Central nervous system involvement in experimental infection with Leishmania (Leishmania) amazonensis

We describe the pathologic alterations of the central nervous system (CNS) observed in experimental tegumentary leishmaniasis in BALB/c and Swiss mice. The mice were subcutaneously infected with 10(4) amastigotes of Leishmania (Leishmania) amazonensis. Animals were killed and brains were removed for histologic and immunocytochemical studies. Histologic examination showed that 66.6% of infected mice had a discrete hyperemia and inflammatory infiltrate in the meninges, composed of mononuclear cells and neutrophils with no detectable parasites. However, parasitized macrophages were detected in the cerebral parenchyma, as well as mast cells, lymphocytes, and polymorphonuclear cells. Necrosis in the cerebral parenchyma was also observed. Confocal fluorescence microscopy showed that CD8(+) T lymphocytes are the major component of the inflammatory infiltrate in the CNS. In addition to these cells, CD4(+), CD11b, and dendritic cells are present, in small numbers, in the inflammatory processes of the CNS. Thus, L. amazonensis is able to cross the blood-brain barrier and cause significant pathologic changes in the CNS.Univ Estadual Maranhao, Dept Patol, Maranhao, BrazilFiocruz MS, Inst Oswaldo Cruz, Lab Imunomodulacao, Dept Protozool, BR-21045900 Rio De Janeiro, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Morfol, Sao Paulo, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, Sao Paulo, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Morfol, Sao Paulo, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, Sao Paulo, BrazilWeb of Scienc

Infection of retinal epithelial cells with L. amazonensis impacts in extracellular matrix proteins

One of the manifestations of leishmaniases is eye injuries which main characteristics are the injury of the anterior chamber of the eye and the resistance to specific treatments. the retinal pigment epithelial (RPE) cells participate in pathogen-induced intraocular inflammatory processes. We investigated Leishmania amazonensis-RPE cells relationship and its impact in laminin and fibronectin production. Using RPE cell (ARPE-19), we demonstrated that L. amazonensis adhere to these cells in the first hour of infection, whereas parasite internalization was only observed after 6 h. Seventy-two hours after infection, vacuoles with parasites debris were observed intracellularly, and no parasite were observed intra- or extracellularly at the 96 h, suggesting that Leishmania can infect ARPE-19 cells although this cells are able to clear the infection. Fibronectin and laminin were associated with L. amazonensis-ARPE-19 interaction. Confocal analysis showed no substantial alterations in fibronectin presence in ARPE-19-infected or ARPE-19-noninfected cells, whereas laminin levels increased three times 10 h after L. amazonensis infection. After this time, laminin levels decreased in infected cells. These results suggest that L. amazonensis-ARPE-19 infection induces increased production of laminin in the beginning of infection which may facilitate parasite-host cell interactions.Instituto Oswaldo CruzFiocruz MS, Inst Oswaldo Cruz, Lab Imunomodulacao & Protozool, BR-21040900 Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilWeb of Scienc

Effects of <i>Passovia ovata</i> Mistletoe on Pro-Inflammatory Markers In Vitro and In Vivo

New agents that can suppress inflammatory responses are being sought, since chronic inflammation is associated with several pathologies. This work aims to elucidate phytochemicals from the hydroethanolic extract of mistletoe Passovia ovata (POH) and its anti-inflammatory potential. POH is submitted to HPLC-UV, qualitative analysis of chemical constituents, and flavonoid quantification. Cytotoxicity is evaluated in RAW 264.7 macrophages by MTT. LPS-stimulated RAW 264.7 cells are treated with POH and, after 48 h, the nitrite and cytokine levels are quantified. BALB/c mice are treated by gavage with POH and stimulated with λ-carrageenan to induce paw oedema or peritonitis. POH yield is 25% with anthraquinones, tannins, anthocyanins, anthocyanidins, flavonols, catechins and flavanones present and flavonoid content of 4.44 ± 0.157 mg QE/g dry weight. POH exhibits low cytotoxicity and significantly reduced (p < 0.01) nitrite, IL-1β, IL-6, and TNF-α quantification at 500 μg/mL. POH at 500 mg/kg prevents paw edema increase and also reduces inflammatory infiltrate and mast cells in the footpad. In the peritonitis model, POH does not influence cytokines levels or cell counts. Overall, POH demonstrates a high concentration of flavonoids and prominent effects in the reduction in pro-inflammatory markers in vitro and in the inhibition of paw oedema

Toxoplasma gondii Oral Infection Induces Intestinal Inflammation and Retinochoroiditis in Mice Genetically Selected for Immune Oral Tolerance Resistance

Toxoplasmosis is a worldwide disease with most of the infections originating through the oral route and generates various pathological manifestations, ranging from meningoencephalitis to retinochoroiditis and inflammatory bowel disease. Animal models for these pathologies are scarce and have limitations. We evaluated the outcome of Toxoplasma gondii oral infection with 50 or 100 cysts of the ME-49 strain in two lines of mice with extreme phenotypes of susceptibility (TS) or resistance (TR) to immune oral tolerance. Therefore, the aim of this study was to evaluate the behaviour of TS and TR mice, orally infected by T. gondii, and determine its value as a model for inflammatory diseases study. Mortality during the acute stage of the infection for TR was 50% for both dosages, while 10 and 40% of the TS died after infection with these respective dosages. in the chronic stage, the remaining TS succumbed while TR survived for 90 days. the TS displayed higher parasite load with lower intestinal inflammation and cellular proliferation, notwithstanding myocarditis, pneumonitis and meningoencephalitis. TR presented massive necrosis of villi and crypt, comparable to inflammatory bowel disease, with infiltration of lymphoid cells in the lamina propria of the intestines. Also, TR mice infected with 100 cysts presented intense cellular infiltrate within the photoreceptor layer of the eyes, changes in disposition and morphology of the retina cell layers and retinochoroiditis. During the infection, high levels of IL-6 were detected in the serum of TS mice and TR mice presented high amounts of IFN-gamma and TNF-alpha. Both mice lineages developed different disease outcomes, but it is emphasized that TR and TS mice presented acute and chronic stages of the infection, demonstrating that the two lineages offer an attractive model for studying toxoplasmosis

Immunofluorescence analysis of parasite in the ileum, liver and brain of TR and TS mice.

<p>Ileum of TR (A) and TS (B) mice. Note higher numbers of parasites in the TS ileum. Liver of TR (C) and TS (D) mice. Brain of TR (E) and TS (F) mice. The cells nuclei were stained by DAPI (blue); Green  =  Anti-<i>T. gondii</i>. Bar size: 25 µm.</p

Genus/groups, primers, size of the fragments and ATCC references of evaluated bacteria in the commensal intestinal microbiota of TR and TS mice.

<p>Genus/groups, primers, size of the fragments and ATCC references of evaluated bacteria in the commensal intestinal microbiota of TR and TS mice.</p

Cytokines concentration in sera (pg/ml) of TR and TS mice measured on days 7, 14 and 21 after the oral infection with 100 and 50 cysts of <i>Toxoplasma gondii</i>.

<p>(A) Concentration of IFN-γ. The TR mice presented about 3 times higher concentrations than TS mice at 7 days of infection. The titers dropped at 14 and 21 day both in TR and TS mice, but TR mice presented higher values on the 21^st day of infection compared with TS mice. (B) Concentration of TNF-α. The titer was higher in the TR mice than in TS mice, especially during the acute stage of toxoplasmosis. Along the course of the disease, concentration of TNF-α in both groups of mice displayed lower titers. (C) Concentration of IL-6. TS mice displayed higher titers of IL-6 during the course of infection compared with the TR mice. Both infected lineages presented higher concentrations, when confronted with non-infected mice. N.I. – non-infected. Bars represent the mean ±SE of three experiments with five mice per group. Statistical differences by the Student <i>t</i> test are indicated by * (p<0.05).</p

Survival rates of TR, TS and C57BL/6 mice and parasite load on TR and TS after oral infection with <i>Toxoplasma gondii</i> cysts.

<p>(A–B) The survival was evaluated during 90 days and is presented in percentage. C57BL/6 mice were used for comparative survival study with TR and TS mice. Representative data from three experiments, n = 18 for TR, TS and C57BL/6. (C–D) Number of parasites ×10⁵/g of liver (C) and brain (D) of TR (black bar) and TS (gray bar) mice, 21 days after oral infection with 50 and 100 cysts of <i>T. gondii</i>. Data are from 3 independent experiments. Number (E) and size (F) of cysts evaluated in the brains of TR and TS mice at the chronic phase of the infection (90 days) after oral infection with 50 and 100 cysts of <i>T. gondii</i>. Means are from six mice per group in two independent experiments. Statistical differences by the Student <i>t</i> test are indicated by * (p<0.05) or ** (p<0.01).</p

Parasite quantification in ileum of TR and TS mice, infected with 50 cists of ME-49, performed by real-time quantitative PCR.

<p>Parasite burden in TR mice (black bar) reached a peak at 14 days of infection and lowered by 21 days, while TS mice (gray bar) showed a constant increase with infection. Values obtained by comparing the amount of fluorescence obtained from serial dilutions, ranging from 1 to 10⁶ parasites. R2 value  = 0.962. Results are from a representative experiment out of three.</p