Shigella flexneri phagosomal escape is independent of invasion

Infections with Salmonella enterica serovar Typhimurium and Shigella flexneri result in mucosal inflammation in response to epithelial cell invasion and macrophage cytotoxicity. These processes are mediated by type III secretion systems encoded in homologous virulence loci in the two species, namely, Salmonella pathogenicity island 1 (SPI-1), carried in the genome, and the Shigella entry region (SER), carried in a large virulence plasmid. Here we show that SPI-1 can functionally complement a deletion of SER in S. flexneri, restoring invasion of epithelial cells, macrophage cytotoxicity, and phagosomal escape. Furthermore, S. flexneri phagosomal escape requires the SER and another gene(s) carried on the large virulence plasmid. We demonstrate that the processes of invasion and phagosomal escape can be uncoupled in S. flexneri.     

Identification of hepatitis A virus mimotopes by phage display, antigenicity and immunogenicity

A phage-displayed peptide approach was used to identify ligands mimicking antigenic determinants of hepatitis A virus (HAV) for the first time. Bacteriophages displaying HAV mimotopes were isolated from a phage-display peptide library by affinity selection on serum antibodies from hepatitis A patients. Selected phage-peptides were screened for reactivity with sera from HAV infected patients and healthy controls. Four cloned peptides with different sequences were identified as mimotopes of HAV; three of them showed similarity in their amino acid sequences with at least one of the VP3 and VP1 antigenic proteins of HAV. One clone was recognised by 92% of the positive sera. The phagotopes competed effectively with HAV for absorption of anti-HAV-specific antibodies in human sera, as determined by ELISA. The four phage clones induced neutralising anti-HAV antibodies in immunised mice. These results demonstrate the potential of this method to elucidate the disease related epitopes of HAV and to use these mimotopes in diagnostic applications or in the development of a mimotope-based hepatitis A vaccine without the necessity of manipulation of the virus.     

Dependence of macrophage phagocytic efficacy on antibody concentration

Macrophages ingest the fungus Cryptococcus neoformans only in the presence of opsonins, and this provides a remarkably clean system for the detailed analysis of phagocytosis. This system is also unusual in that antibody-mediated phagocytosis involves ingestion through both Fc and complement receptors in the absence of complement. Mathematical modeling was used to analyze and explain the experimental data that the macrophage phagocytic index increased with increasing doses of antibody despite saturating concentrations and declined at high concentrations. A model was developed that explains the increase in phagocytic index with increasing antibody doses, differentiates among the contributions from Fc and complement receptors, and provides a tool for estimating antibody concentrations that optimize efficacy of phagocytosis. Experimental results and model calculations revealed that blocking of Fc receptors by excess antibody caused a reduction in phagocytic index but increased phagocytosis through complement receptors rapidly compensated for this effect. At high antibody concentrations, a further reduction in phagocytic index was caused by interference with complement receptor ingestion as a consequence of saturation of the fungal capsule. The ability of our model to predict the antibody dose dependence of the macrophage phagocytic efficacy for C. neoformans strongly suggest that the major variables that determine the efficacy of this process have been identified. The model predicts that the affinity constant of the opsonic antibody for the Fc receptor and the association-dissociation constant of antibody from the microbial antigen are critical parameters determining the efficacy of phagocytosis.     

Comparative Evaluation of Profiles of Antibodies to Mycobacterial Capsular Polysaccharides in Tuberculosis Patients and Controls Stratified by HIV Status

Despite the complexity of tuberculosis (TB) serology, antibodies (Abs) remain attractive biomarkers for TB. Recent evidence of a mycobacterial capsule that consists mainly of the polysaccharides arabinomannan (AM) and glucan provides new options for serologic targets. For this study, Ab responses to AM and glucan for 47 U.S. TB patients (33 HIV negative [HIV⁻], 14 HIV positive [HIV⁺]), 42 healthy controls, and 38 asymptomatic HIV⁺ controls were evaluated by enzyme-linked immunosorbent assays (ELISAs). The results were compared with Ab responses to the mycobacterial glycolipid cell wall antigen lipoarabinomannan (LAM) and to the proteins malate synthase (MS) and MPT51. We found that the main immunoglobulin (Ig) isotype response to polysaccharides was IgG, predominantly of subclass IgG2. IgG responses to AM were significantly higher for HIV⁻ and HIV⁺ TB cases than for controls (P, <0.0001 and <0.01, respectively); significantly higher for HIV⁻ than for HIV⁺ TB cases (P, <0.01); and significantly higher in sputum smear-positive than smear-negative patients in both HIV⁻ and HIV⁺ cases (P, 0.01 and 0.02, respectively). In both TB groups, titers of Ab to glucan were significantly lower than titers of Ab to AM (P, <0.0001). IgG responses to AM and MS or to AM and MPT51 did not correlate with each other in HIV⁻ TB patients, while they correlated significantly in HIV⁺ TB patients (P, 0.01 and 0.05, respectively). We conclude that Ab responses to AM could contribute to the serodiagnosis of TB, especially for HIV⁻ TB patients. This study also provides new and important insights into the differences in the profiles of Abs to mycobacterial antigens between HIV⁻ and HIV⁺ TB patients.     

Functional and prognostic significance of the genomic amplification of frizzled 6 (FZD6) in breast cancer

Frizzled receptors mediate Wnt ligand signalling, which is crucially involved in regulating tissue development and differentiation, and is often deregulated in cancer. In this study, we found that the gene encoding the Wnt receptor frizzled 6 (FZD6) is frequently amplified in breast cancer, with an increased incidence in the triple‐negative breast cancer (TNBC) subtype. Ablation of FZD6 expression in mammary cancer cell lines: (1) inhibited motility and invasion; (2) induced a more symmetrical shape of organoid three‐dimensional cultures; and (3) inhibited bone and liver metastasis in vivo. Mechanistically, FZD6 signalling is required for the assembly of the fibronectin matrix, interfering with the organization of the actin cytoskeleton. Ectopic delivery of fibronectin in FZD6‐depleted, triple‐negative MDA‐MB‐231 cells rearranged the actin cytoskeleton and restored epidermal growth factor‐mediated invasion. In patients with localized, lymph node‐negative (early) breast cancer, positivity of tumour cells for FZD6 protein identified patients with reduced distant relapse‐free survival. Multivariate analysis indicated an independent prognostic significance of FZD6 expression in TNBC tumours, predicting distant, but not local, relapse. We conclude that the FZD6–fibronectin actin axis identified in our study could be exploited for drug development in highly metastatic forms of breast cancer, such as TNBC. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Physical fitness factors to predict male Olympic wrestling performance

To determine differences in maximal strength and muscle power output of the arm and leg extensor muscles, peak and mean power during a modified standing crank-arm Wingate test, running speed, muscle extensibility, and anthropometric markers between elite and amateurs wrestlers according to the weight classes system; 92 male wrestlers were assigned into 6 groups according to their body mass (light, middle and heavy weight) and their competitive level (elite and amateur): Light Weight (body mass ranged between 55 and 68 kg) in elite (LW_E, n = 18) and amateur (LW_A, n = 15) level; Middle Weight (body mass ranged between 68 and 84 kg) in elite (MW_E, n = 18) and amateur (MW_A, n = 19) level; and Heavy Weight (body mass ranged between 84 and 100 kg) in elite (HW_E, n = 10) and amateur (HW_A, n = 12) level. Elite wrestlers were older (8–12%), had more training experience (25–37%), fat-free mass (3–5%), maximal strength in absolute and relative terms (8–25%), muscle power (14–30%), mean and peak power during crank-arm Wingate testing in absolute and relative terms (13–22%), jumping height (8–17%) as well as grip (6–19%) and back strength (7–20%) compared to amateur wrestlers. However, no differences were observed between elite and amateur groups in height, body mass index, percentage of body fat, hamstring extensibility and running speed. The present results suggest that the higher absolute and relative values of maximal strength, muscle power, and anaerobic metabolism, explained in part by the differences in lean mass and neural activation patterns, will give elite wrestlers a clear advantage during the most frequently used techniques in Olympic wrestling.     

Creatine supplementation attenuates hemodynamic and arterial stiffness responses following an acute bout of isokinetic exercise

Arterial stiffness and hemodynamics may be increased following a bout of resistance exercise. Oral creatine supplementation (Cr) may attenuate cardiovascular responses after exercise via improved anaerobic metabolism. This study was aimed to determine the effect of Cr on hemodynamic and arterial stiffness responses after acute isokinetic exercise. Sixteen healthy males (22.6 ± 0.6 year) were randomly assigned to either placebo (Pl, n = 8) or Cr (n = 8) (2 × 5 g/day) for 3 weeks. Brachial systolic blood pressure (SBP), heart rate (HR), brachial-ankle pulse wave velocity (baPWV), and leg PWV were measured in the supine position at rest before and after the interventions. After the supplementation period, parameters were also measured 5 min (PE5) and 15 min (PE15) after two sets of leg isokinetic exercise. There was no difference between the groups in resting measurements before and after the supplementation. Compared with the Pl group, the Cr group had attenuated (P < 0.05) increases in SBP at PE5 (Pl 14.0 ± 2.5, Cr 5.6 ± 2.3 mmHg), HR at both P5 (Pl 28 ± 4 vs. Cr 16 ± 2 beats/min) and PE15 (Pl 21 ± 3, Cr 11 ± 2 beats/min) and rate pressure product at P5 (Pl 45.8 ± 6.4, Cr 24.8 ± 2.2) and P15 (Pl 34.2 ± 5.0, Cr 15.9 ± 6.0). Compared with the Pl group, the Cr group had suppressed increases in baPWV at PE5 (Pl 1.5 ± 0.4, Cr −0.1 ± 0.4 m/s) and PE15 (Pl 1.1 ± 0.2, Cr −0.3 ± 0.3 m/s) and returned SBP to pre-exercise values at PE15 (Pl 10.6 ± 2.8, Cr 2.1 ± 2.6 mmHg). PWV in the exercised leg decreased at PE5 in both groups. These findings suggest that Cr supplementation attenuates the hemodynamic and baPWV responses after acute isokinetic exercise.     

Prognostic impact of chromosomal translocations in myelodysplastic syndromes and chronic myelomonocytic leukemia patients. A study by the spanish group of myelodysplastic syndromes

Chromosomal translocations are rare in the myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML). With the exception of t(3q), translocations are not explicitly considered in the cytogenetic classification of the IPSS‐R and their impact on disease progression and patient survival is unknown. The present study was aimed at determining the prognostic impact of translocations in the context of the cytogenetic classification of the IPSS‐R. We evaluated 1,653 patients from the Spanish Registry of MDS diagnosed with MDS or CMML and an abnormal karyotype by conventional cytogenetic analysis. Translocations were identified in 168 patients (T group). Compared with the 1,485 patients with abnormal karyotype without translocations (non‐T group), the T group had a larger proportion of patients with refractory anemia with excess of blasts and higher scores in both the cytogenetic and global IPSS‐R. Translocations were associated with a significantly shorter survival and higher incidence of transformation into AML at univariate analysis but both features disapeared after multivariate adjustment for the IPSS‐R cytogenetic category. Patients with single or double translocations other than t(3q) had an outcome similar to those in the non‐T group in the intermediate cytogenetic risk category of the IPSS‐R. In conclusion, the presence of translocations identifies a subgroup of MDS/CMML patients with a more aggressive clinical presentation that can be explained by a higher incidence of complex karyotypes. Single or double translocations other than t(3q) should be explicitly considered into the intermediate risk category of cytogenetic IPSS‐R classification. © 2015 Wiley Periodicals, Inc.