Transgenic tomato expressing interleukin-12 has a therapeutic effect in a murine model of progressive pulmonary tuberculosis

Enhancement of CD4+ T Cell Function as a Strategy for Improving Antibiotic Therapy Efficacy in Tuberculosis: Does It Work?

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) remains a major public health problem worldwide due in part to the lack of an effective vaccine and to the lengthy course of antibiotic treatment required for successful cure. Combined immuno/chemotherapeutic intervention represents a major strategy for developing more effective therapies against this important pathogen. Because of the major role of CD4⁺ T cells in containing Mtb infection, augmentation of bacterial specific CD4⁺ T cell responses has been considered as an approach in achieving this aim. Here we present new data from our own research aimed at determining whether boosting CD4⁺ T cell responses can promote antibiotic clearance. In these studies, we first characterized the impact of antibiotic treatment of infected mice on Th1 responses to major Mtb antigens and then performed experiments aimed at sustaining CD4⁺ T cell responsiveness during antibiotic treatment. These included IL-12 infusion, immunization with ESAT-6 and Ag85B immunodominant peptides and adoptive transfer of Th1-polarized CD4⁺ T cells specific for ESAT-6 or Ag85B during the initial month of chemotherapy. These approaches failed to enhance antibiotic clearance of Mtb, indicating that boosting Th1 responses to immunogenic Mtb antigens highly expressed by actively dividing bacteria is not an effective strategy to be used in the initial phase of antibiotic treatment, perhaps because replicating organisms are the first to be eliminated by the drugs. These results are discussed in the context of previously published findings addressing this concept along with possible alternate approaches for harnessing Th1 immunity as an adjunct to chemotherapy.

In vitro regeneration of eight cultivars of Brassica oleracea var. capitata

Eight cultivars of Brassica oleracea var. capitata and two types of explant (hypocotyl and cotyledon) were tested for their potential to regenerate under in vitro conditions. Hypocotyl and cotyledon explants from 10-d-old seedlings were subcultured onto different callus induction media based on Murashige and Skoog (MS) basal medium supplemented with 1% sucrose and different concentrations and combinations of plant growth regulators. Hypocotyl explants were found to be more suitable for callus induction and organogenesis than cotyledon explants for all cultivars tested. In terms of regeneration, the cv. 'Amager' was significantly more responsive than the other cultivars tested and produced the highest number of shoots/buds per explant. Moreover, among five types of media tested, MS + 8.88 μM 6-benzyloaminopurine (BAP) + 0.53 μM α-naphthylacetic acid (NAA) was most effective for shoot regeneration. Rooting was achieved within 10-15 d on all the rooting media, but MS medium containing 5.37 μM NAA produced the maximum number of strong and healthy roots. Plantlets (95%) were subsequently established in the greenhouse, and no phenotypic variations were observed among regenerated plants. This plant regeneration protocol could be suitable for a wide range of cabbage cultivars.

Interleukin-6: a potent biomarker of mycobacterial infection

Background

Human tuberculosis (TB), a chronic inflammatory disease is caused by Mycobacterium tuberculosis, a facultative intramacrophage pathogen. The highly complex interactions between mycobacteria and macrophages (MΦs), characterized in part by the induction and elaboration of several cytokines including IL-1, IL-6, IL-10, IL-12 p40 and IL-12 p70 are not yet fully understood. The cytokines are known to have important bearing on the pathogenesis and host defense during TB. We thus studied different patterns of cytokines elaborated by mouse peritoneal macrophages (PMs) following their interaction with live and heat-killed, virulent and avirulent, and pathogenic and non-pathogenic mycobacteria, in vitro.

Materials and methods

Pathogenic M. tuberculosis H37Rv (virulent) and M. tuberculosis H37Ra (avirulent), and non-pathogenic M. smegmatis were grown in complete Middle Brook 7H9 broth. For some experiments, mycobacteria were heat-killed (80°C; 20 min). The supernatants of cultured PMs, having ingested mycobacteria for 6 h, 24 h, 4 days and 7 days, were harvested for the quantification of IL-1, IL-6, IL-10, IL-12 p40 and IL-12 p70 by using a multiplex suspension cytokine array system.

Results

The PMs infected with heat-killed mycobacteria, as compared to their respective live counterparts, invariably elaborated significantly (p < 0.001) increased (approximately 2–3-fold) amounts of IL-6, at all the time-points studied, in vitro. Further, PMs infected with M. tuberculosis H37Ra, as compared to M. tuberculosis H37Rv, elaborated 4–5-fold more (p < 0.001) IL-6. Non-pathogenic M. smegmatis, as compared to pathogenic M. tuberculosis H37Ra and M. tuberculosis H37Rv, following infection, induced the PMs to elaborate highest (p < 0.001) amounts of IL-6 at all the time-points studied. Curiously, none of these mycobacteria-infected PMs elaborated IL-1, IL-10, IL-12 p40 and IL-12 p70, significantly.

Conclusion

IL-6 appears to be the only major cytokine elaborated by mycobacteria-infected PMs, in vitro, and thus may function as a potent biomarker of mycobacterial infection, either stand-alone or along with other cytokines.

Plant-derived pharmaceuticals for the developing world

Plant-produced vaccines and therapeutic agents offer enormous potential for providing relief to developing countries by reducing the incidence of infant mortality caused by infectious diseases. Vaccines derived from plants have been demonstrated to effectively elicit an immune response. Biopharmaceuticals produced in plants are inexpensive to produce, require fewer expensive purification steps, and can be stored at ambient temperatures for prolonged periods of time. As a result, plant-produced biopharmaceuticals have the potential to be more accessible to the rural poor. This review describes current progress with respect to plant-produced biopharmaceuticals, with a particular emphasis on those that target developing countries. Specific emphasis is given to recent research on the production of plant-produced vaccines toward human immunodeficiency virus, malaria, tuberculosis, hepatitis B virus, Ebola virus, human papillomavirus, rabies virus and common diarrheal diseases. Production platforms used to express vaccines in plants, including nuclear and chloroplast transformation, and the use of viral expression vectors, are described in this review. The review concludes by outlining the next steps for plant-produced vaccines to achieve their goal of providing safe, efficacious and inexpensive vaccines to the developing world.

IL12B expression is sustained by a heterogenous population of myeloid lineages during tuberculosis

IL12B is required for resistance to Mycobacterium tuberculosis (Mtb) infection, promoting the initiation and maintenance of Mtb-specific effector responses. While this makes the IL12-pathway an attractive target for experimental tuberculosis (TB) therapies, data regarding what lineages express IL12B after infection is established are limited. This is not obvious in the lung, an organ in which both hematopoietic and non-hematopoietic lineages produce IL12p40 upon pathogen encounter. Here, we use radiation bone marrow chimeras and Yet40 reporter mice to determine what lineages produce IL12p40 during experimental TB. We observed that hematopoietic IL12p40-production was sufficient to control Mtb, with no contribution by non-hematopoietic lineages. Furthermore, rather than being produced by a single subset, IL12p40 was produced by cells that were heterogenous in their size, granularity, autofluorescence and expression of CD11c, CD11b and CD8α. While depending on the timepoint and tissue examined, the surface phenotype of IL12p40-producers most closely resembled macrophages based on previous surveys of lung myeloid lineages. Importantly, depletion of CD11c(hi) cells during infection had no affect on lung IL12p40-concentrations. Collectively, our data demonstrate that IL12p40 production is sustained by a heterogenous population of myeloid lineages during experimental TB, and that redundant mechanisms of IL12p40-production exist when CD11c(hi) lineages are absent.

Bifidobacterium as an oral delivery carrier of interleukin-12 for the treatment of Coxsackie virus B3-induced myocarditis in the Balb/c mice

IL-12 plays an important role in the treatment of many infectious diseases by being administered intravenously or intramuscularly. However, intravenous or intramuscular administration is difficult and inconvenient and may cause side effects. The aim of this study is to develop a novel oral delivery system for IL-12 using genetically engineered Bifidobacterium longum as the carrier and further investigate the efficacy of IL-12-expressed B. longum on the coxsackie virus B3 (CVB3)-induced myocarditis in mice. A mIL-12 gene expression vector pBBADs-IL-12 for B. longum was constructed and transformed into Bifidobacterium. Subsequently, the expression of mIL-12 in the engineered B. longum was identified in vitro by western blot and enzyme-linked immunosorbent assay (ELISA) after l-arabinose induction. Moreover, our data indicated that oral administration of IL-12-expressed B. longum for two weeks after CVB3 infection in the Balb/c mice could downregulate the severity of virus-induced myocarditis, markedly reduce the virus titers in the heart and induce a Th1 pattern in the spleen and heart compared with the controls. In conclusion, a novel oral delivery system of Bifidobacterium for murine IL-12 has been successfully established. Oral administration of mIL-12-transformed B. longum may play a therapeutic role in the treatment of CVB3-induced myocarditis in the mice.

[Current status and industrialization of transgenic tomatoes]

In this review, the progress in transgenic tomato research, including disease and insect resistance, herbicide resistance, stress tolerance, long-term storage, quality improvement, and male sterility, were described. The recent researches on producing heterologous proteins using transgenic tomatoes were also reviewed. Furthermore, the industrialization status and problems of transgenic tomatoes were analyzed and the prospects of both research and industrialization in transgenic tomatoes were discussed.

The potential impact of plant biotechnology on the Millennium Development Goals

The eight Millennium Development Goals (MDGs) are international development targets for the year 2015 that aim to achieve relative improvements in the standards of health, socioeconomic status and education in the world's poorest countries. Many of the challenges addressed by the MDGs reflect the direct or indirect consequences of subsistence agriculture in the developing world, and hence, plant biotechnology has an important role to play in helping to achieve MDG targets. In this opinion article, we discuss each of the MDGs in turn, provide examples to show how plant biotechnology may be able to accelerate progress towards the stated MDG objectives, and offer our opinion on the likelihood of such technology being implemented. In combination with other strategies, plant biotechnology can make a contribution towards sustainable development in the future although the extent to which progress can be made in today's political climate depends on how we deal with current barriers to adoption.

Advances in plant molecular farming

Plant molecular farming (PMF) is a new branch of plant biotechnology, where plants are engineered to produce recombinant pharmaceutical and industrial proteins in large quantities. As an emerging subdivision of the biopharmaceutical industry, PMF is still trying to gain comparable social acceptance as the already established production systems that produce these high valued proteins in microbial, yeast, or mammalian expression systems. This article reviews the various cost-effective technologies and strategies, which are being developed to improve yield and quality of the plant-derived pharmaceuticals, thereby making plant-based production system suitable alternatives to the existing systems. It also attempts to overview the different novel plant-derived pharmaceuticals and non-pharmaceutical protein products that are at various stages of clinical development or commercialization. It then discusses the biosafety and regulatory issues, which are crucial (if strictly adhered to) to eliminating potential health and environmental risks, which in turn is necessary to earning favorable public perception, thus ensuring the success of the industry.

In planta production of plant-derived and non-plant-derived adjuvants

Recombinant antigen production in plants is a safe and economically sound strategy for vaccine development, particularly for oral/mucosal vaccination, but subunit vaccines usually suffer from weak immunogenicity and require adjuvants that escort the antigens, target them to relevant sites and/or activate antigen-presenting cells for elicitation of protective immunity. Genetic fusions of antigens with bacterial adjuvants as the B subunit of the cholera toxin have been successful in inducing protective immunity of plant-made vaccines. In addition, several plant compounds, mainly plant defensive molecules as lectins and saponins, have shown strong adjuvant activities. The molecular diversity of the plant kingdom offers a vast source of non-bacterial compounds with adjuvant activity, which can be assayed in emerging plant manufacturing systems for the design of new plant vaccine formulations.

In vivo activity of plant-based interleukin-12 in the lung of Balb/c mouse

Background

In the last years, plants are being used for the production of a wide variety of biopharmaceuticals, including cytokines, and have the potential to serve as vehicles for mucosal administration of these molecules. We had previously reported the expression of a cytokine, interleukin-12 (IL-12), in transgenic tomato plants and had demonstrated that it retained its biologic activity in vitro.

Findings

In this work, we administered crude extracts of IL-12-containing tomato fruits to mice through the intratracheal route, measuring endogenous IL-12 and determining biologic activity by quantification of interferon-gamma (IFN-γ) in lungs and by histological analysis. IFN-γ expression in lungs, as well as histological analysis, indicate that tomato-expressed IL-12 retains its biologic activity and, most importantly, its effects are restricted to the site of administration.

Conclusion

Our results indicate that the functional activity of tomato-expressed IL-12 is comparable to that of commercial recombinant IL-12 when given via the mucosal route. This opens the possibility of using crude extracts prepared from tomatoes expressing IL-12 for certain immunotherapies.