High frequency of CD4+ CXCR5+ TFH cells in patients with immune-active chronic hepatitis B

Background

T follicular helper (TFH) cells are a special subpopulation of T helper cells and can regulate humoral immune responses. This study examined whether the frequency of CD4⁺CXCR5⁺ TFH cells could be associated with active immunity in chronic hepatitis B (CHB) patients.

Methodology and Findings

The frequencies of peripheral blood CD4⁺CXCR5⁺ TFH cells, inducible T cell costimulator (ICOS), and/or programmed death 1 (PD-1) positive CD4⁺CXCR5⁺ TFH cells in immune-active (IA), immune-tolerant (IT) CHB, and healthy controls (HC) were characterized by flow cytometry analysis. The effect of adevofir dipivoxil treatment on the frequency of CD4⁺CXCR5⁺ TFH cells, the concentrations of serum IL-2, IFN-γ, TNF-α, IL-4, IL-6, IL-10, IL-21, ALT, AST, HBsAg, HBsAb, HBeAg, HBeAb and HBV loads in IA patients were determined. The potential association of the frequency of CD4⁺CXCR5⁺ TFH cells with clinical measures was analyzed. In addition, the frequency of splenic and liver CD4⁺CXCR5⁺ TFH cells in HBV-transgenic mice was examined. We found that the frequency of CD4⁺CXCR5⁺ TFH cells in IA patients was significantly higher than that of IT patients and HC, and the percentages of CD4⁺CXCR5⁺ TFH in IA patients were positively correlated with AST. Furthermore, the percentages of ICOS⁺, PD-1⁺, and ICOS⁺PD-1⁺ in CD4⁺CXCR5⁺ TFH cells in CHB patients were significantly higher than that of HC. Treatment with adefovir dipivoxil reduced the frequency of CD4⁺CXCR5⁺ TFH, PD-1⁺CD4⁺CXCR5⁺ TFH cells and the concentrations of HBsAg and HBeAg, but increased the concentrations of HBsAb, HBeAb, IL-2 and IFN-γ in IA patients. Moreover, the frequency of splenic and liver CD4⁺CXCR5⁺ TFH cells in HBV-transgenic mice was higher than that of wild-type controls.

Conclusions

These data indicate that CD4⁺CXCR5⁺ TFH cells may participate in the HBV-related immune responses and that high frequency of CD4⁺CXCR5⁺ TFH cells may be a biomarker for the evaluation of active immune stage of CHB patients.     

Significance of thymosin β4 and implication of PINCH-1-ILK-α-parvin (PIP) complex in human dilated cardiomyopathy

Myocardial remodeling is a major contributor in the development of heart failure (HF) after myocardial infarction (MI). Integrin-linked kinase (ILK), LIM-only adaptor PINCH-1, and α-parvin are essential components of focal adhesions (FAs), which are highly expressed in the heart. ILK binds tightly to PINCH-1 and α-parvin, which regulates FA assembly and promotes cell survival via the activation of the kinase Akt. Mice lacking ILK, PINCH or α-parvin have been shown to develop severe defects in the heart, suggesting that these proteins play a critical role in heart function. Utilizing failing human heart tissues (dilated cardiomyopathy, DCM), we found a 2.27-fold (p<0.001) enhanced expression of PINCH, 4 fold for α-parvin, and 10.5 fold (p<0.001) for ILK as compared to non-failing (NF) counterparts. No significant enhancements were found for the PINCH isoform PINCH-2 and parvin isoform β-parvin. Using a co-immunoprecipitation method, we also found that the PINCH-1-ILK-α-parvin (PIP) complex and Akt activation were significantly up-regulated. These observations were further corroborated with the mouse myocardial infarction (MI) and transaortic constriction (TAC) model. Thymosin beta4 (Tβ4), an effective cell penetrating peptide for treating MI, was found to further enhance the level of PIP components and Akt activation, while substantially suppressing NF-κB activation and collagen expression--the hallmarks of cardiac fibrosis. In the presence of an Akt inhibitor, wortmannin, we show that Tβ4 had a decreased effect in protecting the heart from MI. These data suggest that the PIP complex and activation of Akt play critical roles in HF development. Tβ4 treatment likely improves cardiac function by enhancing PIP mediated Akt activation and suppressing NF-κB activation and collagen-mediated fibrosis. These data provide significant insight into the role of the PIP-Akt pathway and its regulation by Tβ4 treatment in post-MI.     

Homocysteine inhibits store-mediated calcium entry in human endothelial cells: evidence for involvement of membrane potential and actin cytoskeleton

The role of homocysteine for store-operated calcium influx was investigated in human umbilical cord endothelial cell line. Homocysteine significantly decreased thapsigargin-evoked Ca2+ entry, membrane hyperpolarization and actin polymerization. GSH and DTT prevented homocysteine-induced inhibition of thapsigargin-evoked Ca2+ entry, membrane hyperpolarization and actin polymerization; while GSSG had the opposite effect. Homocysteine blocked large conductance Ca2+-activated K+ (BK(Ca)) channels in a concentration-dependent manner and related to the redox status of the endothelial cells. BK(Ca) channels opener NS1619 reversed thapsigargin-evoked Ca2+ entry, membrane hyperpolarization and actin polymerization; BK(Ca) channels inhibitor iberiotoxin had the opposite effect. The findings suggest that homocysteine is involved in store-regulated Ca2+ entry through membrane potential-dependent and actin cytoskeleton-dependent mechanisms, redox status of homocysteine and BK(Ca) channels may play a regulatory role in it.     

Investigation of serum protein systems in Chinese pigs

Polymorphisms of transferrin (Tf), pre-albumin (Pa), haemopexin (Hpx), ceruloplasmin (Cp) and amylase (Am) of Duroc pigs and Hunan indigenous pigs were investigated using horizontal starch gel electrophoresis. Allele frequencies of Durocs determined in 2004 were compared with frequencies presented in the paper by Baker L.N. (1968) Serum protein variation in Duroc and Hampshire pigs. Vox Sanguinis15, 154-8. The number of serum protein alleles decreased over time and allele frequencies aggregated across certain alleles, including TfB, PaA, Hpx3, CpB and AmB. Differences in allele frequencies, average heterozygosities and standard genetic distances between the Duroc pigs and Hunan indigenous pig populations were examined. The relationship between Durocs and Hunan indigenous pigs was found to be more distant than those among the three Hunan indigenous pig populations.     

Site-directed spin labeling studies reveal solution conformational changes in a GAAA tetraloop receptor upon Mg(2+)-dependent docking of a GAAA tetraloop

The Mg(2+)-dependent GAAA tetraloop interaction with its 11 nucleotide receptor is one of the most frequently occurring long-range tertiary interactions in RNAs. To explore conformational changes in the receptor during tetraloop docking, nitroxide spin labels were attached at each of four uridine bases, one at a time, within an RNA molecule containing the receptor sequence. In the presence of Mg2+ and the tetraloop, the electron paramagnetic resonance (EPR) spectrum of one of the labeled bases reflected a large increase in mobility, indicating unstacking of the base upon tetraloop docking. This provides direct evidence that base unstacking is an intrinsic feature of the solution tetraloop-receptor complex formed in the presence of Mg2+. Additional evidence suggests that in solution the bound receptor conformation is similar to that observed in the crystal structure of a group I intron ribozyme domain. In Mg2+ alone, a receptor conformation with an unstacked base was not detectable, suggesting that this conformation is of higher standard state free energy than that of the free receptor. This leads to the conclusion that the extensive RNA-RNA interactions observed in the crystal structure of the tetraloop-receptor complex provide larger interaction energy than the measured apparent affinity between the tetraloop and the free receptor. This is compatible with a high specificity of the tetraloop-receptor interaction.     

Calcium changes and the response to methyl jasmonate in rice lodicules during anthesis

Summary. Potassium pyroantimonate precipitation was used to locate loosely bound calcium in rice (Oryza sativa L.) lodicules before and after anthesis, and flowering of panicles was accelerated by treatment with methyl jasmonate. From 1 day to 4 h before anthesis, the number of calcium precipitates in the cell walls and vacuole membranes decreased gradually, whereas they increased remarkably in the cytoplasm and nucleolus. At the beginning of anthesis, the number of calcium granules in lodicules reduced sharply, but there was a large accumulation of flocculent precipitates in the vacuoles. After anthesis, the flocculent precipitates decreased in number until they disappeared, whereas the granular precipitates started to accumulate once again. The rice florets treated with 2 mM methyl jasmonate were induced to open within 10–30 min and they then closed 0.5–1 h later. The nucleolus, cytoplasm, and vacuole membrane of the lodicule cells contained many calcium granules during flowering, although the cell walls lacked calcium. At 1 h after treatment, the number of calcium granules had decreased, while flocculent precipitates were regularly observed in the nondegenerated cells. At 6 h after treatment, calcium grains started to reappear in the cell walls. These changes in calcium precipitates before and after anthesis indicate that the opening and closing of florets correlates with the calcium level in lodicule cells. In addition, excised panicles, with florets judged to be nearing anthesis, were soaked in 2–200 mM EGTA solution for 2 min after treatment with 2 mM methyl jasmonate. The results indicate that EGTA had an antagonistic effect on the methyl jasmonate-induced floret opening in rice. Correspondence and reprints: Key Laboratory of the Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, People’s Republic of China.     

Mechanisms of endothelial dysfunction with development of type 1 diabetes mellitus: role of insulin and C-peptide

Complications associated with insulin-dependent diabetes mellitus (type-1diabetes) primarily represent vascular dysfunction that has its origin in the endothelium. While many of the vascular changes are more accountable in the late stages of type-1diabetes, changes that occur in the early or initial functional stages of this disease may precipitate these later complications. The early stages of type-1diabetes are characterized by a diminished production of both insulin and C-peptide with a significant hyperglycemia. During the last decade numerous speculations and theories have been developed to try to explain the mechanisms responsible for the selective changes in vascular reactivity and/or tone and the vascular permeability changes that characterize the development of type-1diabetes. Much of this research has suggested that hyperglycemia and/or the lack of insulin may mediate the observed functional changes in both endothelial cells and vascular smooth muscle. Recent studies suggest several possible mechanisms that might be involved in the observed decreases in vascular nitric oxide (NO) availability with the development of type-1 diabetes. In addition more recent studies have indicated a direct role for both endogenous insulin and C-peptide in the amelioration of the observed endothelial dysfunction. These results suggest a synergistic action between insulin and C-peptide that facilitates increase NO availability and may suggest new clinical treatment modalities for type-1 diabetes mellitus.