The Fumarprotocetraric Acid Inhibits Tau Covalently, Avoiding Cytotoxicity of Aggregates in Cells

Neurodegenerative disorders, including Tauopathies that involve tau protein, base their pathological mechanism on forming proteinaceous aggregates, which has a deleterious effect on cells triggering an inflammatory response. Moreover, tau inhibitors can exert their mechanism of action through noncovalent and covalent interactions. Thus, Michael's addition appears as a feasible type of interaction involving an α, β unsaturated carbonyl moiety to avoid pathological confirmation and further cytotoxicity. Moreover, we isolated three compounds from Antarctic lichens Cladonia cariosa and Himantormia lugubris: protolichesterinic acid (1), fumarprotocetraric acid (2), and lichesterinic acid (3). The maleimide cysteine labeling assay showed that compounds 1, 2, and 3 inhibit at 50 µM, but compounds 2 and 3 are statistically significant. Based on its inhibition capacity, we decided to test compound 2 further. Thus, our results suggest that compound 2 remodel soluble oligomers and diminish β sheet content, as demonstrated through ThT experiments. Hence, we added externally treated oligomers with compound 2 to demonstrate that they are harmless in cell culture. First, the morphology of cells in the presence of aggregates does not suffer evident changes compared to the control. Additionally, the externally added aggregates do not provoke a substantial LDH release compared to the control, indicating that treated oligomers do not provoke membrane damage in cell culture compared with aggregates alone. Thus, in the present work, we demonstrated that Michael's acceptors found in lichens could serve as a scaffold to explore different mechanisms of action to turn tau aggregates into harmless species.

[Chlamydia pneumoniae in patients with acquired pneumonia in the Santiago of Chile community]

BACKGROUND

The prevalence of Chlamydia pneumoniae infection varies according to the population and geographic area studied.

AIM

To evaluate the incidence of Chlamydia pneumoniae infection in Chilean subjects with community acquired pneumonia.

PATIENTS AND METHODS

Between 1995 and 1997, patients with community acquired pneumonia attending two emergency rooms in Santiago, were studied. The diagnosis of Chlamydia pneumoniae infection was based on the detection of Chlamydia pneumoniae specific IgG antibody in samples from both the acute and convalescent phase, using an indirect microimmunofluorescent technique. Evidence of present infection was defined as seroconversion, a significant increase in the titer of the second sample and an initial titer equal or greater than 1/512.

RESULTS

During the study period, 160 patients consulted and seven (six male), aged 54 +/- 27 years old, complied with the diagnostic criteria of present Chlamydia pneumoniae infection. These patients had no special clinical or radiological features. Five of seven patients improved without any specific treatment.

CONCLUSIONS

Eight percent of this sample of patients with community acquired pneumonia had Chlamydia pneumoniae infection. This agent should be included in the design of empiric treatment schemes, although our results cast doubt on the pathogenic role of Chlamydia pneumoniae in pneumonia.