Lipidomics analysis of outer membrane vesicles and elucidation of the inositol phosphoceramide biosynthetic pathway in Bacteroides thetaiotaomicron

Approximately one-third of the human colonic microbiome is formed by bacteria from the genu

LPS remodeling triggers formation of outer membrane vesicles in Salmonella.

Outer membrane vesicles (OMV) are proposed to mediate multiple functions during pathogenesis and symbiosis. However, the mechanisms responsible for OMV formation remain poorly understood. It has been shown in eukaryotic membranes that lipids with an inverted-cone shape favor the formation of positive membrane curvatures. Based on these studies, we formulated the hypothesis that lipid A deacylation might impose shape modifications that result in the curvature of the outer membrane (OM) and subsequent OMV formation. We tested the effect of lipid A remodeling on OMV biogenesis employing Salmonella enterica serovar Typhimurium as a model organism. Expression of the lipid A deacylase PagL resulted in increased vesiculation, without inducing an envelope stress response. Mass spectrometry analysis revealed profound differences in the patterns of lipid A in OM and OMV, with accumulation of deacylated lipid A forms exclusively in OMV. OMV biogenesis by intracellular bacteria upon macrophage infection was drastically reduced in a pagL mutant strain. We propose a novel mechanism for OMV biogenesis requiring lipid A deacylation in the context of a multifactorial process that involves the orchestrated remodeling of the outer membrane

Evolution of migraine-associated symptoms in menstrually related migraine following symptomatic treatment with almotriptan

In addition to headache, migraine is characterized by a series of symptoms that negatively affects the quality of life of patients. Generally, these are represented by nausea, vomiting, photophobia, phonophobia and osmophobia, with a cumulative percentage of the onset in about 90% of the patients. From this point of view, menstrually related migraine—a particularly difficult-to-treat form of primary headache—is no different from other forms of migraine. Symptomatic treatment should therefore be evaluated not only in terms of headache relief, but also by considering its effect on these migraine-associated symptoms (MAS). Starting from the data collected in a recently completed multicentre, randomized, double-blind, placebo-controlled, cross-over study with almotriptan in menstrually related migraine, an analysis of the effect of this drug on the evolution of MAS was performed. Data suggest that almotriptan shows excellent efficacy on MAS in comparison to the placebo, with a significant reduction in the percentages of suffering patients over a 2-h period of time

Glycoengineered outer membrane vesicles: A novel platform for bacterial vaccines

The World Health Organization has indicated that we are entering into a post-antibiotic era in which infections that were routinely and successfully treated with antibiotics can now be lethal due to the global dissemination of multidrug resistant strains. Conjugate vaccines are an effective way to create a long-lasting immune response against bacteria. However, these vaccines present many drawbacks such as slow development, high price, and batch-to-batch inconsistencies. Alternate approaches for vaccine development are urgently needed. Here we present a new vaccine consisting of glycoengineered outer membrane vesicles (geOMVs). This platform exploits the fact that the initial steps in the biosynthesis of most bacterial glycans are similar. Therefore, it is possible to easily engineer non-pathogenic Escherichia coli lab strains to produce geOMVs displaying the glycan of the pathogen of interest. In this work we demonstrate the versatility of this platform by showing the efficacy of geOMVs as vaccines against Streptococcus pneumoniae in mice, and against Campylobacter jejuni in chicken. This cost-effective platform could be employed to generate vaccines to prevent infections caused by a wide variety of microbial agents in human and animals

Chronic migraine plus medication overuse headache: two entities or not?

Chronic migraine (CM) represents migraine natural evolution from its episodic form. It is realized through a chronicization phase that may require months or years and varies from patient to patient. The transition to more frequent attacks pattern is influenced by lifestyle, life events, comorbid conditions and personal genetic terrain, and it often leads to acute drugs overuse. Medication overuse headache (MOH) may complicate every type of headache and all the drugs employed for headache treatment can cause MOH. The first step in the management of CM complicated by medication overuse must be the withdrawal of the overused drugs and a detoxification treatment. The goal is not only to detoxify the patient and stop the chronic headache but also to improve responsiveness to acute or prophylactic drugs. Different methods have been suggested: gradual or abrupt withdrawal; home treatment, hospitalization, or a day-hospital setting; re-prophylaxes performed immediately or at the end of the wash-out period. Up to now, only topiramate and local injection of onabotulinumtoxinA have shown efficacy as therapeutic agents for re-prophylaxis after detoxification in patients with CM with and without medication overuse. Although the two treatments showed similar efficacy, onabotulinumtoxinA is associated with a better adverse events profile. Recently, the Phase III Research Evaluating Migraine Prophylaxis Therapy (PREEMPT) clinical program proved that patients with CM, even those with MOH, are the ones most likely to benefit from onabotulinumtoxinA treatment. Furthermore, it provided an injection paradigm that can be used as a guide for a correct administration of onabotulinumtoxinA

Emicrania, FOP e alterazioni RMN

L\u2019emicrania e lo shunt dx/sn da forame ovale pervio (FOP) sono considerati fattori di rischio per lo stroke ischemico giovanile (Lechat, et al., 1988, Webster at al., 1988, Ditullio et al., 1992). Dati recenti suggeriscono che, come per lo stroke giovanile, in una percentuale pari al 40% di emicranici con aura (ECA) \ue8 dimostrabile una perviet\ue0 del forame ovale (Del Sette et al., 1998, Anzola et al., 1999), il che induce a supporne un possibile ruolo concausale dell\u2019emicrania (Sztajzel et al., 2002). Inoltre in un nostro precedente studio era stata rilevata una maggior frequenza di lesioni della sostanza bianca alla RMN negli emicranici con FOP (Giberti et al., 2002) .Scopo dello studio, oltre alla conferma di questi risultati, \ue8 quello di correlare le caratteristiche dell\u2019emicrania (presenza/assenza di aura; alta/bassa frequenza degli episodi) con i reperti RMN e la presenza e tipo di FOP. Sono stati arruolati 63 pazienti emicranici, 32 ECA e 31 senz\u2019aura (ESA), privi di fattori di rischio cerebrovascolare, di et\ue0 media 36 anni - \uf073 = 5.89, durata di malattia uniforme (media 8 anni - \uf073 = 1.5), considerando la frequenza delle crisi, la presenza di shunt dx/sn (rilevata con doppler transcranico e confermata dall\u2019ecocardiografia transesofagea) e la presenza di lesioni iperintense della sostanza bianca alla RMN. La distribuzione del tipo di FOP \ue8 significativamente (p = 3.6 * 10^-5) diversa nei pazienti con ECA rispetto a quelli con ESA, indipendentemente dalla frequenza delle crisi (p = 0.21): i soggetti con ECA hanno infatti FOP permanente nel 34% dei casi e FOP latente nel 16%, mentre quelli con ESA hanno FOP permanente nel 10% e FOP latente nel 23% dei casi. Le alterazioni RMN sono a loro volta correlate in maniera pi\uf9 significativa con l\u2019alta frequenza delle crisi (66% di positivit\ue0 tra quelli con alta frequenza, 30% di positivit\ue0 nei casi con bassa frequenza; p = 3.6 * 10^-4) piuttosto che con il tipo di crisi (frequenza lievemente superiore nell\u2019ECA: 47%, rispetto all\u2019ESA: 39%). L\u2019associazione significativa fra FOP permanente e ECA suggerisce un possibile ruolo patogenetico dello shunt nel determinismo della crisi con aura, con meccanismi ancora ipotetici (D\u2019Andrea et al., 1985, Wilmshurst et al., 2000, Pierangeli et al., 2002). Resta da dimostrare il significato delle lesioni alla RM nel follow-up a lungo termine dei pazienti con alta frequenza di crisi, in particolare per quanto concerne l\u2019eventuale sviluppo di disabilit\ue0 neurologic

Surface Exposure and Packing of Lipoproteins into Outer Membrane Vesicles Are Coupled Processes in Bacteroides

Species from the Bacteroides genus are predominant members of the human gut microbiota. OMVs in Bacteroides have been shown to be important for the homeostasis of complex host-commensal relationships, mainly involving immune tolerance and protection from disease. OMVs carry many enzymatic activities involved in the cleavage of complex polysaccharides and have been proposed as public goods that can provide growth to other bacterial species by release of polysaccharide breakdown products into the gut lumen. This work shows that the presence of a negatively charged rich amino acid motif (LES) is required for efficient packing of the surface-exposed alpha-amylase SusG into OMVs. Our findings strongly suggest that surface exposure is coupled to packing of Bacteroides lipoproteins into OMVs. This is the first step in the generation of tailor-made probiotic interventions that can exploit LES-related sequences to generate Bacteroides strains displaying proteins of interest in OMVs.Outer membrane vesicles (OMVs) are spherical structures derived from the outer membranes (OMs) of Gram-negative bacteria. Bacteroides spp. are prominent components of the human gut microbiota, and OMVs produced by these species are proposed to play key roles in gut homeostasis. OMV biogenesis in Bacteroides is a poorly understood process. Here, we revisited the protein composition of Bacteroides thetaiotaomicron OMVs by mass spectrometry. We confirmed that OMVs produced by this organism contain large quantities of glycosidases and proteases, with most of them being lipoproteins. We found that most of these OMV-enriched lipoproteins are encoded by polysaccharide utilization loci (PULs), such as the sus operon. We examined the subcellular locations of the components of the Sus system and found a split localization; the alpha-amylase SusG is highly enriched in OMVs, while the oligosaccharide importer SusC remains mostly in the OM. We found that all OMV-enriched lipoproteins possess a lipoprotein export sequence (LES), and we show that this signal mediates translocation of SusG from the periplasmic face of the OM toward the extracellular milieu. Mutations in the LES motif caused defects in surface exposure and recruitment of SusG into OMVs. These experiments link, for the first time, surface exposure to recruitment of proteins into OMVs. We also show that surface-exposed SusG in OMVs is active and rescues the growth of bacterial cells incapable of growing on starch as the only carbon source. Our results support the role of OMVs as “public goods” that can be utilized by other organisms with different metabolic capabilities