As tumor-associated macrophages (TAM) exercise a plethora of protumor and immune evasive functions, novel strategies targeting TAMs to inhibit tumor progression have emerged within the current arena of cancer immunotherapy. Activation of the mannose receptor 1 (CD206) is a recent approach that recognizes immunosuppressive CD206high M2-like TAMs as a drug target. Ligation of CD206 both induces reprogramming of CD206high TAMs toward a proinflammatory phenotype and selectively triggers apoptosis in these cells. CD206-activating therapeutics are currently limited to the linear, 10mer peptide RP-182, 1, which is not a drug candidate. In this study, we sought to identify a better suitable candidate for future clinical development by synthesizing and evaluating a series of RP-182 analogs. Surprisingly, fatty acid derivative 1a [RP-182-PEG3-K(palmitic acid)] not only showed improved stability but also increased affinity to the CD206 receptor through enhanced interaction with a hydrophobic binding motif of CD206. Peptide 1a showed superior in vitro activity in cell-based assays of macrophage activation which was restricted to CD206high M2-polarized macrophages. Improvement in responses was disproportionally skewed toward improved induction of phagocytosis including cancer cell phagocytosis. Peptide 1a reprogrammed the immune landscape in genetically engineered murine KPC pancreatic tumors toward increased innate immune surveillance and improved tumor control and effectively suppressed tumor growth of murine B16 melanoma allografts.
©2024 The Authors; Published by the American Association for Cancer Research.

Adjuvants added to subunit vaccines augment antigen-specific immune responses. One mechanism of adjuvant action is activation of pattern recognition receptors (PRRs) on innate immune cells. Bordetella colonization factor A (BcfA); an outer membrane protein with adjuvant function, activates TH1/TH17-polarized immune responses to protein antigens from Bordetella pertussis and SARS CoV-2. Unlike other adjuvants, BcfA does not elicit a TH2 response.
To understand the mechanism of BcfA-driven TH1/TH17 vs. TH2 activation, we screened PRRs to identify pathways activated by BcfA. We then tested the role of this receptor in the BcfA-mediated activation of bone marrow-derived dendritic cells (BMDCs) using mice with germline deletion of TLR4 to quantify upregulation of costimulatory molecule expression and cytokine production in vitro and in vivo. Activity was also tested on human PBMCs.
PRR screening showed that BcfA activates antigen presenting cells through murine TLR4. BcfA-treated WT BMDCs upregulated expression of the costimulatory molecules CD40, CD80, and CD86 and produced IL-6, IL-12/23 p40, and TNF-α while TLR4 KO BMDCs were not activated. Furthermore, human PBMCs stimulated with BcfA produced IL-6. BcfA-stimulated murine BMDCs also exhibited increased uptake of the antigen DQ-OVA, supporting a role for BcfA in improving antigen presentation to T cells. BcfA further activated APCs in murine lungs. Using an in vitro TH cell polarization system, we found that BcfA-stimulated BMDC supernatant supported TFH and TH1 while suppressing TH2 gene programming.
Overall, these data provide mechanistic understanding of how this novel adjuvant activates immune responses.
Copyright © 2024 Shamseldin, Read, Hall, Tuazon, Brown, Guo, Gupta, Deora, Oestreich and Dubey.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant cancers worldwide. Despite the promising outcome of immune checkpoint inhibitors and agonist antibody therapies in different malignancies, PDAC exhibits high resistance due to its immunosuppressive tumor microenvironment (TME). Ameliorating the TME is thus a rational strategy for PDAC therapy. The intratumoral application of oncolytic herpes simplex virus-1 (oHSV) upregulates pro-inflammatory macrophages and lymphocytes in TME, and enhances the responsiveness of PDAC to immunotherapy. However, the antitumor activity of oHSV remains to be maximized. The aim of this study is to investigate the effect of the CD40L armed oHSV on the tumor immune microenvironment, and ultimately prolong the survival of the PDAC mouse model.
The membrane-bound form of murine CD40L was engineered into oHSV by CRISPR/Cas9-based gene editing. oHSV-CD40L induced cytopathic effect and immunogenic cell death were determined by microscopy and flow cytometry. The expression and function of oHSV-CD40L was assessed by reporter cell assay. The oHSV-CD40L was administrated intratumorally to the immune competent syngeneic PDAC mouse model, and the leukocytes in TME and tumor-draining lymph node were analyzed by multicolor flow cytometry. Intratumoral cytokines were determined by ELISA.
Intratumoral application of oHSV-CD40L efficiently restrained the tumor growth and prolonged the survival of the PDAC mouse model. In TME, oHSV-CD40L-treated tumor accommodated more maturated dendritic cells (DCs), which in turn activated T helper 1 and cytotoxic CD8+ T cells in an interferon-γ-dependent and interleukin-12-dependent manner. In contrast, the regulatory T cells were significantly reduced in TME by oHSV-CD40L treatment. Repeated dosing and combinational therapy extended the lifespan of PDAC mice.
CD40L-armed oncolytic therapy endues TME with increased DCs maturation and DC-dependent activation of cytotoxic T cells, and significantly prolongs the survival of the model mice. This study may lead to the understanding and development of oHSV-CD40L as a therapy for PDAC in synergy with immune checkpoint blockade.
© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Berberine (BBR) is an isoquinoline alkaloid with various functions in anti-inflammation, blocking tumor immune escape and enhancing the anti-tumor activity of immune cells. However, its immunomodulatory effect on natural killer (NK) cell activity in Hepatocellular carcinoma (HCC) is still unclear. Here, we determined whether BBR enhances the anti-HCC effect of NK cells and its mechanism by focusing on the regulation of the Programmed death-ligand 1 (PD-L1) pathway. It was found that BBR enhanced the cytotoxicity of NK92-MI cells to HCC cells in vitro and in vivo. The combination of BBR and PBMCs inhibited the proliferation and induced the apoptosis of HCC cells. BBR increased the frequency of CD3 − CD56 + and CD3 − CD16 + NK cells in peripheral blood isolated from healthy volunteers. Furthermore, the expression of PD-L1 in HCC cells was up-regulated after co-culture with NK-92MI cells or PBMCs. PD-L1 knockdown increased the sensitivity of HCC cells to NK-92MI cells and PBMCs. Mechanisms for BBR blocked the secretion of Interferon Gamma (IFN-γ), thereby inhibiting PD-L1 expression caused by the interaction of NK92-MI cells/PBMCs and HCC cells. Collectively, we are the first to demonstrate that BBR plays an immunomodulatory role by enhancing the cytotoxic effect of NK cells and inhibiting tumor immune escape by reducing the expression of PD-L1. Our study provides a theoretical basis for the clinical application of BBR combined with NK cells in the treatment of HCC.