The First Record of Aedes vittatus (Diptera: Culicidae) in the Dominican Republic: Public Health Implications of a Potential Invasive Mosquito Species in the Americas.

Aedes vittatus Bigot is distributed throughout Africa, tropical Asia, and southern Europe and occurs in sylvatic as well as peridomestic environments where it readily feeds on humans. Although the vectorial capacity of Ae. vittatus is not well understood, this species is known to play a role in the maintenance and transmission of yellow fever, Zika, chikungunya, and dengue virus within its native range. In October 2019, after a routine inspection of mosquito-breeding containers in Jarabacoa, Dominican Republic, two Ae. vittatus females were captured via human landing catch method. After this finding, a CDC miniature light trap was deployed at the point of initial detection from 18:00 to 08:00 h, 2 d/wk from 3 to 31 October 2019. Potential larval habitats were also sampled via traditional dip method once per week spanning a 150 m radius from point of initial detection. In addition to the 2 adult females, 10 female and 2 male Ae. vittatus were captured. One Ae. vittatus larva also was found in a small puddle formed by an animal hoof print. Conventional PCR and Sanger sequencing were used to confirm morphological identification of collected specimens. This is the first detection of Ae. vittatus in the Dominican Republic as well as the Americas. Therefore, enhanced surveillance is needed to better understand the range and public health risks this potential invasive mosquito species may pose in the Dominican Republic, other Caribbean Islands, and/or the Americas.

Benzo[a]pyrene activates an AhR/Src/ERK axis that contributes to CYP1A1 induction and stable DNA adducts formation in lung cells.

Benzo[a]pyrene (B[a]P), the most extensively studied carcinogen in cigarette smoke, has been regarded as a critical mediator of lung cancer. It is known that B[a]P-mediated Aryl hydrocarbon Receptor (AhR) activation stimulates the mitogen activated protein kinases (MAPK) signaling cascade in different cell models. MAPK pathway disturbances drive alterations in cellular processes, such as differentiation, proliferation, and apoptosis, and the disturbances may also modify the AhR pathway itself. However, MAPK involvement in B[a]P metabolic activation and toxicity in lung tissues is not well understood. Here, we used a non-transformed human bronchial epithelial lung cell line, BEAS-2B, to study the participation of ERK 1/2 kinases in the metabolic activation of B[a]P and in its related genotoxic effects. Our results indicate that B[a]P is not cytotoxic to BEAS-2B cells at relatively low concentrations, but it enhances CYP1A1 gene transcription and protein induction. Additionally, B[a]P promotes Src and ERK 1/2 phosphorylation. Accordingly, inhibition of both Src and ERK 1/2 phosphorylation decreases CYP1A1 protein induction, AhR nuclear translocation and production of B[a]P adducts. Together, these data suggest a crosstalk between AhR and the members of the MAPK pathway, ERK 1/2 mediated by Src kinase. This interaction is important for the adequate AhR pathway signaling that in turn induces transcription and protein induction of CYP1A1 and B[a]P-induced DNA damage in BEAS-2B cells.

IN VIVO AND IN VITRO ANTILEISHMANIAL EFFECTS OF METHANOLIC EXTRACT FROM BARK OF BURSERA APTERA.

BACKGROUND: Cutaneous leishmaniasis lacks effective and well-tolerated treatments. The current therapies mainly rely on antimonial drugs that are inadequate because of their poor efficacy. Traditional medicine offers a complementary alternative for the treatment of various diseases. Additionally, several plants have shown success as anti-leishmanial agents. Therefore, we sought to evaluate the in vitro and in vivo activity of MEBA against Leishmania mexicana. MATERIALS AND METHODS: Methanolic extract of B. aptera was obtained by macetration, after we determined in vitro anti-leishmanial activity of MEBA by MTT assay and the induced apoptosis in promastigotes by flow cytometry. To analyze the in vivo anti-leishmanial activity, we used infected mice that were treated and not treated with MEBA and we determined the levels of cytokines using ELISA. The phytochemical properties were determined by CG-MS and DPPH assay. RESULTS: We determined of LC50 of 0.408 mg/mL of MEBA for in vitro anti-leishmanial activity. MEBA induced apoptosis in promastigotes (15.3% ± 0.86). Treated mice exhibited smaller lesions and contained significantly fewer parasites than did untreated mice; in addition, we found that IFN-γ and TNF-α increased in the sera of MEBA-treated mice. GC-MS analysis showed that podophyllotoxin was the most abundant compound. Evaluation of the activity by DPPH assay demonstrated an SC50 of 11.72 µg/mL. CONCLUSION: Based on the above data, it was concluded that MEBA is a good candidate in the search for new anti-leishmanial agents.

Vascular alpha-1D-adrenoceptors are overexpressed in aorta of the aryl hydrocarbon receptor null mouse: role of increased angiotensin II.

1 The hypothesis that alpha(1D)-adrenoceptors may mediate the pro-hypertensive actions of angiotensin II (Ang II) was tested in isolated aorta (alpha(1D)-adrenoceptor bearing tissue) of the aryl hydrocarbon receptor null mouse (AhR(-/-)), which shows increased levels of Ang II, cardiac hypertrophy and hypertension. 2 The effect of captopril (an angiotensin converting enzyme inhibitor) on both blood pressure and aortic alpha(1D)-adrenoceptor expression and function in mice were determined. 3 Basal blood pressure was higher in AhR(-/-) mice, while captopril therapy decreased it to wild-type (WT) values. 4 Aortas of adult WT and AhR(-/-) mice were stimulated by phenylephrine or noradrenaline to induce contraction; the maximal effect was higher in AhR(-/-) mice, without a significant change in pEC(50). 5 PA(2) values for the selective alpha(1D)-adrenoceptor antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazynil]ethyl]-8-azaspiro [4.5]decane-7,9-dione) were 9.19 and 8.94 for WT and AhR(-/-), respectively; while Schild slopes were not different from 1. 6 PCR experiments showed c. 77% increase in AhR(-/-)alpha(1D)-adrenoceptors cDNA compared with WT mice; while western blot analysis demonstrated c. 88% increase in alpha(1D)-adrenoceptor protein in AhR(-/-) mice. 7 Captopril therapy decreased alpha(1D)-adrenoceptor-induced contraction and protein in AhR(-/-) mice to WT levels. 8 These data support the hypothesis that under conditions where Ang II is elevated, vascular alpha(1D)-adrenoceptors are increased, and further suggest that both Ang II and vascular alpha(1D)-adrenoceptors could be related in the onset of hypertension.

Intact glycans from cestode antigens are involved in innate activation of myeloid suppressor cells.

During helminthic infections, strong Th2 type-biased responses concomitant with impaired cell-proliferative responses to parasitic and unrelated antigens are major immunological hallmarks. Parasite glycan structures have been proposed to play a role in modulating these responses. To understand early events related to immune modulation during cestode infection, we have examined the role of intact glycans of antigens from Taenia crassiceps in the recruitment of innate cells. Soluble antigens from this cestode contained higher levels of carbohydrates than proteins. Intraperitoneal injection of the antigens rapidly recruited a cell population expressing F4/80(+)/Gr-1(+)surface markers, which adoptively suppressed naïve T-cell proliferation in vitro in response to anti-CD3/CD28 MAb stimulation in a cell-contact dependent manner. Soluble antigens with altered glycans by treatment with sodium periodate significantly reduced the recruitment of F4/80(+)/Gr1(+)cells, concomitantly their suppressive activity was abrogated, indicating that glycans have a role in the early activation of these suppressor cells. Using C3H/HeJ and STAT6-KO mice, we found that expansion and suppressive activity of F4/80(+)Gr1(+)cells induced by T. crassiceps intact antigens was TLR4 and Th2-type cytokine independent. Together with previous studies on nematode and trematode parasites, our data support the hypothesis that glycans can be involved on a similar pathway in the immunoregulation by helminths.

CpG-containing ODN has a limited role in the protection against Toxoplasma gondii.

Bacterial DNA containing immunostimulatory motifs (CpG) induces the development of a T(H1) immune response. Since protection against Toxoplasma gondii is correlated with this type of response, the aim of this work was to determine if a synthetic oligodeoxynucleotide (ODN) containing CpG sequences could be useful as adjuvant for the induction of a long-lasting protective immune response against T. gondii. BALB/c mice immunized with a total soluble antigen of T. gondii (TSA2) mixed with ODN-containing CpG sequences developed a typical TH1 response, as determined by antibody isotypes and interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production by spleen cells. However, they did not resist a challenge with the virulent RH strain of the parasite. Absence of protection paralleled with lower levels of IFN-gamma, when compared with mice vaccinated with the live tachyzoites of the attenuated ts.4 strain of the parasite, which resisted this challenge. Intraperitoneal injection of ODN alone to mice induced a high degree of resistance to a lethal challenge inoculated by the same route. Nevertheless, this nonspecific protection was transient. Thus, the use of ODN containing CpG motifs as adjuvant is of limited value for the induction of a protective immune response against T. gondii.

Susceptibility to Leishmania mexicana infection is due to the inability to produce IL-12 rather than lack of IL-12 responsiveness.

Almost all inbred mice are highly susceptible to parasites of the Leishmania mexicana complex that includes L. amazonensis and L. mexicana. Recent studies have reported that T cells from L. amazonensis-infected mice fail to respond to IL-12 due to impaired IL-12R expression. Here, we demonstrate that lymph node cells from L. mexicana-infected C57BL/6 and 129Sv/Ev mice respond efficiently to exogenous IL-12 in vitro and produce IFN-gamma. Moreover, we also show that deletion of signal transducer and activator of transcription (STAT)4 gene in resistant STAT6-/- mice renders them susceptible to L. mexicana. These findings indicate that an inability to produce IL-12 rather than unresponsiveness to this cytokine is responsible for susceptibility to L. mexicana. Moreover, the data also demonstrate that the STAT4-mediated pathway is critical for the development of protective immunity against cutaneous leishmaniasis, regardless of the species of Leishmania and/or genetic background of the mice.

Migration-inhibitory factor gene-deficient mice are susceptible to cutaneous Leishmania major infection.

To determine the role of endogenous migration-inhibitory factor (MIF) in the development of protective immunity against cutaneous leishmaniasis, we analyzed the course of cutaneous Leishmania major infection in MIF gene-deficient mice (MIF(-/-)) and wild-type (MIF(+/+)) mice. Following cutaneous L. major infection, MIF(-/-) mice were susceptible to disease and developed significantly larger lesions and greater parasite burdens than MIF(+/+) mice. Interestingly, antigen-stimulated lymph node cells from MIF(-/-) mice produced more interleukin-4 (IL-4) and gamma interferon (IFN-gamma) than those from MIF(+/+) mice, although the differences were statistically not significant. IFN-gamma-activated resting peritoneal macrophages from MIF(-/-) mice showed impaired macrophage leishmanicidal activity and produced significantly lower levels of nitric oxide and superoxide in vitro. The macrophages from MIF(-/-) mice, however, produced much more IL-6 than macrophages from wild-type mice. These findings demonstrate that endogenous MIF plays an important role in the development of protective immunity against L. major in vivo. Furthermore, they indicate that the susceptibility of MIF(-/-) mice to L. major infection is due to impaired macrophage leishmanicidal activity rather than dysregulation of Th1 and Th2 responses.

Genetically resistant mice lacking IL-18 gene develop Th1 response and control cutaneous Leishmania major infection.

IL-18 has been shown to play a critical role in the development of a Th1 response and immunity against intracellular pathogens. To determine the role of IL-18 in the development of protective immunity against Leishmania major, we have analyzed the course of cutaneous L. major in IL-18-deficient C57BL/6 mice (IL-18-/-) compared with similarly infected wild-type mice (IL-18+/+). After L. major infection, IL-18-/- mice may develop larger lesions during early phase of infection but eventually will resolve them as efficiently as IL-18+/+ mice. By 2 wk after infection, although Ag-stimulated lymph node cells from L. major-infected IL-18+/+ and IL-18-/- mice produced similar levels of IFN-gamma, those from IL-18-/- mice produced significantly more IL-12 and IL-4. By 10 wk after infection, both IL-18+/+ and IL-18-/- mice had resolved L. major infection. At this time, lymph node cells from both IL-18+/+ and IL-18-/- mice produced IL-12 and IFN-gamma but no IL-4. Furthermore, administration of anti-IFN-gamma Abs to IL-18-/- mice rendered them susceptible to L. major. These results indicate that despite the role IL-18 may play in early control of cutaneous L. major lesion growth, this cytokine is not critical for development of protective Th1 response and resolution of L. major infection.

Taenia crassiceps cysticercosis: a role for prostaglandin E2 in susceptibility.

Several biological factors are involved in susceptibility and resistance to murine cysticercosis. A substantial body of evidence implies prostaglandins as potent regulators of immune responses during parasitic diseases. Here we evaluated the role played by prostaglandin E2 in cysticercosis. Mice were treated in vivo with prostaglandin E2 or with indomethacin (a prostaglandin E2 synthesis inhibitor) before infection. Parasite growth was enhanced by prostaglandin treatment, which provoked poor Con-A responses, low Th1-type cytokines secretion, and high levels of IL-6 and IL-10. In contrast, mice receiving indomethacin showed a reduction in parasite load parallel to a strong Con-A response and high levels of IL-2 and IFN-gamma, concomitantly with a decrease in IL-4, IL-6 and IL-10 production. Indirect in vitro studies suggest that an important source of prostaglandin E2 production could be related to host's adherent cells. However, prostaglandin E2 from parasite origin cannot be discarded.

Th1-type cytokines improve resistance to murine cysticercosis caused by Taenia crassiceps.

Resistance and susceptibility to different parasitic diseases have been associated with the predominance of Th1- or Th2-type immune responses. In experimental murine cysticercosis a Th1 response seems to be involved in resistance, whereas Th2 activity is associated with heavy parasite intensities. To test this notion the roles of Th1- and Th2-type cytokines in infected mice were studied after treatment with anticytokine monoclonal antibodies or with recombinant murine cytokines during early stages of infection. Mice receiving anti-interleukin 10 (IL-10) carried lower parasite intensities than did control mice and developed a strong Th1-type response, whereas mice receiving anti-interferon gamma (IFN-gamma) showed a dramatic increase in susceptibility. Treatment with recombinant cytokines confirmed these results; mice receiving IFN-gamma and IL-2 showed low parasite numbers, whereas IL-10 induced a significant increase in parasite loads. Thus, the Th1-type immune response plays a fundamental role in protection against Taenia crassiceps cysticercosis, whereas Th2, at least through IL-10, favors parasite establishment.