Enhancement of humoral and cellular immune responses by an oral Salmonella choleraesuis vaccine expressing porcine prothymosin alpha

Amelioration of Murine Colitis by Attenuated Salmonella choleraesuis Encoding Interleukin-19

The imbalance of mucosal immunity in the lower gastrointestinal tract can lead to chronic inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis. IBD is a chronic inflammatory disorder that causes small and/or large intestines ulceration. According to previous studies, recombinant interleukin (IL)-10 protein and genetically modified bacteria secreting IL-10 ameliorate dextran sulfate sodium (DSS)-induced colitis in mice. IL-19 is a transcriptional activator of IL-10 and can alter the balance of T helper 1 (Th)1/Th2 cells in favor of Th2. In this study, we aimed to investigate whether the expression of the murine IL-19 gene carried by Salmonella choleraesuis (S. choleraesuis) could ameliorate murine IBD. Our results showed that the attenuated S. choleraesuis could carry and express the IL-19 gene-containing plasmid for IBD gene therapy by reducing the mortality and clinical signs in DSS-induced acute colitis mice as compared to the untreated ones. We also found that IL-10 expression was induced in IL-19-treated colitis mice and prevented inflammatory infiltrates and proinflammatory cytokine expression in these mice. We suggest that S. choleraesuis encoding IL-19 provides a new strategy for treating IBD in the future.

Using bugs as drugs: administration of bacteria-related microbes to fight cancer

Driven by the advancement of microbiology and cancer biology, bioengineering of bacteria-related microbes has demonstrated great potential in targeted cancer therapy. Presently, the major administration routes of bacteria-related microbes for cancer treatment include intravenous injection, intratumoral injection, intraperitoneal injection, and oral delivery. Administration routes of bacteria play a key role in anticancer therapeutic efficacy since different delivery approaches might exert an anticancer effect through diverse mechanisms. Herein, we provide an overview of the primary routes of bacteria administration as well as their advantages and limitations. Furthermore, we discuss that microencapsulation can overcome the current challenges of direct administration of free bacteria. We also review the latest advancements in combining functional particles with engineered bacteria to fight against cancer, which can be further coupled with conventional anticancer therapies to improve the therapeutic effect. Eventually, we highlight the application prospect of bioprinting in cancer bacteriotherapy, which enables the long-term sustained delivery and individualized dose regimen, representing a new paradigm for personalized cancer treatment.

Interruption of the long non-coding RNA HOTAIR signaling axis ameliorates chemotherapy-induced cachexia in bladder cancer

BACKGROUND

Cisplatin-based chemotherapy is the first line of treatment for bladder cancer. However, cisplatin induces muscle wasting associated with NF-κB and cancer cachexia. HOTAIR, an oncogenic long non-coding RNA (lncRNA), promotes cancer progression in different cancers. Crosstalk between HOTAIR and NF-κB is documented. Prothymosin α (ProT) plays important roles in cancer progression and inflammation. However, the potential link between HOTAIR, ProT, and cisplatin-induced cancer cachexia remains unexplored. Here, we investigated the contribution of HOTAIR in cisplatin-induced cancer cachexia and dissected the potential signaling cascade involving the epidermal growth factor receptor (EGFR), ProT, NF-κB, and HOTAIR.

MATERIALS AND METHODS

Expression of ProT and HOTAIR transcripts and their correlations in tumor tissues of bladder cancer patients and bladder cancer cell lines were determined by RT-qPCR. Next, levels of phospho-EGFR, EGFR, phospho-NF-κB, and NF-κB were examined by immunoblot analysis in human bladder cancer cells treated with cisplatin. Expression of HOTAIR in cisplatin-treated cells was also assessed by RT-qPCR. Pharmacological inhibitors and overexpression and knockdown approaches were exploited to decipher the signaling pathway. The murine C2C12 myoblasts were used as an in vitro muscle atrophy model. The syngeneic murine MBT-2 bladder tumor was used to investigate the role of mouse Hotair in cisplatin-induced cancer cachexia.

RESULTS

Expression of ProT and HOTAIR was higher in bladder tumors than in normal adjacent tissues. There were positive correlations between ProT and HOTAIR expression in clinical bladder tumors and bladder cancer cell lines. Cisplatin treatment increased EGFR and NF-κB activation and upregulated ProT and HOTAIR expression in bladder cancer cells. ProT overexpression increased, whereas ProT knockdown decreased, HOTAIR expression. Notably, cisplatin-induced HOTAIR upregulation was abrogated by EGFR inhibitors or ProT knockdown. ProT-induced HOTAIR overexpression was diminished by NF-κB inhibitors. HOTAIR overexpression enhanced, whereas its knockdown reduced, cell proliferation, cachexia-associated pro-inflammatory cytokine expression, and muscle atrophy. Cachexia-associated symptoms were ameliorated in mice bearing Hotair-knockdown bladder tumors undergoing cisplatin treatment.

CONCLUSIONS

We demonstrate for the first time a critical role for HOTAIR and identify the involvement of the EGFR-ProT-NF-κB-HOTAIR signaling axis in cisplatin-induced cachexia in bladder cancer and likely other cancers. Our findings also provide therapeutic targets for this disease.

Mucosal IgA and IFN-γ+ CD8 T cell immunity are important in the efficacy of live Salmonella enteria serovar Choleraesuis vaccines

Salmonellosis, a disease caused by non-typhoidal Salmonella strains which can be transmitted from swine to humans, is one of the leading public health problems around the world. Paratyphoid of swine is controlled by vaccinating swine with Salmonella enterica serovar Choleraesuis (S. Choleraesuis) live vaccine strain C500 in China. Although the vaccine has good prophylactic efficacy, the mechanism of immunogenicity is unclear. Using a C500-derived paratyphoid thermo-stable live vaccine (PTSL vaccine), we demonstrated that the PTSL vaccine induces strong primary and memory immune responses in piglets. Mucosal IgA and IFN-γ⁺/CD8⁺ T cells induced by the PTSL vaccine play key roles in the protection of the host from Salmonella infection. Our findings have important implications on the development of new and improved vaccines against salmonellosis and using live-attenuated Salmonella as vaccine carriers.

B cells are required for tumor-targeting Salmonella in host

Systemic administration of Salmonella to tumor-bearing mice leads to the preferential accumulation within tumor sites and retardation of the tumor growth. Host factors including innate and adaptive immune responses influence Salmonella-induced antitumor activity. Antitumor activities of Salmonella are not only determined by the tumor regression but also by the host immune response. Herein, we demonstrated that B cells play an important role in the antitumor activity mediated by Salmonella. Body weight and survival of B cell-deficient mice were decreased compared with wild-type, CD8(+) cell-deficient, or CD4(+) cell-deficient mice after Salmonella administration. Although Salmonella accumulated within the tumors in B cell-deficient mice, the bacterial loads of healthy organs were higher than those in wild-type mice. The inflammation cytokine and bacteremia were found in B cell-deficient mice after Salmonella treatment. When Salmonella accumulated within the tumor, B cells inhibited the dissemination of Salmonella to other healthy organs. The depletion of host B cells resulted in a noticeably higher total number of Salmonella in the tumor and inhibited tumor growth. Meanwhile, B cell-depletive and B cell-adoptive transfer of serum experiments demonstrated that the natural antibody produced by B cell takes part in the control of Salmonella dissemination in tumor-bearing mice. In this study, we want to address the mechanisms of incorporating host immunoresponse as a way to augment the antitumor activities of Salmonella.

Vaccination of mice with salmonella expressing VapA: mucosal and systemic Th1 responses provide protection against Rhodococcus equi infection

Conventional vaccines to prevent the pneumonia caused by Rhodococcus equi have not been successful. We have recently demonstrated that immunization with Salmonella enterica Typhimurium expressing the VapA antigen protects mice against R. equi infection. We now report that oral vaccination of mice with this recombinant strain results in high and persistent fecal levels of antigen-specific IgA, and specific proliferation of the spleen cells of immunized mice in response to the in vitro stimulation with R. equi antigen. After in vitro stimulation, spleen cells of immunized mice produce high levels of Th1 cytokines and show a prominent mRNA expression of the Th1 transcription factor T-bet, in detriment of the Th2 transcription factor GATA-3. Following R. equi challenge, a high H₂O₂, NO, IL-12, and IFN-γ content is detected in the organs of immunized mice. On the other hand, TNF-α and IL-4 levels are markedly lower in the organs of vaccinated mice, compared with the non-vaccinated ones. The IL-10 content and the mRNA transcription level of TGF-β are also higher in the organs of immunized mice. A greater incidence of CD4⁺ and CD8⁺ T cells and B lymphocytes is verified in vaccinated mice. However, there is no difference between vaccinated and non-vaccinated mice in terms of the frequency of CD4⁺CD25⁺Foxp3⁺ T cells. Finally, we show that the vaccination confers a long-term protection against R. equi infection. Altogether, these data indicate that the oral vaccination of mice with S. enterica Typhimurium expressing VapA induces specific and long-lasting humoral and cellular responses against the pathogen, which are appropriately regulated and allow tissue integrity after challenge.

Biological gene delivery vehicles: beyond viral vectors

Gene therapy covers a broad spectrum of applications, from gene replacement and knockdown for genetic or acquired diseases such as cancer, to vaccination, each with different requirements for gene delivery. Viral vectors and synthetic liposomes have emerged as the vehicles of choice for many applications today, but both have limitations and risks, including complexity of production, limited packaging capacity, and unfavorable immunological features, which restrict gene therapy applications and hold back the potential for preventive gene therapy. While continuing to improve these vectors, it is important to investigate other options, particularly nonviral biological agents which include bacteria, bacteriophage, virus-like particles (VLPs), erythrocyte ghosts, and exosomes. Exploiting the natural properties of these biological entities for specific gene delivery applications will expand the repertoire of gene therapy vectors available for clinical use. Here, we review the prospects for nonviral biological delivery vehicles as gene therapy agents with focus on their unique evolved biological properties and respective limitations and potential applications. The potential of these nonviral biological entities to act as clinical gene therapy delivery vehicles has already been shown in clinical trials using bacteria-mediated gene transfer and with sufficient development, these entities will complement the established delivery techniques for gene therapy applications.

Analysis of porcine transcriptional response to Salmonella enterica serovar Choleraesuis suggests novel targets of NFkappaB are activated in the mesenteric lymph node

BACKGROUND

Specific knowledge of the molecular pathways controlling host-pathogen interactions can increase our understanding of immune response biology as well as provide targets for drug development and genetic improvement of disease resistance. Toward this end, we have characterized the porcine transcriptional response to Salmonella enterica serovar Choleraesuis (S. Choleraesuis), a Salmonella serovar that predominately colonizes swine, yet can cause serious infections in human patients. Affymetrix technology was used to screen for differentially expressed genes in pig mesenteric lymph nodes (MLN) responding to infection with S. Choleraesuis at acute (8 hours (h), 24 h and 48 h post-inoculation (pi)) and chronic stages (21 days (d) pi).

RESULTS

Analysis of variance with false discovery rate control identified 1,853 genes with significant changes in expression level (p-value < 0.01, q-value < 0.26, and fold change (FC) > 2) during infection as compared to un-inoculated control pigs. Down-regulation of translation-related genes at 8 hpi and 24 hpi implied that S. Choleraesuis repressed host protein translation. Genes involved in the Th1, innate immune/inflammation response and apoptosis pathways were induced significantly. However, antigen presentation/dendritic cell (DC) function pathways were not affected significantly during infection. A strong NFkappaB-dependent response was observed, as 58 known NFkappaB target genes were induced at 8, 24 and/or 48 hpi. Quantitative-PCR analyses confirmed the microarray data for 21 of 22 genes tested. Based on expression patterns, these target genes can be classified as an "Early" group (induced at either 8 or 24 hpi) and a "Late" group (induced only at 48 hpi). Cytokine activity or chemokine activity were enriched within the Early group genes GO annotations, while the Late group was predominantly composed of signal transduction and cell metabolism annotated genes. Regulatory motif analysis of the human orthologous promoters for both Early and Late genes revealed that 241 gene promoters were predicted to contain NFkappaB binding sites, and that of these, 51 Early and 145 Late genes were previously not known to be NFkappaB targets.

CONCLUSION

Our study provides novel genome-wide transcriptional profiling data on the porcine response to S. Choleraesuis and expands the understanding of NFkappaB signaling in response to Salmonella infection. Comparison of the magnitude and timing of porcine MLN transcriptional response to different Salmonella serovars, S. Choleraesuis and S. Typhimurium, clearly showed a larger but later transcriptional response to S. Choleraesuis. Both microarray and QPCR data provided evidence of a strong NFkappaB-dependent host transcriptional response during S. Choleraesuis infection. Our data indicate that a lack of strong DC-mediated antigen presentation in the MLN may cause S. Choleraesuis infected pigs to develop a systemic infection, and our analysis predicts nearly 200 novel NFkappaB target genes which may be applicable across mammalian species.

Heterologous protection in pigs induced by a plasmid-cured and crp gene-deleted Salmonella choleraesuis live vaccine

In this study, we exploited a crp (cAMP receptor protein) gene-deleted, virulence plasmid-cured Salmonella choleraesuis mutant with decreased carbon source utilization, designated S.C.-Deltacrp/vpl(-), as a live vaccine strain. Normal weight gain with no clinical signs was observed in pigs immunized with high doses of S.C.-Deltacrp/vpl(-) live vaccine. Vaccination in pregnant sows induced high maternal antibodies, which could prevent piglets from Salmonella infection. Moreover, serial transmission of the vaccine strain in piglets produced no evidence of reversion to virulence. Furthermore, the peripheral blood mononuclear cells from immunized piglets also developed Salmonella specific T-cell proliferative response in vitro. Our results indicate that immunogenic antigens in S.C.-Deltacrp/vpl(-) can induce adequate immunity to protect pigs against challenge with a heterologous virulent strain. Thus, this mutant holds promise for the development of a new live S. choleraesuis vaccine.

Coexpression of Flt3 ligand and GM-CSF genes modulates immune responses induced by HER2/neu DNA vaccine

DNA vaccine and dendritic cells (DCs)-based vaccine have emerged as promising strategies for cancer immunotherapy. Fms-like tyrosine kinase 3-ligand (Flt3L) and granulocyte-macrophage-colony-stimulating factor (GM-CSF) have been exploited for the expansion of DC. It was reported previously that combination of plasmid encoding GM-CSF with HER2/neu DNA vaccine induced predominantly CD4(+) T-cell-mediated antitumor immune response. In this study, we investigated the modulation of immune responses by murine Flt3L and GM-CSF, which acted as genetic adjuvants in the forms of bicistronic (pFLAG) and monocistronic (pFL and pGM) plasmids for HER2/neu DNA vaccine (pN-neu). Coexpression of Flt3L and GM-CSF significantly enhanced maturation and antigen-presentation abilities of splenic DC. Increased numbers of infiltrating DC at the immunization site, higher interferon-gamma production, and enhanced cytolytic activities by splenocytes were prominent in mice vaccinated with pN-neu in conjunction with pFLAG. Importantly, a potent CD8(+) T-cell-mediated antitumor immunity against bladder tumors naturally overexpressing HER2/neu was induced in the vaccinated mice. Collectively, our results indicate that murine Flt3L and GM-CSF genes coexpressed by a bicistronic plasmid modulate the class of immune responses and may be superior to those codelivered by two separate monocistronic plasmids as the genetic adjuvants for HER2/neu DNA vaccine.