Vasoactive factors in decompensated cirrhosis. Effect of acute plasma expansion

Plasma volume expansion was performed in 16 cirrhotic patients with ascites, 8 with avid sodium retention (sodium retainers) and 8 with normal sodium balance (sodium excretors). No natriuretic response was observed in sodium retainers (daily UNa = 7.1 +/- 1.5 mEq before expansion and 20.8 +/- 7.8 after expansion; p = not significant). After expansion plasma renin activity and plasma aldosterone showed a fall in both groups, whereas urinary kallikrein excretion decreased significantly in sodium retainers (27.1 +/- 9.7 before expansion and 7.8 +/- 6.4 after expansion; p less than 0.05). Baseline PGE were higher than normal in sodium retainers (997.0 +/- 134.3; p less than 0.02 vs. controls) and increased after expansion. Plasma octopamine was always within normal range. These results suggest that: a) reduction of effective plasma volume is not the main factor involved in sodium retention; b) the renin-angiotensin-aldosterone system has only a permissive role; c) prostaglandin system is activated and could have a protective role in maintaining renal function in cirrhotic patients.     

Hemoglobins S and C in Upper Volta

Summary We have studied the incidence of hemoglobinopathies in 1059 individuals in Upper Volta. We have found that this population has a high frequency of HbS and HbC and -thalassemia. The gene frequency of HbS was high (0.1 for the ^S gene) in the arid Sahel portion of Upper Volta accompanied by a lower frequency for HbC (0.05 for the ^c gene). The reverse was true in the humid Savanna region of this country (0.03 for the ^S gene and 0.14 for the ^c gene). There was no age dependency of the HbS gene frequency, but -thalassemia, detectable in HbS heterozygotes, showed a statistically significant decrease with age. No homozygote for HbS was detected after the age of 1 year, and SC and CC genotypes were found at a lower incidence than expected. The environmental and medical conditions in Upper Volta preclude the survival of SS individuals and decrease the survival of SC and CC genotypes.     

Homozygosity Haplotype and Whole-Exome Sequencing Analysis to Identify Potentially Functional Rare Variants Involved in Multiple Sclerosis among Sardinian Families

Multiple Sclerosis (MS) is a complex multifactorial autoimmune disease, whose sex- and age-adjusted prevalence in Sardinia (Italy) is among the highest worldwide. To date, 233 loci were associated with MS and almost 20% of risk heritability is attributable to common genetic variants, but many low-frequency and rare variants remain to be discovered. Here, we aimed to contribute to the understanding of the genetic basis of MS by investigating potentially functional rare variants. To this end, we analyzed thirteen multiplex Sardinian families with Immunochip genotyping data. For five families, Whole Exome Sequencing (WES) data were also available. Firstly, we performed a non-parametric Homozygosity Haplotype analysis for identifying the Region from Common Ancestor (RCA). Then, on these potential disease-linked RCA, we searched for the presence of rare variants shared by the affected individuals by analyzing WES data. We found: (i) a variant (43181034 T > G) in the splicing region on exon 27 of CUL9; (ii) a variant (50245517 A > C) in the splicing region on exon 16 of ATP9A; (iii) a non-synonymous variant (43223539 A > C), on exon 9 of TTBK1; (iv) a non-synonymous variant (42976917 A > C) on exon 9 of PPP2R5D; and v) a variant (109859349-109859354) in 3′UTR of MYO16.     

Interaction between 4-hydroxy-2,3-alkenals and the platelet-derived growth factor-beta receptor. Reduced tyrosine phosphorylation and downstream signaling in hepatic stellate cells

Hepatic stellate cells (HSC) undergo activation toward myofibroblast-like cells during early stages of liver injury associated with fibrogenesis. Platelet-derived growth factor (PDGF), particularly its BB isoform, has been identified as the most potent mitogen for HSC. 4-Hydroxy-2,3-nonenal and related 4-hydroxy-2, 3-alkenals (HAKs) have been suggested to modulate the process of HSC activation. In this study we investigated the relationship between HAKs and PDGF receptor activation in human HSC. By employing noncytotoxic concentrations (10(-6) m) of HAKs, we observed a significant inhibition of PDGF-BB-dependent DNA synthesis. HAKs inhibited relevant pathways of PDGF-BB-dependent mitogenic signaling, including autophosphorylation of PDGF receptor (PDGF-R) beta subunits and activation of phosphatidylinositol 3-kinase and extracellular regulated kinases 1/2. Inhibition of DNA synthesis was reversible, and recovery of PDGF-mediated mitogenic signaling occurred within 24-48 h and was associated with HAKs-induced up-regulation of PDGF-R beta gene expression. 4-Hydroxy-2,3-nonenal, used as a model HAK, inhibited the intrinsic tyrosine kinase activity associated with the PDGF-R beta subunit, whereas binding of PDGF to its receptor was unaffected. This study identifies a novel regulatory mechanism of reactive aldehydes on PDGF receptor signaling and biologic actions, which may be relevant in several pathophysiological conditions, including liver fibrosis.     

Immunostimulatory Effects Triggered by Enterococcus faecalis CECT7121 Probiotic Strain Involve Activation of Dendritic Cells and Interferon-Gamma Production

Probiotics can modulate the immune system, conferring beneficial effects on the host. Understanding how these microorganisms contribute to improve the health status is still a challenge. Previously, we have demonstrated that Enterococcus faecalis CECT7121 implants itself and persists in the murine gastrointestinal tract, and enhances and skews the profile of cytokines towards the Th1 phenotype in several biological models. Given the importance of dendritic cells (DCs) in the orchestration of immunity, the aim of this work was to elucidate the influence of E. faecalis CECT7121 on DCs and the outcome of the immune responses. In this work we show that E. faecalis CECT7121 induces a strong dose-dependent activation of DCs and secretion of high levels of IL-12, IL-6, TNFα, and IL-10. This stimulation is dependent on TLR signaling, and skews the activation of T cells towards the production of IFNγ. The influence of this activation in the establishment of Th responses in vivo shows the accumulation of specific IFNγ-producing cells. Our findings indicate that the activation exerted by E. faecalis CECT7121 on DCs and its consequence on the cellular adaptive immune response may have broad therapeutic implications in immunomodulation.     

Age‐dependent skewing of X chromosome inactivation appears delayed in centenarians’ offspring. Is there a role for allelic imbalance in Healthy Aging and Longevity?

Recently, it has been proposed that age-related X chromosome inactivation (XCI) skewing can clinically result in late-onset X-linked disorders. This observation leads to hypothesize that age-related skewed XCI might also influence lifespan in women. To investigate this issue, we employed a new experimental model of longevity and healthy aging including 55 female centenarians, 40 of their offspring, 33 age-matched offspring of both non-long-lived parents and 41 young women. Peripheral blood DNA from 169 females was screened for heterozygosity at the HUMARA locus. We confirmed that skewing of XCI is an age-dependent phenomenon. However, skewed XCI was significantly less severe and frequent in centenarians' offspring [degree of skewing (DS) = 0.16 ± 0.02] compared to age-matched offspring of both non-long-lived parents (DS = 0.24 ± 0.02) (P < 0.05). A second goal was to assess whether changes in XCI pattern could be a consequence of loss of methylation on X chromosome. Using a methylation array evaluating 1085 CpG sites across X chromosome and eleven CpG sites located at HUMARA locus, no differences in methylation levels and profiles emerged between all groups analysed, thus suggesting that age-associated epigenetic changes could not influence HUMARA results. In conclusion, the results presented herein highlight for the first time an interesting link between skewing of XCI and healthy aging and longevity. We speculate that the allelic imbalance produced by XCI skewing may compromise the cooperative and compensatory organization occurring between the two cell populations that make up the female mosaic.     

Hemodynamic alterations in liver cirrhosis

In cirrhotic patients, portal hypertension is often associated with a hyperdynamic circulatory syndrome, with high cardiac output and reduced systemic vascular resistance and arterial pressure. The hyperdynamic circulatory syndrome is due to arterial vasodilation that mainly occurs in the splanchnic circulation, while vascular resistance in the other circulatory districts is normal or increased, accordingly with the degree of portal hypertension, liver impairment and activation of the renin-aldosterone and sympathetic nervous system. The mechanism(s) leading to splanchnic vasodilation is unclear. A favored hypothesis translocation of intestinal bacteria and/or some their products, such as endotoxin, into the interstitial space in the splanchnic organs results in the local release of vasodilating factors such as nitric oxide, carbon monoxide and others.     

Altered modulation of lamin A/C‐HDAC2 interaction and p21 expression during oxidative stress response in HGPS

Defects in stress response are main determinants of cellular senescence and organism aging. In fibroblasts from patients affected by Hutchinson–Gilford progeria, a severe LMNA‐linked syndrome associated with bone resorption, cardiovascular disorders, and premature aging, we found altered modulation of CDKN1A, encoding p21, upon oxidative stress induction, and accumulation of senescence markers during stress recovery. In this context, we unraveled a dynamic interaction of lamin A/C with HDAC2, an histone deacetylase that regulates CDKN1A expression. In control skin fibroblasts, lamin A/C is part of a protein complex including HDAC2 and its histone substrates; protein interaction is reduced at the onset of DNA damage response and recovered after completion of DNA repair. This interplay parallels modulation of p21 expression and global histone acetylation, and it is disrupted by LMNAmutations leading to progeroid phenotypes. In fact, HGPS cells show impaired lamin A/C‐HDAC2 interplay and accumulation of p21 upon stress recovery. Collectively, these results link altered physical interaction between lamin A/C and HDAC2 to cellular and organism aging. The lamin A/C‐HDAC2 complex may be a novel therapeutic target to slow down progression of progeria symptoms.     

Characteristics of the microsporidian Enterocytozoon bieneusi: a consequence of its development within short-living enterocytes.

Ultrastructural studies were done on developmental stages of Enterocytozoon bieneusi obtained from HIV seropositive patients suffering from diarrhea. The presence of elaborate multilamellar structures suggest that they give rise to various membrane systems needed for rapid production of disseminating stages.     

Molecular mechanism underlying impaired platelet responsiveness in liver cirrhosis

We have studied platelet function in 10 patients with severe liver cirrhosis, compared to healthy subjects. Using washed platelets, we have investigated the molecular mechanism underlying the defect in platelet aggregation frequently observed in these patients. We have found that platelets from cirrhotic patients have a reduced responsiveness to thrombin and collagen in terms of aggregation, and receptor-dependent activation of phospholipase C, A2 and cyclooxygenase/thromboxane synthetase. We thus suggest that this impairment in transmembrane signalling is responsible for the defective platelet function observed in cirrhosis.