Faeces-derived extracellular vesicles participate in the onset of barrier dysfunction leading to liver diseases

The role of extracellular vesicles (EVs) from faeces (fEVs) and small circulating EVs (cEVs) in liver diseases such as non-alcoholic fatty diseases (NAFLD) and non-alcoholic steatohepatitis (NASH) has not been demonstrated. fEVs and cEVs of healthy donors, NAFLD and NASH patients were isolated and characterized. The effects of EVs were evaluated in intestinal, endothelial, Kupffer and stellate cells. Non-muscular myosin light chain kinase (nmMLCK) deficient mice were used in vivo. Bacterial origins of fEVs were analysed by 16s rDNA gene sequencing. fEVs and small cEVs were composed of prokaryotic and eukaryotic origins. Only NASH-fEVs exerted deleterious effects. NASH-fEVs increased intestinal permeability and reduced expression of tight junction proteins that were prevented by nmMLCK inhibition, increased endothelial cell permeability and inflammatory cytokines and chemokines requiring TLR4/lipopolysaccharide pathway. NASH-fEVs and NASH-cEVs activated profibrotic and proinflammatory proteins of hepatic stellate cells. Treatment with NASH-fEVs evoked an increase in intestinal permeability in wild type but not in nmMLCK deficient mice. Bacterial origins of fEVs were different between NAFLD and NASH patients and 16 amplicon sequence variants were differentially abundant. We demonstrate that fEVs actively participate in barrier dysfunctions leading to liver injuries underscoring the role of nmMLCK and lipopolysaccharide carried by fEVs.

Bacterial and eukaryotic extracellular vesicles and nonalcoholic fatty liver disease: new players in the gut-liver axis?

The liver and intestine communicate in a bidirectional way through the biliary tract, portal vein, and other components of the gut-liver axis. The gut microbiota is one of the major contributors to the production of several proteins and bile acids. Imbalance in the gut bacterial community, called dysbiosis, participates in the development and progression of several chronic liver diseases, such as nonalcoholic fatty liver disease (NAFLD). NAFLD is currently considered the main chronic liver disease worldwide. Dysbiosis contributes to NAFLD development and progression, notably by a greater translocation of pathogen-associated molecular patterns (PAMPs) in the blood. Lipopolysaccharide (LPS) is a PAMP that activates Toll-like receptor 4 (TLR4), induces liver inflammation, and participates in the development of fibrogenesis. LPS can be transported by bacterial extracellular vesicles (EVs). EVs are spherical structures produced by eukaryotic and prokaryotic cells that transfer information to distant cells and may represent new players in NAFLD development and progression. The present review summarizes the role of eukaryotic EVs, either circulating or tissue-derived, in NAFLD features, such as liver inflammation, angiogenesis, and fibrosis. Circulating EV levels are dynamic and correlate with disease stage and severity. However, scarce information is available concerning the involvement of bacterial EVs in liver disease. The present review highlights a potential role of bacterial EVs in insulin resistance and liver inflammation, although the mechanism involved has not been elucidated. In addition, because of their distinct signatures, eukaryotic and prokaryotic EVs may also represent a promising NAFLD diagnostic tool as a "liquid biopsy" in the future.

Microbiota-derived extracellular vesicles and metabolic syndrome

AIM

Metabolic syndrome is a major health problem concerning approximately 25% of worldwide population. Metabolic syndrome regroups a cluster of five metabolic abnormalities predisposing to Type 2 Diabetes mellitus. Dysbiotic gut microbiota is accompanied by an increase of both intestinal permeability and pathogen-associated molecular patterns translocation into blood circulation to induce metabolic endotoxemia responsible for the low-grade systemic inflammation and insulin resistance in metabolic syndrome. Among pathogen-associated molecular patterns, bacterial extracellular vesicles are gaining growing attention. The latter are produced by eukaryotic and prokaryotic cells and are vectors of communication between gut microbiota and its host The present review brings evidence to the importance of the control of the balance between the different subsets of gut microbiota in the development of metabolic diseases including metabolic syndrome.

RESULTS

The ability of bacteria, including gut bacteria, to release extracellular vesicles implicated in host metabolic homeostasis is highlighted with their plethora of actions on intestinal barrier, inflammation and insulin resistance.

CONCLUSION

Bacterial extracellular vesicles can be considered as key players in the pathophysiological of metabolic diseases and may represent an interesting strategy for specific manipulations of microbiome for promoting host health.

Large Extracellular Vesicle-Associated Rap1 Accumulates in Atherosclerotic Plaques, Correlates With Vascular Risks and Is Involved in Atherosclerosis

RATIONALE

Metabolic syndrome (MetS) is a cluster of interrelated risk factors for cardiovascular diseases and atherosclerosis. Circulating levels of large extracellular vesicles (lEVs), submicrometer-sized vesicles released from plasma membrane, from MetS patients were shown to induce endothelial dysfunction, but their role in early stage of atherosclerosis and on vascular smooth muscle cells (SMC) remain to be fully elucidated.

OBJECTIVE

To determine the mechanisms by which lEVs lead to the progression of atherosclerosis in the setting of MetS.

METHODS AND RESULTS

Proteomic analysis revealed that the small GTPase, Rap1 was overexpressed in lEVs from MetS patients compared with those from non-MetS subjects. Rap1 was in GTP-associated active state in both types of lEVs, and Rap1-lEVs levels correlated with increased cardiovascular risks, including stenosis. MetS-lEVs, but not non-MetS-lEVs, increased Rap1-dependent endothelial cell permeability. MetS-lEVs significantly promoted migration and proliferation of human aortic SMC and increased expression of proinflammatory molecules and activation of ERK (extracellular signal-regulated kinase) 5/p38 pathways. Neutralization of Rap1 by specific antibody or pharmacological inhibition of Rap1 completely prevented the effects of lEVs from MetS patients. High-fat diet-fed ApoE^-/- mice displayed an increased expression of Rap1 both in aortas and circulating lEVs. lEVs accumulated in plaque atherosclerotic lesions depending on the progression of atherosclerosis. lEVs from high-fat diet-fed ApoE^-/- mice, but not those from mice fed with a standard diet, enhanced SMC proliferation. Human atherosclerotic lesions were enriched in lEVs expressing Rap1.

CONCLUSIONS

These data demonstrate that Rap1 carried by MetS-lEVs participates in the enhanced SMC proliferation, migration, proinflammatory profile, and activation of ERK5/p38 pathways leading to vascular inflammation and remodeling, and atherosclerosis. These results highlight that Rap1 carried by MetS-lEVs may be a novel determinant of diagnostic value for cardiometabolic risk factors and suggest Rap1 as a promising therapeutic target against the development of atherosclerosis. Graphical Abstract: A graphical abstract is available for this article.

Mycoplasmas are no exception to extracellular vesicles release: Revisiting old concepts

Release of extracellular vesicles (EV) by Gram-negative and positive bacteria is being frequently reported. EV are nano-sized, membrane-derived, non-self-replicating, spherical structures shed into the extracellular environment that could play a role in bacteria-host interactions. Evidence of EV production in bacteria belonging to the class Mollicutes, which are wall-less, is mainly restricted to the genus Acholeplasma and is scanty for the Mycoplasma genus that comprises major human and animal pathogens. Here EV release by six Mycoplasma (sub)species of clinical importance was investigated. EV were obtained under nutritional stress conditions, purified by ultracentrifugation and observed by electron microscopy. The membrane proteins of EV from three different species were further identified by mass spectrometry as a preliminary approach to determining their potential role in host-pathogen interactions. EV were shown to be released by all six (sub)species although their quantities and sizes (30-220 nm) were very variable. EV purification was complicated by the minute size of viable mycoplasmal cells. The proteins of EV-membranes from three (sub)species included major components of host-pathogen interactions, suggesting that EV could contribute to make the host-pathogen interplay more complex. The process behind EV release has yet to be deciphered, although several observations demonstrated their active release from the plasma membrane of living cells. This work shed new light on old concepts of "elementary bodies" and "not-cell bound antigens".

[Tricuspid reoperation in the surgery of rheumatic valve diseases. Apropos of 24 cases]

Twenty four patients were reoperated on the tricuspid valve alone between 1967 and 1981. The first operation had been performed for mitral valve disease and consisted of 23 mitral valve replacements and one commissurotomy associated with two aortic valve replacements. The surgical decision with regard to the tricuspid valve at the initial operation had been abstention (10 cases), tricuspid valvuloplasty (10 cases) and tricuspid valve replacement (4 cases). Reoperation on the tricuspid valve is rare (0,2 p. 100 of mitral valve operations, 1 p. 100 of mitro-tricuspid valve operations). The 24 cases were divided into 2 groups: --Group I, in which reoperation was indicated for curable tricuspid lesions: .4 reoperations for prosthetic valve dysfunction (4 mechanical prostheses were responsible for 3 thromboses and 1 perivalvular leak); .3 reoperations for failed valvuloplasty (2 Kay valvuloplasties and 1 Carpentier annuloplasty); .2 reoperations for aggravation of neglected functional lesions at the first operation and which were reoperated after 3,5 and 4,5 years, because of increased dilatation of the annulus; .5 reoperations for aggravation of organic lesions which had been neglected in 3 cases and treated by valvuloplasty in 2 cases. Five prosthetic valve replacements were carried out, on average 17 months after the first operation. --Group II, in which reoperation was unable to improve congestive heart failure; dilatation of the tricuspid annulus was only a consequence of the cardiac failure. The secondary tricuspid valve surgery (5 valvuloplasties, 5 annuloplasties) did not alter the extremely poor prognosis of these patients (5 hospital deaths, 3 postoperative deaths within 2 years).(ABSTRACT TRUNCATED AT 250 WORDS)

[Treatment of single ventricle by direct atriopulmonary anastomosis without tube or valve. Apropos of a case operated on]

A case of single ventricle with pulmonary stenosis operated at 20 years of age by direct atrio-pulmonary anastamosis is presented. This procedure in contrast to classical techniques does not use an intraventricular patch or a valved ventriculo-pulmonary conduit. It is an adaptation of the Fontan technique initially proposed for tricuspid atresia. The operation consisted of closing the right atrioventricular orifice with a piece of Dacron, suturing the pulmonary valves (which were stenosed) and connecting the right atrium and pulmonary artery by a direct anastamosis using the auricle. The clinical result remains satisfactory one year after surgery: the cyanosis has regressed, the functional tolerance is perfect, there is no hepatomegaly and the patient is in sinus rhythm. The technique is very simple and involves less risk to the His bundle than intraventricular septalisation. It should be reserved to cases of single ventricle with low pulmonary pressures and resistance without cardiac failure. The long-term prognosis depends on the tolerance of the right atrium and is, at present, unknown.

[Disulfiram-induced peripheral neuropathies (author's transl)]

A 28-year-old woman experienced a confusional attack with hallucinations associated with moderate motor deficiency of the lower limbs during treatment with disulfiram 1 g/day. Later on, a temporary increase in disulfiram dosage to 1.75 g/day was followed by quadriplegia and paralysis of the facial and glosso-pharyngeal nerves. Paralysis regressed rapidly in the cranial and upper limb areas, but very slowly in the lower limbs. Disulfiram-induced peripheral neuropathies are not uncommon. They may take various forms, such as optic neuritis, polyneuritis of the limbs and, exceptionally, severe multiple paralysis with psychic disorders, as in the case reported here.