Does T Helper Differentiation Correlate with Resistance or Susceptibility to Infection with L. major? Some Insights From the Murine Model

The murine model of Leishmania major infection has been an invaluable tool in understanding T helper differentiation in vivo. The initial evidence for a role of distinct CD4+ T helper subsets in the outcome of infection was first obtained with this experimental model. The development of CD4+ Th1 cells was associated with resolution of the lesion, control of parasite replication, and resistance to re-infection in most of the mouse strains investigated (i.e., C57BL/6). In contrast, differentiation of CD4+ Th2 cells correlated with the development of unhealing lesions, and failure to control parasite load in a few strains (i.e., BALB/c). Since these first reports, an incredible amount of effort has been devoted to understanding the various parameters involved in the differentiation of these, and more recently discovered T helper subsets such as Th17 and T regulatory cells. The discovery of cross-talk between T helper subsets, as well as their plasticity force us to reevaluate the events driving a protective/deleterious T helper immune response following infection with L. major in mice. In this review, we describe the individual contributions of each of these CD4+ T helper subsets following L. major inoculation, emphasizing recent advances in the field, such as the impact of different substrains of L. major on the pathogenesis of disease

Selective Expression of the Vβ14 T Cell Receptor on Leishmania guyanensis-Specific CD8+ T Cells during Human Infection

Peripheral blood mononuclear cells from subjects never exposed to Leishmania were stimulated with Leishmania guyanensis. We demonstrated that L. guyanensis-stimulated CD8+ T cells produced interferon (IFN)-γ and preferentially expressed the Vb14 T cell receptor (TCR) gene family. In addition, these cells expressed cutaneous lymphocyte antigen and CCR4 surface molecules, suggesting that they could migrate to the skin. Results obtained from the lesions of patients with localized cutaneous leishmaniaisis (LCL) showed that Vβ14 TCR expression was increased in most lesions (63.5%) and that expression of only a small number of Vb gene families (Vβ1, Vβ6, Vβ9, Vβ14, and Vβ24) was increased. The presence of Vβ14 T cells in tissue confirmed the migration of these cells to the lesion site. Thus, we propose the following sequence of events during infection with L. guyanensis. After initial exposure to L. guyanensis, CD8+ T cells preferentially expressing the Vb14 TCR and secreting IFN-γ develop and circulate in the periphery. During the infection, these cells migrate to the skin at the site of the parasitic infection. The role of these Vβ14 CD8+ T cells in resistance to infection remains to be determined conclusivel

T Cell Reactivity against Mycolyl Transferase Antigen 85 of M. tuberculosis in HIV-TB Coinfected Subjects and in AIDS Patients Suffering from Tuberculosis and Nontuberculous Mycobacterial Infections

The mycolyl transferase antigen 85 complex is a major secreted protein family from mycobacterial culture filtrate, demonstrating powerful T cell stimulatory properties in most HIV-negative, tuberculin-positive volunteers with latent M.tuberculosis infection and only weak responses in HIV-negative tuberculosis patients. Here, we have analyzed T cell reactivity against PPD and Ag85 in HIV-infected individuals, without or with clinical symptoms of tuberculosis, and in AIDS patients with disease caused by nontuberculous mycobacteria. Whereas responses to PPD were not significantly different in HIV-negative and HIV-positive tuberculin-positive volunteers, responses to Ag85 were significantly decreased in the HIV-positive (CDC-A and CDC-B) group. Tuberculosis patients demonstrated low T cell reactivity against Ag85, irrespective of HIV infection, and finally AIDS patients suffering from NTM infections were completely nonreactive to Ag85. A one-year follow-up of twelve HIV-positive tuberculin-positive individuals indicated a decreased reactivity against Ag85 in patients developing clinical tuberculosis, highlighting the protective potential of this antigen

In Leishmaniasis due to Leishmania guyanensis infection, distinct intralesional interleukin-10 and foxp3 mRNA expression are associated with unresponsiveness to treatment

The presence of intralesional natural regulatory T cells, characterized by the expression of Foxp3 mRNA, was analyzed in patients with localized leishmaniasis due to Leishmania guyanensis infection that was unresponsive to treatment with pentamidine isethionate. Foxp3 mRNA levels were associated with unresponsiveness to treatment among patients with a lesion duration of ⩾1 month, but this association was not observed among patients with a lesion duration of <1 month. In conclusion, high intralesional expression of Foxp3 might be an indicator of poor response to treatment, depending on the duration of lesion

Neutrophil-Derived CCL3 Is Essential for the Rapid Recruitment of Dendritic Cells to the Site of Leishmania major Inoculation in Resistant Mice

Neutrophils are rapidly and massively recruited to sites of microbial infection, where they can influence the recruitment of dendritic cells. Here, we have analyzed the role of neutrophil released chemokines in the early recruitment of dendritic cells (DCs) in an experimental model of Leishmania major infection. We show in vitro, as well as during infection, that the parasite induced the expression of CCL3 selectively in neutrophils from L. major resistant mice. Neutrophil-secreted CCL3 was critical in chemotaxis of immature DCs, an effect lost upon CCL3 neutralisation. Depletion of neutrophils prior to infection, as well as pharmacological or genetic inhibition of CCL3, resulted in a significant decrease in DC recruitment at the site of parasite inoculation. Decreased DC recruitment in CCL3−/− mice was corrected by the transfer of wild type neutrophils at the time of infection. The early release of CCL3 by neutrophils was further shown to have a transient impact on the development of a protective immune response. Altogether, we identified a novel role for neutrophil-secreted CCL3 in the first wave of DC recruitment to the site of infection with L. major, suggesting that the selective release of neutrophil-secreted chemokines may regulate the development of immune response to pathogens

Lessons learned developing a massive open online course in implementation research in infectious diseases of poverty in low- and middle-income countries

Daniel Reidpath - ORCID: 0000-0002-8796-0420 https://orcid.org/0000-0002-8796-0420This study uses a case study approach to examine the development of a massive open online course (MOOC) on intervention and implementation research in infectious diseases of poverty for learners in low- and middle-income countries (LMICs). Implementation research (IR) seeks to understand and address barriers to effective implementation of health interventions, strategies, and policies. In recent years, IR has attracted increased interest, and corresponding demand for training, however, current training opportunities are not easily accessible to learners in LMICs. In 2017, the MOOC was introduced to a diverse range of learners to enhance access to training materials and has been offered yearly since. Findings are based on the experiences of the MOOC working group which included developers and facilitators, and on interpretations of data such as forum discussion activity and Facebook posts. The use of material from local contexts and in local languages, and professional facilitation of discussion forums was identified by the working group to be key considerations in developing the MOOC. Other findings include the importance of using clear instructions and preparing discussion questions to stimulate learner engagement. These findings add to the limited knowledge of MOOCs developed for LMICs and are of value to others developing professional development MOOCs in LMIC health contexts.http://doi.org/10.5944/openpraxis.13.1.117213pubpub

Leishmaniavirus-dependent metastatic leishmaniasis is prevented by blocking IL-17A

Cutaneous leishmaniasis has various outcomes, ranging from self-healing reddened papules to extensive open ulcerations that metastasise to secondary sites and are often resistant to standard therapies. In the case of L. guyanensis (L.g), about 5-10% of all infections result in metastatic complications. We recently showed that a cytoplasmic virus within L.g parasites (LRV1) is able to act as a potent innate immunogen, worsening disease outcome in a murine model. In this study, we investigated the immunophenotype of human patients infected by L.g and found a significant association between the inflammatory cytokine IL-17A, the presence of LRV1 and disease chronicity. Further, IL-17A was inversely correlated to the protective cytokine IFN-γ. These findings were experimentally corroborated in our murine model, where IL-17A produced in LRV1+ L.g infection contributed to parasite virulence and dissemination in the absence of IFN-γ. Additionally, IL-17A inhibition in mice using digoxin or SR1001, showed therapeutic promise in limiting parasite virulence. Thus, this murine model of LRV1-dependent infectious metastasis validated markers of disease chronicity in humans and elucidated the immunologic mechanism for the dissemination of Leishmania parasites to secondary sites. Moreover, it confirms the prognostic value of LRV1 and IL-17A detection to prevent metastatic leishmaniasis in human patients

The process of developing a joint theory of change across three global entities: can this help to make their efforts to strengthen capacity for implementation research more effective?

Introduction A Theory of Change is a visual representation of the pathway by which a programme anticipates it will achieve its goal. It usually starts with discussions around the goal and works backwards through outcomes and outputs to activities. Methods We used a Theory of Change to improve coherence across three research entities at the World Health Organisation. Part of the remit of all three entities is to strengthen capacity in low- and middle-income countries for implementation research. Results Representatives from the three entities were able to formulate a joint goal for strengthening capacity in implementation research. They identified three pathways by which this could be achieved: a) conducting implementation research, b) strengthening implementation research systems and c) utilising implementation research for public health priorities. Conclusion The process of developing the Theory of Change and the logic framework it created, provided a means to track progress towards the goal and to guide improvements in programmes within their lifetime. The process we used to develop the Theory of Change and the pathways to achieve the joint goal, are adaptable and could be used by other organisations that also aim to strengthen research capacity. This would lead to more coherence, better translation of research findings into decision-making and ultimately improvements in public health

Development of the Good Health Research Practice course: ensuring quality across all health research in humans.

Quality and ethics need to be embedded into all areas of research with human participants. Good Clinical Practice (GCP) guidelines are international ethical and scientific quality standards for designing, conducting, recording and reporting trials involving human participants. Compliance with GCP is expected to provide public assurance that the rights, safety and wellbeing of participants are protected and that the clinical research data are credible. However, whilst GCP guidelines, particularly their principles, are recommended across all research types, it is difficult for non-clinical trial research to fit in with the exacting requirements of GCP. There is therefore a need for guidance that allows health researchers to adhere to the principles of GCP, which will improve the quality and ethical conduct of all research involving human participants. These concerns have led to the development of the Good Health Research Practice (GHRP) course. Its goal is to ensure that research is conducted to the highest possible standards, similar to the conduct of trials to GCP. The GHRP course provides training and guidance to ensure quality and ethical conduct across all health-related research. The GHRP course has been run so far on eight occasions. Feedback from delegates has been overwhelmingly positive, with most delegates stating that the course was useful in developing their research protocols and documents. Whilst most training in research starts with a guideline, GHRP has started with a course and the experience gained over running the courses will be used to write a standardised guideline for the conduct of health-related research outside the realm of clinical trials, so that researchers, funders and ethics committees do not try to fit non-trials into clinical trials standards

Developing the ethics of implementation research in health

Implementation research (IR) is growing in recognition as an important generator of practical knowledge that can be translated into health policy. With its aim to answer questions about how to improve access to interventions that have been shown to work but have not reached many of the people who could benefit from them, IR involves a range of particular ethical considerations that have not yet been comprehensively covered in international guidelines on health research ethics. The fundamental ethical principles governing clinical research apply equally in IR, but the application of these principles may differ depending on the IR question, context, and the nature of the proposed intervention. IR questions cover a broad range of topics that focus on improving health system functioning and improving equitable and just access to effective health care interventions. As such, IR designs are flexible and often innovative, and ethical principles cannot simply be extrapolated from their applications in clinical research. Meaningful engagement with all stakeholders including communities and research participants is a fundamental ethical requirement that cuts across all study phases of IR and links most ethical concerns. Careful modification of the informed consent process may be required in IR to permit study of a needed intervention. The risks associated with IR may be difficult to anticipate and may be very context-specific. The benefits of IR may not accrue to the same groups who participate in the research, therefore justifying the risks versus benefits of IR may be ethically challenging. The expectation that knowledge generated through IR should be rapidly translated into health policy and practice necessitates up-front commitments from decision-makers to sustainability and scalability of effective interventions. Greater awareness of the particular ethical implications of the features of IR is urgently needed to facilitate optimal ethical conduct of IR and uniform ethical review