Could the Decision of Trial Participation Precede the Informed Consent Process? Evidence From Burkina Faso

Background

Over the last years, the number of clinical trials carried out in low-income countries with poor medical infrastructure and limited access to health care has increased. In these settings, the decision of participating in a clinical study may be influenced by factors related to participants’ vulnerability that limit the efficacy of the informed consent.

Methods

A mixed methods social science study, based on the triangulation of qualitative and quantitative data, was carried out in a socio-economically disadvantaged and semi-urban area of Bobo Dioulasso, Burkina Faso. The study aimed at assessing the relevance of the informed consent procedure on the decision-making process of the parents and/or guardians of potential participants in a pediatric malaria trial.

Results

For most parents (70.4%), the decision of participating had already been taken before undergoing the informed consent process and was based on the information conveyed through the community. Access to free and good quality health care often inspired this decision. In addition, the parents’ willingness to have their child included in the trial made them develop active strategies to achieve this purpose.

Discussion

In a context of socio-economic vulnerability and poor access to free health care, the process of informed consent does not always accomplish its goal of informing people and enabling them to make a free and informed decision. This information role is somehow anticipated by the community and trial participation becomes a strategic action to secure otherwise unavailable health resources leading community members to decide on participation even prior to the informed consent process.     

Association of Ficolin-3 with Severity and Outcome of Chronic Heart Failure

Background

Inflammatory mechanisms involving complement activation has been shown to take part in the pathophysiology of congestive heart failure, but the initiating mechanisms are unknown. We hypothesized that the main initiator molecules of the lectin complement pathway mannose-binding lectin (MBL), ficolin-2 and ficolin-3 were related to disease severity and outcome in chronic heart failure.

Methods and Results

MBL, ficolin-2 and ficolin-3 plasma concentrations were determined in two consecutive cohorts comprising 190 patients from Hungary and 183 patients from Norway as well as controls. Disease severity and clinical parameters were determined at baseline, and all-cause mortality was registered after 5-years follow-up. In univariate analysis a low level of ficolin-3, but not that of MBL or ficolin-2, was significantly associated with advanced heart failure (New York Heart Association Class IV, p<0.001 for both cohorts) and showed inverse correlation with B- type natriuretic peptide (BNP) levels (r = −0.609, p<0.001 and r = −0.467, p<0.001, respectively). In multivariable Cox regression analysis, adjusted for age, gender and BNP, decreased plasma ficolin-3 was a significant predictor of mortality (HR 1.368, 95% CI 1.052–6.210; and HR 1.426, 95% CI 1.013–2.008, respectively). Low ficolin-3 levels were associated with increased complement activation product C3a and correspondingly decreased concentrations of complement factor C3.

Conclusions

This study provides evidence for an association of low ficolin-3 levels with advanced heart failure. Concordant results from two cohorts show that low levels of ficolin-3 are associated with advanced heart failure and outcome. The decrease of ficolin-3 was associated with increased complement activation.     

The role of the liver X receptor in chronic obstructive pulmonary disease

Background

There is a need for novel anti-inflammatory therapies to treat COPD. The liver X receptor (LXR) is a nuclear hormone receptor with anti-inflammatory properties.

Methods

We investigated LXR gene and protein expression levels in alveolar macrophages and whole lung tissue from COPD patients and controls, the effect of LXR activation on the suppression of inflammatory mediators from LPS stimulated COPD alveolar macrophages, and the effect of LXR activation on the induction of genes associated with alternative macrophage polarisation.

Results

The levels of LXR mRNA were significantly increased in whole lung tissue extracts in COPD patients and smokers compared to non-smokers. The expression of LXR protein was significantly increased in small airway epithelium and alveolar epithelium in COPD patients compared to controls. No differences in LXR mRNA and protein levels were observed in alveolar macrophages between patient groups. The LXR agonist GW3965 significantly induced the expression of the LXR dependent genes ABCA1 and ABCG1 in alveolar macrophage cultures. In LPS stimulated alveolar macrophages, GW3965 suppressed the production of CXCL10 and CCL5, whilst stimulating IL-10 production.

Conclusions

GW3965 did not significantly suppress the production of TNFα, IL-1β, or CXCL8. Our major finding is that LXR activation has anti-inflammatory effects on CXC10, CCL5 and IL-10 production from alveolar macrophages.     

Further insights into the isoenzyme composition and activity of glutamate dehydrogenase in Arabidopsis thaliana

Following the discovery that in Arabidopsis, a third isoenzyme of NADH-dependent glutamate dehydrogenase (GDH) is expressed in the mitochondria of the root companion cells, we have re-examined the GDH isoenzyme composition. By analyzing the NADH-GDH isoenzyme composition of single, double and triple mutants deficient in the expression of the three genes encoding the enzyme, we have found that the α, β and γ polypeptides that comprise the enzyme can be assembled into a complex combination of heterohexamers in roots. Moreover, we observed that when one or two of the three root isoenzymes were missing from the mutants, the remaining isoenzymes compensated for this deficiency. The significance of such complexity is discussed in relation to the metabolic and signaling function of the NADH-GDH enzyme. Although it has been shown that a fourth gene encoding a NADPH-dependent enzyme is present in Arabidopsis, we were not able to detect corresponding enzyme activity, even in the triple mutant totally lacking NADH-GDH activity.     

Distinct Binding and Immunogenic Properties of the Gonococcal Homologue of Meningococcal Factor H Binding Protein

Neisseria meningitidis is a leading cause of sepsis and meningitis. The bacterium recruits factor H (fH), a negative regulator of the complement system, to its surface via fH binding protein (fHbp), providing a mechanism to avoid complement-mediated killing. fHbp is an important antigen that elicits protective immunity against the meningococcus and has been divided into three different variant groups, V1, V2 and V3, or families A and B. However, immunisation with fHbp V1 does not result in cross-protection against V2 and V3 and vice versa. Furthermore, high affinity binding of fH could impair immune responses against fHbp. Here, we investigate a homologue of fHbp in Neisseria gonorrhoeae, designated as Gonococcal homologue of fHbp (Ghfp) which we show is a promising vaccine candidate for N. meningitidis. We demonstrate that Gfhp is not expressed on the surface of the gonococcus and, despite its high level of identity with fHbp, does not bind fH. Substitution of only two amino acids in Ghfp is sufficient to confer fH binding, while the corresponding residues in V3 fHbp are essential for high affinity fH binding. Furthermore, immune responses against Ghfp recognise V1, V2 and V3 fHbps expressed by a range of clinical isolates, and have serum bactericidal activity against N. meningitidis expressing fHbps from all variant groups.     

Conformational flexibility of the leucine binding protein examined by protein domain coarse-grained molecular dynamics

Periplasmic binding proteins are the initial receptors for the transport of various substrates over the inner membrane of gram-negative bacteria. The binding proteins are composed of two domains, and the substrate is entrapped between these domains. For several of the binding proteins it has been established that a closed-up conformation exists even without substrate present, suggesting a highly flexible apo-structure which would compete with the ligand-bound protein for the transporter interaction. For the leucine binding protein (LBP), structures of both open and closed conformations are known, but no closed-up structure without substrate has been reported. Here we present molecular dynamics simulations exploring the conformational flexibility of LBP. Coarse grained models based on the MARTINI force field are used to access the microsecond timescale. We show that a standard MARTINI model cannot maintain the structural stability of the protein whereas the ELNEDIN extension to MARTINI enables simulations showing a stable protein structure and nanosecond dynamics comparable to atomistic simulations, but does not allow the simulation of conformational flexibility. A modification to the MARTINI-ELNEDIN setup, referred to as domELNEDIN, is therefore presented. The domELNEDIN setup allows the protein domains to move independently and thus allows for the simulation of conformational changes. Microsecond domELNEDIN simulations starting from either the open or the closed conformations consistently show that also for LBP, the apo-structure is flexible and can exist in a closed form.

Unexpected island effects at an extreme: reduced Y chromosome and mitochondrial DNA diversity in Nias

The amount of genetic diversity in a population is determined by demographic and selection events in its history. Human populations which exhibit greatly reduced overall genetic diversity, presumably resulting from severe bottlenecks or founder events, are particularly interesting, not least because of their potential to serve as valuable resources for health studies. Here, we present an unexpected case, the human population of Nias Island in Indonesia, that exhibits severely reduced Y chromosome (non-recombining portion of the Y chromosome [NRY]) and to a lesser extent also reduced mitochondrial DNA (mtDNA) diversity as compared with most other populations from the Asia/Oceania region. Our genetic data, collected from more than 400 individuals from across the island, suggest a strong previously undetected bottleneck or founder event in the human population history of Nias, more pronounced for males than for females, followed by subsequent genetic isolation. Our findings are unexpected given the island's geographic proximity to the genetically highly diverse Southeast Asian world, as well as our previous knowledge about the human history of Nias. Furthermore, all NRY and virtually all mtDNA haplogroups observed in Nias can be attributed to the Austronesian expansion, in line with linguistic data, and in contrast with archaeological evidence for a pre-Austronesian occupation of Nias that, as we show here, left no significant genetic footprints in the contemporary population. Our work underlines the importance of human genetic diversity studies not only for a better understanding of human population history but also because of the potential relevance for genetic disease-mapping studies.     

Accelerated aging phenotype in mice with conditional deficiency for mitochondrial superoxide dismutase in the connective tissue

The free radical theory of aging postulates that the production of mitochondrial reactive oxygen species is the major determinant of aging and lifespan. Its role in aging of the connective tissue has not yet been established, even though the incidence of aging-related disorders in connective tissue-rich organs is high, causing major disability in the elderly. We have now addressed this question experimentally by creating mice with conditional deficiency of the mitochondrial manganese superoxide dismutase in fibroblasts and other mesenchyme-derived cells of connective tissues in all organs. Here, we have shown for the first time that the connective tissue-specific lack of superoxide anion detoxification in the mitochondria results in reduced lifespan and premature onset of aging-related phenotypes such as weight loss, skin atrophy, kyphosis (curvature of the spine), osteoporosis and muscle degeneration in mutant mice. Increase in p16(INK4a) , a robust in vivo marker for fibroblast aging, may contribute to the observed phenotype. This novel model is particularly suited to decipher the underlying mechanisms and to develop hopefully novel connective tissue-specific anti-aging strategies.     

High affinity nanobodies against the Trypanosome brucei VSG are potent trypanolytic agents that block endocytosis

The African trypanosome Trypanosoma brucei, which persists within the bloodstream of the mammalian host, has evolved potent mechanisms for immune evasion. Specifically, antigenic variation of the variant-specific surface glycoprotein (VSG) and a highly active endocytosis and recycling of the surface coat efficiently delay killing mediated by anti-VSG antibodies. Consequently, conventional VSG-specific intact immunoglobulins are non-trypanocidal in the absence of complement. In sharp contrast, monovalent antigen-binding fragments, including 15 kDa nanobodies (Nb) derived from camelid heavy-chain antibodies (HCAbs) recognizing variant-specific VSG epitopes, efficiently lyse trypanosomes both in vitro and in vivo. This Nb-mediated lysis is preceded by very rapid immobilisation of the parasites, massive enlargement of the flagellar pocket and major blockade of endocytosis. This is accompanied by severe metabolic perturbations reflected by reduced intracellular ATP-levels and loss of mitochondrial membrane potential, culminating in cell death. Modification of anti-VSG Nbs through site-directed mutagenesis and by reconstitution into HCAbs, combined with unveiling of trypanolytic activity from intact immunoglobulins by papain proteolysis, demonstrates that the trypanolytic activity of Nbs and Fabs requires low molecular weight, monovalency and high affinity. We propose that the generation of low molecular weight VSG-specific trypanolytic nanobodies that impede endocytosis offers a new opportunity for developing novel trypanosomiasis therapeutics. In addition, these data suggest that the antigen-binding domain of an anti-microbial antibody harbours biological functionality that is latent in the intact immunoglobulin and is revealed only upon release of the antigen-binding fragment.