Regulation of the High Affinity IgE Receptor (FcεRI) in Human Neutrophils: Role of Seasonal Allergen Exposure and Th-2 Cytokines

The high affinity IgE receptor, FcεRI, plays a key role in the immunological pathways involved in allergic asthma. Previously we have demonstrated that human neutrophils isolated from allergic asthmatics express a functional FcεRI, and therefore it was of importance to examine the factors regulating its expression. In this study, we found that neutrophils from allergic asthmatics showed increased expression of FcεRI-α chain surface protein, total protein and mRNA compared with those from allergic non asthmatics and healthy donors (p<0.001). Interestingly, in neutrophils isolated from allergic asthmatics, FcεRI-α chain surface protein and mRNA expression were significantly greater during the pollen season than outside the pollen season (n = 9, P = 0.001), an effect which was not observed either in the allergic non asthmatic group or the healthy donors (p>0.05). Allergen exposure did not affect other surface markers of neutrophils such as CD16/FcγRIII or IL-17R. In contrast to stimulation with IgE, neutrophils incubated with TH2 cytokines IL-9, GM-CSF, and IL-4, showed enhanced FcεRI-α chain surface expression. In conclusion, these results suggest that enhanced FcεRI expression in human neutrophils from allergic asthmatics during the pollen season can make them more susceptible to the biological effects of IgE, providing a possible new mechanism by which neutrophils contribute to allergic asthma

Detection of multiple strains of Mycobacterium tuberculosis using MIRU-VNTR in patients with pulmonary tuberculosis in Kampala, Uganda

<p>Abstract</p> <p>Background</p> <p>Many studies using DNA fingerprinting to differentiate <it>Mycobacterium tuberculosis </it>(MTB) strains reveal single strains in cultures, suggesting that most disease is caused by infection with a single strain. However, recent studies using molecular epidemiological tools that amplify multiple targets have demonstrated simultaneous infection with multiple strains of MTB. We aimed to determine the prevalence of MTB multiple strain infections in Kampala, and the impact of these infections on clinical presentation of tuberculosis (TB) and response to treatment.</p> <p>Methods</p> <p>A total of 113 consecutive smear and culture positive patients who previously enrolled in a house-hold contact study were included in this study. To determine whether infection with multiple MTB strains has a clinical impact on the initial presentation of patients, retrospective patient data (baseline clinical, radiological and drug susceptibility profiles) was obtained. To determine presence of infections with multiple MTB strains, MIRU-VNTR (Mycobacterial Interspersed Repetitive Unit-Variable-Number Tandem Repeats) -PCR was performed on genomic DNA extracted from MTB cultures of smear positive sputum samples at baseline, second and fifth months.</p> <p>Results</p> <p>Of 113 patients, eight (7.1%) had infection with multiple MTB strains, coupled with a high rate of HIV infection (37.5% versus 12.6%, <it>p </it>= 0.049). The remaining patients (105) were infected with single MTB strains. The proportions of patients with MTB smear positive cultures after two and five months of treatment were similar. There was no difference between the two groups for other variables.</p> <p>Conclusion</p> <p>Infection with multiple MTB strains occurs among patients with first episode of pulmonary tuberculosis in Kampala, in a setting with high TB incidence. Infection with multiple MTB strains had little impact on the clinical course for individual patients. This is the first MIRU-VNTR-based study from in an East African country.</p

Genetic variants affecting responses of plasma lipids and cholesterol kinetics to dietary cholesterol versus plant sterol consumption in a founder population

Lowering plasma LDL-cholesterol (LDL-C) and increasing HDL-cholesterol (HDL-C) concentrations remain the primary targets in cardiovascular disease (CVD) risk reduction. Dietary cholesterol and plant sterols differentially modulate cholesterol kinetics and lipoprotein distribution. Inter-individual variations in the rates of cholesterol absorption and synthesis, and the reciprocal interaction between them affect the responses to dietary sterols. Genetic heterogeneity profoundly influences such responsiveness. However, limited research exists on the genetic determinants of dietary cholesterol versus plant sterols responsiveness in healthy individuals, especially in a founder population, such as the Hutterites in Manitoba of European descent who practice a communal living system. Our study examined the differential effects of dietary cholesterol versus plant sterol consumption on plasma lipoprotein levels, subclasses, and cholesterol kinetics and assessed how genetic variants influenced these responses. A double-blind, randomized, crossover study with three interventional periods of 4 wk duration each was conducted. Healthy Hutterite individuals (n=49) from Manitoba consumed daily either 2 g of plant sterols or 600 mg of cholesterol incorporated into milkshakes, or a placebo during each period. Plasma lipid profile and lipoprotein subclass distribution were determined. Cholesterol absorption and synthesis were assessed by stable isotopic tracer techniques. Participants were genotyped for 38 candidate single nucleotide polymorphisms across 25 genes involved in cholesterol and lipoprotein metabolism. Dietary cholesterol consumption increased plasma TC, HDL-C concentrations and large HDL subclasses with no changes in cholesterol absorption or synthesis. In contrast, plant sterol intake failed to reduce LDL-C concentrations, with a modest reduction in cholesterol absorption, and did not affect lipoprotein subclasses. However, a large non-compensatory increase in cholesterol synthesis was observed due to plant sterol consumption. Gender and common genetic variants affected plasma HDL-C and HDL subclass distribution to dietary cholesterol and plant sterol consumption. ACAT2 and NPC1L1 gene variants affected plasma campesterol and β-sitosterol concentrations respectively, to plant sterol intake by modifying cholesterol absorption. In summary, our results demonstrate that dietary cholesterol and plant sterol intake differentially modulate cholesterol trafficking in a manner dependent on common genetic variants and gender in healthy individuals. Such knowledge facilitates the development of effective cholesterol lowering strategies for the alleviation of CVD burden.October 201

Elucidating emergence and transmission of multidrug-resistant tuberculosis in treatment experienced patients by whole genome sequencing.

BACKGROUND: Understanding the emergence and spread of multidrug-resistant tuberculosis (MDR-TB) is crucial for its control. MDR-TB in previously treated patients is generally attributed to the selection of drug resistant mutants during inadequate therapy rather than transmission of a resistant strain. Traditional genotyping methods are not sufficient to distinguish strains in populations with a high burden of tuberculosis and it has previously been difficult to assess the degree of transmission in these settings. We have used whole genome analysis to investigate M. tuberculosis strains isolated from treatment experienced patients with MDR-TB in Uganda over a period of four years. METHODS AND FINDINGS: We used high throughput genome sequencing technology to investigate small polymorphisms and large deletions in 51 Mycobacterium tuberculosis samples from 41 treatment-experienced TB patients attending a TB referral and treatment clinic in Kampala. This was a convenience sample representing 69% of MDR-TB cases identified over the four year period. Low polymorphism was observed in longitudinal samples from individual patients (2-15 SNPs). Clusters of samples with less than 50 SNPs variation were examined. Three clusters comprising a total of 8 patients were found with almost identical genetic profiles, including mutations predictive for resistance to rifampicin and isoniazid, suggesting transmission of MDR-TB. Two patients with previous drug susceptible disease were found to have acquired MDR strains, one of which shared its genotype with an isolate from another patient in the cohort. CONCLUSIONS: Whole genome sequence analysis identified MDR-TB strains that were shared by more than one patient. The transmission of multidrug-resistant disease in this cohort of retreatment patients emphasises the importance of early detection and need for infection control. Consideration should be given to rapid testing for drug resistance in patients undergoing treatment to monitor the emergence of resistance and permit early intervention to avoid onward transmission