Necrotic activity of ExhC from Mammaliicoccus sciuri is mediated by specific amino acid residues.

Mammaliicoccus sciuri, a commensal and pathogenic bacterium of significant clinical and veterinary relevance, expresses exfoliative toxin C (ExhC), a specific glutamyl endopeptidase belonging to the chymotrypsin family as the principal virulence factor. However, unlike most members of this family, ETs are inactive against a wide range of substrates and possess exquisite specificity for desmoglein-1 (Dsg1), a cadherin-like adhesion molecule that is crucial to maintain tissue integrity, thereby preventing the separation of skin cells and the entry of pathogens. ExhC is of clinical importance since in addition to causing exfoliation in pigs and mice, it induces necrosis in multiple mammalian cell lines, a property not observed for other ETs. Previous experiments have implicated the ExhC79-128 fragment in causing necrosis. Site-directed mutagenesis of specific residues within this fragment were studied and led to the design of an ExhC variant containing four-point mutations (ExhCmut4) lacking necrotic potential but retaining nearly wild-type (wt) levels of enzymatic activity. Moreover, the determination of the ExhCwt and ExhCmut4 crystal structures identified the conformation in the necrosis-linked region. These results constitute an important step toward the understanding of the mechanisms underlying the necrotic and epidermolytic activity of ExhC.

The Dimeric Peptide (KKYRYHLKPF)2K Shows Broad-Spectrum Antiviral Activity by Inhibiting Different Steps of Chikungunya and Zika Virus Infection.

Chikungunya virus (CHIKV) and Zika virus (ZIKV) are important disease-causing agents worldwide. Currently, there are no antiviral drugs or vaccines approved to treat these viruses. However, peptides have shown great potential for new drug development. A recent study described (p-BthTX-I)2K [(KKYRYHLKPF)2K], a peptide derived from the Bothropstoxin-I toxin in the venom of the Bothrops jararacussu snake, showed antiviral activity against SARS-CoV-2. In this study, we assessed the activity of this peptide against CHIKV and ZIKV and its antiviral action in the different stages of the viral replication cycle in vitro. We observed that (p-BthTX-I)2K impaired CHIKV infection by interfering with the early steps of the viral replication cycle, reducing CHIKV entry into BHK-21 cells specifically by reducing both the attachment and internalization steps. (p-BthTX-I)2K also inhibited the ZIKV replicative cycle in Vero cells. The peptide protected the cells against ZIKV infection and decreased the levels of the viral RNA and the NS3 protein of this virus at viral post-entry steps. In conclusion, this study highlights the potential of the (p-BthTX-I)2K peptide to be a novel broad-spectrum antiviral candidate that targets different steps of the replication cycle of both CHIKV and ZIKV.

Clinical Landscape and Rate of Exposure to Ilheus Virus: Insights from Systematic Review and Meta-Analysis.

Ilheus fever is a mosquito-borne, poorly known tropical disease. We aimed to report the pooled rate of exposure to the Ilheus virus (ILHV) and clinical outcomes of infection to determine the epidemiological patterns of ILHV. We conducted a meta-analysis of 37 studies (n = 17,722 individuals) from Latin America. The common clinical characteristics of ILHV infection were fever (82.3%), headache (52.9%), and myalgia (52.9%). Encephalitis complicated the course of the infection in 29.4% cases. Monotypic serological reactions detected a pooled rate of exposure of 2% to ILHV (95% CI: 1-2). Studies were mainly conducted in Brazil, with a pooled proportion of ILHV positivity of 8% (95% CI: 3-14). Males (12%) had higher rates of seropositivity than females (7%) and had high chances of ILHV infection (OR: 1.7, 95% CI: 1.2-2.5). Seropositivity increased with age, from 2% (95% CI: 2-3) among people aged 0-14 years to 8% (95% CI: 6-10) among people aged 15-64 years. Our analysis indicated a low and relatively constant burden of ILHV in Latin America. More research is needed to evaluate and innovate serological assays for ILHV to better estimate the burden and dynamics of epidemiological changes in ILHV infection in different regions.

Recent advances in SARS-CoV-2 Spike protein and RBD mutations comparison between new variants Alpha (B.1.1.7, United Kingdom), Beta (B.1.351, South Africa), Gamma (P.1, Brazil) and Delta (B.1.617.2, India).

New variants of SARS-CoV-2 Alpha (B.1.1.7); Beta (B.1.351) Gamma (P.1) and Delta (B.1.617.2) quickly spread in the UK, South Africa, Brazil and India, respectively. To address whether mutations in SARS-CoV-2 RBD spike protein could affect virus infectivity, peptides containing RBD amino acids mutations have been constructed and interacted with human ACE2 by computational methods. Our results suggest that mutations in RBD amino acids K417, E484, L452, T478 and N501 are expressively increasing the affinity of this protein with human angiotensin-converting enzyme 2 (ACE2), consequently, variants Alpha (B.1.1.7), Beta (B1.351), Gamma (P.1) and Delta (B.1.617.2) could be more infective in human cells compared with SARS-CoV-2 isolated in Wuhan-2019 and the Gamma and Delta variants could be the most infective among them.

Amphipathic chitosans improve the physicochemical properties of siRNA-chitosan nanoparticles at physiological conditions.

Chitosan has received a lot of attention as a carrier for small interfering RNA (siRNA), due to its capacity for complexation and intracellular release of these molecules. However, one of its limitations is its insolubility at neutral pH and the tendency towards aggregation of its nanoparticles in isotonic ionic strength. In this study, a series of amphipathic chitosans were synthesized by varying the degree of acetylation (DA) from ˜2 to ˜30 mol% and the degree of substitution (DS) from 5 to 25%. by tertiary amino groups (DEAE) The results showed that the adjustment of these parameters decreases the interparticle interactions mediated by hydrogen bonding to obtain nanoparticles with improved colloidal stability. siRNA-containing nanoparticles of 100 to 150 nm with low polydispersities (0.15-0.2) and slightly positive zeta potentials (˜+ 5 mV) were resistant to aggregation at pH 7.4 and ionic strength of 150 mM. This resistance to aggregation is provided by changes on the nanoparticle surface and highlights the importance of more organized self-assembly in providing colloidal stability at physiological conditions. Additionally, the PEGylation of the most promising vectors conferred favorable physicochemical properties to nanoparticles. The chitosans and their nanoparticles exhibited low toxicity and an efficient cell uptake, as probed by confocal microscopy of rhodamine labeled vectors. The results provide a new approach to overcome the limited stability of chitosan nanoparticles at physiological conditions and show the potential of these amphipathic chitosans as siRNA carriers.

Downregulation of OCLN and GAS1 in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is the most common histological subtype of kidney cancer. This carcinoma is histologically characterized by the presence of clear and abundant cytoplasm. In the present study, we sought to identify genes differentially expressed in ccRCC and build a molecular profile of this cancer. We selected genes described in the literature related to cellular differentiation and proliferation. We analyzed the gene and protein expression by quantitative PCR (qPCR) and immunohistochemistry, respectively, and examined possible epigenetic mechanisms that regulate their expression in ccRCC samples and cell lines. Occludin (OCLN) and growth arrest-specific 1 (GAS1) genes were underexpressed in ccRCC, and we report that miR-122 and miR-34a, respectively, may regulate their expression in this cancer. Furthermore, we showed by qPCR and immunohistochemistry that solute carrier family 2 member 1 (SLC2A1) was significantly overexpressed in ccRCC. The set of genes identified in the present study furthers our understanding of the molecular basis and development of ccRCC.

Differentially expressed genes in giant cell tumor of bone.

Giant cells tumors of bone (GCTB) are benign in nature but cause osteolytic destruction with a number of particular characteristics. These tumors can have uncertain biological behavior often contain a significant proportion of highly multinucleated cells, and may show aggressive behavior. We have studied differential gene expression in GCTB that may give a better understanding of their physiopathology, and might be helpful in prognosis and treatment. Rapid subtractive hybridization (RaSH) was used to identify and measure novel genes that appear to be differentially expressed, including KTN1, NEB, ROCK1, and ZAK using quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry in the samples of GCTBs compared to normal bone tissue. Normal bone was used in the methodology RaSH for comparison with the GCTB in identification of differentially expressed genes. Functional annotation indicated that these genes are involved in cellular processes related to their tumor phenotype. The differential expression of KTN1, ROCK1, and ZAK was independently confirmed by qRT-PCR and immunohistochemistry. The expression of the KTN1 and ROCK1 genes were increased in samples by qRT-PCR and immunohistochemistry, and ZAK had reduced expression. Since ZAK have CpG islands in their promoter region and low expression in tumor tissue, their methylation pattern was analyzed by MSP-PCR. The genes identified KTN1, ROCK1, and ZAK may be responsible for loss of cellular homeostasis in GCTB since they are responsible for various functions related to tumorigenesis such as cell migration, cytoskeletal organization, apoptosis, and cell cycle control and thus may contribute at some stage in the process of formation and development of GCTB.

Genomic and epigenomic integration identifies a prognostic signature in colon cancer.

PURPOSE: The importance of genetic and epigenetic alterations maybe in their aggregate role in altering core pathways in tumorigenesis. EXPERIMENTAL DESIGN: Merging genome-wide genomic and epigenomic alterations, we identify key genes and pathways altered in colorectal cancers (CRC). DNA methylation analysis was tested for predicting survival in CRC patients using Cox proportional hazard model. RESULTS: We identified 29 low frequency-mutated genes that are also inactivated by epigenetic mechanisms in CRC. Pathway analysis showed the extracellular matrix (ECM) remodeling pathway is silenced in CRC. Six ECM pathway genes were tested for their prognostic potential in large CRC cohorts (n = 777). DNA methylation of IGFBP3 and EVL predicted for poor survival (IGFBP3: HR = 2.58, 95% CI: 1.37-4.87, P = 0.004; EVL: HR = 2.48, 95% CI: 1.07-5.74, P = 0.034) and simultaneous methylation of multiple genes predicted significantly worse survival (HR = 8.61, 95% CI: 2.16-34.36, P < 0.001 for methylation of IGFBP3, EVL, CD109, and FLNC). DNA methylation of IGFBP3 and EVL was validated as a prognostic marker in an independent contemporary-matched cohort (IGFBP3 HR = 2.06, 95% CI: 1.04-4.09, P = 0.038; EVL HR = 2.23, 95% CI: 1.00-5.0, P = 0.05) and EVL DNA methylation remained significant in a secondary historical validation cohort (HR = 1.41, 95% CI: 1.05-1.89, P = 0.022). Moreover, DNA methylation of selected ECM genes helps to stratify the high-risk stage 2 colon cancers patients who would benefit from adjuvant chemotherapy (HR: 5.85, 95% CI: 2.03-16.83, P = 0.001 for simultaneous methylation of IGFBP3, EVL, and CD109). CONCLUSIONS: CRC that have silenced genes in ECM pathway components show worse survival suggesting that our finding provides novel prognostic biomarkers for CRC and reflects the high importance of integrative analyses linking genetic and epigenetic abnormalities with pathway disruption in cancer.

Gene expression analysis reveals novel altered genes in nasal polyps.

Nasal polyposis (NP) is a chronic inflammatory disease of the nasal mucosa characterized by the infiltration of inflammatory cells, mainly eosinophils. Although nasal polyposis occurs in 4% of the population, its physiopathology remains unclear. The aim of this study was to identify and characterize differentially expressed genes that can be used in the prognosis, treatment and elucidation of this physiopathology. To identify novel genes differentially expressed in NP, we applied real-time quantitative PCR to 11 NP samples and to a pool of total RNA from a subset of 13 normal nasal mucosa samples from human autopsies. For selecting genes, the methylated CpG island amplification technique was used. Five differentially methylated clones (ATP2A1, NOVA1, PLCD3, SOLH and TGFßI) were identified. However, these genes presented methylated CpG islands between exons, i.e., not in the promoter regions of the genes. Thus, as shown by real-time PCR, the ATP2A1, SOLH, PLDC3 and TGFßI genes were overexpressed in NP. The genes identified in this study are probably involved in some stage of the process of formation and development of nasal polyposis, as they were highly expressed in the nasal polyp samples.

Gene expression profiling reveals molecular marker candidates of laryngeal squamous cell carcinoma.

Laryngeal squamous cell carcinoma is very common in head and neck cancer, with high mortality rates and poor prognosis. In this study, we compared expression profiles of clinical samples from 13 larynx tumors and 10 non-neoplastic larynx tissues using a custom-built cDNA microarray containing 331 probes for 284 genes previously identified by informatics analysis of EST databases as markers of head and neck tumors. Thirty-five genes showed statistically significant differences (SNR > or = | 1.0 |, p< or =0.001) in the expression between tumor and non-tumor larynx tissue samples. Functional annotation indicated that these genes are involved in cellular processes relevant to the cancer phenotype, such as apoptosis, cell cycle, DNA repair, proteolysis, protease inhibition, signal transduction and transcriptional regulation. Six of the identified transcripts map to intronic regions of protein-coding genes and may comprise non-annotated exons or as yet uncharacterized long ncRNAs with a regulatory role in the gene expression program of larynx tissue. The differential expression of 10 of these genes (ADCY6, AES, AL2SCR3, CRR9, CSTB, DUSP1, MAP3K5, PLAT, UBL1 and ZNF706) was independently confirmed by quantitative real-time RT-PCR. Among these, the CSTB gene product has cysteine protease inhibitor activity that has been associated with an antimetastatic function. Interestingly, CSTB showed a low expression in the tumor samples analyzed (p<0.0001). The set of genes identified here contribute to a better understanding of the molecular basis of larynx cancer, and provide candidate markers for improving diagnosis, prognosis and treatment of this carcinoma.

Genetic alterations in benign lesions: chronic gastritis and gastric ulcer.

AIM: To investigate the occurrence of chromosome 3, 7, 8, 9, and 17 aneuploidies, TP53 gene deletion and p53 protein expression in chronic gastritis, atrophic gastritis and gastric ulcer, and their association with H pylori infection. METHODS: Gastric biopsies from normal mucosa (NM, n=10), chronic gastritis (CG, n=38), atrophic gastritis (CAG, n=13) and gastric ulcer (GU, n=21) were studied using fluorescence in situ hybridization (FISH) and immunohistochemical assay. A modified Giemsa staining technique and PCR were used to detect H pylori. An association of the gastric pathologies and aneuploidies with H pylori infection was assessed. RESULTS: Aneuploidies were increasingly found from CG (21%) to CAG (31%) and to GU (62%), involving mainly monosomy and trisomy 7, trisomies 7 and 8, and trisomies 7, 8 and 17, respectively. A significant association was found between H pylori infection and aneuploidies in CAG (P=0.0143) and GU (P=0.0498). No TP53 deletion was found in these gastric lesions, but p53-positive immunoreactivity was detected in 45% (5/11) and 12% (2/17) of CG and GU cases, respectively. However, there was no significant association between p53 expression and H pylori infection. CONCLUSION: The occurrence of aneuploidies in benign lesions evidences chromosomal instability in early stages of gastric carcinogenesis associated with H pylori infection, which may confer proliferative advantage. The increase of p53 protein expression in CG and GU may be due to overproduction of the wild-type protein related to an inflammatory response in mucosa.