Bile salt-induced apoptosis involves NADPH oxidase isoform activation

BACKGROUND & AIMS: Hydrophobic bile salts trigger a rapid oxidative stress response as an upstream event of CD95 activation and hepatocyte apoptosis. METHODS: The underlying mechanisms were studied by Western blot, immunocytochemistry, protein knockdown, and fluorescence resonance energy transfer microscopy in rat hepatocytes and human hepatoma cell line 7 (Huh7). RESULTS: The rapid oxidative stress formation in response to taurolithocholate-3-sulfate (TLCS) was inhibited by diphenyleneiodonium, apocynin, and neopterin, suggestive for the involvement of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases. TLCS induced a rapid serine phosphorylation of the regulatory subunit p47phox, which was sensitive to inhibition of sphingomyelinase and protein kinase Czeta (PKCzeta). Inhibitors of p47phox phosphorylation and p47phox protein knockdown abolished the TLCS-induced oxidative stress response and blunted subsequent CD95 activation. Consequences of TLCS-induced oxidative stress were c-Jun-N-terminal kinase activation and Yes-dependent activation of the epidermal growth factor receptor (EGFR), followed by EGFR-catalyzed CD95 tyrosine phosphorylation, formation of the death-inducing signaling complex, and execution of apoptosis. As shown by fluorescence resonance energy transfer experiments in Huh7 cells, TLCS induced a c-Jun-N-terminal kinase-dependent EGFR/CD95 association in the cytosol and trafficking of this protein complex to the plasma membrane. Inhibition of EGFR tyrosine kinase activity by AG1478 allowed for cytosolic EGFR/CD95 association, but prevented targeting of the EGFR/CD95 complex to the plasma membrane. Both processes, and TLCS-induced Yes and EGFR activation, were sensitive to inhibition of sphingomyelinase, PKCzeta, or NADPH oxidases. CONCLUSIONS: The data suggest that hydrophobic bile salts activate NADPH oxidase isoforms with the resulting oxidative stress response triggering activation of the CD95 system and apoptosis.     

Secretory products from human adipocytes impair endothelial function via nuclear factor kappaB

Hyperplasia and hypertrophy of fat cells can be found in obesity, and increased adiposity is associated with endothelial dysfunction as an early event of atherosclerosis. However, it is unclear whether human adipocytes directly influence endothelial function. To study the crosstalk between fat and endothelial cells, human umbilical venous endothelial cells (HUVECs), and human coronary artery endothelial cells (HCAECs) were cultured in infranatants (Adipo) of primary differentiated human adipocytes. Interestingly, incubation of HUVECs and HCAECs with Adipo significantly increased monocyte adhesion 7.3 and 2.2-fold, respectively. VCAM-1, ICAM-1, and E-selectin in HUVECs were upregulated 3.9, 3.0, and 9.5-fold, respectively, under these conditions. Furthermore, Adipo significantly stimulated NFkappaB activity 1.9-fold. The NFkappaB inhibitor MG-132 and heat inactivation significantly reversed Adipo-stimulated monocyte adhesion. TNFalpha-neutralizing antibodies partly reversed Adipo-induced monocyte adhesion. In contrast, thiazolidinedione-pretreatment of human adipocytes did not alter the effects of Adipo. Adipo did not show cytotoxic effects. Taken together, we demonstrate that endothelial dysfunction is induced by adipocyte-secreted factors via NFkappaB partly dependent on TNFalpha.     

The uniqueness of subjective ageing: convergent and discriminant validity

Although a large body of research has demonstrated the predictive power of subjective ageing for several decisive developmental outcomes, there remains some controversy about whether subjective ageing truly represents a unique construct. Thus, information about the convergent and discriminant validity of different approaches to measuring subjective ageing is still critically needed. Using data from the 2014 wave of the German Ageing Survey, we examined how three established subjective ageing measures (subjective age, global attitude toward own ageing, multidimensional ageing-related cognitions) were inter-related as well as distinct from general dispositions (optimism, self-efficacy) and well-being (negative affect, depressive symptoms, self-rated health). Using correlational and multivariate regression analysis, we found that the three subjective ageing measures were significantly inter-related (r = |.09| to |.30|), and that each measure was distinct from general dispositions and well-being. The overlap with dispositional and well-being measures was lowest for subjective age and highest for global attitudes towards own ageing. The correlation between global attitudes towards own ageing and optimism was particularly striking. Despite the high convergent validity of the different dimensions of ageing cognitions, we nevertheless observed stronger associations between specific dimensions of ageing cognitions with negative affect and self-rated health. We conclude that researchers should be aware of the multidimensional nature of subjective ageing. Furthermore, subjective age appears to be a highly aggregated construct and future work is needed to clarify its correlates and reference points.Electronic supplementary materialThe online version of this article (10.1007/s10433-019-00529-7) contains supplementary material, which is available to authorized users.     

Surgical treatment for Zenker’s diverticulum: comparison between diverticulectomy and diverticulopexy

Background

The ideal surgical technique for symptomatic Zenker’s diverticulum has not been identified yet. Endoscopic treatment, although frequently performed, has not replaced the open cricopharyngeal myotomy, which is still deemed the standard therapy by many dedicated physicians. The management of the diverticular sac after myotomy is still a matter of debate. The aim of this study is to compare the results of diverticulectomy and diverticulopexy after cricopharyngeal myotomy, in homogeneous groups of patients.

Methods

Thirty-seven patients were treated for Zenker’s diverticulum at the same university medical school, but in two different units, with open cricopharyngeal myotomy, associated with diverticulectomy in 17 patients and with diverticulopexy in the remaining. No clinical criteria influenced the different choice of treatment of the diverticular pouch, but only the surgeon’s preference. Clinical data, diverticulum size, postoperative course, and complications were analyzed. Patients were followed up for median duration of 37 months (range 12–113 months) through contrast swallow study and clinical evaluation, aided by a specifically conceived questionnaire. Records were analyzed by Mann–Whitney–Wilcoxon test and Fisher’s exact test.

Results

Homogeneous comparative values for sex, age, diverticulum size, and symptoms were found in the two groups. Statistical analysis indicated that diverticulopexy, as compared with diverticulectomy, allowed reduced postoperative complications and slightly improved long-term swallowing.

Conclusions

Diverticulopexy is feasible also in large Zenker’s diverticula and can achieve equivalent or even better results than diverticulectomy with a smoother postoperative course.

     

Histopathological and clinical findings in renal transplants with Banff type II and III acute cellular rejection without tubulointerstitial infiltrates

According to the Banff guidelines for renal transplants, pure endothelialitis without any tubulointerstitial infiltrates (with the Banff components v?≥?1, i0, t0) has to be called acute cellular rejection (ACR). The pathophysiology of this rare lesion abbreviated as v_only is currently unclear, as well as its clinical, serological, and prognostic implications. Therefore, we conducted this retrospective comparative study. We compared all 23 biopsies with v_only from Hannover Medical School between 2003 and 2010 with 23 matched biopsies with the Banff components v?≥?1, i?≥?1, and t?≥?1 (v_plus) and 23 biopsies with v0, i0, and t0 (v0i0t0). Serological (available in 10, 11, and 14 patients, respectively), histological, and clinical data were compared. Of all biopsies, 0.4 % had findings of v_only. v_only, v_plus, and v0i0t0 only showed minimal differences in the Banff components apart from the cohort-defining components. Endothelialitis in v_only more frequently involved the arcuate arteries than the smaller preglomerular vessels compared to v_plus and vice versa. Combining histopathological data and serological data, v_only more frequently showed criteria for acute humoral rejection than v0i0t0 (albeit not persistent after the Bonferroni–Holm correction in pairwise comparisons), while there was no difference between v_only and v_plus. No difference could be demonstrated regarding clinical presentation at biopsy or outcome. Our results show minimal differences regarding clinical presentation, outcome, and histological features between v_only and v_plus. Patients with v_only should be thoroughly investigated for evidence of acute humoral rejection.     

Heterogeneity of stromal cells in the human splenic white pulp. Fibroblastic reticulum cells,follicular dendritic cells and a third superficial stromal cell type

At least three phenotypically and morphologically distinguishable types of branched stromal cells are revealed in the human splenic white pulp by subtractive immunohistological double-staining. CD271 is expressed in fibroblastic reticulum cells of T-cell zones and in follicular dendritic cells of follicles. In addition, there is a third CD271⁻ and CD271^+/− stromal cell population surrounding T-cell zones and follicles. At the surface of follicles the third population consists of individually variable partially overlapping shells of stromal cells exhibiting CD90 (Thy-1), MAdCAM-1, CD105 (endoglin), CD141 (thrombomodulin) and smooth muscle α-actin (SMA) with expression of CD90 characterizing the broadest shell and SMA the smallest. In addition, CXCL12, CXCL13 and CCL21 are also present in third-population stromal cells and/or along fibres. Not only CD27⁺ and switched B lymphocytes, but also scattered IgD⁺⁺ B lymphocytes and variable numbers of CD4⁺ T lymphocytes often occur close to the third stromal cell population or one of its subpopulations at the surface of the follicles. In contrast to human lymph nodes, neither podoplanin nor RANKL (CD254) were detected in adult human splenic white pulp stromal cells. The superficial stromal cells of the human splenic white pulp belong to a widespread cell type, which is also found at the surface of red pulp arterioles surrounded by a mixed T-cell/B-cell population. Superficial white pulp stromal cells differ from fibroblastic reticulum cells and follicular dendritic cells not only in humans, but apparently also in mice and perhaps in rats. However, the phenotype of white pulp stromal cells is species-specific and more heterogeneous than described so far.