Borrelia valaisiana resist complement-mediated killing independently of the recruitment of immune regulators and inactivation of complement components

Spirochetes belonging to the Borrelia (B.) burgdorferi sensu lato complex differ in their resistance to complement-mediated killing, particularly in regard to human serum. In the present study, we elucidate the serum and complement susceptibility of B. valaisiana, a genospecies with the potential to cause Lyme disease in Europe as well as in Asia. Among the investigated isolates, growth of ZWU3 Ny3 was not affected while growth of VS116 and Bv9 was strongly inhibited in the presence of 50% human serum. Analyzing complement activation, complement components C3, C4 and C6 were deposited on the surface of isolates VS116 and Bv9, and similarly the membrane attack complex was formed on their surface. In contrast, no surface-deposited components and no aberrations in cell morphology were detected for serum-resistant ZWU3 Ny3. While further investigating the protective role of bound complement regulators in mediating complement resistance, we discovered that none of the B. valaisiana isolates analyzed bound complement regulators Factor H, Factor H-like protein 1, C4b binding protein or C1 esterase inhibitor. In addition, B. valaisiana also lacked intrinsic proteolytic activity to degrade complement components C3, C3b, C4, C4b, and C5. Taken together, these findings suggest that certain B. valaisiana isolates differ in their capability to resist complement-mediating killing by human serum. The molecular mechanism utilized by B. valaisiana to inhibit bacteriolysis appears not to involve binding of the key host complement regulators of the alternative, classical, and lectin pathways as already known for serum-resistant Lyme disease or relapsing fever borreliae

Human malarial disease: a consequence of inflammatory cytokine release

Malaria causes an acute systemic human disease that bears many similarities, both clinically and mechanistically, to those caused by bacteria, rickettsia, and viruses. Over the past few decades, a literature has emerged that argues for most of the pathology seen in all of these infectious diseases being explained by activation of the inflammatory system, with the balance between the pro and anti-inflammatory cytokines being tipped towards the onset of systemic inflammation. Although not often expressed in energy terms, there is, when reduced to biochemical essentials, wide agreement that infection with falciparum malaria is often fatal because mitochondria are unable to generate enough ATP to maintain normal cellular function. Most, however, would contend that this largely occurs because sequestered parasitized red cells prevent sufficient oxygen getting to where it is needed. This review considers the evidence that an equally or more important way ATP deficency arises in malaria, as well as these other infectious diseases, is an inability of mitochondria, through the effects of inflammatory cytokines on their function, to utilise available oxygen. This activity of these cytokines, plus their capacity to control the pathways through which oxygen supply to mitochondria are restricted (particularly through directing sequestration and driving anaemia), combine to make falciparum malaria primarily an inflammatory cytokine-driven disease

Cerebrospinal fluid CXCL13 in Lyme neuroborreliosis and asymptomatic HIV infection

<p>Abstract</p> <p>Background</p> <p>It has been suggested that cerebrospinal fluid (CSF) CXCL13 is a diagnostic marker of Lyme neuroborreliosis (LNB), as its levels have been shown to be significantly higher in LNB than in several other CNS infections. Levels have also been shown to decline after treatment with intravenous ceftriaxone, but levels after treatment with oral doxycycline have previously not been studied. Like <it>Borrelia burgdorferi</it>, HIV also has neurotropic properties. Elevated serum CXCL13 concentrations have been reported in HIV patients, but data on CSF levels are limited.</p> <p>Methods</p> <p>We longitudinally analysed CSF CXCL13 concentrations in 25 LNB patients before and after oral doxycycline treatment. Furthermore, we analysed CSF CXCL13 concentrations in 16 untreated LNB patients, 27 asymptomatic untreated HIV-1 infected patients and 39 controls with no signs of infectious or inflammatory disease.</p> <p>Results</p> <p>In the longitudinal LNB study, initially high CSF CXCL13 levels declined significantly after doxycycline treatment, which correlated to a decreased CSF mononuclear cell count. In the cross-sectional study, all the LNB patients had CSF CXCL13 levels elevated above the lowest standard point of the assay (7.8 pg/mL), with a median concentration of 500 pg/mL (range 34–11,678). Of the HIV patients, 52% had elevated CSF CXCL13 levels (median 10 pg/mL, range 0–498). There was a clear overlap in CSF CXCL13 concentrations between LNB patients and asymptomatic HIV patients. All but one of the 39 controls had CSF CXCL13 levels below 7.8 pg/mL.</p> <p>Conclusions</p> <p>We confirm previous reports of highly elevated CSF CXCL13 levels in LNB patients and that these levels decline after oral doxycycline treatment. The same pattern is seen for CSF mononuclear cells. CSF CXCL13 levels are elevated in neurologically asymptomatic HIV patients and the levels overlap those of LNB patients. The diagnostic value of CSF CXCL13 in LNB remains to be established.</p

'Bordure Protectrice' ou l'art de dilapider ses atouts

"Bordure protectrice" est l'histoire d'un paradoxe majeur : Benyamin Netanyahou ne voulait pas d'un pareil affrontement, même si dès son élection en 2009 il s'était présenté comme l'homme qui "saura vaincre le Hamas"..