Mycobacterium tuberculosis exploits the formation of new blood vessels for its dissemination.

The mechanisms by which the airborne pathogen Mycobacterium tuberculosis spreads within the lung and leaves its primary niche to colonize other organs, thus inducing extrapulmonary forms of tuberculosis (TB) in humans, remains poorly understood. Herein, we used a transcriptomic approach to investigate the host cell gene expression profile in M. tuberculosis-infected human macrophages (ΜΦ). We identified 33 genes, encoding proteins involved in angiogenesis, for which the expression was significantly modified during infection, and we show that the potent angiogenic factor VEGF is secreted by M. tuberculosis-infected ΜΦ, in an RD1-dependent manner. In vivo these factors promote the formation of blood vessels in murine models of the disease. Inhibiting angiogenesis, via VEGF inactivation, abolished mycobacterial spread from the infection site. In accordance with our in vitro and in vivo results, we show that the level of VEGF in TB patients is elevated and that endothelial progenitor cells are mobilized from the bone marrow. These results strongly strengthen the most recent data suggesting that mycobacteria take advantage of the formation of new blood vessels to disseminate.

Delivery of human mesenchymal adipose-derived stem cells restores multiple urological dysfunctions in a rat model mimicking radical prostatectomy damages through tissue-specific paracrine mechanisms.

Urinary incontinence (UI) and erectile dysfunction (ED) are the most common functional urological disorders and the main sequels of radical prostatectomy (RP) for prostate cancer. Mesenchymal stem cell (MSC) therapy holds promise for repairing tissue damage due to RP. Because animal studies accurately replicating post-RP clinical UI and ED are lacking, little is known about the mechanisms underlying the urological benefits of MSC in this setting. To determine whether and by which mechanisms MSC can repair damages to both striated urethral sphincter (SUS) and penis in the same animal, we delivered human multipotent adipose stem cells, used as MSC model, in an immunocompetent rat model replicating post-RP UI and ED. In this model, we demonstrated by using noninvasive methods in the same animal from day 7 to day 90 post-RP injury that MSC administration into both the SUS and the penis significantly improved urinary continence and erectile function. The regenerative effects of MSC therapy were not due to transdifferentiation and robust engraftment at injection sites. Rather, our results suggest that MSC benefits in both target organs may involve a paracrine process with not only soluble factor release by the MSC but also activation of the recipient's secretome. These two effects of MSC varied across target tissues and damaged-cell types. In conclusion, our work provides new insights into the regenerative properties of MSC and supports the ability of MSC from a single source to repair multiple types of damage, such as those seen after RP, in the same individual.

Extracellular adenosine triphosphate affects the response of human macrophages infected with Mycobacterium tuberculosis.

Granulomas are the hallmark of Mycobacterium tuberculosis infection. As the host fails to control the bacteria, the center of the granuloma exhibits necrosis resulting from the dying of infected macrophages. The release of the intracellular pool of nucleotides into the surrounding medium may modulate the response of newly infected macrophages, although this has never been investigated. Here, we show that extracellular adenosine triphosphate (ATP) indirectly modulates the expression of 272 genes in human macrophages infected with M. tuberculosis and that it induces their alternative activation. ATP is rapidly hydrolyzed by the ecto-ATPase CD39 into adenosine monophosphate (AMP), and it is AMP that regulates the macrophage response through the adenosine A2A receptor. Our findings reveal a previously unrecognized role for the purinergic pathway in the host response to M. tuberculosis. Dampening inflammation through signaling via the adenosine A2A receptor may limit tissue damage but may also favor bacterial immune escape.

Stiripentol exhibits higher anticonvulsant properties in the immature than in the mature rat brain.

PURPOSE: After the first positive experimental data in rodents in the early 1970s demonstrating the anticonvulsant effect of stiripentol (STP), in vitro studies showed that STP acts directly on γ-aminobutyric acid A (GABAA ) receptors. Chloride influx is higher when these receptors contain an α3 subunit, leading to the hypothesis that STP might exhibit higher efficacy in the immature brain. METHODS: We explored this issue by studying the efficacy of STP in P21 and P75 rats using the pentylenetetrazol model of acute seizures or the lithium-pilocarpine status epilepticus model. P21 and adult rats received vehicle, 150, 250, or 350 mg/kg of STP, i.p., 1 h before evaluating the anticonvulsant. We also studied the blood and brain levels of STP as well as the expression and the messenger RNA (mRNA) levels of the α3 subunit of the GABAA receptors at both ages. KEYS FINDINGS: STP exhibited anticonvulsant properties in both models at both ages, but STP was more effective in P21 than in P75 rats. This was shown by the significant suppression of seizure or status epilepticus occurrence in P21 with 350 mg/kg STP, whereas the same dose had no significant effect at P75. The blood level, brain level, and blood/brain ratio of STP did not explain these differences between the two age groups. Moreover, the higher anticonvulsant properties in the immature brain were not explained by the mRNA level or protein expression of the GABAA α3 subunit at either age. SIGNIFICANCE: Stiripentol exhibits higher anticonvulsant properties in the immature than in the mature brain. These findings require further investigation because it might lead to new clinical developments.

Oral administration of docosahexaenoic acid/eicosapentaeinoic acids is not anticonvulsant in rats: implications for translational research.

Omega-3 and omega-6 poly-unsaturated fatty acids (PUFAs) are dietary fatty acids that are involved in a myriad of physiological processes in the brain. Although experimental data have shown that PUFAs have anticonvulsant properties, the outcomes of clinical trials have been controversial. Docosahexaenoic acid (DHA) is a PUFA which has been reported to exert anticonvulsant effects. Here we studied anticonvulsant potential of a mixture of enriched n-3 PUFA upon their oral administration in rats. We did not observe an anticonvulsant effect of n-3 PUFA in the i.v. pentylentetrazol threshold test. n-3 PUFA component was increased in the plasma of rats treated with the eicosapentaenoic acid (EPA)/DHA mix (275 mg/kg/d/400 mg/kg/d) due to the increase of both DHA and EPA. We also found modification of PUFA composition in the brain. Despite PUFA profiles modified both in plasma and in the brain, we did not find any anticonvulsant effect of orally administered DHA. Further studies are needed to define the type and the amount of fatty acids that would possess anticonvulsant properties. As the existing literature suggests that the route of administration of PUFA may be crucial, future studies should involve oral administration to provide relevant clinical information.

Inflammation in rat pups subjected to short hyperthermic seizures enhances brain long-term excitability.

UNLABELLED: Inflammatory processes in response to infection are involved in the pathophysiological mechanisms of febrile seizures (FS). Prolonged FS may promote the development of temporal lobe epilepsy. It has been shown in rats that prolonged hyperthermic seizures (HS) are followed by long-term modification of brain excitability. To examine whether short FS results in modification of brain excitability, we induced an inflammatory response in combination with short HS. METHODS: HS were induced in rat pups at either P11 or P16 using a heating lamp with a continuous monitoring of the core temperature. Rat pups were maintained at the temperature seizure threshold during 5 min. In order to induce an inflammatory response, lipopolysaccharide (LPS, Eschericha coli 055:B5) was injected i.p. at 5 microg/kg or 50 microg/kg, 2h prior seizure induction. After 1 month, pentylenetetrazol threshold (PTZth) was used to assess the change of brain excitability. Histological studies were performed 24h after the FS (Fluorojade-B) and after the PTZth (cresyl violet). RESULTS: The temperature thresholds to induce the seizures were not different among the groups. The PTZth was not significantly different between sham and FS only groups, and decreased dose-dependently when LPS was combined to FS. Histological studies suggested the absence of cell injury. CONCLUSION: Lower PTZth obtained by using LPS in combination with HS in rat pups suggests a change in brain excitability. Our model with only 5 min of HS in combination with LPS suggests that an inflammatory response could, in part, explain long-term change in brain excitability following short FS.

Anticonvulsant effects of linolenic acid are unrelated to brain phospholipid cell membrane compositions.

PURPOSE: Recent studies have revealed that polyunsaturated fatty acids (PUFAs) have anticonvulsive properties. Clinical trials using PUFAs reported conflicting results. It was suggested that PUFAs have anticonvulsant effects via modifications of brain phospholipids. Moreover, some authors suggested that the effect of the ketogenic diet (KD) leads to a high PUFA content. The aim of the study was to evaluate the anticonvulsant properties of a mixture containing alpha-linolenic acid (ALA) and linolenic acid (LA). METHODS: Four-week-old male Wistar rats were fed one of the following diets for 30 days: KD, standard diet, and standard diet with daily LA/ALA oral supplementation. Pentylenetetrazol (PTZ) threshold was used to assess the anticonvulsive effects of the diets. Nutritional status was monitored by body composition evaluation. Fatty acids composition of both plasma and brain phospholipids were also assessed. RESULTS: Animals fed the KD and those who had the daily LA/ALA supplementation exhibited an increase in PTZ threshold. The animals did not show any modification of body composition or brain phospholipid composition. The plasma fatty acids composition was modified by KD and LA/ALA. A decrease in arachidonic acid (AA) concentrations was observed in both the KD and LA/ALA groups, while an increase in eicosapentanoic acid (EPA) and ALA concentrations was only observed in the LA/ALA group. CONCLUSIONS: Our study shows that LA/ALA supplementation exerts anticonvulsive properties comparable to KD. Nutritional status can not explain the anticonvulsive effects of PUFAs supplementation. Brain phospholipids were not different within groups. The anticonvulsive effects of LA supplementation seem to be unrelated to brain phospholipid composition.

Fenofibrate, a peroxisome proliferator-activated receptor-alpha agonist, exerts anticonvulsive properties.

The underlying mechanisms of the ketogenic diet (KD) remain unknown. Involvement of peroxisome proliferator-activated receptor-alpha (PPARalpha) has been suggested. The aim of this study was to assess the anticonvulsant properties of fenofibrate, a PPARalpha agonist. Wistar rats were fed at libitum during 14 days by regular diet, KD, regular diet containing 0.2% fenofibrate (F), or KD containing 0.2% fenofibrate (KD + F). Pentylenetetrazol (PTZ) threshold and latencies to the onset of status epilepticus induced by lithium-pilocarpine were used to assess diet treatments with anticonvulsive effects. Myoclonic and generalized seizure PTZ thresholds were increased in F- and KD-treated animals in comparison to control. No difference was observed between KD + F group and the others groups (control, F, KD). Latencies to the onset of status epilepticus were increased in F and KD groups compared to control. Fenofibrate exerts anticonvulsive properties comparable to KD in adult rats using PTZ and lithium-pilocarpine models. The underlying mechanisms such as PPARalpha activation and others should be investigated. These findings may provide insights into future directions to simplify KD protocols.