Helena Autio-Harmainen

Expression of MMP2, MMP9, MT1‐MMP, TIMP1, and TIMP2 mRNA in valvular lesions of the heart

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play an important role in several diseases. This study was undertaken to investigate the mRNA synthesis of MMP2, MMP9, membrane‐type 1 (MT1)‐MMP, and matrix metalloproteinase inhibitors TIMP1 and TIMP2 by in situ hybridization in a set of heart mitral and aortic valves operatively removed due to degenerative or inflammatory valvular diseases. The material consisted of 21 valves, eight with endocarditis and 13 with a degenerative valvular disease. The samples were studied by in situ hybridization with specific probes for MMP2, MMP9, MT1‐MMP, TIMP1, and TIMP2. Synthesis of MMP2u2009mRNA was found in seven valves, five with endocarditis and two with degenerative valvular disease. Signals for MMP9u2009mRNA were found in two cases with endocarditis and five cases with degenerative valvular disease. No signal for MT1‐MMP mRNA was found in the lesions. TIMP1u2009mRNA, on the other hand, was found in 17 cases, both endocarditis and degenerative valvular disease. TIMP2u2009mRNA was found in three cases of endocarditis. The signals for MMP2, MMP9, TIMP1, and TIMP2u2009mRNA were localized in endothelial cells and in fibroblast‐like cells expressing α‐smooth muscle actin, thus showing myofibroblast‐type differentiation. The results show that matrix metalloproteinases MMP2 and MMP9, and matrix metalloproteinase inhibitors TIMP1 and TIMP2u2009mRNAs are synthesized in diseased valves and suggest that they may contribute to matrix remodelling in valvular disease. Copyright

Cyclosporin A for the treatment of severe Henoch-Schönlein glomerulonephritis

We evaluated the efficacy of cyclosporin A (CyA) for treating pediatric patients with severe Henoch-Schönlein glomerulonephritis (HSP-GN) and nephrotic-range proteinuria. Seven pediatric HSP-GN patients (5 boys, 2 girls) were treated with CyA, with a mean age of 10.6xa0years at diagnosis (range 7.2–15.2xa0years) and mean follow-up times of 6.0xa0years (range 4.4–8.9xa0years) from diagnosis and 5.2xa0years (range 3.4–7.7xa0years) from the beginning of the CyA treatment. All had developed nephrotic-range proteinuria within 1–3xa0months of the HSP diagnosis. A renal biopsy was performed on all the patients, and two showed rapidly progressive glomerulonephritis. They all received additional angiotensin converting enzyme inhibitor medication and one to three types of immunosuppressive treatment had been tried in five of the seven patients before CyA was initiated at a mean interval of 0.7xa0years after diagnosis (range 0.1–2.0xa0years). All the patients responded to the CyA treatment within a mean of 1.4xa0months (range 1xa0week to 4xa0months). Four patients achieved a stable remission and had been without CyA treatment for a mean of 3.7xa0years (range 2.9–5.3xa0years) by the end of the follow-up. Three patients seemed to become CyA dependent, since they developed proteinuria when the treatment was stopped. CyA treatment had been started significantly earlier (P=0.045) in the former group (mean 0.2xa0years, range 0.1–0.3xa0years) than in the latter (mean 1.5xa0years, range 1.2–2.0xa0years). Renal function was preserved in all patients, the glomerular filtration rate, plasma cystatin C, serum albumin, and serum creatinine being within normal limits at the end of the follow-up. We conclude that CyA treatment for severe treatment-resistant HSP-GN is promising, since four of the seven patients enjoy stable remission and all have retained their renal function after a mean follow-up of 6.0xa0years. However, some patients seem to develop CyA-dependent nephritis.

Long-term outcome 19 years after childhood IgA nephritis: a retrospective cohort study

We evaluated the natural long-term outcome after childhood IgA nephritis. Altogether 55 patients with biopsy-proven IgA nephritis were identified, 37 (67%) responded to the health questionnaire and 31 (56%) participated in the medical examination after a mean follow-up of 18.7xa0years (SD 6.2; range 8.5–29.8). The results of medical examination, onset data and the re-analysis of original biopsies of 31 participants were used when analyzing the predictive factors for persistent nephropathy, i.e. constant proteinuria/hematuria or end-stage renal disease (ESRD). All patients’ medical history data were obtained from regional hospitals and renal survival data from the national kidney register. Six (11%) of the 55 identified patients had developed ESRD. Sixteen (52%) of the 31 participants were not attending for regular follow-up visits after the acute phase. Twenty-two (71%) had renal symptoms and 12 (39%) were receiving drugs for hypertension/proteinuria at their latest follow-up visit. The chronicity index and total biopsy score in the first renal biopsy were higher in patients with persistent nephropathy or ESRD than in those without (p=0.022 and p=0.014, respectively). Nine (69%) of the 13 subjects who had been over 16xa0years of age at diagnosis had persistent nephropathy or ESRD, compared with 4 (22%) of the 18 subjects who had been under 16xa0years of age (relative risk 3.1, 95% CI 1.2–8.0). Pregnancy complications were common: 12 (55%) of the 22 pregnancies had been complicated by proteinuria and/or hypertension, and the prematurity rate was 30%. Long-term follow-up during adulthood is needed even after mild childhood IgA nephritis, especially in women during and after pregnancy.

Cyclosporine A vs. methylprednisolone for Henoch–Schönlein nephritis: a randomized trial

Knowledge about how to treat severe Henoch–Schönlein nephritis (HSN) is scarce. The aim of our study is to compare cyclosporine A (CyA) and methylprednisolone pulses (MP) in the treatment of severe HSN. Out of 24 pediatric HSN patients with nephrotic-range proteinuria or crescentic HSN in kidney biopsy, seven were randomized to receive CyA for 12xa0months at an initial dose of 5xa0mg/kg and eight to receive 3 MP pulses of 30xa0mg/kg followed by prednisone for 4xa0months. The other nine patients received identical treatment without randomization. Kidney biopsies were performed at inclusion and after 2xa0years. The primary outcomes were the duration of proteinuria and hematuria, estimated glomerular filtration rate, and renal biopsy histology. All the 11 CyA-treated patients achieved resolution of nephrotic-range proteinuria within 3xa0months, while the MP-group response was slower, and in 6/13 was not achieved with the initial treatment. Additional immunosuppressive treatment was needed in none of the CyA-treated patients but in six patients treated with MP (difference in proportion 46%, pu2009=u20090.008). The 2-year control biopsies were similarly improved in both groups. After mean 6.1xa0years (2.2–10.4xa0years), 16 patients (eight CyA, eight MP) had no renal symptoms and six (three CyA, three MP) had persistent nephropathy but normal renal function. One MP-treated patient had reduced renal function and another had developed ESRD and received a renal transplant. CyA gave a 100% resolution of nephrotic-range proteinuria and a 100% renal survival rate without additional therapy after a mean follow-up of 6xa0years. Treatment of HSN with CyA is efficacious, safe and not inferior to MP.

Differential expression of basement membrane components in lymphatic tissues

Peripheral lymphoid tissues act as important organs of immunological defense. Characteristic of their architecture is the rich reticular fiber meshwork composed of various extracellular matrix (ECM) molecules with which the stationary non-lymphatic cells stay in intimate contact and form channels through which the lymphatic cells travel. Here we studied the distribution of various laminin (Ln) chains and different types of collagens in human spleen, lymph node, and tonsil to clarify their chain-specific distribution. The most widely distributed proteins in all these organs were Ln chains α5, β1, γ1 and collagen types IV and XVIII, which were present in practically all compartments. Conversely, Ln α1, α2, α4, and type VII collagen showed a more restricted expression pattern. A unique feature was that Ln α3-, β3-, and γ2-chains, which normally are not localized to the vascular wall in non-lymphatic tissues, were present also in capillary basement membranes (BMs) of the follicular structures of lymph node and tonsil and in Ln α1-chain and type VII collagen also in the splenic white pulp. We also found that collagen XVII was exclusively present in the ring fibers of the spleen. The results indicate that BMs of lymphatic tissues contain a variety of macromolecules that probably contribute strongly to immunological events. In addition, capillaries of the lymphoid tissue exhibit a specified BM composition resembling that in epithelial BMs of non-lymphoid tissues.

Differential expression of collagen types XVIII/endostatin and XV in normal, keratoconus, and scarred human corneas.

Purpose: This study was designed to clarify the expression of 2 closely related collagen (Col) types XVIII and XV, and the proteolytically derived endostatin fragment of ColXVIII in normal, keratoconus, and scarred human corneas. Methods: Immunohistochemistry, in situ hybridization, immunoelectron microscopy, and Western immunoblotting were used for human corneal samples obtained from penetrating keratoplasty. Results: In the normal cornea, ColXVIII was immunolocalized to the corneal and conjunctival epithelial basement membrane (EBM), Descemet s membrane, and the limbal and conjunctival capillaries. Immunoreaction for endostatin was otherwise similar, but it also was present in corneal epithelial cells. Western immunoblotting showed that normal cornea contains several endostatin fragments ranging from 20 to 100 kDa. ColXV was present in the EBM of the limbus and conjunctiva, but not in EBM of the clear cornea. In situ hybridization revealed that corneal basal epithelial cells were responsible for the synthesis of ColXVIII mRNA. Keratoconus cases were characterized by an irregular EBM immunoreactivity for ColXVIII and endostatin and patchy immunoreactivity beneath EBM. In scarred corneas, highly increased immunoreactivity for ColXVIII, endostatin, and ColXV was present within stroma. Conclusions: The results indicate that ColXVIII and ColXV are differentially expressed in normal human corneas. Constant expression of ColXVIII by corneal EBM suggests that it is an important structural molecule. Aberrant expression of ColXVIII, endostatin, and ColXV in keratoconus and scarred corneas emphasizes the active role these molecules in the wound healing process.

Transmembrane collagen XVII is a novel component of the glomerular filtration barrier

The kidney filtration barrier consists of the capillary endothelium, the glomerular basement membrane and the slit diaphragm localized between foot processes of neighbouring podocytes. We report that collagen XVII, a transmembrane molecule known to be required for epithelial adhesion, is expressed in podocytes of normal human and mouse kidneys and in endothelial cells of the glomerular filtration barrier. Immunoelectron microscopy has revealed that collagen XVII is localized in foot processes of podocytes and in the glomerular basement membrane. Its role in kidney has been analysed in knockout mice, which survive to birth but have high neonatal mortality and skin blistering and structural abnormalities in their glomeruli. Morphometric analysis has shown increases in glomerular volume fraction and surface densities of knockout kidneys, indicating an increased glomerular amount in the cortex. Collagen XVII deficiency causes effacement of podocyte foot processes; however, major slit diaphragm disruptions have not been detected. The glomerular basement membrane is split in areas in which glomerular and endothelial basement membranes meet. Differences in the expression of collagen IV, integrins α3 or β1, laminin α5 and nephrin have not been observed in mutant mice compared with controls. We propose that collagen XVII has a function in the attachment of podocyte foot processes to the glomerular basement membrane. It probably contributes to podocyte maturation and might have a role in glomerular filtration.

Differential Expression of Laminin Isoforms in Ovarian Epithelial Carcinomas Suggesting Different Origin and Providing Tools for Differential Diagnosis

Immunohistochemistry was used to study the distribution of laminin (Ln) chains, collagen types IV (α 1/2), VII, and XVIII and Lutheran antigen (Lu) in 36 frozen ovarian carcinoma samples. Surface epithelial basement membrane (BM) of the normal ovary showed immunoreactivity for Ln α1, α3-α5, β1-3, γ1, and γ2 chains and type IV and XVIII collagens. Chains of Ln-5 (α3β3γ2) and Ln-10 (α5β1γ1) as well as type IV and XVIII collagens were found in most tumor BMs, but Ln α2 chain and type VII collagen were detected only in few tumors. Contrary to serous tumors, BMs of mucinous carcinomas showed Ln α4 chain, but not Ln α1 and β2 chains. Ln α1 chain was found in most endometrioid carcinomas, whereas chains of Ln-5 were only moderately detectable in comparison with serous and mucinous carcinomas. In the normal ovary, Lu immunoreactivity was confined to basal aspect in the ovarian epithelial cells, but in tumor specimens Lu immunostainings showed variable polarized and nonpolarized patterns. The results suggest that the three types of ovarian carcinoma have distinct differences in their Ln distribution and can be grouped based on their expression pattern. This suggests that they may have histogenetically different precursors and may help to distinguish these tumors from each other.

Collagen XVII expression correlates with the invasion and metastasis of colorectal cancer

Collagen XVII has a well-established role as an adhesion molecule and a cell surface receptor located in the type I hemidesmosome of stratified epithelia. Its ectodomain is constitutively shed from the cell surface and suggested to regulate the adhesion, migration, and signaling of cutaneous epithelial cells. Collagen XVII was not previously thought to be expressed by colon epithelial cells. Immunohistochemical analysis of tissue microarray samples of 141 cases of colorectal carcinoma showed that collagen XVII is expressed in normal human colonic mucosa and colorectal carcinoma. In colorectal carcinoma, increased collagen XVII expression was significantly associated with higher TNM stage. It also correlated with infiltrative growth pattern and tumor budding as well as lymph node and distant metastasis. Increased collagen XVII expression was associated with decreased disease-free and cancer-specific survival. Immunofluorescence staining of collagen XVII and its well-known binding partner laminin γ2 chain demonstrated a partial colocalization in normal and tumor tissue. In vitro, the overexpression of murine collagen XVII promoted the invasion of CaCo-2 colon carcinoma cells through Matrigel (BD Biosciences; Bedford, MA). To conclude, this study reports for the first time the expression of collagen XVII in colon epithelium and the association of increased collagen XVII immunoexpression with poor outcome in colorectal carcinoma.

A mutant collagen XIII alters intestinal expression of immune response genes and predisposes transgenic mice to develop B-cell lymphomas.

Epithelial cells of mucosal surfaces are critical for maintaining immune homeostasis by aiding in the discrimination of pathogenic and commensal microorganisms and modulating the activities of antigen-presenting cells and lymphocytes. Functional breakdowns resulting in chronic infection and inflammation are associated with the development of hematologic and solid neoplasms for which detailed pathogenetic mechanisms are poorly understood. Mice heterozygous for a transgene Col13a1(del) expressing a mutant collagen XIII developed clonal mature B-cell lineage lymphomas originating in mesenteric lymph nodes (MLN). The tumors were associated with T cells and macrophages. The incidence of disease was reduced 2-fold in transgenic mice raised under specific pathogen-free conditions, suggesting a role for infectious agents. The lymphomas did not express the mutant collagen XIII, indicating that its influence on tumorigenesis was B-cell extrinsic and likely to be associated with collagen XIII-positive tissues drained by the MLN. Studies of the small intestines of transgenic mice showed that the subepithelial basement membranes (BM) were highly abnormal and that they exhibited heightened expression of genes involved in immune responses. These results define collagen XIII-dependent maintenance of the intestinal BM as a previously unappreciated component of immune responses and a critical determinant of cancer susceptibility.