Studying the effect of chloroquine on sporozoite-induced protection and immune responses in Plasmodium berghei malaria

BACKGROUND Sporozoite immunization of animals and humans under a chemo-prophylactic cover of chloroquine (CPS-CQ) efficiently induces sterile protection against malaria. In humans, CPS-CQ is strikingly more efficient than immunization with radiation attenuated sporozoites (RAS), raising the hypothesis that this might be partially due to CQ. Chloroquine, an established anti-malarial drug, is also well known for its immune modulating properties including improvement of cross-presentation. The aim of this study was to investigate whether co-administration of CQ during sporozoite immunization improves cellular responses and protective efficacy in Plasmodium berghei models. METHODS A number of experiments in selected complimentary P. berghei murine models in Balb/cByJ and C57BL/6j mice was performed. First, the effect of CQ administration on the induction of protection and immune responses by RAS immunization was studied. Next, the effect of CQ on the induction of circumsporozoite (CS) protein-specific CD8(+) T cells by immunization with P. berghei parasites expressing a mutant CS protein was investigated. Finally, a direct comparison of CPS-CQ to CPS with mefloquine (MQ), an anti-malarial with little known immune modulating effects, was performed. RESULTS When CQ was co-administered during immunization with graded numbers of RAS, this did not lead to an increase in frequencies of total memory CD8(+) T cells or CS protein-specific CD8(+) T cells. Also parasite-specific cytokine production and protection remained unaltered. Replacement of CQ by MQ for CPS immunization resulted in significantly reduced percentages of IFNγ producing memory T cells in the liver (p = 0.01), but similar protection. CONCLUSIONS This study does not provide evidence for a direct beneficial effect of CQ on the induction of sporozoite-induced immune responses and protection in P. berghei malaria models. Alternatively, the higher efficiency of CPS compared to RAS might be explained by an indirect effect of CQ through limiting blood-stage exposure after immunization or to increased antigen exposure and, therefore, improved breadth of the immune response.EMB was supported by Top Institute Pharma (grant T4-102) and KN was supported by the NWO Mozaiek (grant no. 017.005.011)

Dynamics of P. falciparum gametocytemia in symptomatic patients in an area of intense perennial transmission in Tanzania.

We investigated the dynamics of Plasmodium falciparum gametocytemia in symptomatic patients attending a local dispensary in the Kilombero district, Tanzania. Consenting individuals aged one and above, with varying asexual and sexual parasitemias were treated appropriately and asked to return weekly for 28 days. Gametocyte prevalence was highest on Day 7 of follow-up in all age groups (overall 30.5%). Multifactorial analysis showed that young age (chi2 = 18.4; P = 0.004), high asexual parasitemia on presentation (chi2 = 19.4; P = 0.0007) and gametocyte positivity on presentation (chi2 = 29.4; P = 0.001) were all significantly associated with the presence of gametocytes on Days 7 and 14 of follow-up. High presentation of asexual parasitemia alone was positively correlated with higher gametocyte densities on both days of follow-up (F4, 297 = 2.0; P = 0.049). Gametocyte incidence rates decreased significantly with age (chi2 = 7.6, P < 0.005). In summary, in this group of chloroquine-treated individuals, gametocyte prevalence and incidence rates decreased with age, while densities remained relatively constant

Dynamics of P. Falciparum Gametocytemia in Symptomatic Patients in an Area of Intense Perennial Transmission in Tanzania.

We investigated the dynamics of Plasmodium falciparum gametocytemia in symptomatic patients attending a local dispensary in the Kilombero district, Tanzania. Consenting individuals aged one and above, with varying asexual and sexual parasitemias were treated appropriately and asked to return weekly for 28 days. Gametocyte prevalence was highest on Day 7 of follow-up in all age groups (overall 30.5%). Multifactorial analysis showed that young age (chi2 = 18.4; P = 0.004), high asexual parasitemia on presentation (chi2 = 19.4; P = 0.0007) and gametocyte positivity on presentation (chi2 = 29.4; P = 0.001) were all significantly associated with the presence of gametocytes on Days 7 and 14 of follow-up. High presentation of asexual parasitemia alone was positively correlated with higher gametocyte densities on both days of follow-up (F4, 297 = 2.0; P = 0.049). Gametocyte incidence rates decreased significantly with age (chi2 = 7.6, P < 0.005). In summary, in this group of chloroquine-treated individuals, gametocyte prevalence and incidence rates decreased with age, while densities remained relatively constant

Evaluation of an Interprofessional Continuing Professional Development Course on Comprehensive Diabetes Care: A Mixed-Methods Approach

RATIONALE: Since there are only 33 endocrinologists within the Department of Defence and over 150 000 beneficiaries with diabetes, most patients with diabetes will be treated by primary care providers (PCPs). Comprehensive diabetes care visits are extensive and the clinical practice guidelines (CPGs) routinely change; thus, providing current evidence-based care is difficult. Most professional development courses aim to update PCPs on CPGs but are often inadequate as they focus on only the PCPs (not the interdisciplinary team) without a plan to implement changes into practice. OBJECTIVE: To evaluate the biannual (twice yearly), 3-day, interprofessional Diabetes Champion Course (DCC) developed by the US Air Force Diabetes Center of Excellence on comprehensive diabetes care. METHODS: A mixed-methods approach was used to evaluate three iterations of the DCC course (Sept 2014-Sept 2015). Quantitatively, pre-course and post-course surveys were used to obtain impact on knowledge, skills, and intention to change clinical practice. Qualitatively, semi-structured phone interviews were conducted with participants to obtain benefits to their clinic related to attending the DCC and barriers to implementation of the CPG process improvement project. RESULTS: Twelve of 19 responding clinics (63%) reported implementing all or part of their original CPG project developed at the DCC, and 17 of 19 clinics (89%) reported improvements associated with attending the DCC. Post-course surveys, from on location participants, revealed significant improvements in knowledge (P \u3c 0.01). Likewise, foot exam skills and ability to demonstrate glucose meters to patients improved. Even with high pre-course confidence, 97% of providers reported acquiring new knowledge about prescribing and titrating insulin. CONCLUSION: The DCC is innovative as it employs a team-based, interprofessional, didactic, and interactive approach that is effective in improving knowledge, skills, and intention to change clinical practice, which should translate to better care for patients with diabetes

Whole-blood transcriptomic signatures induced during immunization by chloroquine prophylaxis and Plasmodium falciparum sporozoites

A highly effective vaccine that confers sterile protection to malaria is urgently needed. Immunization under chemoprophylaxis with sporozoites (CPS) consistently confers high levels of protection in the Controlled Human Malaria infection (CHMI) model. To provide a broad, unbiased assessment of the composition and kinetics of direct ex vivo human immune responses to CPS, we profiled whole-blood transcriptomes by RNA-seq before and during CPS immunization and following CHMI challenge. Differential expression of genes enriched in modules related to T cells, NK cells, protein synthesis, and mitochondrial processes were detected in fully protected individuals four weeks after the first immunization. Non-protected individuals demonstrated transcriptomic changes after the third immunization and the day of treatment, with upregulation of interferon and innate inflammatory genes and downregulation of B-cell signatures. Protected individuals demonstrated more significant interactions between blood transcription modules compared to non-protected individuals several weeks after the second and third immunizations. These data provide insight into the molecular and cellular basis of CPS-induced immune protection from P. falciparum infection

Integrated transcriptomic and proteomic analyses ofP. falciparumgametocytes: molecular insight into sex-specific processes and translational repression

Sexual differentiation of malaria parasites into gametocytes in the vertebrate host and subsequent gamete fertilization in mosquitoes is essential for the spreading of the disease. The molecular processes orchestrating these transitions are far from fully understood. Here, we report the first transcriptome analysis of male and female Plasmodium falciparum gametocytes coupled with a comprehensive proteome analysis. In male gametocytes there is an enrichment of proteins involved in the formation of flagellated gametes; proteins involved in DNA replication, chromatin organization and axoneme formation. On the other hand, female gametocytes are enriched in proteins required for zygote formation and functions after fertilization; protein-, lipid- and energy-metabolism. Integration of transcriptome and proteome data revealed 512 highly expressed maternal transcripts without corresponding protein expression indicating large scale translational repression in P. falciparum female gametocytes for the first time. Despite a high degree of conservation between Plasmodium species, 260 of these 'repressed transcripts' have not been previously described. Moreover, for some of these genes, protein expression is only reported in oocysts and sporozoites indicating that repressed transcripts can be partitioned into short- and long-term storage. Finally, these data sets provide an essential resource for identification of vaccine/drug targets and for further mechanistic studies