Interstitial Vimentin Research Articles

Comparative study of chronic kidney disease in dogs and cats: Induction of myofibroblasts

We investigated the kidneys of dogs and cats to clarify whether renal myofibroblasts induction is associated with the severity of chronic kidney disease (CKD). Immunohistochemical expression of myofibroblast markers, α-smooth muscle actin (SMA) and vimentin, were evaluated quantitatively. The degrees of glomerulosclerosis, glomerular hypertrophy, interstitial cell infiltration, and interstitial fibrosis were also evaluated quantitatively. The plasma creatinine (pCre) concentrations correlated with glomerulosclerosis, cell infiltration, and fibrosis in dogs, and only with fibrosis in cats. The α-SMA expression correlated with pCre, glomerulosclerosis, cell infiltration, and fibrosis in dogs, and with pCre and fibrosis in cats. Tubular vimentin expression correlated with fibrosis in cats, but not in dogs. Interstitial vimentin expression correlated with pCre, glomerulosclerosis, cell infiltration, and fibrosis in dogs, but only with pCre in cats. In conclusion, it was suggested that the severity of CKD in dogs and cats was mediated by different pathways associated with myofibroblasts expression.

What is the significance of CD34 immunostaining in the extraglomerular and intraglomerular mesangium?

CD34, traditionally a marker of hematopoietic stem cells (HSCs), was found on endothelial cells and fibroblasts as well. At the level of the extraglomerular or intraglomerular mesangium, CD34 may signal either the presence of HSCs or, conversely, may be a marker of transdifferentiation. CD34-positive cells of the extraglomerular mesangium could migrate into the intraglomerular mesangium and participate in reparative processes at this level. The aim of our study was to analyze the presence of CD34 at the level of the extraglomerular and intraglomerular mesangium and its relationship with histological markers of activity and chronicity, as well as with other immunohistochemical markers in glomerulonephritis (GN). A cross-sectional study of 36 patients with GN was conducted. Conventional stains: hematoxylin-eosin, periodic acid Schiff, and Trichrome Gömöri, as well as immunohistochemistry: CD34, alpha smooth muscle actin (alpha SMA), vimentin, and proliferating cell nuclear antigen (PCNA) were employed. Activity and chronicity of GN were evaluated according to a scoring system initially used for lupus nephritis and antineutrophil-cytoplasmic-antibody-associated vasculitis. Immunohistochemistry was assessed using a semiquantitative score. The mean age was 46.44 +/- 12.97 years; 22 were male and 14 were female. The extraglomerular mesangium was visible on specimens in 30 patients. CD34 was present in the extraglomerular mesangium in 15 patients: 11 of these patients showed concomitant intraglomerular and extraglomerular mesangial CD34 immunostaining, while four showed only extraglomerular mesangial immunostaining. In three patients, CD34 immunostaining was present only in the intraglomerular mesangium. Twelve patients showed negative immunostaining in both the extraglomerular and the intraglomerular mesangium. Overall, there was a fair degree of relationship, which did not reach statistical significance between CD34 in the extraglomerular mesangium and CD34 in the intraglomerular mesangium across the 36 patients. In the intraglomerular mesangium, CD34 did not significantly correlate with mesangial alpha SMA, vimentin, PCNA, and activity or chronicity index. In the extraglomerular mesangium, CD34 did not show a significant correlation with alpha SMA, vimentin, or PCNA. The activity index and the chronicity index showed a good correlation with serum creatinine. Mesangial cell proliferation correlated well with the mesangial matrix increase, while interstitial vimentin showed a good correlation with interstitial alpha SMA. We demonstrated the presence of CD34 in the extraglomerular mesangium, which could be related to transdifferentiated mesangial cells or to HSCs in the absence of blood vessels at this level. Our study shows the value of histological indices for evaluating GN but cannot assign significance to CD34 immunolabeling for the assessment of GN.

Histological, immunohistochemical and biological data in assessing interstitial fibrosis in patients with chronic glomerulonephritis

The aim of this study was to determine the relationship between histological, immunohistochemical (IHC) and biological data in the assessment of interstitial fibrosis in patients with glomerular diseases. A group of 41 patients with primary and secondary glomerulonephritis was studied. In order to quantify the histological changes and to assess the extent of active-inflammatory and chronic-sclerotic/fibrotic interstitial lesions, we adapted a scoring system, initially used for lupus nephritis, and ANCA-associated vasculitis. IHC labeling procedures with monoclonal antibodies anti-smooth muscle actin (SMA), anti-vimentin and anti-transforming growth factor beta (TGFbeta) were assessed using a semi-quantitative score, correlated with the histological and biological data. Our results showed that interstitial labeling of SMA correlated with scores for sclerotic/fibrotic lesions (chronicity index) and with active-inflammatory lesions (interstitial infiltrate, activity index). Interstitial vimentin correlated with the score for interstitial infiltrate. Both interstitial vimentin and TGFbeta immunopositivity correlated with sclerotic/fibrotic lesions (interstitial fibrosis, tubular atrophies, vascular hyalinosis/fibrosis, chronicity index), and negatively with glomerular filtration rate. An important correlation was found between the interstitial labeling of the two IHC markers of myofibroblasts (SMA and vimentin). We conclude that IHC studies related to clinico-biological and histological data can have an important role in the evaluation of the glomerular diseases, but the classical histological investigation assessed through quantification has still not lost its importance.

Cytoskeletal protein expression and regenerative markers in schistosomal nephropathy.

Progression of renal diseases is related to the abnormal regulation of cellular and extracellular matrix turnover. Other factors in addition to schistosomal antigens may be relevant to the progression of schistosomal nephropathy (SN). The validity of markers of fibroblastic differentiation, alpha smooth muscle actin (alphaSMA), and vimentin, as well as the regenerative activity (PCNA/apoptosis index) in determination of progression of SN in comparison to other forms of non-schistosomal nephropathy (non-SN) is investigated. Three groups were included; group I pure SN (n=16), group II a diverse group of non-schistosomal patients with comparable pathologic changes on renal biopsy (n=40) and a control group (n=5). Immunohistochemical staining of myofibroblasts (alphaSMA and vimentin) and proliferating cells (PCNA) and histomorphometric analysis was done. In situ end labelling (ISEL) of DNA was used to evaluate apoptosis. No differences in the patterns of distribution of positivity of the different studied markers were observed between the different nephropathy groups. Both alphaSMA and vimentin were detected in glomerular mesangial, tubular epithelial, interstitial inflammatory fibroblast-like cells and occasionally endothelial cells. PCNA and apoptotic cells were detected in tubular epithelial and interstitial cells with paucity of positive cells in the glomerulus. Significant positive correlations were detected in group I between glomerular sclerosis and interstitial markers including interstitial alphaSMA (r=0.609, P=0.001), interstitial vimentin (r=0.812, P=0.00) and interstitial apoptosis (r=0.733, P=0.001). On the other hand, glomerulosclerosis in group II showed significant positive correlations with predominantly the glomerular markers; glomerular alphaSMA (r=0.475, P=0.002), glomerular apoptosis (r=0.684, P=0.00) and glomerular PCNA (r=0.691, P=0.00). Interstitial fibrosis correlated significantly with interstitial markers in group I including interstitial alphaSMA (r=0.837, P=0.00) interstitial vimentin (r=0.929, P=0.00), interstitial apoptosis (r=0.807, P=0.00) and interstitial PCNA (r=0.617, P=0.01), while in group II it correlated with both interstitial and glomerular markers. In addition, the tubulo-interstitial ratio was significantly higher in group I in comparison with group II (P=0.024), with no difference between groups II and III. Although SN may start as glomerulopathy associated with increased mesangial cellularity, the interstitial rather than the glomerular markers of myofibroblastic differentiation and those of cell turnover are playing a crucial role in late stages of schistosomal, but not in non-schistosomal nephropathies.

Expression of Cytoskeletal Proteins Differentiates between Progressors and Non-Progressors in Treated Idiopathic Membranous Nephropathy

Myofibroblasts play an important role in wound healing in a variety of tissue injuries. They have also been implicated in tissue fibrosis including renal scarring. This study was aimed at defining their role in one of the commonest forms of nephrotic syndrome in adults, namely membranous nephropathy. We have studied 21 patients with biopsy proven idiopathic membranous nephropathy who were treated with glucocorticoids, attempting to define the role of myofibroblasts (α-smooth muscle actin-positive as well as vimentin-positive cells) in the progression of this form of nephropathy. There were 13 non-progressors (NP) and 8 progressors (P). The clinical, histological, and immunohistochemical characteristics of both groups were compared. Immunohistochemical staining for myofibroblasts cytoplasmic markers α-smooth muscle actin (α-SMA) and vimentin relied on an avidin-biotin-peroxidase method. The level of blood pressure, degree of proteinuria, severity of interstitial infiltrate and interstitial fibrosis did not differentiate P from NP. However, vascular sclerosis was more severe in P compared to NP (p < 0.016) and its severity predicted the subsequent functional outcome (slope of the 1/serum creatinine against time; r² = 0.618, p < 0.01). Mesangial α-SMA was significantly higher in P (31 ± 18.6%) than in NP (14.5 ± 9.8%), p < 0.015. Interstitial α-SMA immunostain was also higher in P but did not reach statistical significance. However, the number of interstitial myofibroblasts (α-SMA positive cells) closely predicted the subsequent rate of the progression of chronic renal failure (r² = 0.919, p < 0.0001). Mesangial vimentin expression was not different between both groups. By contrast, interstitial vimentin immunostain was higher in P (19.1 ± 8.8%) compared to NP (7.9 ± 5.6%), p < 0.002. These data suggest that the expression of mesangial and interstitial cytoskeletal proteins (α-SMA and vimentin) may have useful prognostic implications as they appear to differentiate between patients with membranous nephropathy who respond to immunosuppression and those who continue to progress.