Overcoming the nutritional immunity by engineering iron-scavenging bacteria for cancer therapy.

Certain bacteria demonstrate the ability to target and colonize the tumor microenvironment, a characteristic that positions them as innovative carriers for delivering various therapeutic agents in cancer therapy. Nevertheless, our understanding of how bacteria adapt their physiological condition to the tumor microenvironment remains elusive. In this work, we employed liquid chromatography-tandem mass spectrometry to examine the proteome of E. coli colonized in murine tumors. Compared to E. coli cultivated in the rich medium, we found that E. coli colonized in tumors notably upregulated the processes related to ferric ions, including the enterobactin biosynthesis and iron homeostasis. This finding indicated that the tumor is an iron-deficient environment to E. coli. We also found that the colonization of E. coli in the tumor led to an increased expression of lipocalin 2 (LCN2), a host protein that can sequester the enterobactin. We therefore engineered E. coli in order to evade the nutritional immunity provided by LCN2. By introducing the IroA cluster, the E. coli synthesizes the glycosylated enterobactin, which creates steric hindrance to avoid the LCN2 sequestration. The IroA-E. coli showed enhanced resistance to LCN2 and significantly improved the anti-tumor activity in mice. Moreover, the mice cured by the IroA-E. coli treatment became resistant to the tumor re-challenge, indicating the establishment of immunological memory. Overall, our study underscores the crucial role of bacteria's ability to acquire ferric ions within the tumor microenvironment for effective cancer therapy.

Bacteria colonization in tumor microenvironment creates a favorable niche for immunogenic chemotherapy.

The tumor microenvironment (TME) presents differential selective pressure (DSP) that favors the growth of cancer cells, and monovalent therapy is often inadequate in reversing the cancer cell dominance in the TME. In this work, we introduce bacteria as a foreign species to the TME and explore combinatorial treatment strategies to alter DSP for tumor eradication. We show that cancer-selective chemotherapeutic agents and fasting can provide a strong selection pressure against tumor growth in the presence of bacteria. Moreover, we show that an immunogenic drug (oxaliplatin), but not a non-immunogenic one (5-FU), synergizes with the bacteria to activate both the innate and adaptive immunity in the TME, resulting in complete tumor remission and a sustained anti-tumor immunological memory in mice. The combination of oxaliplatin and bacteria greatly enhances the co-stimulatory and antigen-presenting molecules on antigen-presenting cells, which in turn bridge the cytotoxic T cells for cancer-cell killing. Our findings indicate that rational combination of bacterial therapy and immunogenic chemotherapy can promote anticancer immunity against the immunosuppressive TME.

Improvement of Gene Delivery by Minimal Bacteriophage Particles.

Direct delivery of therapeutic genes is a promising approach for treating cancers and other diseases. The current human viral vectors, however, suffer from several drawbacks, including poor cell-type specificity and difficult large-scale production. The M13 phage provides an alternative vehicle for gene therapy with engineerable specificity, but the low transduction efficiency seriously limits its translational application. In this work, we discovered important factors of cells and phages that greatly influence the phage transduction. The up-regulation of PrimPol or the down-regulation of DMBT1 in cells significantly enhanced the phage transduction efficiency. Furthermore, we found that the phage transduction efficiency was inversely correlated with the phage size. By carefully reconstructing the phage origin with the gene of interest, we designed "TransPhage" with a minimal length and maximal transduction efficiency. We showed that TransPhage successfully transduced the human cells with an excellent efficiency (up to 95%) comparable to or superior to that of the adeno-associated virus vectors. Moreover, we showed that TransPhage's tropism was specific to the cells that overexpress the target antigen, whereas adeno-associated viruses (AAVs) promiscuously infected many cell types. Using TransPhage as a gene therapy vehicle, we invented an NK-cell-mediated immunotherapy in which a membrane-bound fragment crystallizable region was introduced to cancer cells. We showed in vitro that the cancer cells expressing the membrane-bound fragment crystallizable (Fc) were effectively killed by CD16+ NK cells through an antibody-dependent cell-mediated cytotoxicity (ADCC)-like mechanism. In the xenograft mouse model, the administration of TransPhage carrying the membrane-bound Fc gene greatly suppressed tumor growth.

FeNxC Based Catalysts Prepared by the Calcination of Iron-Ethylenediamine@Polyaniline as the Cathode-Catalyst of Proton Exchange Membrane Fuel Cell.

Calcinated tris(ethylenediamine)iron(III) chloride was used as a non-precious metal catalyst (NPMCs) for a proton exchanged membrane fuel cell (PEMFC) under the protection of polyaniline (PANI), which behaves as both nitrogen source and carbon supporter. The optimal ratio of FeCl3/EDA was found to be close to 1/3 under the consideration of the electrocatalytic performance, such as better oxygen reduction reaction (ORR) and higher power density. Two-stage calcination, one at 900 °C in N2 and the other at 800 °C in mixed gases of N2 and NH3, result in an FeNxC catalyst (FeNC-900-800-A) with pretty high specific surface area of 1098 m2·g-1 covered with both micro- and mesopores. The ORR active sites focused mainly on Fe-Nx bonding made of various pyridinic, pyrrolic, and graphitic N-s after calcination. The max. power density reaches 140 mW·cm-2 for FeNC-900-800-A, which is superior to other FeNxC catalysts, experiencing only one-stage calcination in N2. The FeNxC demonstrates only 10 mV half-wave-voltage (HWV) loss at 1600 rpm after 1000 redox cycles, as compared to be 27 mV for commercial Pt/C catalyst in the durability test.