Intratumoral injection of caerin 1.1 and 1.9 peptides increases the efficacy of vaccinated TC‐1 tumor‐bearing mice with PD‐1 blockade by modulating macrophage heterogeneity and the activation of CD8⁺ T cells in the tumor microenvironment

Abstract

Objectives Developing a vaccine formula that alters the tumor‐infiltrating lymphocytes to be more immune active against a tumor is key to the improvement of clinical responses to immunotherapy. Here, we demonstrate that, in conjunction with E7 antigen‐specific immunotherapy, and IL‐10 and PD‐1 blockade, intratumoral administration of caerin 1.1/1.9 peptides improves TC‐1 tumor microenvironment (TME) to be more immune active than injection of a control peptide. Methods We compared the survival time of vaccinated TC‐1 tumor‐bearing mice with PD‐1 and IL‐10 blockade, in combination with a further injection of caerin 1.1/1.9 or control peptides. The tumor‐infiltrating haematopoietic cells were examined by flow cytometry. Single‐cell transcriptomics and proteomics were used to quantify changes in cellular activity across different cell types within the TME. Results The injection of caerin 1.1/1.9 increased the efficacy of vaccinated TC‐1 tumor‐bearing mice with anti‐PD‐1 treatment and largely expanded the populations of macrophages and NK cells with higher immune activation level, while reducing immunosuppressive macrophages. More activated CD8 + T cells were induced with higher populations of memory and effector‐memory CD8 + T subsets. Computational integration of the proteome with the single‐cell transcriptome supported activation of Stat1 ‐modulated apoptosis and significant reduction in immune‐suppressive B‐cell function following caerin 1.1 and 1.9 treatment. Conclusions Caerin 1.1/1.9‐containing treatment results in improved antitumor responses. Harnessing the novel candidate genes preferentially enriched in the immune active cell populations may allow further exploration of distinct macrophages, T cells and their functions in TC‐1 tumors.

Topical Application of Temperature-Sensitive Gel Containing Caerin 1.1 and 1.9 Peptides on TC-1 Tumour-Bearing Mice Induced High-Level Immune Response in the Tumour Microenvironment

“…Isolated from the epidermal secretion of Australian amphibians, Litoria genus , caerin 1.1 and 1.9 peptides were found to significantly inhibit the proliferation of TC-1 ( 20 , 21 ) and HeLa cells ( 22 ) at the concentrations non-toxic to typical cells. They appeared to stimulate the signalling of TNFα-mediated apoptosis and activate the TCR pathway in HeLa cells ( 22 , 23 ). Caerin 1.1 and 1.9 largely inhibited the growth of TC-1 tumour in mice, and the inhibition required an intact adaptive immune system; in addition, the treatment prolonged the survival time of vaccinated and PD-1 blocked TC-1 tumour-bearing mice significantly ( 23 ).…”

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“…The antiproliferative activity of caerin 1.1 and 1.9 against HeLa cells in vitro was investigated, which found that the TNF-a-dependent apoptosis signals were stimulated by the caerin peptides (22). In a recent study, we have shown that intratumoral injection of the caerin 1.1/1.9 mixture significantly prolonged the survival time of TC-1 tumour-bearing mice that were immunised with an HPV16 E7 peptide-based vaccine along with IL-10 and PD-1 blockade (23). The TME was largely altered to a higher immune activation level, possibly with Stat1 as a key modulator, which synergistically functions with the activated NF-kB pathway to induce more iNOS and triggers the recruitment of T cells.…”

“…CD4 + CD8 + T cells had the lowest number of cells, with the marker genes such as Cd226, Klrg1 and Cxcr6. Fibroblast (cluster 6; Nusap1, Top2a, Pclaf and Mki67) (28), adipogenic stem and precursor cells (ASPCs) (cluster 11; Col11a1, Plpp3, Col6a1 and Gas1) (23,29), basal cells (cluster 12; Ccnb2, Cdkn3, Hmmr and Birc5) (30) and osteoclast (Cluster 17; Oscar, Ctsk and Mmp9) (31) were detected as possible contaminants (also see Supplementary Data 2).…”

“…Isolated from the epidermal secretion of Australian amphibians, Litoria genus, caerin 1.1 and 1.9 peptides were found to significantly inhibit the proliferation of TC-1 (20,21) and HeLa cells (22) at the concentrations non-toxic to typical cells. They appeared to stimulate the signalling of TNFa-mediated apoptosis and activate the TCR pathway in HeLa cells (22,23). Caerin 1.1 and 1.9 largely inhibited the growth of TC-1 tumour in mice, and the inhibition required an intact adaptive immune system; in addition, the treatment prolonged the survival time of vaccinated and PD-1 blocked TC-1 tumour-bearing mice significantly (23).…”

“…They appeared to stimulate the signalling of TNFa-mediated apoptosis and activate the TCR pathway in HeLa cells (22,23). Caerin 1.1 and 1.9 largely inhibited the growth of TC-1 tumour in mice, and the inhibition required an intact adaptive immune system; in addition, the treatment prolonged the survival time of vaccinated and PD-1 blocked TC-1 tumour-bearing mice significantly (23). However, the detailed molecular mechanism underpinning the tumour suppressive effect induced by these caerin peptides remains elusive.…”