Lysosomal fusion and SNARE function are impaired by cholesterol accumulation in lysosomal storage disorders

The function of lysosomes relies on the ability of the lysosomal membrane to fuse with several target membranes in the cell. It is known that in lysosomal storage disorders (LSDs), lysosomal accumulation of several types of substrates is associated with lysosomal dysfunction and impairment of endocytic membrane traffic. By analysing cells from two severe neurodegenerative LSDs, we observed that cholesterol abnormally accumulates in the endolysosomal membrane of LSD cells, thereby reducing the ability of lysosomes to efficiently fuse with endocytic and autophagic vesicles. Furthermore, we discovered that soluble N‐ethylmaleimide‐sensitive factor attachment protein (SNAP) receptors (SNAREs), which are key components of the cellular membrane fusion machinery are aberrantly sequestered in cholesterol‐enriched regions of LSD endolysosomal membranes. This abnormal spatial organization locks SNAREs in complexes and impairs their sorting and recycling. Importantly, reducing membrane cholesterol levels in LSD cells restores normal SNARE function and efficient lysosomal fusion. Our results support a model by which cholesterol abnormalities determine lysosomal dysfunction and endocytic traffic jam in LSDs by impairing the membrane fusion machinery, thus suggesting new therapeutic targets for the treatment of these disorders.     

Vaccination of a melanoma patient with mature dendritic cells pulsed with MAGE-3 peptides triggers the activity of nonvaccine anti-tumor cells

We previously characterized the CTL response of a melanoma patient who experienced tumor regression following vaccination with an ALVAC virus coding for a MAGE-A3 Ag. Whereas anti-vaccine CTL were rare in the blood and inside metastases of this patient, anti-tumor CTL recognizing other tumor Ags, mainly MAGE-C2, were 100 times more frequent in the blood and considerably enriched in metastases following vaccination. In this study we report the analysis of the CTL response of a second melanoma patient who showed a mixed tumor response after vaccination with dendritic cells pulsed with two MAGE-A3 antigenic peptides presented, respectively, by HLA-A1 and HLA-DP4. Anti-MAGE-3.A1 CD8 and anti-MAGE-3.DP4 CD4 T cells became detectable in the blood after vaccination at a frequency of approximately 10(-5) among the CD8 or CD4 T cells, respectively, and they were slightly enriched in slowly progressing metastases. Additional anti-tumor CTL were present in the blood at a frequency of 2x10(-4) among the CD8 T cells and, among these, an anti-MAGE-C2 CTL clone was detected only following vaccination and was enriched by >1,000-fold in metastases relative to the blood. The striking similarity of these results with our previous observations further supports the hypothesis that the induction of a few anti-vaccine T cells may prime or restimulate additional anti-tumor T cell clones that are mainly responsible for the tumor regression.     

Cerebrospinal Fluid Biomarkers in the Diagnosis of Creutzfeldt-Jakob Disease in Slovak Patients: over 10-Year Period Review

Creutzfeldt-Jakob disease is a rare, but rapidly progressive, up to now untreatable and fatal neurodegenerative disorder. Clinical diagnosis of Creutzfeldt-Jakob disease (CJD) is difficult; however, it can be facilitated by suitable biomarkers. Aim of the present study is to compare levels of cerebrospinal fluid biomarkers (total tau protein, phosphorylated-tau protein, protein 14-3-3 and amyloid beta) in Slovak population of CJD suspect cases, retrospectively in over a 10-year period. One thousand three hundred sixty-four CSF samples from patients with suspect CJD, forming a homogenous group in terms of geographical as well as of equal transport conditions, storage and laboratory processing, were analysed. Definite diagnosis of Creutzfeldt-Jakob disease was confirmed in 101 patients with genetic form, and 60 patients with its sporadic form of the disease. Specificity of protein 14-3-3 and total tau in both forms CJD was similar (87 % for P14-3-3/85 % for total tau), sensitivity to P 14-3-3 and total tau was higher in sporadic Creutzfeldt-Jakob disease (sCJD) (90/95 %) than in genetic Creutzfeldt-Jakob disease (gCJD) (89/74 %). As expected, the total tau levels were significantly higher in CJD patients than in controls, but there was also significant difference between gCJD and sCJD (levels in gCJD were lower; p = 0.003). There was no significant difference in p-tau and Aβ 1-42 levels neither between both CJD forms nor between CJD patients and control group.     

Identification of a mutated receptor-like protein tyrosine phosphatase kappa as a novel,class II HLA-restricted melanoma antigen

Recent studies increasingly point to a pivotal role of CD4(+) T cells in human anti-tumor immune response. Here we show that lymphocytes purified from a tumor-infiltrated lymph node of a melanoma patient that had remained disease free for 10 years after surgical resection of a lymph node metastasis comprised oligoclonal class II HLA-restricted CD4(+) T cells recognizing the autologous tumor cells in vitro. In fact, the CD4(+) T cell clones isolated from these lymphocytes displayed a tumor-specific, cytotoxic activity in addition to a Th1-like cytokine profile. By a genetic approach, a peptide derived from a mutated receptor-like protein tyrosine phosphatase kappa was identified as a novel HLA-DR10-restricted epitope for all the melanoma-specific CD4(+) T cell clones. The immunogenic peptide was shown to contain the mutated residue that was crucial for T cell recognition and activation. Moreover, a systemic immunity against the mutated peptide was detectable in the patient's peripheral blood T lymphocytes obtained during the disease-free period of follow-up. These findings further support the relevance of CD4(+) T cells directed against mutated epitopes in tumor immunity and provide the rationale for a possible usage of mutated, tumor-specific Ags for immunotherapy of human cancer.     

Spike‐in SILAC proteomic approach reveals the vitronectin as an early molecular signature of liver fibrosis in hepatitis C infections with hepatic iron overload

Hepatitis C virus (HCV)‐induced iron overload has been shown to promote liver fibrosis, steatosis, and hepatocellular carcinoma. The zonal‐restricted histological distribution of pathological iron deposits has hampered the attempt to perform large‐scale in vivo molecular investigations on the comorbidity between iron and HCV. Diagnostic and prognostic markers are not yet available to assess iron overload‐induced liver fibrogenesis and progression in HCV infections. Here, by means of Spike‐in SILAC proteomic approach, we first unveiled a specific membrane protein expression signature of HCV cell cultures in the presence of iron overload. Computational analysis of proteomic dataset highlighted the hepatocytic vitronectin expression as the most promising specific biomarker for iron‐associated fibrogenesis in HCV infections. Next, the robustness of our in vitro findings was challenged in human liver biopsies by immunohistochemistry and yielded two major results: (i) hepatocytic vitronectin expression is associated to liver fibrogenesis in HCV‐infected patients with iron overload; (ii) hepatic vitronectin expression was found to discriminate also the transition between mild to moderate fibrosis in HCV‐infected patients without iron overload.     

Association between a Genetic Variant of Type-1 Cannabinoid Receptor and Inflammatory Neurodegeneration in Multiple Sclerosis

Genetic ablation of type-1 cannabinoid receptors (CB₁Rs) exacerbates the neurodegenerative damage of experimental autoimmune encephalomyelitis, the rodent model of multiple sclerosis (MS). To address the role on CB₁Rs in the pathophysiology of human MS, we first investigated the impact of AAT trinucleotide short tandem repeat polymorphism of CNR1 gene on CB₁R cell expression, and secondly on the inflammatory neurodegeneration process responsible for irreversible disability in MS patients. We found that MS patients with long AAT repeats within the CNR1 gene (≥12 in both alleles) had more pronounced neuronal degeneration in response to inflammatory white matter damage both in the optic nerve and in the cortex. Optical Coherence Tomography (OCT), in fact, showed more severe alterations of the retinal nerve fiber layer (RNFL) thickness and of the macular volume (MV) after an episode of optic neuritis in MS patients carrying the long AAT genotype of CNR1. MS patients with long AAT repeats also had magnetic resonance imaging (MRI) evidence of increased gray matter damage in response to inflammatory lesions of the white matter, especially in areas with a major role in cognition. In parallel, visual abilities evaluated at the low contrast acuity test, and cognitive performances were negatively influenced by the long AAT CNR1 genotype in our sample of MS patients. Our results demonstrate the biological relevance of the (AAT)_n CNR1 repeats in the inflammatory neurodegenerative damage of MS.     

Dermatophytosis in Military in the Central-West Region of Brazil: Literature Review

Background

Dermatophytes represent a group of keratinophilic fungi capable of invading the superficial layer of the skin, hair, and nails of humans and animals. There is a high prevalence of dermatomycosis in tropical regions, and military personnel are susceptible to this kind of infection due to the type of occupational activities.

Objective

This study was to investigate dermatophytosis in military, in addition to predisposing factors to such infections.

Methods

The direct examination of the 221 samples obtained was conducted by preparing fresh slides, clarified with KOH. The clinical materials were seeded in duplicate in SDA and in Mycosel agar medium. The identification of the etiologic agents was performed according to the Riddell technique.

Results

99/221 (44.8 %) of the dermatophyte infection agents distributed in the three taxonomic genera that cause Tinea were recovered. The Trichophyton genus was the most representative and T. rubrum species 33 (33.3 %), the most prevalent. The other species found were as follows: T. tonsurans 13 (13.1 %), T. verrucosum 11 (11.1 %), T. interdigitale 9 (9.1 %), and T. mentagrophytes 6 (6.1 %). Among the most affected anatomical sites were skin 83 (83.8 %) and nails 17 (17.2 %).

Conclusions

Dermatophyte infections are common disorders in tropical countries. These infections lead to a variety of clinical manifestations. This study reports the incidence of dermatophytosis in the military personnel in the Central-West Region of Brazil. The occupational activities of the military individuals, in addition to the hot and humid climate of the region, can predispose them to infection by these fungal entities.