Autophagy stimulation as a promising approach in treatment of neurodegenerative diseases

Autophagy is a process of degradation of macromolecules in the cytoplasm, particularly proteins of a long half-life, as well as whole organelles, in eukaryotic cells. Lysosomes play crucial roles during this degradation. Autophagy is a phylogenetically old, and evolutionarily conserved phenomenon which occurs in all eukaryotic cells. It can be found in yeast Saccharomyces cerevisiae, insect Drosophila melanogaster, and mammals, including humans. Its high importance for cell physiology has been recognized, and in fact, dysfunctions causing impaired autophagy are associated with many severe disorders, including cancer and metabolic brain diseases. The types and molecular mechanisms of autophagy have been reviewed recently by others, and in this paper they will be summarized only briefly. Regulatory networks controlling the autophagy process are usually described as negative regulations. In contrast, here, we focus on different ways by which autophagy can be stimulated. In fact, activation of this process by different factors or processes can be considered as a therapeutic strategy in metabolic neurodegenerative diseases. These aspects are reviewed and discussed in this article.     

Induction of bystander tolerance and immune deviation after Fel d 1 peptide immunotherapy

1. Download high-res image (231KB)
2. Download full-size image

     

Correction of Huntington’s Disease Phenotype by Genistein-Induced Autophagy in the Cellular Model

Huntington’s disease (HD) is a monogenic disorder, caused by mutations in the HTT gene which result in expansion of CAG triplets. The product of the mutated gene is misfolded huntingtin protein that forms aggregates leading to impairment of neuronal function, neurodegeneration, motor abnormalities and cognitive deficits. No effective cure is currently available for HD. Here we studied effects of genistein (trihydroxyisoflavone) on a HD cellular model consisting of HEK-293 cells transfected with a plasmid bearing mutated HTT gene. Both level of mutated huntingtin and number of aggregates were significantly decreased in genistein-treated HD cell model. This led to increased viability of the cells. Autophagy was up-regulated while inhibition of lysosomal functions by chloroquine impaired the genistein-mediated degradation of the mutated huntingtin aggregates. Hence, we conclude that through stimulating autophagy, genistein removes the major pathogenic factor of HD. Prolonged induction of autophagy was suspected previously to be risky for patients due to putative adverse effects; however, genistein has been demonstrated recently to be safe and suitable for long-term therapies even at doses as high as 150 mg/kg/day. Therefore, results presented in this report provide a basis for the use of genistein in further studies on development of the potential treatment of HD.     

Comprehensive phenotypic analysis of the gut intra-epithelial lymphocyte compartment: perturbations induced by acute reovirus 1/L infection of the gastrointestinal tract

Intestinal intra-epithelial lymphocytes (IELs) form a highly specialized lymphoid compartment. IELs consist primarily of T cells that are dispersed as single cells within the epithelial cell layer that surrounds the intestinal lumen. These lymphocytes along with lamina propria lymphocytes are considered to play an important role in the regulation of immune responses. IELs are heterogeneous with regard to phenotype, and they contain sub-populations with diverse functions. In our most recent study, we found that intra-duodenal inoculation of mice with reovirus serotype 1/strain Lang (reovirus 1/L) induced expression of both germinal center and T cell antigen and CD11c on IELs suggesting these cells to be the recently stimulated cells in gut mucosal tissue. We also demonstrated that IELs from these mice when cultured in vitro in the presence of reovirus 1/L-pulsed antigen-presenting cells generated reovirus 1/L-specific MHC-restricted CTL whose function was mediated utilizing perforin, Fas-FasL and TRAIL mechanisms. This present study provides a comprehensive analysis of the diverse subsets of IELs, which function with other mucosal cells to provide a strong, protective immunity in a highly regulated fashion inside the microenvironment of the intestinal epithelium. We demonstrated that the IEL population contains both thymus-dependent (TD) and thymus-independent (TI) lymphocytes in mice and that a complex phenotype is present when sub-populations are analyzed for TCR, Thy-1, CD4, CD8 and B220 expression in a comprehensive manner. In reovirus 1/L-inoculated mice, we found a decrease in the TI population and an increase in the TD population characterized by significant alterations in various sub-populations. This increase was largely due to an increase in CD4(+), CD8(+) and CD4/CD8 double-positive sub-populations of TD IELs. Intracellular cytokine analysis demonstrated induction of IFN-gamma and an increase in effector/cytotoxic CD8 and CD4 cells after reovirus 1/L infection. These results suggest that TD IELs may play an important role in the clearance of reovirus 1/L infection from gut.     

The Delta Delta: Gaps in screening and patient assessment for hepatitis D virus infection

Hepatitis D virus (HDV) infection is highly prevalent in patients with chronic hepatitis B (CHB). AASLD guidelines recommend a risk-based screening approach. Our aim was to ascertain if the risk-based approach leads to appropriate HDV screening, identify targets to improve screening rates, and study HDV clinical burden. CHB patients screened for HDV from 01/2016 to 12/2021 were identified. Level of training and specialty of providers ordering HDV screening tests were determined. HDV seropositive (HDV+) patient charts were reviewed for the presence of individual risk factors per the AASLD guidelines to determine if they met screening criteria. The severity of liver disease at the time of HDV screening was compared between the HDV+ group and a matched (based on age, hepatitis B e antigen status, BMI and sex) HDV seronegative (HDV−) group. During the study period, 1444/11,190 CHB patients were screened for HDV. Most screening tests were ordered by gastroenterology (90.2%) specialists and attending physicians (80.5%). HDV+ rate was 88/1444 (6%), and 72 HDV+ patients had complete information for analysis. 18% of HDV+ patients would be missed by a risk-based screening approach due to unreported or negative risk factors (see Table). A significantly higher number of HDV+ patients had developed significant fibrosis (p = 0.001) and cirrhosis (p < 0.01) by the time of screening than HDV− (n = 67) patients. In conclusion, targeted interventions are needed towards trainees and primary care clinics to improve screening rates. Current risk-based criteria do not appropriately screen for HDV. It is time for universal screening of HDV in CHB patients.