Molecular engineering of antibodies for site-specific conjugation to lipid polydopamine hybrid nanoparticles

Conjugation of antibodies to nanoparticles allows specific cancer targeting, but conventional conjugation methods generate heterogeneous conjugations that cannot guarantee the optimal orientation and functionality of the conjugated antibody. Here, a molecular engineering technique was used for site-specific conjugation of antibodies to nanoparticles. We designed an anti-claudin 3 (CLDN3) antibody containing a single cysteine residue, h4G3cys, then linked it to the maleimide group of lipid polydopamine hybrid nanoparticles (LPNs). Because of their negatively charged lipid coating, LPNs showed high colloidal stability and provided a functional surface for site-specific conjugation of h4G3cys. The activity of h4G3cys was tested by measuring the binding of h4G3cys-conjugated LPNs (C-LPNs) to CLDN3-positive tumor cells and assessing its subsequent photothermal effects. C-LPNsspecifically recognized CLDN3-overexpressing T47D breast cancer cells but not CLDN3-negative Hs578T breast cancer cells. High binding of C-LPNs to CLDN3-overexpressing T47D cells resulted in significantly higher temperature generation upon NIR irradiation and potent anticancer photothermal efficacy. Consistent with this, intravenous injection of C-LPNsin a T47D xenograft mouse model followed by NIR irradiation caused remarkable tumor ablation compared with other treatments through high temperature increases. Our results establish an accurate antibody-linking method and demonstrate the possibility of developing therapeutics using antibody-guided nanoparticles.     

Clostridium Perfringens Enterotoxin (CPE) and CPE-Binding Domain (c-CPE) for the Detection and Treatment of Gynecologic Cancers

Clostridium perfringens enterotoxin (CPE) is a three-domain polypeptide, which binds to Claudin-3 and Claudin-4 with high affinity. Because these receptors are highly differentially expressed in many human tumors, claudin-3 and claudin-4 may provide an efficient molecular tool to specifically identify and target biologically aggressive human cancer cells for CPE-specific binding and cytolysis. In this review we will discuss these surface proteins as targets for the detection and treatment of chemotherapy-resistant gynecologic malignancies overexpressing claudin-3 and -4 using CPE-based theranostic agents. We will also discuss the use of fluorescent c-CPE peptide in the operative setting for real time detection of micro-metastatic tumors during surgery and review the potential role of CPE in other medical applications.     

Claudin-1和Claudin-2在大鼠急性结肠炎黏膜中的表达

目的 观察紧密连接蛋白Claudin-1和Claudin-2在急性结肠炎大鼠模型结肠黏膜中的表达.方法 对16只SD大鼠采用三硝基苯磺酸灌肠建立急性结肠炎模型,各取8只分别于1周和2周后观察结肠组织的病理学变化,另取5只正常大鼠作对照.应用量子点免疫标记技术检测两种蛋白在正常大鼠、结肠炎1、2周大鼠结肠黏膜中的表达及分布,测定蛋白表达的荧光强度.结果 与正常组比较,急性结肠炎1周时大鼠的Claudin-1和Claudin-2表达均明显增强(荧光强度分别为66.01±25.14比48.12±13.25,70.35±24.36比40.12±9.56,P均<0.01)且分布更广,2周时表达水平较1周时回落(P<0.05),其中Claudin-1下降较为明显,Claudin-2仍维持一个较高水平[分别为54.64±14.26和60.87±14.27,与正常组比较,差异均有统计学意义(P<0.05,P<0.01)].Claudin-1和Claudin-2表达的变化与结肠炎病理学观察的结果 基本一致.结论 急性结肠炎导致肠黏膜的Claudin-1和Claudin-2表达增强,尤以Claudin-2增加明显,两者的变化与急性结肠炎的病理改变密切相关.

Abstract：

Objective To study the expression of Claudin-1 and Claudin-2 in colonic epithelium of trinitrobenzene sulfonic acid (TNBS)-induced acute colitis models in rats.Methods Sixteen TNBS-induced colitis models in rats were established, and pathologic changes of colonic epithelium were analyzed after one or two weeks respectively. Fluorescence of quantum dots-labelled Claudin-1 and Claudin-2 expression was detected in colonic epithelial cells of normal, one-week colitis, and two-week colitis rats. Fluorescence intensity and distribubition of fluorescence signals were recorded and analyzed.Results As compared with that in normal rats (n=5), both Claudin-1 and Claudin-2 expression was increased in one-week colitis rats (relative fluorescence intensity: 66.01±25.14 vs. 48.12±13.25, 70.35±24.36 vs 40.12±9.56, both P<0.01) with wider distribution in crypt. In two-week colitis rats, Claudin-1 and Claudin-2 expression levels were dropped, but Claudin-2 expression was decreased less than Claudin-1, and both remained at a higher level than normal rats (54.64±14.26 and 60.87±14.27, respectively, P<0.05 and P<0.01, respectively vs normal). The changes of expression of Claudin-1 and Claudin-2 were in accordance with the results of pathologic scoring for colitis.Conclusion Along with the pathologic changes in colonic epithelium, Claudin-1 and Claudin-2 expression levels are increased in acute colitis rats, and Claudin-2 expression seems more significant than Claudin-1 as an indicator for colitis.     

唾液腺紧密连接蛋白Claudin的研究进展

紧密连接(tight junction, TJ)是参与旁细胞分泌途径中蛋白质相互作用的复杂动态系统,具有屏障功能和栅栏功能。Claudin家族构成紧密连接链的主干,在唾液腺放射性损伤、炎症性疾病、舍格伦综合征和糖尿病等病理状况下会出现表达模式的异常改变,导致紧密连接结构和功能异常,间接表现为唾液腺功能障碍。此外,唾液腺肿瘤中Claudin蛋白的表达差异也可作为判断肿瘤类型及预后的指标。本文重点综述了唾液腺常见Claudin蛋白的研究进展,包括结构、功能、相关疾病的表达模式及其应用,为Claudin蛋白相关疾病的临床研究和基础研究提供新思路。     

The application of an alanine-substituted mutant of the C-terminal fragment of Clostridium perfringens enterotoxin as a mucosal vaccine in mice

Efficient delivery of antigen to mucosal immune tissues is an essential part of mucosal vaccination. Claudin-4 is expressed on the epithelial cells that cover the mucosal immune tissues. We previously found that claudin-4-targeting is a promising strategy for mucosal vaccination by using a claudin-4 binder, the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE). Substitution of Asn and Ser at positions 309 and 313, respectively, with alanine increased the affinity of C-CPE for claudin-4. However, application of the C-CPE mutant as a mucosal vaccine has never been tried. Here, we investigated whether the C-CPE mutant could serve as a mucosal vaccine. We used ovalbumin (OVA) as a model antigen and fused the C-CPE mutant to it. The resultant fusion protein was bound to claudin-4. When mice were immunized with the C-CPE mutant-fused OVA, OVA-specific serum IgG and nasal IgA increased relative to levels in mice immunized with a C-CPE-fused antigen. Immunization with the C-CPE mutant-fused OVA activated Th1- and Th2-type responses and led to increased anti-tumor activity against OVA-expressing thymoma cells relative to that of mice immunized with the C-CPE-fused antigen. These findings suggest that the alanine-substituted C-CPE mutant shows promise as a claudin-targeted mucosal vaccine.     

Claudins 1, 3, 4 and 5 in gastric carcinoma, loss of claudin expression associates with the diffuse subtype

In this study expression of claudins 1, 3, 4 and 5 were studied in 118 cases of gastric carcinoma and compared with proliferation, apoptosis and E-cadherin expression. Expression of all these claudins could be seen in gastric carcinoma, most prominently for claudin 4, and least expression was found for claudin 5. All claudins showed significantly more expression in gastric carcinomas of intestinal type. Their expression was significantly associated with each other. Expression of claudins 4 and 5 was associated with E-cadherin. Strong expression of claudin 5 was associated with higher cell proliferation and apoptosis. Claudin 3 expression had an association with a better prognosis of the patients, especially in the intestinal type. The results show that expression of claudins 1, 3, 4 and 5 is lower in diffuse-type gastric carcinomas. Possibly they play a role in determining the diffuse phenotype and loose cohesion of cells in diffuse type of gastric carcinoma in a similar manner as E-cadherin. The loss of their expression does not clearly associate with poorer prognosis of the patients, except for claudin 3, where strong expression was associated with a better outcome of the patients, a feature especially related to intestinal-type tumours.     

Folate-linked lipoplexes for short hairpin RNA targeting claudin-3 delivery in ovarian cancer xenografts

Ovarian cancers highly overexpress folate receptor α (FRα) and claudin3 (CLDN3), both of which are associated with tumor progression and poor prognosis of patients. Downregulation of FRα and CLDN3 in ovarian cancer may suppress tumor growth and promote benign differentiation of tumor. In this study, F-P-LP/CLDN3, a FRα targeted liposome loading with short hairpin RNA (shRNA) targeting CLDN3 was prepared and the pharmaceutical properties were characterized. Then, the antitumor effect of F-P-LP/CLDN3 was studied in an in vivo model of advanced ovarian cancer. Compared with Control, F-P-LP/CLDN3 promoted benign differentiation of tumor and achieved about 90% tumor growth inhibition. In the meantime, malignant ascites production was completely inhibited, and tumor nodule number and tumor weight were significantly reduced (p < 0.001). FRα and CLDN3 were downregulated together in tumor tissues treated by F-P-LP/CLDN3. The antitumor mechanisms were achieved by promoting tumor cell apoptosis, inhibiting tumor cell proliferation and reducing microvessel density. Finally, safety evaluation indicated that F-P-LP/CLDN3 was a safe formulation in intraperitoneally administered cancer therapy. We come to a conclusion that F-P-LP/CLDN3 is a potential targeting formulation for ovarian cancer gene therapy.     

血脑屏障紧密连接蛋白claudin与脑缺血及其分子机制

组成血脑屏障紧密连接的重要物质,跨膜蛋白Claudin,对维持血脑屏障的紧密连接的完整性及其正常的生理功能起着重要作用,当Claudin蛋白出现结构或功能上的障碍时,血脑屏障功能也会随之改变。目前研究显示,脑缺血对Claudin的分布和表达等都影响着血脑屏障的功能,进而影响着整个内环境的稳态。所以,研究Claudin蛋白的结构、基因表达、病理状态下的变化和与之有关的信号转导等都对了解血脑屏障的选择性开放机制、及药物治疗靶点中的作用都有着深远的意义。