Therapeutic use of a cationic antimicrobial peptide from the spider Acanthoscurria gomesiana in the control of experimental candidiasis.

BACKGROUND: Antimicrobial peptides are present in animals, plants and microorganisms and play a fundamental role in the innate immune response. Gomesin is a cationic antimicrobial peptide purified from haemocytes of the spider Acanthoscurria gomesiana. It has a broad-spectrum of activity against bacteria, fungi, protozoa and tumour cells. Candida albicans is a commensal yeast that is part of the human microbiota. However, in immunocompromised patients, this fungus may cause skin, mucosal or systemic infections. The typical treatment for this mycosis comprises three major categories of antifungal drugs: polyenes, azoles and echinocandins; however cases of resistance to these drugs are frequently reported. With the emergence of microorganisms that are resistant to conventional antibiotics, the development of alternative treatments for candidiasis is important. In this study, we evaluate the efficacy of gomesin treatment on disseminated and vaginal candidiasis as well as its toxicity and biodistribution. RESULTS: Treatment with gomesin effectively reduced Candida albicans in the kidneys, spleen, liver and vagina of infected mice. The biodistribution of gomesin labelled with technetium-99 m showed that the peptide is captured in the kidneys, spleen and liver. Enhanced production of TNF-α, IFN-γ and IL-6 was detected in infected mice treated with gomesin, suggesting an immunomodulatory activity. Moreover, immunosuppressed and C. albicans-infected mice showed an increase in survival after treatment with gomesin and fluconazole. Systemic administration of gomesin was also not toxic to the mice. CONCLUSIONS: Gomesin proved to be effective against experimental Candida albicans infection. It can be used as an alternative therapy for candidiasis, either alone or in combination with fluconazole. Gomesin's mechanism is not fully understood, but we hypothesise that the peptide acts through the permeabilisation of the yeast membrane leading to death and/or releasing the yeast antigens that trigger the host immune response against infection. Therefore, data presented in this study reinforces the potential of gomesin as a therapeutic antifungal agent in both humans and animals.

Venous thromboembolism after ultrasound guided foam sclerotherapy.

OBJECTIVE: To analyze prevalence of venous thromboembolism (VTE) after ultrasound guided foam sclerotherapy. METHOD: Clinical retrospective study with patients treated from 2004 to 2014. Charts with incomplete data and follow-up less than 60 days were excluded. Polidocanol foam (Tessari method) was used. The primary outcome was the prevalence of VTE and the secondary were possible risk factors. Chi-square test and Marascuillo prodecure were applied at a significance level of 5%. RESULTS: 2,616 patients were included with 4,712 lower limbs treated. The mean age was 50.7±0.86, in majority female, 83.7%. VTE occurred in 0.49% (pulmonary embolism 0,3%) in a mean time of 44.0±42.2 days. Male gender, personal or family history of phlebitis or DVT and high caliber varicose veins were significantly associated to VTE. CONCLUSION: incidence of VTE is low, male gender, personal or family history of VTE and caliber of varicose veins greater than 7 mm increased the risk.

The transcription factor Relish controls Anaplasma marginale infection in the bovine tick Rhipicephalus microplus.

Rhipicephalus microplus is an important biological vector of Anaplasma marginale, the etiological agent of bovine anaplasmosis. The knowledge of tick immune responses to control bacterial infections remains limited. In this study, we demonstrate that transcription factor Relish from the IMD signaling pathway has an important role in the control of A. marginale infection in ticks. We found that RNA-mediated silencing of Relish caused a significant increase in the number of A. marginale in the midgut and salivary glands of R. microplus. In addition, the IMD pathway regulates the expression of the gene that encodes the antimicrobial peptide (AMP) microplusin. Moreover, microplusin expression was up-regulated in the midgut (2×) and salivary glands (8×) of A. marginale infected R. microplus. Therefore, it is plausible to hypothesize that microplusin may be involved in the A. marginale control. This study provides the first evidence of IMD signaling pathway participation on the A. marginale control in R. microplus.

In vitro establishment of ivermectin-resistant Rhipicephalus microplus cell line and the contribution of ABC transporters on the resistance mechanism.

The cattle tick Rhipicephalus microplus is one of the most economically damaging livestock ectoparasites, and its widespread resistance to acaricides is a considerable challenge to its control. In this scenario, the establishment of resistant cell lines is a useful approach to understand the mechanisms involved in the development of acaricide resistance, to identify drug resistance markers, and to develop new acaricides. This study describes the establishment of an ivermectin (IVM)-resistant R. microplus embryonic cell line, BME26-IVM. The resistant cells were obtained after the exposure of IVM-sensitive BME26 cells to increasing doses of IVM in a step-wise manner, starting from an initial non-toxic concentration of 0.5 µg/mL IVM, and reaching 6 µg/mL IVM after a 46-week period. BME26-IVM cell line was 4.5 times more resistant to IVM than the parental BME26 cell line (lethal concentration 50 (LC50) 15.1 ± 1.6 µg/mL and 3.35 ± 0.09 µg/mL, respectively). As an effort to determine the molecular mechanisms governing resistance, the contribution of ATP-binding cassette (ABC) transporter was investigated. Increased expression levels of ABC transporter genes were found in IVM-treated cells, and resistance to IVM was significantly reduced by co-incubation with 5 µM cyclosporine A (CsA), an ABC transporter inhibitor, suggesting the involvement of these proteins in IVM-resistance. These results are similar to those already described in IVM-resistant tick populations, and suggest that similar resistance mechanisms are involved in vitro and in vivo. They reinforce the hypothesis that ABC transporters are involved in IVM resistance and support the use of BME26-IVM as an in vitro approach to study acaricide resistance mechanisms.

ABC transporter efflux pumps: a defense mechanism against ivermectin in Rhipicephalus (Boophilus) microplus.

ATP-binding cassette (ABC) transporters are efflux transporters found in all organisms. These proteins are responsible for pumping xenobiotic and endogenous metabolites through extra- and intracellular membranes, thereby reducing cellular concentrations of toxic compounds. ABC transporters have been associated with drug resistance in several nematodes and parasitic arthropods. Here, the ability of ABC transporter inhibitors to enhance ivermectin (IVM) sensitivity was tested in larvae and adult females of Rhipicephalus (Boophilus) microplus. Larvae of susceptible and IVM-resistant tick populations were pre-exposed to sub-lethal doses of the ABC transporter inhibitors Cyclosporin A (CsA) and MK571, and subsequently treated with IVM in a Larval Packet Test (LPT). ABC transporter inhibition by both drugs significantly reduced the concentration for 50% lethality (LC(50)) values of four IVM-resistant populations but IVM sensitivity of a susceptible population remained unchanged. IVM sensitivity in adults was assessed through an artificial feeding assay. The addition of CsA to a blood meal substantially affected IVM toxicity in adult female ticks from a resistant population by reducing oviposition and egg viability, although it did not alter IVM toxicity in susceptible females. Three partial nucleotide sequences with similarity to ABC transporters were retrieved from the DFCI Boophilus microplus Gene Index (http://compbio.dfci.harvard.edu/index.html). Their transcriptional levels in the midgut of resistant and susceptible females were determined by quantitative PCR, showing that one of these sequences was significantly up-regulated in IVM-resistant females and suggesting its participation in IVM detoxification. We believe this work reports the first known evidence for the participation of ABC transporters in IVM resistance in R. microplus.