of TGFbeta-1 and Type I TGFbeta-receptor on sequential biopsies of renal transplants with chronic allograft nephropathy

The aim of this study was to determine the expression of transforming growth factor-beta (TGFbeta)-1 and type I TGFbeta-receptor on sequential biopsies from renal transplants with and without chronic allograft nephropathy. Twenty-four renal transplant recipients entered the study. They underwent sequential biopsies performed before (T1: 1.44 +/- 1.2 months) and 6 months after (T2: 15.96 +/- 7.2 months) transplantation. Lesions were graded according to the criteria of the Banff classification. C4d was detected by fluorescence microscopy. Immunohistochemistry was performed in order to identify cells expressing TGFbeta-1 and type I TGFbeta-receptor. In normal renal tissue (n = 4), TGFbeta-1 is expressed by tubular epithelial cells and endothelial cells lining glomerular and peritubular capillaries, whereas type 1 TGFbeta-receptor is expressed by tubular epithelial cells and smooth muscle cells in the media of arteries. In recipients with chronic allograft nephropathy (group 1, n = 14), diffuse epithelial expression of both molecules was found in more patients at T2 than at T1 (42.8% vs 21.4%). In contrast, this pattern of expression remained stable or decreased over time in recipients with long-term normal transplants (group 2, n = 10). Furthermore, type 1 TGFbeta-receptor was detected on the smooth muscle cells of arteries in 12/14 (85.7%) of recipients in group 1 and only in 4/9 (44.4%) of recipients in group 2. No relationship was noticed with regard to C4d deposits. These data suggest that the synthesis of TGFbeta-1 and type I TGFbeta-receptor increases over time in recipients developing chronic allograft nephropathy. Further studies are in progress in order to quantify mRNA of both molecules with real-time polymerase chain reaction.

What is the best way to assess microsatellite instability status in colorectal cancer? Study on a population base of 462 colorectal cancers

The assessment of the microsatellite instability (MSI) status in colorectal cancers is presently warranted for three reasons: 1) as a screening tool for hereditary nonpolyposis colorectal cancer, 2) as a prognostic marker, and 3) as a potential predictive factor of chemotherapy response. The aim of this study was to evaluate, on a large scale with tissue samples coming from a number of different sources, the difficulties met with routine use of immunohistochemistry (IHC) and to determine if it really does offer an accurate alternative to PCR genotyping. Colorectal carcinomas from 462 consecutive patients resected in public or private hospitals were assessed for MSI status by two methods: MSI testing (with BAT-26 microsatellite) and IHC detection of hMLH1, hMSH2, and hMSH6 proteins. Of the 398 cancers tested, immunohistochemistry was noncontributory in 42 (10.5%), focal in 9 (2.3%), and discordant with the PCR results in 36 (9%). For these 87 cases, complementary analyses were performed to explain discrepancy. After additional IHC assay with modified processing protocols, 8 cases remained noncontributory, 2 focal, and 28 discordant: 18 microsatellite stability IHC/MSI PCR and 10 MSI IHC/microsatellite stability PCR. For these discordant cases, we performed a multiplex PCR assay on DNA extracted from the frozen sample and BAT-26 was amplified from DNA extracted from the paraffin blocks used for IHC. Four discordant cases were reclassified after PCR multiplex assay (3 as MSI and 1 as microsatellite stability). Five other cases displayed intratumoral heterogeneity and 19 remained discordant. The discrepancy could be partly explained by variable technical protocols of fixation in the different laboratories, leading to variations in staining quality and difficulties in IHC interpretation. This population-based study is the first one to show that IHC is not sensitive and specific enough to be used routinely. Immunohistochemistry analysis of MMR proteins must be performed in standardized conditions and interpreted by confirmed pathologists. It cannot replace PCR as long as protocols are not optimized and harmonized.

Sporadic colorectal cancers with defective mismatch repair display a number of specific morphological characteristics: relationship between the expression of hMLH1 and hMSH2 proteins and clinicopathological features of 273 adenocarcinomas

AIMS

The aim of this study was to assess the independent value of pathological criteria in the diagnosis of mismatch repair (MMR)-defective sporadic colorectal cancers.

METHODS AND RESULTS

Resected colorectal adenocarcinomas (n = 273) were reviewed in order to identify a number of specific morphological features of MMR-defective carcinomas. Of the 273 cases, 35.2% were right-sided and 5.9% were poorly differentiated. Focal extracellular mucin secretion was seen in 5.1% of cases and a stromal follicular reaction in 4.6%. The expression of the two major MMR proteins hMLH1 and hMSH2 was studied by immunohistochemistry. Carcinomas were considered deficient in the MMR system when a loss of nuclear signal in neoplastic cells was observed for one of the proteins. Such an extinction was seen in 37 of the cases (13.6%). The hMLH1 protein was the one most frequently altered (86.5%). After multivariate analysis, three independent factors were significantly associated with MMR deficiency: proximal location [odds ratio (OR) = 9.30; 95% confidence interval (CI) 2.79, 30.98], the presence of a true stromal follicular reaction (OR = 13.60; 95% CI 2.98, 62.00) and poor differentiation (OR = 8.33; 95% CI 1.63, 40.32).

CONCLUSIONS

These results confirm that sporadic colorectal MMR-defective adenocarcinomas display certain specific morphological characteristics. However, these pathological features are not sufficiently predictive and immunohistochemistry is needed to identify such tumours accurately.

Microsatellite instability and intratumoural heterogeneity in 100 right-sided sporadic colon carcinomas

Microsatellite instability has been proposed as an alternative pathway of colorectal carcinogenesis. The aim of this study was to evaluate the interest of immunohistochemistry as a new tool for highlighting mismatch repair deficiency and to compare the results with a PCR-based microsatellite assay. A total of 100 sporadic proximal colon adenocarcinomas were analysed. The expression of hMLH1, hMSH2 and hMSH6 proteins evaluated by immunohistochemistry was altered in 39% of the cancers, whereas microsatellite instability assessed by PCR was detected in 43%. There was discordance between the two methods in eight cases. After further analyses performed on other tumoural areas for these eight cases, total concordance between the two techniques was observed (Kappa=100%). Our results demonstrate that immunohistochemistry may be as efficient as microsatellite amplification in the detection of unstable phenotype provided that at least two samples of each carcinoma are screened, because of intratumoural heterogeneity.