Seneca Valley Virus Exploits TEM8, a Collagen Receptor Implicated in Tumor Growth

Oncolytic senecavirus A in tumor immunotherapy: Mechanisms, progress, and future directions

Oncolytic virotherapy has emerged as a promising immunotherapy strategy against cancer. As the first picornavirus tested in humans for its oncolytic potential, Senecavirus A (SVA) possesses several advantageous features, including its small size, rapid replication, and ability to penetrate the vascular system of solid tumors, allowing for the specific targeting and lysis of tumor cells. Additionally, SVA does not integrate into the host genome, thus avoiding potential genomic damage, and it lacks oncogenes or other virulence genes. Importantly, no significant pathogenic effects have been observed in humans or companion animals. Due to its simple genetic structure, SVA is amenable to various genetic modifications, allowing it to carry exogenous genes to further enhance tumor therapy. This review summarizes current knowledge of SVA's mechanisms of action and its progress in oncolytic therapy research, while also addressing the challenges and future directions.

Elevated expression of ANTXR1 gene in tumors is a poor prognostic biomarker for patients with bladder cancer

The TEM8 protein coded by the ANTXR1 gene represents an emerging biomarker in solid tumors. In addition to the various roles TEM8 plays in oncogenesis, including angiogenesis, epithelial-to-mesenchymal transition, and cell migration, it has also been shown that the overexpression of the ANTXR1 gene in solid tumors correlates with poor prognostic indicators in several solid tumor histologies. As such, TEM8 has been identified as the target of novel oncologic therapies. It is especially attractive given its selective expression on the surface of solid tumor cells and associated stromal cells, such as cancer stem cells, invasive cancer cells, and immune cells, such as macrophages, angiogenic endothelial cells, pericytes, and cancer-associated fibroblasts. Furthermore, TEM8 plays this unique role as a mostly non-mutated gene in solid cancers. Here, we demonstrate that elevated expression of ANTXR1 in bladder cancer showed a statistical difference not only in overall survival (OS) but in progression-free survival (PFS), confirming the prognostic biomarker power of ANTXR1 expression.

Oncolytic virotherapy against lung cancer: key receptors and signaling pathways of viral entry

Lung cancer accounts for the highest cancer-related mortality worldwide. While immunotherapies targeting anti-tumor immune responses have demonstrated efficacy in clinical practice, the demand for novel treatment modalities remains urgent. Oncolytic viruses (OVs), which selectively kill tumor cells while stimulating an anti-tumor immune response, represent a potential breakthrough in lung cancer therapy. The induction of anti-tumor immunity by OVs is central to their overall therapeutic effectiveness. Many natural receptors on the surface of cancer cells are dysregulated, providing potential entry points for OVs. Furthermore, the inherent dysregulation of some key signaling pathways in lung cancer cells promotes proliferation, progression and metastasis, which may facilitate selective viral replication. In this review, we explore the application of OVs in lung cancer by analyzing several major OVs and their corresponding entry receptors. Then, we also examine the key signaling pathways and molecules with the potential to synergize with OVs in modulating the immune tumor microenvironment. Finally, we discuss the combination and administration strategies that warrant further clinical trials for validation. Despite certain limitations, the tolerability of OVs positions virotherapy as a promising avenue in the future of lung cancer treatment.

Novel Therapies in Glioblastoma Treatment: Review of Glioblastoma; Current Treatment Options; and Novel Oncolytic Viral Therapies

One of the most prevalent primary malignant brain tumors is glioblastoma (GB). About 6 incidents per 100,000 people are reported annually. Most frequently, these tumors are linked to a poor prognosis and poor quality of life. There has been little advancement in the treatment of GB. In recent years, some innovative medicines have been tested for the treatment of newly diagnosed cases of GB and recurrent cases of GB. Surgery, radiotherapy, and alkylating chemotherapy are all common treatments for GB. A few of the potential alternatives include immunotherapy, tumor-treating fields (TTFs), and medications that target specific cellular receptors. To provide new multimodal therapies that focus on the molecular pathways implicated in tumor initiation and progression in GB, novel medications, delivery technologies, and immunotherapy approaches are being researched. Of these, oncolytic viruses (OVs) are among the most recent. Coupling OVs with certain modern treatment approaches may have significant benefits for GB patients. Here, we discuss several OVs and how they work in conjunction with other therapies, as well as virotherapy for GB. The study was based on the PRISMA guidelines. Systematic retrieval of information was performed on PubMed. A total of 307 articles were found in a search on oncolytic viral therapies for glioblastoma. Out of these 83 articles were meta-analyses, randomized controlled trials, reviews, and systematic reviews. A total of 42 articles were from the years 2018 to 2023. Appropriate studies were isolated, and important information from each of them was understood and entered into a database from which the information was used in this article. One of the most prevalent malignant brain tumors is still GB. Significant promise and opportunity exist for oncolytic viruses in the treatment of GB and in boosting immune response. Making the most of OVs in the treatment of GB requires careful consideration and evaluation of a number of its application factors.

TEM8 in Oncogenesis: Protein Biology, Pre-Clinical Agents, and Clinical Rationale

The TEM8 protein represents an emerging biomarker in many solid tumor histologies. Given the various roles it plays in oncogenesis, including but not limited to angiogenesis, epithelial-to-mesenchymal transition, and cell migration, TEM8 has recently served and will continue to serve as the target of novel oncologic therapies. We review herein the role of TEM8 in oncogenesis. We review its normal function, highlight the additional roles it plays in the tumor microenvironment, and synthesize pre-clinical and clinical data currently available. We underline the protein's prognostic and predictive abilities in various solid tumors by (1) highlighting its association with more aggressive disease biology and poor clinical outcomes and (2) assessing its associated clinical trial landscape. Finally, we offer future directions for clinical studies involving TEM8, including incorporating pre-clinical agents into clinical trials and combining previously tested oncologic therapies with currently available treatments, such as immunotherapy.

Structural and nonstructural proteins of Senecavirus A: Recent research advances, and lessons learned from those of other picornaviruses

Senecavirus A (SVA) is an emerging virus, causing vesicular disease in swine. SVA is a single-stranded, positive-sense RNA virus, which is the only member of the genus Senecavirus in the family Picornaviridae. SVA genome encodes 12 proteins: L, VP4, VP2, VP3, VP1, 2A, 2B, 2C, 3A, 3B, 3C and 3D. The VP1 to VP4 are structural proteins, and the others are nonstructural proteins. The replication of SVA in host cells is a complex process coordinated by an elaborate interplay between the structural and nonstructural proteins. Structural proteins are primarily involved in the invasion and assembly of virions. Nonstructural proteins modulate viral RNA translation and replication, and also take part in antagonizing the antiviral host response and in disrupting some cellular processes to allow virus replication. Here, we systematically reviewed the molecular functions of SVA structural and nonstructural proteins by reference to literatures of SVA itself and other picornaviruses.

Development and Evaluation of a Competitive Enzyme-Linked Immunosorbent Assay Based on Swine Monoclonal Antibodies for Detecting Neutralizing Antibodies against Senecavirus A

Senecavirus A (SVA) is an emerging viral pathogen related to vesicular disease and neonatal mortality in swine, which results in enormous economic losses to the global swine industry. The clinical signs of SVA are indistinguishable from those of other vesicular diseases, such as foot-and-mouth disease, which is an economically devastating animal disease. Therefore, development of a rapid, sensitive, and specific diagnostic method for the detection of SVA infection is critical for the prevention and control of SVA and would help to rule out other exotic diseases. In this study, two whole-porcine anti-SVA antibodies (1M5 and 1M25) were produced using single B cell antibody technology. 1M5 and 1M25 possessed neutralizing activity against SVA but recognized different conformational epitopes that depended on the intact virion. Using 1M5 as the capture antibody and biotinylated 1M25 as the detection antibody, a reliable and rapid competitive enzyme-linked immunosorbent assay for detecting neutralizing antibodies (NAC-ELISA) against SVA was developed. Receiver-operating characteristic curve analysis showed that the sensitivity and specificity of the assay were 98.11% and 100%, respectively, with a cutoff percent inhibition value of 45%. The NAC-ELISA was specific for detecting SVA-specific antibodies, without cross-reactivity to other virus-infected sera. The results of the NAC-ELISA showed a strong agreement with the results of the virus neutralization test. Therefore, the NAC-ELISA developed in this study represents a sensitive, specific, and reliable tool for the detection of SVA-specific antibodies, which is applicable for serodiagnosis and serological surveillance of SVA and is conducive to the prevention and control of SVA. IMPORTANCE Senecavirus A (SVA) is an emerging picornavirus related to vesicular disease and neonatal mortality in swine, which results in enormous economic losses worldwide. Additionally, the clinical characteristics of the disease are indistinguishable from those of other vesicular diseases, such as foot-and-mouth disease. Therefore, developing tools for rapidly and accurately detecting SVA infection is critical and urgent. In this study, two porcine-derived monoclonal antibodies against SVA were generated, and a competitive ELISA for the detection of neutralizing antibodies (NAC-ELISA) against SVA was successfully developed using these two porcine monoclonal antibodies. The NAC-ELISA was SVA specific with no cross-reactivity to other related pathogens and had high sensitivity, specificity, and reproducibility for detecting SVA-specific antibody. Therefore, the NAC-ELISA developed in this study may be of great value as a simple and reliable tool for serodiagnosis or surveillance of SVA and may facilitate the prevention and control of SVA.

A Structure-Guided Genetic Modification Strategy: Developing Seneca Valley Virus Therapy against Nonsensitive Nonsmall Cell Lung Carcinoma

Numerous studies have illustrated that the Seneca Valley virus (SVV) shows sufficient oncolytic efficacy targeting small cell lung cancer (SCLC). However, the therapeutics of nonsmall cell lung carcinoma (NSCLC, accounts for 85% of lung cancer cases) using oncolytic virus have been resisting due to the filtration of neutralizing antibody and limited reproduction capacity. Here, we employed structural biology and reverse genetics to optimize novel oncolytic SVV mutants (viral receptor-associated mutant SVV-S177A and viral antigenic peptide-related variant SVV-S177A/P60S) with increased infectivity and lower immunogenicity. The results of the NSCLC-bearing athymic mouse model demonstrated that wild-type (wt) SVV-HB extended the median overall survival (mOS) from 11 days in the PBS group to 19 days. Notably, the newly discovered mutations significantly (P < 0.001) prolonged the mOS from 11 days in the control cohort to 23 days in the SVV-S177A cohort and the SVV-S177A/P60S cohort. Taken together, we present a structure-guided genetic modification strategy for oncolytic SVV optimization and provide a candidate for developing oncolytic viral therapy against nonsensitive NSCLC. IMPORTANCE Nonsmall cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer cases (more than 1.85 million cases with 1.48 million deaths in 2020). In the present study, two novel oncolytic SVV mutants modified based on structural biology and reverse genetics (viral receptor-associated mutant SVV-S177A and viral antigenic peptide-related mutant SVV-S177A/P60S) with increased infectivity or lower immunogenicity significantly (P < 0.001) prolonged the mOS from 11 days in the control cohort to 23 days in the SVV-S177A cohort and the SVV-S177A/P60S cohort in the NSCLC-bearing athymic mouse model, which may provide the direction for modifying SVV to improve the effect of oncolysis.

ANTXR1 as a potential sensor of extracellular mechanical cues

Cell adhesion molecules mediate cell-cell or cell-matrix interactions, some of which are mechanical sensors, such as integrins. Emerging evidence indicates that anthrax toxin receptor 1 (ANTXR1), a newly identified cell adhesion molecule, can also sense extracellular mechanical signals such as hydrostatic pressure and extracellular matrix (ECM) rigidity. ANTXR1 can interact with ECM through connecting intracellular cytoskeleton and ECM molecules (just like integrins) to regulate numerous biological processes, such as cell adhesion, cell migration or ECM homeostasis. Although with high structural similarity to integrins, its functions and downstream signal transduction are independent from those of integrins. In this perspective, based on existing evidence in literature, we analyzed the structural and functional evidence that ANTXR1 can act as a potential sensor for extracellular mechanical cues. To our knowledge, this is the first in-depth overview of ANTXR1 from the perspective of mechanobiology. STATEMENT OF SIGNIFICANCE: An overview of ANTXR1 from the perspective of mechanobiology; An analysis of mechanical sensitivity of ANTXR1 in structure and function; A summary of existing evidence of ANTXR1 as a potential mechanosensor.

Recent Developments in Glioblastoma Therapy: Oncolytic Viruses and Emerging Future Strategies

Glioblastoma is the most aggressive form of malignant brain tumor. Standard treatment protocols and traditional immunotherapy are poorly effective as they do not significantly increase the long-term survival of glioblastoma patients. Oncolytic viruses (OVs) may be an effective alternative approach. Combining OVs with some modern treatment options may also provide significant benefits for glioblastoma patients. Here we review virotherapy for glioblastomas and describe several OVs and their combination with other therapies. The personalized use of OVs and their combination with other treatment options would become a significant area of research aiming to develop the most effective treatment regimens for glioblastomas.

Croix B. Cancer cell survival depends on collagen uptake into tumor-associated stroma

Collagen I, the most abundant protein in humans, is ubiquitous in solid tumors where it provides a rich source of exploitable metabolic fuel for cancer cells. While tumor cells were unable to exploit collagen directly, here we show they can usurp metabolic byproducts of collagen-consuming tumor-associated stroma. Using genetically engineered mouse models, we discovered that solid tumor growth depends upon collagen binding and uptake mediated by the TEM8/ANTXR1 cell surface protein in tumor-associated stroma. Tumor-associated stromal cells processed collagen into glutamine, which was then released and internalized by cancer cells. Under chronic nutrient starvation, a condition driven by the high metabolic demand of tumors, cancer cells exploited glutamine to survive, an effect that could be reversed by blocking collagen uptake with TEM8 neutralizing antibodies. These studies reveal that cancer cells exploit collagen-consuming stromal cells for survival, exposing an important vulnerability across solid tumors with implications for developing improved anticancer therapy.

Evolving role of seneca valley virus and its biomarker TEM8/ANTXR1 in cancer therapeutics

Oncolytic viruses have made a significant inroad in cancer drug development. Numerous clinical trials are currently investigating oncolytic viruses both as single agents or in combination with various immunomodulators. Oncolytic viruses (OV) are an integral pillar of immuno-oncology and hold potential for not only delivering durable anti-tumor responses but also converting “cold” tumors to “hot” tumors. In this review we will discuss one such promising oncolytic virus called Seneca Valley Virus (SVV-001) and its therapeutic implications. SVV development has seen seismic evolution over the past decade and now boasts of being the only OV with a practically applicable biomarker for viral tropism. We discuss relevant preclinical and clinical data involving SVV and how bio-selecting for TEM8/ANTXR1, a negative tumor prognosticator can lead to first of its kind biomarker driven oncolytic viral cancer therapy.

Serum Proteomic Analysis by Tandem Mass Tag-Based Quantitative Proteomics in Pediatric Obstructive Sleep Apnea

Pediatric obstructive sleep apnea (OSA) is a frequent respiratory disorder with an estimated prevalence of 3–6% in the general population. However, the underlying pathophysiology of OSA remains unclear. Recently, proteomic analysis using high-resolution and high-throughput mass spectrometry has been widely used in the field of medical sciences. In the present study, tandem mass tag (TMT)-based proteomic analysis was performed in the serum of patients with OSA. The proteomic analysis revealed a set of differentially expressed proteins that may be associated with the pathophysiology of OSA. The differentially expressed proteins in patients with OSA were enriched in pathways including phagosome and glycan synthesis/degradation, immune response, and the hedgehog signaling pathway, indicating that such functions are key targets of OSA. Moreover, the experimental validation studies revealed that four proteins including ANTXR1, COLEC10, NCAM1, and VNN1 were reduced in the serum from patients with moderate and severe OSA, while MAN1A1 and CSPG4 protein levels were elevated in the serum from patients with severe OSA. The protein levels of ANTXR1, COLEC10, NCAM1, and VNN1 were inversely correlated with apnea-hypopnea index (AHI) in the recruited subjects, while the protein level of MAN1A1 was positively correlated with AHI, and no significant correlation was detected between CSPG4 protein and AHI. In summary, the present study for the first time identified differentially expressed proteins in the serum from OSA patients with different severities by using TMT-based proteomic analysis. The functional enrichment studies suggested that several signaling pathways may be associated with the pathophysiology of OSA. The experimental validation results indicated that six proteins including ANTXR1, COLEC10, NCAM1, VNN1, CGPG4, and MAN1A1 may play important roles in the pathophysiology of OSA, which requires further mechanistic investigation.

Senecavirus A as an Oncolytic Virus: Prospects, Challenges and Development Directions

Oncolytic viruses have the capacity to selectively kill infected tumor cells and trigger protective immunity. As such, oncolytic virotherapy has become a promising immunotherapy strategy against cancer. A variety of viruses from different families have been proven to have oncolytic potential. Senecavirus A (SVA) was the first picornavirus to be tested in humans for its oncolytic potential and was shown to penetrate solid tumors through the vascular system. SVA displays several properties that make it a suitable model, such as its inability to integrate into human genome DNA and the absence of any viral-encoded oncogenes. In addition, genetic engineering of SVA based on the manipulation of infectious clones facilitates the development of recombinant viruses with improved therapeutic indexes to satisfy the criteria of safety and efficacy regulations. This review summarizes the current knowledge and strategies of genetic engineering for SVA, and addresses the current challenges and future directions of SVA as an oncolytic agent.

Disruption of anthrax toxin receptor 1 in pigs leads to a rare disease phenotype and protection from senecavirus A infection

Senecavirus A (SVA) is a cause of vesicular disease in pigs, and infection rates are rising within the swine industry. Recently, anthrax toxin receptor 1 (ANTXR1) was revealed as the receptor for SVA in human cells. Herein, the role of ANTXR1 as a receptor for SVA in pigs was investigated by CRISPR/Cas9 genome editing. Strikingly, ANTXR1 knockout (KO) pigs exhibited features consistent with the rare disease, GAPO syndrome, in humans. Fibroblasts from wild type (WT) pigs supported replication of SVA; whereas, fibroblasts from KO pigs were resistant to infection. During an SVA challenge, clinical symptoms, including vesicular lesions, and circulating viremia were present in infected WT pigs but were absent in KO pigs. Additional ANTXR1-edited piglets were generated that were homozygous for an in-frame (IF) mutation. While IF pigs presented a GAPO phenotype similar to the KO pigs, fibroblasts showed mild infection, and circulating SVA nucleic acid was decreased in IF compared to WT pigs. Thus, this new ANTXR1 mutation resulted in decreased permissiveness of SVA in pigs. Overall, genetic disruption of ANTXR1 in pigs provides a unique model for GAPO syndrome and prevents circulating SVA infection and clinical symptoms, confirming that ANTXR1 acts as a receptor for the virus.

Transcriptome Analyses of Senecavirus A-Infected PK-15 Cells: RIG-I and IRF7 Are the Important Factors in Inducing Type III Interferons

Senecavirus A (SVA) is a new type of virus related to swine vesicular disease, which results in enormous economic losses worldwide. At present, the host transcriptional responses to SVA infection, host-SVA interactions, and the mechanism of SVA in innate immune modulation are not well understood. This study explores the gene expression profiles of PK-15 cells at 0, 6, 12, 18, 24, 36 h SVA post-infection by RNA sequencing. Our analysis identified 61, 510, 1,584, 2,460, and 2,359 differentially expressed genes (DEGs) in the comparison groups S6 vs. Control, S12 vs. Control, S18 vs. Control, S24 vs. Control, S36 vs. Control, respectively. The reproducibility and repeatability of the results were validated by RT-qPCR, and all DEGs exhibited expression patterns consistent with the RNA-seq results. According to GO enrichment analysis and KEGG pathway analysis of DEGs in different periods after SVA infection, we found that SVA infection significantly modified the host cell gene-expression patterns and the host cells responded in highly specific manners, including response to signal reception and transmission, external biotic stimulus, response to the virus and host immune defense response. Notably, we observed the specific induction of type III interferon IFN-λ1 and IFN-λ3, which indicated that type III interferon plays an important antiviral function in PK-15 cells. Furthermore, our results showed that SVA might be recognized by RIG-I/MDA-5 receptors first after infecting PK-15 cells and then activates downstream IRF7-mediated signaling pathways, causing an increase in the expression of type III interferon. This study could provide important insights into the modulation of host metabolism during SVA infection and provide a strong theoretical basis for a better understanding of the pathogenic mechanism and immune escape mechanism of SVA.

Latest therapeutic target for gastric cancer: Anthrax toxin receptor 1

Anthrax toxin receptor 1 (ANTXR1), also known as tumor endothelial marker 8, is a highly conserved cell surface protein overexpressed in tumor-infiltrating vessels. It was first found in vascular endothelial cells of human colorectal cancer. Although our understanding of its physiological function is limited, it has been found that ANTXR1 binds collagen and promotes migration of endothelial cells in vitro. ANTXR1 is upregulated in vessels of different tumor types in mice and humans, and is also expressed by tumor cells themselves in some tumors, such as gastric, lung, intestinal and breast cancer. Developmental angiogenesis and wound healing were not disturbed in ANTXR1 knockout mice, but compared with wild-type mice, growth of melanoma was impaired after ANTXR1 knockout, indicating that host-derived ANTXR1 can promote tumor growth on the basis of immune activity. Previous studies have shown that ANTXR1 vaccines or sublethal doses of anthrax toxin can inhibit angiogenesis, slow tumor growth and prolong survival. These studies suggest that ANTXR1 is necessary for tumor rather than physiological angiogenesis. It has been found that ANTXR1 plays an important role in tumor angiogenesisas well as in the growth and metastasis of many kinds of tumors. This article reviews the physiological function of ANTXR1 and its role in different kinds of cancer.

Clinical Application of Oncolytic Viruses: A Systematic Review

Leveraging the immune system to thwart cancer is not a novel strategy and has been explored via cancer vaccines and use of immunomodulators like interferons. However, it was not until the introduction of immune checkpoint inhibitors that we realized the true potential of immunotherapy in combating cancer. Oncolytic viruses are one such immunotherapeutic tool that is currently being explored in cancer therapeutics. We present the most comprehensive systematic review of all oncolytic viruses in Phase 1, 2, and 3 clinical trials published to date. We performed a systematic review of all published clinical trials indexed in PubMed that utilized oncolytic viruses. Trials were reviewed for type of oncolytic virus used, method of administration, study design, disease type, primary outcome, and relevant adverse effects. A total of 120 trials were found; 86 trials were available for our review. Included were 60 phase I trials, five phase I/II combination trials, 19 phase II trials, and two phase III clinical trials. Oncolytic viruses are feverously being evaluated in oncology with over 30 different types of oncolytic viruses being explored either as a single agent or in combination with other antitumor agents. To date, only one oncolytic virus therapy has received an FDA approval but advances in bioengineering techniques and our understanding of immunomodulation to heighten oncolytic virus replication and improve tumor kill raises optimism for its future drug development.

Comprehensive review on immunopathogenesis, diagnostic and epidemiology of Senecavirus A

Senecavirus A (SVA), formerly known as Seneca Valley virus, is a single-strand, positive-sense RNA virus in the family Picornaviridae. This virus has been associated with recent outbreaks of vesicular disease (SVA-VD) and epidemic transient neonatal losses (ETNL) in several swine-producing countries. The clinical manifestation of and lesion caused by SVA are indistinguishable from other vesicular diseases. Pathogenicity studies indicate that SVA could regulate the host innate immune response to facilitate virus replication and the spread of the virus to bystander cells. SVA infection can induce specific humoral and cellular responses that can be detected within the first week of infection. However, SVA seems to produce persistent infection, and the virus can be shed in oral fluids for a month and detected in tissues for approximately two months after experimental infection. SVA transmission could be horizontal or vertical in infected herds of swine, while positive animals can also remain subclinical. In addition, mice seem to act as reservoirs, and the virus can persist in feed and feed ingredients, increasing the risk of introduction into naïve farms. Besides the pathological effects in swine, SVA possesses cytolytic activity, especially in neoplastic cells. Thus, SVA has been evaluated in phase II clinical trials as a virotherapy for neuroendocrine tumors. The goal of this review is summarize the current SVA-related research in pathogenesis, immunity, epidemiology and advances in diagnosis as well as discuses current challenges with subclinical/persistent presentation.

A comparative analysis of secreted protein disulfide isomerases from the tropical co-endemic parasites Schistosoma mansoni and Leishmania major

The human parasites Schistosoma mansoni and Leishmania major are co-endemic and a major threat to human health. Though displaying different tissue tropisms, they excrete/secrete similar subsets of intracellular proteins that, interacting with the host extracellular matrix (ECM), help the parasites invading the host. We selected one of the most abundant proteins found in the secretomes of both parasites, protein disulfide isomerase (PDI), and performed a comparative screening with surface plasmon resonance imaging (SPRi), looking for ECM binding partners. Both PDIs bind heparan sulfate; none of them binds collagens; each of them binds further ECM components, possibly linked to the different tropisms. We investigated by small-angle X-ray scattering both PDIs structures and those of a few complexes with host partners, in order to better understand the differences within this conserved family fold. Furthermore, we highlighted a previously undisclosed moonlighting behaviour of both PDIs, namely a concentration-dependent switch of function from thiol-oxidoreductase to holdase. Finally, we have tried to exploit the differences to look for possible compounds able to interfere with the redox activity of both PDI.