Temporal and Spatial Analysis of Clinical and Molecular Parameters in Dextran Sodium Sulfate Induced Colitis

Background

Inflammatory bowel diseases (IBD), including mainly ulcerative colitis (UC) and Crohn''s disease (CD), are inflammatory disorders of the gastrointestinal tract caused by an interplay of genetic and environmental factors. Murine colitis model induced by Dextran Sulfate Sodium (DSS) is an animal model of IBD that is commonly used to address the pathogenesis of IBD as well as to test efficacy of therapies. In this study we systematically analyzed clinical parameters, histological changes, intestinal barrier properties and cytokine profile during the colitic and recovery phase.

Methods

C57BL/6 mice were administered with 3.5% of DSS in drinking water for various times. Clinical and histological features were determined using standard criteria. Myeloperoxidase (MPO) activity, transepithelial permeability and proinflammatory mediators were determined in whole colon or proximal and distal parts of colon.

Results

As expected after administration of DSS, mice manifest loss of body weight, shortening of colon length and bloody feces. Histological manifestations included shortening and loss of crypts, infiltration of lymphocytes and neutrophil, symptoms attenuated after DSS withdrawal. The MPO value, as inflammation indicator, also increases significantly at all periods of DSS treatment, and even after DSS withdrawal, it still held at very high levels. Trans-mucosal permeability increased during DSS treatment, but recovered to almost control level after DSS withdrawal. The production of proinflammatory mediators by colonic mucosa were enhanced during DSS treatment, and then recovered to pre-treated level after DSS withdrawal. Finally, enhanced expression of proinflammatory mediators also revealed a different profile feature in proximal and distal parts of the colon.

Conclusion

Experimental colitis induced by DSS is a good animal model to study the mechanisms underlying the pathogenesis and intervention against IBD, especially UC.     

Interaction of 1,3,4-thiadiazolium mesoionic derivatives with mitochondrial membrane and scavenging activity: Involvement of their effects on mitochondrial energy-linked functions

The aim of this work was to assess the significance of the interaction of the 1,3,4-thiadiazolium derivatives MI-J, MI-4F and MI-2,4diF with mitochondrial membrane and their effects on energy-linked functions. Mitochondrial swelling in the absence of substrate was inhibited by all derivatives; however, the fluorine derivatives were most effective. MI-4F decreased swelling by ~32% even at the lowest concentration (65 nmol mg(-1) protein), reaching ~67% at the concentration of 130 nmol mg(-1) protein. Swelling of mitochondria in the presence of oxidizable substrates was also strongly decreased by all derivatives. This effect was more pronounced when using glutamate plus malate, and also fluorine derivatives, which promoted complete inhibition at all concentrations (6.5-130 nmol mg(-1) protein). Swelling occurred when succinate was the substrate in the presence of MI-J (6.5-65 nmol mg(-1) protein); however, the shrinkage rate was strongly decreased. MI-4F and MI-2,4diF also inhibited swelling, with total inhibition occurring at a concentration of 65 nmol mg(-1) protein. Lipid peroxidation induced by Fe(3+)-ADP/2-oxoglutarate in isolated mitochondria was inhibited time- and dose-dependently by the derivatives, reaching complete inhibition at the highest concentration (80 nmol mg(-1) protein). However, when lipid peroxidation was initiated by peroxyl radicals generated from AAPH, the inhibition was less intense, reaching ~50%, ~40% and ~58% with MI-J, MI-4F and MI-2,4diF (80 nmol mg(-1) protein), respectively. The mesoionic compounds also showed superoxide radical scavenging ability of ~22%, ~32% and ~40% (80 nmol mg(-1) protein), respectively. Fluorescence polarization experiments showed that the derivatives are able to enter the bilayer, decreasing its fluidity in the hydrophobic DMPC membrane region and ordering the fluid phase. Our results suggest that MI-J, MI-4F and MI-2,4diF interact significantly, albeit in different modes, with mitochondrial membrane, and that fluorine derivatives seem to alter the membrane's properties more markedly.     

Impact of internal RNA on aggregation and electrokinetics of viruses: comparison between MS2 phage and corresponding virus-like particles

We compare for the first time the electrokinetic and aggregation properties of MS2 phage (pH 2.5 to 7, 1 to 100 mM NaNO(3) electrolyte concentration) with those of the corresponding virus-like particles (VLPs), which lack entirely the inner viral RNA component. In line with our previous work (J. Langlet, F. Gaboriaud, C. Gantzer, and J. F. L. Duval, Biophys. J. 94:3293-3312, 2008), it is found that modifying the content of RNA within the virus leads to very distinct electrohydrodynamic and aggregation profiles for MS2 and MS2 VLPs. Under the given pH and concentration conditions, MS2 VLPs exhibit electrophoretic mobility larger in magnitude than that of MS2, and both have similar isoelectric point (IEP) values (～4). The electrokinetic results reflect a greater permeability of MS2 VLPs to electroosmotic flow, developed within/around these soft particles during their migration under the action of the applied electrical field. Results also support the presence of some remaining negatively charged component within the VLPs. In addition, MS2 phage systematically forms aggregates at pH values below the IEP, regardless of the magnitude of the solution ionic strength, whereas MS2 VLPs aggregate under the strict condition where the pH is relatively equal to the IEP at sufficiently low salt concentrations (<10 mM). It is argued that the stability of VLPs against aggregation and the differences between electrokinetics of MS2 and corresponding VLPs conform to recently developed formalisms for the stability and electrohydrodynamics of soft multilayered particles. The differences between the surface properties of these two kinds of particles reported here suggest that VLPs may not be appropriate for predicting the behavior of pathogenic viruses in aqueous media.     

Human immunodeficiency virus type 1 infection is associated with increased NK cell polyfunctionality and higher levels of KIR3DL1+ NK cells in ugandans carrying the HLA-B Bw4 motif

Natural killer (NK) cells are important innate effector cells controlled by an array of activating and inhibitory receptors. Some alleles of the inhibitory killer-cell immunoglobulin-like receptor KIR3DL1 in combination with its HLA class I ligand Bw4 have been genetically associated with slower HIV-1 disease progression. Here, we observed that the presence of HLA-B Bw4 was associated with elevated frequencies of KIR3DL1(+) CD56(dim) NK cells in chronically HIV-1-infected individuals from the rural district of Kayunga, Uganda. In contrast, levels of KIR2DL1(+) CD56(dim) NK cells were decreased, and levels of KIR2DL3(+) CD56(dim) NK cells were unchanged in infected subjects carrying their respective HLA-C ligands. Furthermore, the size of the KIR3DL1(+) NK cell subset correlated directly with viral load, and this effect occurred only in HLA-B Bw4(+) patients, suggesting that these cells expand in response to viral replication but may have relatively poor antiviral capacity. In contrast, no association with viral load was present for KIR2DL1(+) and KIR2DL3(+) NK cells. Interestingly, chronic HIV-1 infection was associated with an increased polyfunctional response in the NK cell compartment, and, upon further investigation, KIR3DL1(+) CD56(dim) NK cells exhibited a significantly increased functional response in the patients carrying HLA-B Bw4. These results indicate that chronic HIV-1 infection is associated with increased NK cell polyfunctionality and elevated levels of KIR3DL1(+) NK cells in Ugandans carrying the HLA-B Bw4 motif.     

Comparative analysis of different biofactories for the production of a major diabetes autoantigen

The 65-kDa isoform of human glutamic acid decarboxylase (hGAD65) is a major diabetes autoantigen that can be used for the diagnosis and (more recently) the treatment of autoimmune diabetes. We previously reported that a catalytically-inactive version (hGAD65mut) accumulated to tenfold higher levels than its active counterpart in transgenic tobacco plants, providing a safe and less expensive source of the protein compared to mammalian production platforms. Here we show that hGAD65mut is also produced at higher levels than hGAD65 by transient expression in Nicotiana benthamiana (using either the pK7WG2 or MagnICON vectors), in insect cells using baculovirus vectors, and in bacterial cells using an inducible-expression system, although the latter system is unsuitable because hGAD65mut accumulates within inclusion bodies. The most productive of these platforms was the MagnICON system, which achieved yields of 78.8 μg/g fresh leaf weight (FLW) but this was substantially less than the best-performing elite transgenic tobacco plants, which reached 114.3 μg/g FLW after six generations of self-crossing. The transgenic system was found to be the most productive and cost-effective although the breeding process took 3 years to complete. The MagnICON system was less productive overall, but generated large amounts of protein in a few days. Both plant-based systems were therefore advantageous over the baculovirus-based production platform in our hands.     

HIV Prevalence and Incidence in a Cohort of Women at Higher Risk for HIV Acquisition in Chókwè, Southern Mozambique

Background

Reliable HIV incidence estimates for Mozambique are limited. We conducted a prospective HIV incidence study as part of a clinical research site development initiative in Chókwè district, Gaza Province, southern Mozambique.

Methods

Between June 2010 and October 2012, we recruited women at sites where women at higher risk of HIV infection would likely be found. We enrolled and tested 1,429 sexually active women in the screening phase and 479 uninfected women in the prospective phase. Participants were scheduled for 12+ months follow-up, when they underwent face-to-face interviews, HIV counseling and testing, and pregnancy testing. We observed a total of 373.1 woman-years (WY) of follow-up, with mean (median) of 9.4 (9.7) women-months per participant.

Results

The prevalence of HIV was 29.4% (95% confidence interval [CI]: 27.0–31.8%). In multivariable logistic regression analysis, factors that remained significantly associated with prevalent HIV were: older age (OR: 0.6; 95% CI: 0.4–0.7), lower educational level (OR: 0.4; 95% CI: 0.3–0.7), and using hormonal contraception (OR: 0.6; 95% CI: 0.4–0.7) or condoms (OR: 0.5; 95% CI: 0.3–0.7). We observed an HIV incidence rate of 4.6 per 100 WY (95% CI: 2.7, 7.3). The HIV incidence was 4.8 per 100 WY (95% CI: 2.5, 8.3) in women aged 18–24 years, 4.5 per 100 WY (95% CI: 1.2, 11.4) in women aged 25–29 years and 3.2 per 100 WY (95% CI: 0.1, 18.0) in the 30–35 years stratum. None of the demographic factors or time-varying behavioral factors examined was significantly associated with incident HIV infection in bivariable analysis at p≤0.10.

Conclusions

We found a high HIV incidence among sexually active young women in Chókwè, Mozambique. HIV prevention programs should be strengthened in the area, with more comprehensive reproductive health services, regular HIV testing, condom promotion, and messaging about multiple sexual partners.     

Effect of pertussis toxin on water metabolism in the rat

Pertussis toxin administered to rats resulted in a polyuric state that was due to enhanced renal water excretion. Pertussis toxin also induced a defect in renal water conservation. These abnormalities in renal water excretion could not be attributed to polydipsia, impaired synthesis and/or release of arginine vasopressin or renal tubular dysfunction with solute diuresis. No evidence of pertussis toxin-induced renal tubular damage was present. These results indicate that pertussis toxin induces nephrogenic diabetes insipidus and this defect occurs at the level of the renal collecting tubule.