Enhanced transduction of colonic cell lines in vitro and the inflamed colon in mice by viral vectors, derived from adeno-associated virus serotype 2, using virus-microbead conjugates bearing lectin

Blocking IL-17A enhances tumor response to anti-PD-1 immunotherapy in microsatellite stable colorectal cancer

BACKGROUND

Immune checkpoint inhibitors (ICIs), including anti-PD-1 therapy, have limited efficacy in patients with microsatellite stable (MSS) colorectal cancer (CRC). Interleukin 17A (IL-17A) activity leads to a protumor microenvironment, dependent on its ability to induce the production of inflammatory mediators, mobilize myeloid cells and reshape the tumor environment. In the present study, we aimed to investigate the role of IL-17A in resistance to antitumor immunity and to explore the feasibility of anti-IL-17A combined with anti-PD-1 therapy in MSS CRC murine models.

METHODS

The expression of programmed cell death-ligand 1 (PD-L1) and its regulation by miR-15b-5p were investigated in MSS CRC cell lines and tissues. The effects of miR-15b-5p on tumorigenesis and anti-PD-1 treatment sensitivity were verified both in vitro and in colitis-associated cancer (CAC) and APC^min/+ murine models. In vivo efficacy and mechanistic studies were conducted using antibodies targeting IL-17A and PD-1 in mice bearing subcutaneous CT26 and MC38 tumors.

RESULTS

Evaluation of clinical pathological specimens confirmed that PD-L1 mRNA levels are associated with CD8+ T cell infiltration and better prognosis. miR-15b-5p was found to downregulate the expression of PD-L1 at the protein level, inhibit tumorigenesis and enhance anti-PD-1 sensitivity in CAC and APC^min/+ CRC models. IL-17A led to high PD-L1 expression in CRC cells through regulating the P65/NRF1/miR-15b-5p axis. Combined IL-17A and PD-1 blockade had efficacy in CT26 and MC38 tumors, with more cytotoxic T lymphocytes cells and fewer myeloid-derived suppressor cells in tumors.

CONCLUSIONS

IL-17A increases PD-L1 expression through the p65/NRF1/miR-15b-5p axis and promotes resistance to anti-PD-1 therapy. Blocking IL-17A improved the efficacy of anti-PD-1 therapy in MSS CRC murine models. IL-17A might serve as a therapeutic target to sensitize patients with MSS CRC to ICI therapy.

Short-fiber protein of ad40 confers enteric tropism and protection against acidic gastrointestinal conditions

The lack of vectors for selective gene delivery to the intestine has hampered the development of gene therapy strategies for intestinal diseases. We hypothesized that chimeric adenoviruses of Ad5 (species C) displaying proteins of the naturally enteric Ad40 (species F) might hold the intestinal tropism of the species F and thus be useful for gene delivery to the intestine. As oral-fecal dissemination of enteric adenovirus must withstand the conditions encountered in the gastrointestinal tract, we studied the resistance of chimeric Ad5 carrying the short-fiber protein of Ad40 to acid milieu and proteases and found that the Ad40 short fiber confers resistance to inactivation in acidic conditions and that AdF/40S was further activated upon exposure to low pH. In contrast, the chimeric AdF/40S exhibited only a slightly higher protease resistance compared with Ad5 to proteases present in simulated gastric juice. Then, the biodistribution of different chimeric adenoviruses by oral, rectal, and intravenous routes was tested. Expression of reporter β-galactosidase was measured in extracts of 15 different organs 3 days after administration. Our results indicate that among the chimeric viruses, only intrarectally given AdF/40S infected the colon (preferentially enteroendocrine cells and macrophages) and to a lesser extent, the small intestine, whereas Ad5 infectivity was very poor in all tissues. Additional in vitro experiments showed improved infectivity of AdF/40S also in different human epithelial cell lines. Therefore, our results point at the chimeric adenovirus AdF/40S as an interesting vector for selective gene delivery to treat intestinal diseases.

Oral colon-specific therapeutic approaches toward treatment of inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic relapsing idiopathic disease. In clinical terms, most patients require lifelong medication associated with possible unpleasant adverse effects. Oral colon-specific drug delivery systems are designed to deliver therapeutic drugs to the inflamed colon to target pathophysiological manifestations of IBD. The aim is to maintain the drug with proper concentration in the inflamed colon, to enhance drug residence time and to minimize drug absorption by healthy tissues.

AREAS COVERED

This review addresses the main barriers for colon-specific drug delivery from organism, tissue and cell levels, respectively. It also summarizes novel colon-specific therapeutic strategies using microparticles and nanoparticles.

EXPERT OPINION

Oral colon-specific drug delivery represents a possible approach toward efficient treatment of IBD. As the environment of the gastrointestinal tract is harsh and intricate, this approach requires that drug carriers can respond to specific environmental factors of the inflamed colon, permitting stimulus-responsive release of loaded drugs to specific cells or even into specific organelles within cells.

Identification of adeno-associated viral vectors suitable for intestinal gene delivery and modulation of experimental colitis

Effective gene transfer with sustained gene expression is an important adjunct to the study of intestinal inflammation and future therapy in inflammatory bowel disease. Recombinant adeno-associated virus (AAV) vectors are ideal for gene transfer and long-term transgene expression. The purpose of our study was to identify optimal AAV pseudotypes for transduction of the epithelium in the small intestine and colon, which could be used for studies in experimental colitis. The tropism and transduction efficiencies of AAV pseudotypes 1-10 were examined in murine small intestine and colon 8 wk after administration by real-time PCR and immunohistochemistry. The clinical and histopathological effects of IL-10-mediated intestinal transduction delivered by AAVrh10 were examined in the murine IL-10⁻/⁻ enterocolitis model. Serum IL-10 levels and IL-10 expression were followed by ELISA and real-time PCR, respectively. AAV pseudotypes 4, 7, 8, 9, and 10 demonstrated optimal intestinal transduction. Transgene expression was sustained 8 wk after administration and was frequently observed in enteroendocrine cells. Long-term IL-10 gene expression and serum IL-10 levels were observed following AAV transduction in an IL-10-/- model of enterocolitis. Animals treated with AAVrh10-IL-10 had lower disease activity index scores, higher colon weight-to-length ratios, and lower microscopic inflammation scores. This study identifies novel AAV pseudotypes with small intestine and colon tropism and sustained transgene expression capable of modulating mucosal inflammation in a murine model of enterocolitis.

Expression of recombinant human adenovirus-p53 gene delivered into rabbit VX2 tumors by interventional methods

AIM: To investigate the expression of recombinant human adenovirus-p53 gene (rAd-p53, 1×10¹² VP) delivered into rabbit VX2 tumors by interventional methods.

METHODS: Thirty New Zealand rabbits were used to establish an animal model of hepatocarcinoma by implantation of the VX2 tumors into the liver. Eleven days after implantation, magnetic resonance imaging (MRI) and computed tomography (CT) scans were performed. Successful implantation was achieved in 27 rabbits. These rabbits were randomly divided into three groups: A, B and C. Groups A and B were infused through the hepatic artery with rAd-p53 (5 × 10⁶ VP) alone and rAd-p53 (5 × 10⁶ VP) plus lipiodol ultra fluid (0.5 mL), respectively, while group C was injected with rAd-p53 (5 × 10⁶ VP) into tumors by surgery. All model rabbits underwent digital subtraction angiography (DSA) during operation. The expression of P53, Bax and Bcl-2 proteins in tumor and peritumoral tissue was detected by immunohistochemistry at 24 and 72 hours and on 6 days after the operation.

RESULTS: MRI and CT scans showed that successful implantation was achieved in 27 rabbits, and the success rate was 95%. Immunohistochemical analysis indicated that P53, Bax and Bcl-2 proteins were expressed in all the three groups. The expression levels of P53 and Bax reached the peak at 72 hours. The expression levels of P53 and Bax in group C at 72 hours were significantly higher than those in groups A and B (P53: 70.3% ± 3.4% vs 62.4% ± 3.2% and 65.4% ± 2.1%; Bax: 43.7% ± 2.1% vs 35.7% ± 1.3% and 37.6% ± 2.4%, respectively; all P < 0.05). In contrast, the expression level of Bcl-2 in group C at 72 hours was significantly lower than those in groups A and B (12.0% ± 2.6% vs 18.0% ± 4.3% and 16.2% ± 3.1%, respectively; both P < 0.05).

CONCLUSION: P53 protein is expressed in rabbit VX2 tumors in a time-dependent manner. The expression level of P53 protein depends on the delivery methods used. The highest expression of P53 protein is achieved by intratumoral injection, followed by infusion of rAd-p53 plus lipiodol ultra fluid and rAd-p53 alone through the hepatic artery.