Myeloid Mixed Lineage Kinase 3 Contributes to Chronic Ethanol-Induced Inflammation and Hepatocyte Injury in Mice

Proinflammatory activity of hepatic macrophages plays a key role during progression of alcoholic liver disease (ALD). Since mixed lineage kinase 3 (MLK3)-dependent phosphorylation of JNK is involved in the activation of macrophages, we tested the hypothesis that myeloid MLK3 contributes to chronic ethanol-induced inflammatory responses in liver, leading to hepatocyte injury and cell death. Primary cultures of Kupffer cells, as well in vivo chronic ethanol feeding, were used to interrogate the role of MLK3 in the progression of liver injury. Phosphorylation of MLK3 was increased in primary cultures of Kupffer cells isolated from ethanol-fed rats compared to cells from pair-fed rats. Kupffer cells from ethanol-fed rats were more sensitive to LPS-stimulated cytokine production; this sensitization was normalized by pharmacological inhibition of MLK3. Chronic ethanol feeding to mice increased MLK3 phosphorylation robustly in F4/80⁺ Kupffer cells, as well as in isolated nonparenchymal cells. MLK3^−/− mice were protected from chronic ethanol-induced phosphorylation of MLK3 and JNK, as well as multiple indicators of liver injury, including increased ALT/AST, inflammatory cytokines, and induction of RIP3. However, ethanol-induced steatosis and hepatocyte apoptosis were not affected by MLK3. Finally, chimeric mice lacking MLK3 only in myeloid cells were also protected from chronic ethanol-induced phosphorylation of JNK, expression of inflammatory cytokines, and increased ALT/AST. MLK3 expression in myeloid cells contributes to phosphorylation of JNK, increased cytokine production, and hepatocyte injury in response to chronic ethanol. Our data suggest that myeloid MLK3 could be targeted for developing potential therapeutic strategies to suppress liver injury in ALD patients.Key words: Alcoholic liver disease (ALD), Kupffer cells, Necroptosis, Toll-like receptor 4 (TLR4), Cytokines     

Kidney Function and Plasma Copeptin Levels in Healthy Kidney Donors and Autosomal Dominant Polycystic Kidney Disease Patients

Background and objectives

Plasma copeptin, a marker of arginine vasopressin, is elevated in patients with autosomal dominant polycystic kidney disease and predicts disease progression. It is unknown whether elevated copeptin levels result from decreased kidney clearance or as compensation for impaired concentrating capacity. Data from patients with autosomal dominant polycystic kidney disease and healthy kidney donors before and after donation were used, because after donation, overall GFR decreases with a functionally normal kidney.

Design, setting, participants, & measurements

Data were obtained between October of 2008 and January of 2012 from healthy kidney donors who visited the institution for routine measurements predonation and postdonation and patients with autosomal dominant polycystic kidney disease who visited the institution for kidney function measurement. Plasma copeptin levels were measured using a sandwich immunoassay, GFR was measured as ¹²⁵I-iothalamate clearance, and urine concentrating capacity was measured as urine-to-plasma ratio of urea. In patients with autosomal dominant polycystic kidney disease, total kidney volume was measured with magnetic resonance imaging.

Results

Patients with autosomal dominant polycystic kidney disease (n=122, age=40 years, men=56%) had significantly higher copeptin levels (median=6.8 pmol/L; interquartile range=3.4–15.7 pmol/L) compared with donors (n=134, age=52 years, men=49%) both predonation and postdonation (median=3.8 pmol/L; interquartile range=2.8–6.3 pmol/L; P<0.001; median=4.4 pmol/L; interquartile range=3.6–6.1 pmol/L; P<0.001). In donors, copeptin levels did not change after donation, despite a significant fall in GFR (from 105±17 to 66±10; P<0.001). Copeptin and GFR were significantly associated in patients with autosomal dominant polycystic kidney disease (β=−0.45, P<0.001) but not in donors. In patients with autosomal dominant polycystic kidney disease, GFR and total kidney volume were both associated significantly with urine-to-plasma ratio of urea (β=0.84, P<0.001; β=−0.51, P<0.001, respectively).

Conclusions

On the basis of the finding in donors that kidney clearance is not a main determinant of plasma copeptin levels, it was hypothesized that, in patients with autosomal dominant polycystic kidney disease, kidney damage and associated impaired urine concentration capacity determine copeptin levels.     

CD4/CD8 ratio is a promising candidate for non-invasive measurement of liver fibrosis in chronic HCV-monoinfected patients

The extent of liver fibrosis is an important factor in prognosis and clinical decision-making in chronic hepatitis C virus (HCV) infection. We investigated CD4/CD8 ratio in HCV-monoinfected and HIV/HCV-coinfected patients, in order to reveal its relation with liver fibrosis. CD4/CD8 ratio in the peripheral blood was assessed by flow cytometry in a cohort of 19 HCV-monoinfected, 14 HIV/HCV-coinfected, ten HIV-monoinfected patients and 15 healthy controls. Liver fibrosis was assessed by transient elastography (n?=?25) or by liver biopsy (n?=?8). Coinfection with HIV was associated with decreased CD4/CD8 ratios in chronic HCV-infected patients, despite adequate antiretroviral treatment. Furthermore, HCV-monoinfected patients with F3-F4 liver fibrosis demonstrated much lower CD4/CD8 ratios than patients with F0-F2 fibrosis (1.4 versus 2.5, p?=?0.023). Similarly, we observed a strong negative correlation between the CD4/CD8 ratio and liver stiffness measured by transient elastography (R?=??0.78, p?=?0.0006). ROC analysis revealed that CD4/CD8 ratio as a non-invasive marker for fibrosis is very promising (area under the curve 0.8). Although our study was performed with a relatively small number of patients, our findings suggest that the CD4/CD8 ratio is a promising candidate for non-invasive evaluation of liver fibrosis in HCV-monoinfected patients.     

A region of euchromatin coincides with an extensive tandem repeat on the mouse (Mus musculus) inactive X chromosome

Euchromatic features are largely absent from the human inactive X chromosome (Xi), with the exception of several large tandem repeats that can be detected as euchromatin bands at metaphase. Despite residing megabases apart, these tandem repeats make frequent inactive X-specific interactions. The mouse homologue has been reported for at least one of the tandem repeats, but whether the mouse Xi is also characterized by distinct bands of euchromatin remains unknown. We examined the mouse Xi for the presence of euchromatin bands by examining the pattern of histone H3 dimethylated at lysine 4 and detected two major signals. The first band resides in the subtelomeric region of band XF5 and may correspond to the pseudoautosomal region. The second band localizes to XE3 and coincides with an extensive complex repeat composed of a large tandem and inverted repeat segment as well as several large short interspersed nuclear element (SINE)-rich tandem repeats. Fluorescence in situ hybridization reveals that sequences with homology to the repeat region are scattered along the length of the Y chromosome. Immunofluorescence analysis of histone H3 trimethylated at lysine 9 on metaphase chromosomes indicates that the repeat region corresponds to a band of constitutive heterochromatin on the male X and female active X chromosomes, whereas the euchromatin signal appears to be female specific. These data suggest that the band of euchromatin observed at XE3 is unique to the mouse Xi, comparable to the chromatin arrangement of several large tandem repeats located on the human X chromosome.     

Emerging role of interleukin‐33 in autoimmune diseases

Interleukin‐33 (IL‐33) is a member of the IL‐1 cytokine family. It predominantly induces type 2 immune responses and thus is protective against atherosclerosis and nematode infections but contributes to allergic airway inflammation. Interleukin‐33 also plays a pivotal role in the development of many autoimmune diseases through mechanisms that are still not fully understood. In this review, we focus on the recent advances in understanding of the expression and function of IL‐33 in some autoimmune disorders, aiming to provide insight into its potential role in disease development.     

Coenzyme Q10 attenuates diastolic dysfunction, cardiomyocyte hypertrophy and cardiac fibrosis in the db/db mouse model of type 2 diabetes

Aims/hypothesis  

An increase in the production of reactive oxygen species is commonly thought to contribute to the development of diabetic cardiomyopathy. This study aimed to assess whether administration of the antioxidant coenzyme Q₁₀ would protect the diabetic heart against dysfunction and remodelling, using the db/db mouse model of type 2 diabetes. Furthermore, we aimed to compare the efficacy of coenzyme Q₁₀ to that of the ACE inhibitor ramipril.