Antitumor Study Of Tetrahydroxybacterial Porphyrin Hyaluronate Micelles In Combination With Anti-PD-L1

Photodynamic therapy and chemokinetic therapy are active oxygen-mediated tumor therapies,which have the advantages of spatio-temporal selectivity,non-invasive and negligible drug resistance.As a key factor of PDT,photosensitizer determines the tissue penetration depth of light and the quantum yield of ¹O₂,which directly affects the PDT effect.Therefore,the development of photosensitizer has become the focus of PDT research.PDT therapy depends on the content of intracellular oxygen,and the anoxic tumor microenvironment restricts the effect of PDT.Meanwhile,the consumption of reactive oxygen species（¹O₂）by intracellular glutathione with high expression is another factor restricting the effect of PDT.Chlorophyll derivatives are important photosensitizers of PDT.Although PDT has good effect,it has poor water solubility and shallow treatment depth.Chemokinetic therapy is a^·OH mediated therapy based on Fenton-like reaction decomposition of hydrogen peroxide to generate^·OH,but insufficient H₂O₂ activity in tumor cells restricts its clinical application.In order to maintain REDOX balance,glutathione with high expression in cells destroys reactive oxygen species（¹O₂,^·OH）,which is an important obstacle to PDT and CDT.A large number of literatures have also reported that PDT/CDT has a good synergistic enhancement of anti-tumor effects.Based on the above analysis,a new chlorophyll derivate-3¹,3²,7,8-Tetera Hydroxyl-4H-MPPa（HMPPa）was designed and synthesized in this paper.Compared with the developed chlorophyll derivate-hydroxyl,the irradiation wavelength of that was extended to 740 nm,significantly increasing the therapeutic depth of PDT.Meanwhile,the introduction of 4 hydrophilic hydroxyl groups effectively improved the poor water solubility of chlorophyll derivatives.Pharmacological experiments in vitro and in vivo verified that HMPPa had good antitumor activity.Considering that single therapeutic effect may be limited in the anticancer process,HCHC nanoparticles were prepared by introducing Cu²⁺to realize complexation with HMPPa,binding hyaluronic acid,and embedding in hyaluronic acid micellar.Hyaluronic acid is a ligand of CD44,which is highly expressed on the cell surface and is targeted to accumulate in tumor entities under CD44 mediation.Under the stimulation of tumor microenvironment,hyaluronic acid micellar disintegrates Cu²⁺and HMPPa,and Cu²⁺generates^·OH based on Fenton-like reaction.Laser irradiation of HMPPa produces singlet oxygen.Cu²⁺consumes GSH cascade amplification^·OH and ¹O₂levels.Fenton-like reaction produces O₂,which is oxygenated in situ in cells,significantly alleviates tumor hypoxia and inhibits the expression of hypoxia-inducing factor 1a（HIF-1a）.CDT and PDT induced a large number of cell apoptosis,causing immune response,high expression of immune markers CRT and ATP,activation of T cell immune activity,combined with immune checkpoint blockers anti-PD-L1 inhibited distal tumor and ablated primary tumor,demonstrating excellent in vitro and in vivo antitumor and immunotherapeutic activity.All the compounds were characterized by structure and photophysical properties by absorption and emission spectra.The structures of HMPPa and HCHC were characterized by transmission electron microscopy and X-ray electron spectroscopy.The antitumor activity in vitro was evaluated by MTT method,and the antitumor activity in vivo was evaluated by Balb/c tumor-bearing mice.HCHC was modified on the basis of HMPPa,and it was found that the antitumor activity of HCHC was significantly improved through experimental comparison.