Background: Endothelial cells are well known inflammatory effectors, but TLR4 expression and function in human pericytes have not been addressed. Results: Pericytes express TLR4, and stimulation with LPS or HMGB1 promotes cytokine and chemokine secretion and overexpression of adhesion molecules via NF-B. Conclusion: TLR4 activation in pericytes triggers a proinflammatory and proangiogenic program. Significance: Pericytes are active players in inflammatory responses beyond their homeostatic role.

The redirection of T cell activity using bispecific antibodies is one of the most promising cancer immunotherapy approaches currently in development, but it is limited by cytokine storm-related toxicities, as well as the pharmacokinetics and tumor-penetrating capabilities of current bispecific antibody formats. Here, we have engineered the ATTACK (Asymmetric Tandem Trimerbody for T cell Activation and Cancer Killing), a novel T cell-recruiting bispecific antibody which combines three EGFR-binding single-domain antibodies (VHH; clone EgA1) with a single CD3-binding single-chain variable fragment (scFv; clone OKT3) in an intermediate molecular weight package. The two specificities are oriented in opposite directions in order to simultaneously engage cancer cells and T cell effectors, and thereby promote immunological synapse formation. EgA1 ATTACK was expressed as a homogenous, non-aggregating, soluble protein by mammalian cells and demonstrated an enhanced binding to EGFR, but not CD3, when compared to the previously characterized tandem bispecific antibody which has one EgA1 VHH and one OKT3 scFv per molecule. EgA1 ATTACK induced synapse formation and early signaling pathways downstream of TCR engagement at lower concentrations than the tandem VHH-scFv bispecific antibody. Furthermore, it demonstrated extremely potent, dose-dependent cytotoxicity when retargeting human T cells towards EGFR-expressing cells, with an efficacy over 15-fold higher than that of the tandem VHH-scFv bispecific antibody. These results suggest that the ATTACK is an ideal format for the development of the next-generation of T cell-redirecting bispecific antibodies.

Snail1 is a transcriptional factor that plays an important role in epithelial-mesenchymal transition and in the acquisition of invasive properties by epithelial cells. In colon tumors, Snail1 expression in the stroma correlates with lower specific survival of cancer patients. However, the role(s) of Snail1 expression in stroma and its association with patients' survival have not been determined. We used human primary carcinoma-associated fibroblasts (CAFs) or normal fibroblasts (NFs) and fibroblast cell lines to analyze the effects of Snail1 expression on the protumorigenic capabilities in colon cancer cells. Snail1 expression was higher in CAFs than in NFs and, as well as a-SMA, a classic marker of activated CAFs. Moreover, in tumor samples from 50 colon cancer patients, SNAI1 expression was associated with expression of other CAF markers, such as a-SMA and fibroblast activation protein. Interestingly, coculture of CAFs with colon cells induced a significant increase in epithelial cell migration and proliferation, which was associated with endogenous SNAI1 expression levels. Ectopic manipulation of Snail1 in fibroblasts demonstrated that Snail1 expression controlled migration as well as proliferation of cocultured colon cancer cells in a paracrine manner. Furthermore, expression of Snail1 in fibroblasts was required for the coadjuvant effect of these cells on colon cancer cell growth and invasion when coxenografted in nude mice. Finally, cytokine profile changes, particularly MCP-3 expression, in fibroblasts are put forward as mediators of Snail1-derived effects on colon tumor cell migration. In summary, these studies demonstrate that Snail1 is necessary for the protumorigenic effects of fibroblasts on colon cancer cells.Snail1 transcriptional factor is a key factor for triggering epithelial-mesenchymal transition (EMT), a process characterized by the loss of epithelial characteristics and the acquisition of mesenchymal traits and higher motility. 1 Snail1 expression is observed at different stages during embryo development and is required for numerous developmental processes.2 Snail1 expression and EMT features have also been observed in breast, prostate, lung, ovarian, melanoma, colon and esophageal cancers. [3][4][5][6][7][8][9][10][11][12][13] In most cases, Snail1 is detected in the invasive areas of the tumor. An analysis of colon tumors has shown that Snail1 is mainly detected in the tumor stroma, in cells with a fibroblast phenotype. Furthermore, Snail1 expression in tumor stroma is associated with shorter specific survival in colon cancer patients. 12 In addition, we recently noted the paracrine effects of Snail1 expression in human colon cells, showing downregulation of CDH1 and VDR gene expression when cocultured with Snail1-overexpressing colon cancer cells.14 However, the molecular mechanism underlying this association is not yet clear.

Here, we describe a new class of multivalent and multispecific antibody-based reagents for therapy. The molecules, termed “trimerbodies,” use a modified version of the N-terminal trimerization region of human collagen XVIII noncollagenous 1 domain flanked by two flexible linkers as trimerizing scaffold. By fusing single-chain variable fragments (scFv) with the same or different specificity to both N- and C-terminus of the trimerizing scaffold domain, we produced monospecific or bispecific hexavalent molecules that were efficiently secreted as soluble proteins by transfected mammalian cells. A bispecific anti-laminin x anti-CD3 N-/C-trimerbody was found to be trimeric in solution, very efficient at recognizing purified plastic-immobilized laminin and CD3 expressed at the surface of T cells, and remarkably stable in human serum. The bispecificity was further demonstrated in T cell activation studies. In the presence of laminin-rich substrate, the bispecific anti-laminin x anti-CD3 N-/C-trimerbody stimulated a high percentage of human T cells to express surface activation markers. These results suggest that the trimerbody platform offers promising opportunities for the development of the next-generation therapeutic antibodies, i.e., multivalent and bispecific molecules with a format optimized for the desired pharmacokinetics and adapted to the pathological context.

Gene therapy to achieve in vivo secretion of recombinant anti-CD3 x anti-tumor bispecific antibodies in cancer patients is being explored as a strategy to counterbalance rapid renal elimination, thereby sustaining levels of bispecific antibodies in the therapeutic range. Here, we performed a comparative analysis between single- and two-chain configurations for anti-CD3 x anti-CEA (carcinoembryonic antigen) bispecific antibodies secreted by genetically-modified human cells. We demonstrate that tandem single-chain variable fragment (scFv) antibodies and two-chain diabodies are expressed as soluble secreted proteins with similar yields. However, we found significant differences in their biological functionality (i.e., antigen binding) and in their ability to induce non-specific T cell activation. Whereas single-chain tandem scFvs induced human T cell activation and proliferation in an antigen-independent manner, secreted two-chain diabodies exerted almost no proliferative stimulus when human T cells were cultured alone or in co-cultures with CEA negative cells. Thus, our data suggest that two-chain diabodies are preferable to single-chain tandem scFvs for immunotherapeutic strategies comprising in vivo secretion of bispecific antibodies aiming to recruit and activate anticancer specific lymphocytic effector T cells.

Here, we describe a new strategy that allows the rapid and efficient engineering of mono and multispecific trivalent antibodies. By fusing single-domain antibodies from camelid heavy-chain-only immunoglobulins (VHHs) to the N-terminus of a human collagen XVIII trimerization domain (TIEXVIII) we produced monospecific trimerbodies that were efficiently secreted as soluble functional proteins by mammalian cells. The purified VHH-TIEXVIII trimerbodies were trimeric in solution and exhibited excellent antigen binding capacity. Furthermore, by connecting with two additional glycine-serine-based linkers three VHH-TIEXVIII modules on a single polypeptide chain, we present an approach for the rational design of multispecific tandem trimerbodies with defined stoichiometry and controlled orientation. Using this technology we report here the construction and characterization of a tandem VHH-based trimerbody capable of simultaneously binding to three different antigens: carcinoembryonic antigen (CEA), epidermal growth factor receptor (EGFR) and green fluorescence protein (GFP). Multispecific tandem VHH-based trimerbodies were well expressed in mammalian cells, had good biophysical properties and were capable of simultaneously binding their targeted antigens. Importantly, these antibodies were very effective in inhibiting the proliferation of human epidermoid carcinoma A431 cells. Multispecific VHH-based trimerbodies are therefore ideal candidates for future applications in various therapeutic areas.

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