Evaluation of the biological function of ribosomal protein S18 from cattle tick Rhipicephalus microplus.

Rhipicephalus (Boophilus) microplus, also known as the cattle tick, causes severe parasitism and transmits different pathogens to vertebrate hosts, leading to massive economic losses. In the present study, we performed a functional characterization of a ribosomal protein from R. microplus to investigate its importance in blood feeding, egg production and viability. Ribosomal protein S18 (RPS18) is part of the 40S subunit, associated with 18S rRNA, and has been previously pointed to have a secondary role in different organisms. Rhipicephalus microplus RPS18 (RmRPS18) gene expression levels were modulated in female salivary glands during blood feeding. Moreover, mRNA levels in this tissue were 10 times higher than those in the midgut of fully engorged female ticks. Additionally, recombinant RmRPS18 was recognized by IgG antibodies from sera of cattle naturally or experimentally infested with ticks. RNAi-mediated knockdown of the RmRPS18 gene was performed in fully engorged females, leading to a significant (29 %) decrease in egg production. Additionally, egg hatching was completely impaired, suggesting that no viable eggs were produced by the RmRPS18-silenced group. Furthermore, antimicrobial assays revealed inhibitory activities against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria, affecting bacterial growth. Data presented here show the important role of RmRPS18 in tick physiology and suggest that RmRPS18 can be a potential target for the development of novel strategies for tick control.

Biochemical characterization of a novel sphingomyelinase-like protein from the Rhipicephalus microplus tick.

Sphingomyelinase D is a toxin present in venomous spiders and bacteria and is associated with infection symptoms in patients affected by spider bites. It was observed that in Ixodes scapularis ticks, sphingomyelinase-like protein secreted in saliva can modulate the host immune response, affecting the transmission of flavivirus to the host via exosomes. In this work, a sphingomyelinase D-like protein (RmSMase) from R. microplus, a tick responsible for economic losses and a vector of pathogens for cattle, was investigated. The amino acid sequence revealed the lack of important residues for enzymatic activity, but the recombinant protein showed sphingomyelinase D activity. RmSMase shows Ca2+ and Mg2+ dependence in acidic pH, differing from IsSMase, which has Mg2+ dependence in neutral pH. Due to the difference between RmSMase and other SMases described, the data suggest that RmSMase belongs to SMase D class IIc. RmSMase mRNA transcription levels are upregulated during tick feeding, and the recombinant protein was recognized by host antibodies elicited after heavy tick infestation, indicating that RmSMase is present in tick saliva and may play a role in the tick feeding process.

Use of monoclonal faecal elastase-1 concentration for pancreatic status assessment in cystic fibrosis patients.

OBJECTIVE: To assess the concentration of faecal elastase-1 (EL-1) in pediatric patients with cystic fibrosis with mutation DeltaF508. METHODS: Cross-sectional study with samples collected consecutively from 51 patients aged 4 months to 17 years old (mean 9.11±4.74); 32 (62.8%) patients were male. Clinical-demographic data were collected, as well as data on the type of mutation. Exocrine pancreatic insufficiency was established by the activity of faecal EL-1 < 200 µg/g. EL-1 was quantified through the monoclonal ELISA method (ScheBo Biotech AG, Germany). Pancreatic supplements were used in 46 (90.2%) patients. RESULTS: Forty-one (80.4%) patients presented with pancreatic insufficiency (EL-1 fecal < 100 µg/g): 17 (41.5%) were homozygous, 14 were heterozygous (34.1%) and 10 were non-DeltaF508 (24.4%). Regarding the mutation, there was a statistically significant association of homozygosity with faecal EL-1 concentration < 100 µg/g (p = 0.010). All patients considered to be pancreatic insufficient (n = 41) by the test were using pancreatic supplements. Ten (19.6%) presented faecal EL-1 > 200 µg/g, and 5/10 (50%) used enzymes. CONCLUSIONS: The activity of faecal EL-1 < 100 µg/g, indicating pancreatic insufficiency, was observed in 17/17 (100%) of homozygous patients, as expected, and was less frequent in patients who were heterozygous for DeltaF508 and in patients without the mutation. There was no association of faecal EL-1 concentration with age and sex of patients. The test was standardized, is easy to execute, and can be used to assess the pancreatic status of patients with cystic fibrosis.

Utilidade da concentração da elastase-1 fecal monoclonal na avaliação da função pancreática nos pacientes com fibrose cística / Use of monoclonal faecal elastase-1 concentration for pancreatic status assessment in cystic fibrosis patients

OBJETIVO: Avaliar a concentração da elastase-1 (EL-1) fecal em pacientes pediátricos com fibrose cística, portadores da mutação ∆F508. MÉTODOS: Estudo transversal com amostras colhidas consecutivamente de 51 pacientes com idade entre 4 meses e 17 anos (média 9,11±4,74), sendo 32 (62,8 por cento) pacientes do sexo masculino. Houve coleta de dados clínico-demográficos e do tipo de mutação. A insuficiência pancreática exócrina foi definida pela atividade da EL-1 fecal < 200 µg/g. A quantificação da EL-1 foi realizada pelo método ELISA monoclonal (ScheBo Biotech AG, Germany). A suplementação pancreática foi utilizada em 46 (90,2 por cento) pacientes. RESULTADOS: Quarenta e um (80,4 por cento) pacientes apresentaram insuficiência pancreática (EL-1 fecal < 100 µg/g), sendo 17 (41,5 por cento) homozigotos, 14 heterozigotos (34,1 por cento) e 10 sem ∆F508 (24,4 por cento). Ao considerar a mutação, houve associação estatisticamente significativa entre os homozigotos e a concentração da EL-1 fecal < 100 µg/g (p = 0,010). Todos os pacientes considerados insuficientes pancreáticos (n = 41) pelo teste utilizavam suplemento pancreático. Dez (19,6 por cento) apresentaram EL-1 fecal > 200 µg/g, e 5/10 (50 por cento) utilizavam enzimas. CONCLUSÕES: A atividade de EL-1 fecal < 100 µg/g, indicativa de insuficiência pancreática, apresentou-se em 17/17 (100 por cento) dos homozigotos, conforme o esperado, sendo menos frequente nos heterozigotos para ∆F508 e nos pacientes com ausência dessa mutação. Não houve relação entre a concentração da EL-1 fecal com idade e sexo dos pacientes. O teste foi padronizado, é de fácil execução e poderá ser utilizado para avaliação da função pancreática dos pacientes com fibrose cística.

OBJECTIVE: To assess the concentration of faecal elastase-1 (EL-1) in pediatric patients with cystic fibrosis with mutation ∆F508. METHODS: Cross-sectional study with samples collected consecutively from 51 patients aged 4 months to 17 years old (mean 9.11±4.74); 32 (62.8 percent) patients were male. Clinical-demographic data were collected, as well as data on the type of mutation. Exocrine pancreatic insufficiency was established by the activity of faecal EL-1 < 200 µg/g. EL-1 was quantified through the monoclonal ELISA method (ScheBo Biotech AG, Germany). Pancreatic supplements were used in 46 (90.2 percent) patients. RESULTS: Forty-one (80.4 percent) patients presented with pancreatic insufficiency (EL-1 fecal < 100 µg/g): 17 (41.5 percent) were homozygous, 14 were heterozygous (34.1 percent) and 10 were non-∆F508 (24.4 percent). Regarding the mutation, there was a statistically significant association of homozygosity with faecal EL-1 concentration < 100 µg/g (p = 0.010). All patients considered to be pancreatic insufficient (n = 41) by the test were using pancreatic supplements. Ten (19.6 percent) presented faecal EL-1 > 200 µg/g, and 5/10 (50 percent) used enzymes. CONCLUSIONS: The activity of faecal EL-1 < 100 µg/g, indicating pancreatic insufficiency, was observed in 17/17 (100 percent) of homozygous patients, as expected, and was less frequent in patients who were heterozygous for ∆F508 and in patients without the mutation. There was no association of faecal EL-1 concentration with age and sex of patients. The test was standardized, is easy to execute, and can be used to assess the pancreatic status of patients with cystic fibrosis.