Expression Of Thrombospondin Type-1 Domain-containing 7A Research Articles

Correlation Between THSD7A Expression and Tumor Characteristics of Azoxymethane-Induced Colon Cancer Model in Rats.

Thrombospondin type 1 domain-containing 7A (THSD7A) has emerged as a new potential molecular tool for multiple tumors since that THSD7A was detected to be expressed in various malignant tumor types including colorectal cancer (CRC). Thus, we investigated the correlation between THSD7A expression and pathologic determinants of azoxymethane (AOM)-induced CRC in a rat model. A total of 30 rats were included in the study (experimental group; n = 15, control group; n = 15). Azoxymethane was administered to the experimental group weekly as subcutaneous injections at a dose of 15 mg/kg bodyweight for 3 weeks. Five months later, 42 tumors were obtained in the study group and histopathologic evaluation of CRC tumors for THSD7A was performed by immunohistochemical staining. Thrombospondin type 1 domain-containing 7A expression was classified according to staining levels. While 28.6% of the colonic tumors were stained as negative, mild-moderate and strong staining was determined in 61.9% and 9.5% of the tumors, respectively. Thrombospondin type 1 domain-containing 7A expression levels inversely correlated with Ki-67 expression (P < .001) and tumor grade (P =.02). Receiver operating characteristic analysis showed Ki-67 staining ≥20.5% was determined as a cut-off value for negatively stained THSD7A tumors with 91% sensitivity and 69% specificity (P = .001, area under curve: 0.822). Moreover, higher Ki-67 expression was found to be associated with higher tumor grade (P < .001), presence of lymphatic invasion (P = .003), and higher T stage (P = .003). Negative staining for THSD7A seems to be linked to invasive pathologic determinants in AOM-induced CRC in rats.

THSD7A expression: a novel immunohistochemical determinant in predicting overall survival of metastatic renal cell carcinoma treated with targeted therapy.

The association of thrombospondin type 1 domain-containing 7A (THSD7A) expression, a novel angiogenesis-related marker, with survival outcomes of tumors including renal cell carcinoma (RCC) remains to be clarified. Therefore, we investigated the impact of THSD7A on outcomes of metastatic RCC (mRCC) patients treated with targeted therapy. A total of 86 mRCC patients were included. The expression of THSD7A in nephrectomy material of the patients was assessed by immunohistochemistry and expression patterns were categorized into two groups: negative (no staining) and positive. Univariable and multivariable Cox regression models evaluated the impact of THSD7A expression on progression free survival (PFS) and overall survival (OS) of the patients. THSD7A expression was determined in 77.9% of the patients. Kaplan-Meier analyses showed that while the patients with THSD7A expression had significantly inferior OS times than those with negative THSD7A expression (19.9months vs. 52.2months, P = 0.024, respectively), there was no association between THSD7A expression and PFS. The univariate analyses demonstrated that the significant variables in predicting OS were presence of bone metastasis (P = 0.030), THSD7A expression (P = 0.028), and International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) scoring system (P < 0.001). However, applying multivariate analyses, the independent variables in predicting OS were THSD7A expression (HR: 2.639, P = 0.037) and IMDC scoring system (P < 0.001). We revealed that THSD7A expression was associated with OS of mRCC patients treated with targeted therapy. There might be an important link between THSD7A expression and resistance to targeted therapy.

Effects of phospholipase A2 receptor and thrombospondin type-1 domain-containing 7A expression in glomerular basement membranes on treatment response and renal outcome in membranous nephropathy.

The aim of this study was to define the clinicopathologic features of phospholipase A2 receptor (PLA2R) and/or thrombospondin type-1 domain-containing 7A (THSD7A) associated membranous nephropathy(MN) focusing on their impact to disease relapse and response to treatment. A total of 201 patients were enrolled for baseline clinical and histopathological features and 102 patients with a clinical follow-up for more than 1year were evaluated for outcomes. Immunohistochemical staining was performed with PLA2R and THSD7A antibodies on kidney biopsies and glomerular staining was evaluated. PLA2R expression was observed in 75% of the patients' biopsies; however, THSD7A expression was present only in 7 patients' biopsies (3.5%). No significant difference was found between histopathological and clinical features of PLA2R positive and negative patients, collectively. Glomerular PLA2R expression was significantly associated with complete and complete/partial remission with first-line treatment; however, overall complete, and complete/partial remission rates did not differ from PLA2R negative patients (p = 0.2 and p = 0.8). Male gender, the presence of IgG4 staining and a necessity of immunosuppressive treatment were significantly associated with glomerular PLA2R expression. One patient, who developed end-stage renal disease, had glomerular expression for both PLA2R and THSD7A. Three patients with THSD7A-positive MN achieved complete remission. The probability of achieving complete remission is high in patients with PLA2R-positive MN for whom the relapse rate was also higher. The overall renal outcome did not differ from PLA2R negative cases. Low incidence of THSD7A-positive MN reduces the possibility of future randomized controlled trials.

Renal expression of PLA2R, THSD7A, and IgG4 in patients with membranous nephropathy and correlation with clinical findings.

Membranous nephropathy (MN) is the most common cause of nephrotic syndrome in nondiabetic adults. M-type phospholipase A2 receptor (PLA2R), thrombospondin type-1 domain-containing 7A (THSD7A) are known as target podocyte antigens in membranous nephropathy (MN). Antibodies against these podocyte antigens are used in the initiation of treatment and response monitoring. However, the relationship between renal podocyte antigens and treatment response is not clear yet. We evaluated the relationship between immunohistochemical PLA2R, THSD7A and IgG4 staining, clinical findings and treatment response in kidney biopsies. Fifty-eight patients with MN were included in this retrospective study. In the renal biopsy samples of the patients, PLA2R, THSD7A and IgG4 were stained immunohistochemically and evaluated by light microscopy. The clinical, laboratory and treatment results of the patients were obtained from the hospital records. The study included a total of 58 patients with MN and a mean follow-up period of 32.3±19.7months. In patients with primary MN; PLA2R, THSD7A and IgG4 were positive in 57.1% (n=28), 12.2% (n=6) and 69.4% (n=34), respectively. Only PLA2R staining was distinctly higher in patients with primary MN than secondary MN (P=.025). Dual positivity (PLA2R+THSD7A) was detected in five (10.2%) of patients with primary MN. We did not determine any relationship between the PLA2R, THSD7A and IgG4 staining patterns and treatment response of the patients. It was found no correlation between PLA2R, THSD7A and IgG4 staining in kidney tissue and treatment response. Interestingly, dual positivity (PLA2R+THSD7A) was detected only in primary MN.

Clinicopathological features in membranous nephropathy with cancer: A retrospective single-center study and literature review.

Membranous nephropathy is the most common glomerular disease related to malignancy. However, it is difficult to distinguish between true malignancy-related membranous nephropathy and idiopathic membranous nephropathy coincident with cancer. It has been reported that phospholipase A2 receptor (PLA2R) is the first autoantigen involved in idiopathic membranous nephropathy and thrombospondin type-1 domain-containing 7A (THSD7A) may have a close relationship with malignancy-related membranous nephropathy. Therefore, the aim of this study was to compare the clinicopathological characteristics between membranous nephropathy patients with cancer and idiopathic membranous nephropathy patients without cancer to better detect malignancy-related membranous nephropathy, including glomerular PLA2R and THSD7A depositions and their circulating antibodies, together with glomerular IgG4 deposition. Twelve membranous nephropathy patients with cancer and 257 idiopathic membranous nephropathy patients without cancer were included in this study and had been followed up for more than 1 year. The glomerular expression of PLA2R, THSD7A, and IgG4 was analyzed by immunohistochemistry. Circulating anti-PLA2R and anti-THSD7A antibodies were assessed by enzyme-linked immunosorbent assay and indirect immunofluorescence testing, respectively. Membranous nephropathy patients with cancer were significantly older and had higher serum creatinine and a lower estimated glomerular filtration rate than idiopathic membranous nephropathy patients (P<0.05). The positive rates of glomerular PLA2R and IgG4 depositions and circulating anti-PLA2R antibodies in membranous nephropathy patients with cancer were significantly lower than those in idiopathic membranous nephropathy patients without cancer (P<0.01). The absence of glomerular PLA2R deposition and negative circulating anti-PLA2R antibodies, along with negative glomerular IgG4 staining, may be useful clues to more accurately screen underlying malignancies in membranous nephropathy patients.

SUN-030 PHOSPHOLIPASE A2 RECEPTOR AND THROMBOSPONDIN TYPE-1 DOMAIN-CONTAINING 7A IN MALIGNANCY MEMBRANOUS NEPHROPATHY

Phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A) have recently been identified as pathogenic antigens in patients with membranous nephropathy (MN). Notably, PLA2R is detected in a few patients with malignancy-associated MN. Furthermore, a high incidence of cancer is reported in patients with THSD7A-associated MN. It is thus necessary to clarify the usefulness of PLA2R and THSD7A in malignancy-associated MN. Serum anti-PLA2R antibodies and glomerular PLA2R expression were first screened in 36 patients with malignancy-associated MN by enzyme-linked immunosorbent assay (ELISA) and immunofluorescence, respectively, followed by examination of serum anti-THSD7A antibodies and glomerular THSD7A. THSD7A expression in cancer tissues was also assessed in 9 of the 36 patients. Among the 36 patients, 12 (33%) were positive for both glomerular PLA2R staining and serum anti-PLA2R antibodies, and 2 were positive for either glomerular PLA2R staining or serum anti-PLA2R antibodies. IgG4 was the dominant IgG subclass in PLA2R-related patients. One patient with positve glomerular PLA2R staining was also positive for THSD7A staining. Among the remaining 22 (61%) patients who were double negative for glomerular PLA2R staining and serum anti-PLA2R antibodies, 17 of 20 (85%) had IgG1 dominant deposits in glomeruli, and 2 (9%) were positive for glomerular THSD7A staining. Serum anti-THSD7A antibody was not detected in any of the 36 patients. Among the 9 patients with available cancer tissues, enhanced expression of THSD7A in the cancer tissues was observed for 5 (56%), and one also showed enhanced glomerular expression of THSD7A. Screening of glomerular PLA2R antigen and serum anti-PLA2R antibodies is necessary in patients with malignancy-associated MN, whereas the incidence of glomerular THSD7A antigen or circulating anti-THSD7A antibodies is uncommon.

Thrombospondin Type 1 Domain-Containing 7A Localizes to the Slit Diaphragm and Stabilizes Membrane Dynamics of Fully Differentiated Podocytes.

About 3%-5% of adults with membranous nephropathy have autoantibodies directed against thrombospondin type 1 domain-containing 7A (THSD7A), a podocyte-expressed transmembrane protein. However, the temporal and spatial expression of THSD7A and its biologic function for podocytes are unknown, information that is needed to understand the effects of THSD7A autoantibodies in this disease. Using a variety of microscopic techniques, we analyzed THSD7A localization in postnatal, adult, and autoantibody-injected mice as well as in human podocytes. We also analyzed THSD7A function in human podocytes using confocal microscopy; Western blotting; and adhesion and migration assays. We found that THSD7A expression begins on glomerular vascularization with slit diaphragm formation in development. THSD7A localizes to the basal aspect of foot processes, closely following the meanders of the slit diaphragm in human and mice. Autoantibodies binding to THSD7A localize to the slit diaphragm. In human podocytes, THSD7A expression is accentuated at filopodia and thin arborized protrusions, an expression pattern associated with decreased membrane activity of cytoskeletal regulators. We also found that, phenotypically, THSD7A expression in human podocytes is associated not only with increases in cell size, enhanced adhesion, and reduced detachment from collagen type IV-coated plates but also, with decreased ability to migrate. Our findings suggest that THSD7A functions as a foot process protein involved in the stabilization of the slit diaphragm of mature podocytes and that autoantibodies to THSD7A, on the basis of their localization, might structurally and functionally alter the slit diaphragm's permeability to protein.

Antigen-Specific IgG Subclasses in Primary and Malignancy-Associated Membranous Nephropathy.

Membranous nephropathy (MN) is an autoimmune disease caused by binding of circulating antibodies to podocyte antigens in the kidney. For decades and still today primary MN has been considered to have an unspecified IgG4-driven autoimmune genesis, while secondary MN has been associated with other diseases, most notably cancer, and not linked to IgG4. Immunologic mechanisms of primary and malignancy-associated MN are assumed to be different, however, this has never been systematically evaluated. The identification of Phospholipase A2 Receptor 1 (PLA2R1) and Thrombospondin Type-1 Domain-Containing 7A (THSD7A) as target antigens in MN allows a pathogenesis-driven differential diagnosis. Recent data showing a molecular link between increased THSD7A-expression in tumors and THSD7A-antibody positive MN suggest a similar pathogenesis of malignancy-associated and primary MN. In order to better define the underlying immunologic processes, we systematically analyzed circulating antigen-specific IgG subclasses in the serum of 76 patients with PLA2R1-associated MN and 41 patients with THSD7A-associated MN in relationship to concurrent malignancy and disease outcome. Twenty-three patients in the study had malignancy-associated MN. We analyzed antigen-specific IgG subclasses in the serum of all patients at baseline and in 55 patients during follow-up by Western blot applying antigens derived from human kidney and lung. At baseline all 117 patients were positive for IgG4-antibodies against either PLA2R1 or THSD7A, while IgG3, IgG1, and IgG2-antibodies were found in 87, 72, and 26% of patients, respectively. There were no differences in the IgG subclass distribution between patients with primary vs. cancer-associated MN and no association with disease outcome. Moreover, levels of antigen-specific IgG4-antibodies were not different between primary and malignancy-associated MN and levels of all IgG subclasses did not differ between these groups. Both podocytes and lung bronchioles showed expression of both PLA2R1 and THSD7A when analyzed by immunofluorescence and Western blot. Every antigen-specific IgG subclass showed identical binding in both organs and autoantibodies bound the respective antigen only under non-reducing conditions. We conclude that antigen-specific IgG subclasses do not differentiate primary from malignancy-associated MN or predict disease prognosis. These data support the view that one common pathway may lead to primary and cancer-associated MN induced by PLA2R1- or THSD7A-antibodies.

Membranous nephropathy-one morphologic pattern with different diseases.

Since the discovery of the phospholipase A2 receptor 1 (PLA2R1) and thrombospondin type-1 domain-containing 7A (THSD7A) as endogenous antigens involved in the development of membranous nephropathy (MN) in over 80% of adult patients, substantial progress in the diagnosis, prognosis, and therapy of MN has been made. In most cases of patients with MN, it is now possible to specifically define the responsible pathogenic mechanisms of disease and make a diagnosis even without a renal biopsy. Moreover, the presence of antibodies in the blood and the detection of the antigens in renal biopsies allow the definite diagnosis without the morphologic uncertainties, which now still apply for only about 20% of all renal biopsies showing MN. The discovery that the expression of THSD7A in malignant tumors might serve as the site of primary antigen recognition for the immune system to start MN might lead to a better understanding of not only tumor-associated MN, which accounts for up to 10% of all patients with MN, but also of the pathomechanisms relevant for MN development in general.

THSD7A expression in human cancer.

We recently described a case of a Thrombospondin Type-1 Domain containing 7A (THSD7A) associated membranous nephropathy in a female patient who was synchronously suffering from a THSD7A-positive malignancy. We here investigated the role of THSD7A as a new potential tumor antigen by evaluating over 20000 tissue spots in more than 70 different tumor entities by immunohistochemistry using tissue microarrays. THSD7A expression was highly variable in different neoplasias with differing staining patterns. Both gain and loss of THSD7A expression compared to expression status in non-tumor tissue were linked to tumor-specific markers in the different tumor entities and were of prognostic value. The potential role of THSD7A in tumor development and therapy needs further investigation.

An Indirect Immunofluorescence Method Facilitates Detection of Thrombospondin Type 1 Domain-Containing 7A-Specific Antibodies in Membranous Nephropathy.

Thrombospondin type 1 domain-containing 7A (THSD7A) is a target antigen identified in adult membranous nephropathy (MN) along with the major antigen phospholipase A2 receptor 1 (PLA2R1). The prevalence of THSD7A-Ab-positive patients is unknown, and it is unclear whether the clinical presentation differs between patients positive for PLA2R1-Ab or THSD7A-Ab. We screened serum samples of 1276 patients with MN from three different cohorts for the presence of THSD7A-Ab by Western blot analysis and a newly developed indirect immunofluorescence test (IFT). Compared with Western blot analysis, the IFT had a 92% sensitivity and a 100% specificity. The prevalence of THSD7A-associated MN in a prospective cohort of 345 patients with MN was 2.6%, and most were women. In this cohort, the percentage of patients with THSD7A-associated MN and malignant disease significantly exceeded that of patients with PLA2R1-associated MN and malignant disease. In all cohorts, we identified 40 patients with THSD7A-associated MN, eight of whom developed a malignancy within a median time of 3 months from diagnosis of MN. In one patient with THSD7A-associated MN and metastases of an endometrial carcinoma, immunohistochemistry showed THSD7A expression on the metastatic cells and within follicular dendritic cells of the metastasis-infiltrated lymph node. We conclude that the IFT allows sensitive and specific measurement of circulating THSD7A-Ab in patients with MN. Patients with THSD7A-associated MN differ in their clinical characteristics from patients with PLA2R1-associated MN, and more intensive screening for the presence of malignancies may be warranted in those with THSD7A-associated MN.

Prevalence of Enhanced Granular Expression of Thrombospondin Type-1 Domain-Containing 7A in the Glomeruli of Japanese Patients with Idiopathic Membranous Nephropathy.

Membranous nephropathy (MN) is a leading cause of nephrotic syndrome in adults. Autoantibodies against M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A), which mainly belong to the IgG4 subclass, were reported as associated antibodies for the development of MN. Although PLA2R is a major target antigen for idiopathic MN, the prevalence of MN patients seropositive for PLA2R in Japan is lower than that in other countries. In this study, we conducted immunohistochemical analysis of the presence of THSD7A and PLA2R in renal specimens of MN patients to estimate the prevalence of THSD7A/PLA2R-related idiopathic MN in Japan. Enhanced granular expression of THSD7A and PLA2R was detected in 9.1% and 52.7%, respectively, of the patients with idiopathic MN. Although none of patients with secondary MN displayed enhanced granular expression of THSD7A, 5.4% of them had enhanced granular expression of PLA2R. In conclusion, the prevalence of enhanced granular expression of THSD7A in the glomeruli of Japanese patients with idiopathic MN was higher than the prevalence of MN patients seropositive for THSD7A in USA and Europe.