Serological biomarker for assessing human exposure to Aedes mosquito bites during a randomized vector control intervention trial in northeastern Thailand

BackgroundAedes mosquitoes are vectors for several major arboviruses of public health concern including dengue viruses. The relationships between Aedes infestation and disease transmission are complex wherein the epidemiological dynamics can be difficult to discern because of a lack of robust and sensitive indicators for predicting transmission risk. This study investigates the use of anti-Aedes saliva antibodies as a serological biomarker for Aedes mosquito bites to assess small scale variations in adult Aedes density and dengue virus (DENV) transmission risk in northeastern Thailand. Individual characteristics, behaviors/occupation and socio-demographics, climatic and epidemiological risk factors associated with human-mosquito exposure are also addressed.MethodsThe study was conducted within a randomized clustered control trial in Roi Et and Khon Kaen provinces over a consecutive 19 months period. Thirty-six (36) clusters were selected, each of ten houses. Serological and entomological surveys were conducted in all houses every four months and monthly in three sentinel households per cluster between September 2017 and April 2019 for blood spot collections and recording concurrent immature and adult Aedes indices. Additionally, the human exposure to Aedes mosquito bites (i.e., Mosquito Exposure Index or MEI) was estimated by ELISA measuring levels of human antibody response to the specific Nterm-34 kDa salivary antigen. The relationships between the MEI, vector infestation indices (adult and immature stages) and vector DENV infection were evaluated using a two-level (house and individual levels) mixed model analysis with one-month lag autoregressive correlation.ResultsThere was a strong positive relationship between the MEI and adult Aedes (indoor and outdoor) density. Individuals from households with a medium mosquito density (mean difference: 0.091, p<0.001) and households with a high mosquito density (mean difference: 0.131, p<0.001) had higher MEI’s compared to individuals from households without Aedes. On a similar trend, individuals from households with a low, medium or high indoor Aedes densities (mean difference: 0.021, p<0.007, 0.053, p<0.0001 and 0.037, p<0.0001 for low, medium and high levels of infestation, respectively) had higher MEI than individuals from houses without indoor Aedes. The MEI was driven by individual characteristics, such as gender, age and occupation/behaviors, and varied according to climatic, seasonal factors and vector control intervention (p<0.05). Nevertheless, the study did not demonstrate a clear correlation between MEI and the presence of DENV-infected Aedes.ConclusionThis study represents an important step toward the validation of the specific IgG response to the Aedes salivary peptide Nterm-34kDa as a proxy measure for Aedes infestation levels and human-mosquito exposure risk in a dengue endemic setting. The use of the IgG response to the Nterm-34 kDa peptide as a viable diagnostic tool for estimating dengue transmission requires further investigations and validation in other geographical and transmission settings.     

Immunocytochemical detection of p16INK4a protein in scraped cervical cells

OBJECTIVE: To develop an immunocytochemical technique for p16INK4a protein detection in scraped cervical cells for cancer screening. STUDY DESIGN: We took duplicate cervical scrapes from each participant, the first for a Pap smear and the second for p16INK4a protein detection. From a 50-microL cell suspension prepared from the scrape rinsing, a 10-microL aliquot was dropped in a 5-mm-diameter circle on a glass slide, air dried and fixed in 0.1% formal saline (1 hour) and in 95% ethanol (10 minutes). Using the immunocytochemical technique, slides from 30 samples of each Pap diagnosis class were stained sequentially with mouse monoclonal anti-p16INK4a (primary antibody), biotinylated goat antimouse IgG (secondary antibody), horse-radish peroxidase-labelled streptavidin and 3,3'-diaminobenzidine and mixed hydrogen peroxide, then counterstained with hematoxylin. A positive sample had to contain > or = 3 immunoreactive cells. Results were confirmed by western blot analysis of lysates from the remaining 40 microL of each cervical cell suspension. RESULTS: Samples were grouped as control (normal cervical cells), mild dysplasia (ASCUS, LSIL) and high abnormality (HSIL, SCC). Using the immunocytochemical technique, > 95% of the positive (SiHa cells) but 0% of the negative controls (human embryonic lung fibroblast cells) showed immunoreactive cells. All slides displayed a clear background without mucus, and positive cells were stained in both the cytoplasm and nucleus. p16INK4a Protein was detected in 17 of 30 (56.67%) ASCUS and 10 of 30 (33.33%) LSIL and increased with the degree of abnormality to 93.33% (28 of 30) and 96.67% (29 of 30) in the HSIL and SCC group, respectively. Normal cervical cells and degenerated malignant cells were nonimmunoreactive. Western blot analysis confirmed similar positive samples in the low-abnormality group, while the whole high-abnormality group was immunoreactive. A sampling error might have caused the 2 HSIL and 1 SCC sample to be negative using our immunocytochemical technique. CONCLUSION: p16INK4a Protein detection in scraped cervical cells using the immunocytochemical technique correlated with western blot analysis and was nontraumatic and precise. It offers a significant diagnostic adjunct to the Pap test for cervical cancer screening.     

Up-Regulation of miR-21 Is Associated with Cervicitis and Human Papillomavirus Infection in Cervical Tissues

MicroRNA-21 (miR-21) is recognized as an oncomir and shows up-regulation in many types of human malignancy. The aim of this study was to investigate the association of miR-21 expression associated with HPV infection in normal and abnormal cervical tissues. Cervical tissue samples with different cytological or histopathological grades were investigated for HPV by PCR and for miR-21 and programmed cell death, protein 4 (PDCD4) expression using quantitative real-time PCR (qRT-PCR). Laser capture microdissection (LCM) of stromal and epithelial tissues and in situ hybridization (ISH) using locked nucleic acid (LNA) probes were performed on a subset of fixed specimens. Cell line experiments were conducted on fibroblasts stimulated in culture media from HeLa cells, which were then assessed for miR-21, PDCD4, IL-6 and α-SMA expression by qRT-PCR. Twenty normal cervical cell, 12 cervicitis, 14 cervical intraepithelial neoplastic I (CIN I), 22 CIN II-III and 43 cervical squamous cell carcinoma (SCC) specimens were investigated. miR-21 levels were significantly lower in normal than in abnormal tissues. The expression of miR-21 in HPV negative normal cytology was significantly lower than in HPV positive samples in abnormal tissue and SCC. The miR-21 expression was significantly higher in HPV negative cervicitis than HPV negative normal cells. LCM and ISH data showed that miR-21 is primarily expressed in the tumor-associated stromal cell microenvironment. Fibroblasts treated with HeLa cell culture media showed up-regulated expression of miR-21, which correlated with increased expression of α-SMA and IL-6 and with down-regulation of PDCD4. These results demonstrate that miR-21 is associated with HPV infection and involved in cervical lesions as well as cervicitis and its up-regulation in tumor-stroma might be involved in the inflammation process and cervical cancer progression.     

The cationic cell-penetrating KT2 peptide promotes cell membrane defects and apoptosis with autophagy inhibition in human HCT 116 colon cancer cells

The anticancer activity of cationic antimicrobial peptides (AMPs) has become more interesting because some AMPs have selective recognition against cancer cells. However, their antitumor properties and underlying mechanisms in cancer cells have not been clearly understood. In this study, we evaluated the effects of KT2 (lysine/tryptophan-rich AMP) on the cellular uptake and internalization mechanism, cell viability, surface charge of the cell membrane, membrane integrity, apoptotic cell death, and autophagy in human HCT 116 colon cancer cells. We found that KT2 interacted with the cell membrane of HCT 116 cells and was internalized into HCT 116 cells via clathrin-mediated and caveolae-mediated endocytosis mechanisms. The interaction of KT2 with cells caused cell membrane structure change, elevated membrane permeability, and KT2 also affected the lipid component. The results of atomic force microscopy showed cellular membrane defects of KT2-treated cells. The internalized KT2 induced nuclear condensation and apoptotic cell death. It elevated the apoptotic factor levels including those of cytochrome c and apoptosis-inducing factor. Furthermore, KT2 inhibited autophagy by the suppression of autophagy-related 5, autophagy-related 7, autophagy-related 16 like 1, and Beclin-1 proteins. In conclusion, these results revealed the cytotoxicity of cationic KT2 against HCT 116 cells and may help to clarify the interactions between cationic AMPs and cancer cells.     

Risk factors for cholangiocarcinoma in high-risk area of Thailand: role of lifestyle, diet and methylenetetrahydrofolate reductase polymorphisms

Background and aim: Cholangiocarcinoma (CCA) is the most common cancer in Northeast Thailand. Endemicity of Opisthorchis viverrini (OV) – a known carcinogen – is responsible, but although infection is very common, the lifetime risk of CCA is only 5%. Other co-factors must exist, including aspects of lifestyle or diet along with variations in genetic susceptibility to them. Change in methylenetetrahydrofolate reductase (MTHFR) activity may influence both DNA methylation and synthesis. This study investigates risk factors for CCA with a focus on lifestyle, diet and MTHFR polymorphisms. Methods: Nested case–control study within cohort study was conducted. 219 subjects with primary CCA were each matched with two non-cancer controls from the same cohort on sex, age at recruitment and presence/absence of OV eggs in stool. Lifestyle and dietary data were obtained at recruitment. MTHFR polymorphisms were analyzed using PCR with high resolution melting analysis. The associations were assessed using conditional logistic regression. Results: Consumption of alcohol, raw freshwater fish and beef sausage increased the risk of CCA, while fruit and/or vegetables consumption reduced risk. There were interactions between MTHFR and preserved freshwater fish and beef. These dietary items are either a source of OV or of pre-formed nitrosamine, folate and antioxidants that are of possible relevance in OV carcinogenesis. Conclusions: Primary prevention of CCA in high-risk population is based upon efforts to reduce OV infection. Reduced consumption of alcohol and preserved meats, and increased consumption of dietary folate, actions with a wider preventive potential, may also help in the reduction of CCA burden.     

Bioactive constituents from the leaves of Clinacanthus nutans Lindau

Three chlorophyll derivatives (phaeophytins) were isolated from the chloroform extract of Clinacanthus nutans Lindau leaves by means of chromatographic techniques and bioactivity-guided fractionation to give three pure compounds. Structure elucidation of the isolated compounds was carried out on the basis of spectral analyses. Three of these were known compounds with structures related to chlorophyll a and chlorophyll b namely 13²-hydroxy-(13²-R)-phaeophytin b, 13²-hydroxy-(13²-S)-phaeophytin a and 13²-hydroxy-(13²-R)-phaeophytin a. These compounds, which have not previously been reported in this plant, were shown to have anti-herpes simplex activity. They exhibited anti-HSV-1F activity at subtoxic concentrations. Their inhibitory activity affected the virus before viral entry to the host cells. This effect might be virucidal or interference with viral adsorption or penetration.