anti-mouse CD18

anti-mouse CD18 (Clone: 2E6)

Shanker, A., et al. (2015). “Bortezomib Improves Adoptive T-cell Therapy by Sensitizing Cancer Cells to FasL Cytotoxicity.” Cancer Res 75(24): 5260-5272. PubMed

Cancer immunotherapy shows great promise but many patients fail to show objective responses, including in cancers that can respond well, such as melanoma and renal adenocarcinoma. The proteasome inhibitor bortezomib sensitizes solid tumors to apoptosis in response to TNF-family death ligands. Because T cells provide multiple death ligands at the tumor site, we investigated the effects of bortezomib on T-cell responses in immunotherapy models involving low-avidity antigens. Bortezomib did not affect lymphocyte or tissue-resident CD11c(+)CD8(+) dendritic cell counts in tumor-bearing mice, did not inhibit dendritic cell expression of costimulatory molecules, and did not decrease MHC class I/II-associated antigen presentation to cognate T cells. Rather, bortezomib activated NF-kappaB p65 in CD8(+) T cells, stabilizing expression of T-cell receptor CD3zeta and IL2 receptor-alpha, while maintaining IFNgamma secretion to improve FasL-mediated tumor lysis. Notably, bortezomib increased tumor cell surface expression of Fas in mice as well as human melanoma tissue from a responsive patient. In renal tumor-bearing immunodeficient Rag2(-/-) mice, bortezomib treatment after adoptive T-cell immunotherapy reduced lung metastases and enhanced host survival. Our findings highlight the potential of proteasome inhibitors to enhance antitumor T-cell function in the context of cancer immunotherapy.

 

Tanaka, E., et al. (2014). “Notch2 activation ameliorates nephrosis.” Nat Commun 5: 3296. PubMed

Activation of Notch1 and Notch2 has been recently implicated in human glomerular diseases. Here we show that Notch2 prevents podocyte loss and nephrosis. Administration of a Notch2 agonistic monoclonal antibody ameliorates proteinuria and glomerulosclerosis in a mouse model of nephrosis and focal segmental glomerulosclerosis. In vitro, the specific knockdown of Notch2 increases apoptosis in damaged podocytes, while Notch2 agonistic antibodies enhance activation of Akt and protect damaged podocytes from apoptosis. Treatment with triciribine, an inhibitor of Akt pathway, abolishes the protective effect of the Notch2 agonistic antibody. We find a positive linear correlation between the number of podocytes expressing activated Notch2 and the number of residual podocytes in human nephrotic specimens. Hence, specific activation of Notch2 rescues damaged podocytes and activating Notch2 may represent a novel clinical strategy for the amelioration of nephrosis and glomerulosclerosis.

 

Haynes, N. M., et al. (2010). “CD11c+ dendritic cells and B cells contribute to the tumoricidal activity of anti-DR5 antibody therapy in established tumors.” J Immunol 185(1): 532-541. PubMed

The selective targeting of the tumor-associated death-inducing receptors DR4 and DR5 with agonistic mAbs has demonstrated preclinical and clinical antitumor activity. However, the cellular and molecular mechanisms contributing to this efficacy remain poorly understood. In this study, using the first described C57BL/6 (B6) TRAIL-sensitive experimental tumor models, we have characterized the innate and adaptive immune components involved in the primary rejection phase of an anti-mouse DR5 (mDR5) mAb, MD5-1 in established MC38 colon adenocarcinomas. FcR mediated cross-linking of MD5-1 significantly inhibited the growth of MC38 colon adenocarcinomas through the induction of TRAIL-R-dependent tumor cell apoptosis. The loss of host DR5, TRAIL, perforin, FasL, or TNF did not compromise anti-DR5 therapy in vivo. By contrast, anti-DR5 therapy was completely abrogated in mice deficient of B cells or CD11c(+) dendritic cells (DCs), providing the first direct evidence that these cells play a critical role. Importantly, the requirement for an intact B cell compartment for optimal anti-DR5 antitumor efficacy was also observed in established AT-3 mammary tumors. Interestingly, MD5-1-mediated apoptosis as measured by early TUNEL activity was completely lost in B cell-deficient microMT mice, but intact in mice deficient in CD11c(+) DCs. Overall, these data show that Ab-mediated targeting of DR5 triggers tumor cell apoptosis in established tumors in a B cell-dependent manner and that CD11c(+) DCs make a critical downstream contribution to anti-DR5 antitumor activity.

 

Shibata, K., et al. (2007). “Resident Vdelta1+ gammadelta T cells control early infiltration of neutrophils after Escherichia coli infection via IL-17 production.” J Immunol 178(7): 4466-4472. PubMed

Neutrophils infiltrate the site of infection and play critical roles in host defense, especially against extracellular bacteria. In the present study, we found a rapid and transient production of IL-17 after i.p. infection with Escherichia coli, preceding the influx of neutrophils. Neutralization of IL-17 resulted in a reduced infiltration of neutrophils and an impaired bacterial clearance. Ex vivo intracellular cytokine flow cytometric analysis revealed that gammadelta T cell population was the major source of IL-17. Mice depleted of gammadelta T cells by mAb treatment or mice genetically lacking Vdelta1 showed diminished IL-17 production and reduced neutrophil infiltration after E. coli infection, indicating an importance of Vdelta1(+) gammadelta T cells as the source of IL-17. It was further revealed that gammadelta T cells in the peritoneal cavity of naive mice produced IL-17 in response to IL-23, which was induced rapidly after E. coli infection in a TLR4 signaling-dependent manner. Thus, although gammadelta T cells are generally regarded as a part of early induced immune responses, which bridge innate and adaptive immune responses, our study demonstrated a novel role of gammadelta T cells as a first line of host defense controlling neutrophil-mediated innate immune responses.

 

Takeda, K., et al. (2004). “Induction of tumor-specific T cell immunity by anti-DR5 antibody therapy.” J Exp Med 199(4): 437-448. PubMed

Because tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) preferentially induces apoptosis in tumor cells and plays a critical role in tumor surveillance, its receptor is an attractive target for antibody-mediated tumor therapy. Here we report that a monoclonal antibody (mAb) against the mouse TRAIL receptor, DR5, exhibited potent antitumor effects against TRAIL-sensitive tumor cells in vivo by recruiting Fc receptor-expressing innate immune cells, with no apparent systemic toxicity. Administration of the agonistic anti-DR5 mAb also significantly inhibited experimental and spontaneous tumor metastases. Notably, the anti-DR5 mAb-mediated tumor rejection by innate immune cells efficiently evoked tumor-specific T cell immunity that could also eradicate TRAIL-resistant variants. These results suggested that the antibody-based therapy targeting DR5 is an efficient strategy not only to eliminate TRAIL-sensitive tumor cells, but also to induce tumor-specific T cell memory that affords a long-term protection from tumor recurrence.