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Amélioration des propriétés antibactériennes et anticoagulantes des prothèses vasculaires en polyester par immobilisation et libération contrôlée de principes actifs / Improvement of antibacterial and anticoagulant properties of polyester vascular prostheses by immobilization and controlled release of biologically active compoundsJean Baptiste, Elixène 20 June 2012 (has links)
Les prothèses et les endoprothèses vasculaires, une fois implantées dans le corps humain, sont sujettes à un certain nombre de complications. Les infections, les thromboses précoces et les occlusions tardives sont les plus fréquentes, générant des conséquences cliniques très souvent délétères et parfois létales. Les difficultés de prise en charge de ces complications sont à l’origine des efforts déployés dans la recherche de solutions visant à améliorer les matériaux prothétiques. Aucune avancée clinique majeure n’a jusque-là été notée. Des études réalisées antérieurement dans notre laboratoire ont permis de développer des prothèses vasculaires en polyester dotées d’un revêtement de polymère d’hydroxypropyl-β-cyclodextrine capable d’adsorber puis de libérer de manière prolongée divers antibiotiques. Au cours des présents travaux nous avons déterminé les conditions optimales pour une libération effective de trois antibiotiques à partir de ces prothèses revêtues d’hydroxypropyl-β-cyclodextrine. Nous en avons testé l’efficacité dans des modèles in vitro et in vivo d’infections vasculaires. Nous avons eu recours à neuf souches pathogènes parmi les plus fréquemment rencontrées dans ce contexte en pathologie humaine. Nous avons parallèlement évalué in vivo l’innocuité, la tolérance tissulaire et la biocompatibilité de ces prothèses dans la perspective d’une application clinique. Le système développé s’est avéré efficace en libérant in situ sur une huitaine de jours les molécules antibactériennes sélectionnées. Les concentrations requises des solutions ainsi que le temps nécessaire d’imprégnation des prothèses étaient compatibles avec la pratique chirurgicale. Une activité bactéricide par réduction significative de l’adhésion, de la croissance et de la prolifération bactérienne a été observée comparativement aux témoins dans les différents modèles d’infections testés. Nos résultats démontrent aussi la possibilité d’utiliser ces molécules seules ou en association sans qu’il y ait d’antagonisme. Il deviendra ainsi possible de moduler et d’adapter le traitement antibiotique local, délivré in situ, en ciblant les divers pathogènes rencontrés dans le cadre d’infections mono ou polymicrobiennes. Les prothèses revêtues d’hydroxypropyl-β-cyclodextrine ont démontré in vivo une bonne intégration tissulaire et une excellente tolérance locale sans signe de toxicité systémique. [...] / Synthetic vascular prosthesis likewise vascular endoprosthesis are prone to several complications after implantation into the human body. Infections, thromboses and late occlusions are the most challenging and the most common, leading to serious clinical consequences that are sometimes lethal. Management of those complications is still fraught with tremendous difficulties justifying the economic burden and the continuous efforts in research development for improving vascular prosthetic materials. This research investment is, however, yet to yield any great clinical advance. Previous studies conducted in our research laboratory have led to the development of polyester vascular prostheses coated with a polymer of hydroxypropyl-β-cyclodextrin. This was achieved in order to increase the loading and eluting capacities of these vascular prostheses towards several antibiotics. In the current works, we sought to determine the optimal conditions for effective controlled release of three antibiotics from those prosthetic platforms. We have also evaluated their efficacy in both in vitro and in vivo models of vascular infections. This was carried-out against nine different bacteria strains that are among the most common in human vascular infections. Moreover, we have assessed in vivo their safety, their healing properties, their systemic toxicity and their biocompatibility in the prospect of clinical application.The above-mentioned drug delivery system has been proved to be effective in releasing in situ the selected antibacterial agents over a seven-day desorption period in human plasma. Optimal batch concentration and time for prosthetic immersion into the antibiotic solutions were well compatible with current surgical practice standards. A bactericidal activity evidenced by significant reduction of bacterial adhesion, growth and proliferation was revealed when compared to appropriate controls in the various tested vascular infection models. We have also studied antibacterial molecules alone or in combination. In this latter setting, no antagonistic effects were depicted. This provides a unique opportunity to customize local antibiotic treatment delivered in situ from vascular device fabrics and to adapt it to the evolving ecology of both monomicrobial and polymicrobial vascular prosthetic infection. The polyester vascular prostheses coated with a polymer of hydroxypropyl-β-cyclodextrin were proved in vivo safe and demonstrated excellent biocompatibility, healing properties and tissue integration without any signs of systemic toxicity. [...]
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Comparative in-vitro activities of trimethoprimsulfamethoxazole and the new fluoroquinolones against confirmed extended spectrum beta-lactamase producing Stenotrophomonas maltophilia in Nkonkobe Municipality, Eastern Cape environmentAdeyemi, Oluwatosin Oluwakemi January 2012 (has links)
Stenotrophomonas maltophilia is increasingly emerging as an opportunistic pathogen of global concern. Due to its inherent resistance to several classes of antibiotics including carbapenems and its ability to acquire mobile resistance elements, treatment of infections caused by S. maltophilia is a constant challenge for clinicians. Trimethoprim-sulphamethoxazole (TMP-SMX) is the generally accepted antibiotic of choice for the treatment of infections caused by this organism, but resistance to the drug is increasingly being reported; hence, the need for alternative therapeutic options. In this study, the antimicrobial susceptibility profile of 110 commensal S. maltophilia isolates obtained from Nkonkobe municipality, Eastern Cape Province, Republic of South Africa was investigated. Twenty-one antibiotics including TMP-SMX and the newer fluoroquinolones; levofloxacin, gatifloxacin and moxifloxacin were included in the antibiotic panel. About 63.4 percent of the isolates were susceptible to TMP-SMX with a resistance rate of 28.2 percent. The fluoroquinolones were more effective with susceptibilities ranging from 76 percent to 94.7 percent. Resistance to the fluoroquinolones ranged from 1.3 percent to 2.7 percent. Levofloxacin was the most effective fluoroquinolone tested. Phenotypic dectection of extended spectrum β-lactamases (ESBLs) showed double disc synergy test (DDST) positivity in 59.5 percent of the isolates. Cefepime was the most sensitive indicator cephalosporin in the DDST with 77.3 percent of suspected ESBL-producing isolates showing cefepime-clavulanic acid synergy. Isolates exhibited nine different ESBL phenotypes, however, PCR amplification of the bla genes revealed four isolates that possessed genes belonging to the CTX-M group (CTX-M-1 and CTX-M-8 groups). ESBL genes are usually carried on mobile elements such as plasmids and transposons which may also bear genes that mediate resistance to aminoglycosides, tetracyclines, TMP-SMX and fluoroquinolones. ESBL positive isolates appeared more susceptible to the fluoroquinolones compared to TMP-SMX but there was no significant relationship between ESBL production and susceptibility to these drugs (p > 0.05). The newer fluoroquinolones are a possible alternative treatment option for S. maltophilia infections in this environment but further studies and clinical investigations are needed to determine the in vivo efficacy of these drugs.
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Assessment of the antibacterial properties of n-Hexane extract of Cocos Nucifera and its interactions with some conventional antibioticsAkinyele, Taiwo Adesola January 2011 (has links)
Cocos nucifera belong to the family Aracaceae (palm Family). The English name is coconut and it is used extensively as medicinal remedies against infections such as urinary tract infections, gastro intestinal infections, skin and wound infections. The in vitro antibacterial (including anti-listerial and anti-vibrio) properties as well as the evaluation of the combination potentials of the plant extract with six front-line antibiotics were evaluated in this study using standard procedures. The in vitro anti-listerial properties of the crude aqueous and n-Hexane extract of the husk of Cocos nucifera were carried out against 37 Listeria isolates. Twenty-nine of the test organisms were susceptible to the aqueous extract while thirty were susceptible to the n-Hexane extract both at the screening concentration of 25 mg/ml. Minimum Inhibitory Concentration (MIC) values for all the susceptible bacteria ranged between 0.6 - 5.0 mg/ml. For the aqueous extract, average log reduction in viable cell count ranged between 0.32 Log10 and 4.8 Log10 CFU/ml after 8 hours interaction in 1 × MIC and 2 × MIC. For the n-Hexane extract, the log reduction ranged between 2.4 Log10 and 6.2 Log10 CFU/ml after 8 hours interaction in 1 × MIC and 2 × MIC. The time-kill characteristics of the two extracts suggest that at higher concentration (2 × MIC) and longer duration of interaction (8 hr), more bacteria were killed. In vitro anti-vibrio and antibacterial properties experiment revealed that of all the 45 vibrio and 25 bacteria strains that was tested, 37 were susceptible to the aqueous extract and 38 to the n-Hexane extract, while 17 were susceptible to the aqueous extract and 21 to the n-Hexane extract. Minimum Inhibitory Concentration (MIC) values for all the susceptible bacteria ranged between 0.3 - 5.0 mg/ml. viii The time kill studies revealed that for the aqueous extract, average log reduction in viable cell count in time kill assay ranged between 0.12 Log10 and 4.2 Log10 CFU/ml after 8 hr interaction at 1 × MIC and 2 × MIC. For the n-Hexane extract, the log reduction ranged between 0.56 Log10 and 6.4 Log10 CFU/ml after 8 hr interaction in 1 × MIC and 2 × MIC. In the test for the combination interactions, the checkerboard method revealed synergy of 67% and indifferent of 33%, while the time kill assay detected synergy in 72% and indifferent in 28% of the combinations tested. The synergy detected was not specific to any of the antibiotics or the Gram reaction of the bacteria, and no antagonism was detected. We conclude that the aqueous and n-Hexane extract of the husk of C. nucifera contains potential broad spectrum antibiotics resistance modulating compounds that could be relevant in the treatment of infections caused by these pathogens. In addition, the husk which is being discarded as agro waste will opens up a vista of opportunities for utilization for therapeutic purposes
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In vitro activity of bioactive compounds of selected South African medicinal plants on clinical isolates of Helicobacter pyloriOkeleye, Benjamin Ifeoluwa January 2011 (has links)
The stem bark of Peltophorum africanum and Bridelia micrantha are used in South Africa traditional medicine for treatment of intestinal parasites, relieve problems and human immunodeficiency virus/ acquired immune deficiency syndrome (HIV/AIDS). The growing problem of antibiotic resistance by Helicobacter pylori the major etiological agent in gastritis, gastric cancer, peptic and gastric ulcer demands the search for novel compounds from plant based sources. This study was aimed to determine the antimicrobial activity of five solvent (ethylacetate, acetone, ethanol, methanol and water) extracts of the stem bark of P. africanum and B. micrantha on clinical strains of H. pylori in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. H. pylori strains were isolated from patients presenting with gastric related morbidities at the Livingstone Hospital, Port Elizabeth for endoscopy and confirmed following standard microbiology procedures. The plant extracts including clarithromycin were tested against 31 clinical strains of H. pylori by the agar well diffusion method. The most potent extract was evaluated by the microdilution method to determine the Minimum Inhibitory Concentration (MIC50&90), followed by the rate of kill. Preliminary phytochemical analysis was carried out. The one way ANOVA test was used to statistically analyse the results. All the extracts demonstrated anti-H. pylori activity with zone diameters of inhibition that ranged from 0 to 23 mm for the extracts and 0 to 35 mm for clarithromycin. Marked susceptibility (100%) was recorded for the ethyl acetate extract of P. africanum (P. afr. EA) and the acetone extract of B. micrantha (B. mic. A), which were statistically significant (P < 0.05) compared to all other extracts and clarithromycin. For B. micrantha ethyl acetate extract, 93.5 percent susceptibility was observed while for the control iv antibiotic, clarithromycin it was 58.1 percent. The MIC50 ranged from 0.0048 to 0.313 mg/mL for P. afr. EA, and from 0.0048 to 0.156 mg/mL for B. mic. EA; MIC90 ranged from 0.156 mg/mL to 0.625 mg/mL and 0.0048 to 2.5 mg/mL for P. afr. EA and B. mic. EA respectively. There was a significant statistical difference observed in potency of both P. afr. EA and B. mic. A compared to the two antibiotics (P < 0.05). One hundred percent killing by P. afr EA was observed at 0.05 mg/mL (½ x MIC) and 0.2 mg/mL (2 x MIC) in 66 h for strain PE466C and PE252C respectively. For B. mic. EA, 100 percent killing effect of both strains (PE430C and PE369C) was observed at 0.1 mg/mL (2 x MIC) in 66 h. Qualitative phytochemical analysis confirmed the presence of alkaloids, flavonoids, steroids, tannins and saponins in the ethyl acetate extracts of both plants, which could be a potential template of lead molecule for the design of new anti- Helicobacter pylori therapies.
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Interação de Leptospira interrogans com o sistema proteolítico plasminogênio/plasmina: análise, caracterização e possíveis implicações na infecção. / Leptospira interrogans interactions with the plasminogen/plasmin proteolytic system: analysis, characterization and possible implications for the infection.Mônica Larucci Vieira 05 October 2012 (has links)
A leptospirose é uma zoonose causada por bactérias patogênicas do gênero Leptospira. Apesar de sua importância, a patogênese e virulência permanecem não elucidadas. As leptospiras não apresentam proteases conhecidas de degradação de matriz extracelular, atividade crucial para a penetração e disseminação nos hospedeiros. Assim, foi proposta a investigação da interação de leptospiras com plasminogênio/plasmina e as implicações para a infecção. As leptospiras capturam plasminogênio na superfície, e este é convertido à plasmina por ativadores do hospedeiro. A plasmina associada propicia degradação de componentes de matriz extracelular, habilidade de penetração e evasão imune. Adicionalmente, as leptospiras estimulam a expressão de ativadores de plasminogênio e metaloproteases de matriz. Os resultados contribuem para o conhecimento do processo infeccioso das leptospiras, descrevendo um novo mecanismo de patogenicidade. / Leptospirosis is a zoonosis caused by pathogenic bacteria from genus Leptospira. Despite its importance, the pathogenicity and virulence remain to be elucidated. The leptospires do not present known proteases able to degrade extracellular matrix, an activity essential for the penetration and dissemination within the hosts. Therefore, we proposed the investigation of the leptospiral interaction with plasminogen/plasmin and its implications for infection. Leptospires capture plasminogen on the surface, which is converted to plasmin by hosts activators. Surface-bound plasmin confers extracellular matrix components degradation, penetration ability and immune evasion. Additionally, leptospires stimulate plasminogen activators and matrix metaloproteases expressions. The results constitute one possible mechanism that contributes to the invasion process and the rapid dissemination of Leptospira.
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Fatores que determinam a produção de IL-12 em macrófagos murinos ativados por Bordetella pertussis e B. parapertussis. / Factors determining the production of IL-12 in murine macrophages activated by Bordetella pertussis and B. parapertussis.Cynthia Soares Galhardo 29 October 2013 (has links)
Bordetella pertussis e B. parapertussis são agentes etiológicos da coqueluche. A IL-12 liga a imunidade inata e adaptativa. Investigamos alguns mecanismos que controlam a síntese de IL-12 em macrófagos medulares murinos (MfDM) ativados in vitro com estas duas espécies de bactérias. Demonstramos que IL-12p40 e TNF-a foram produzidos pelos MfDM ativados com qualquer uma das bactérias. A síntese de IL-12p40 foi dependente de TNF-a, MyD88 e NFkB e independente de MAPK p38 e ERK 1/2. Durante a estimulação com B. pertussis a produção de IL-12p40 foi dependente de TLR-4, mas com B. parapertussis envolveu outras vias independentes de MyD88 e TLR-4. Estas bactérias não induziram a síntese de IL-12p70, necessitando de sinais moleculares adicionais de IFN-g, que aumentou a síntese desta citocina. A produção de IL-12 p70 aumentou após o bloqueio das vias PI3K, MAPK p38 e ERK1/2 assim como após a adição exógena de PT sobre MfDM ativados com B. parapertussis. Portanto, diversas vias de sinais dependentes e independentes de TLR-4 controlam a produção de IL-12 neste modelo. / Bordetella pertussis and B. parapertussis are etiological agents of whooping cough. IL-12 links the innate and adaptive immunity. We investigated the ability of both bacteria to modulate IL-12 by in vitro activation of bone marrow derived macrophages (MfDM). We demonstrated that IL-12p40 and TNF-a were produced after stimulation of cells with either bacterium. IL-12p40 production was dependent on TNF-a, MyD88 and NFkB but independent of MAPK p38 and ERK 1/2. During B. pertussis activation the production of IL-12p40 was dependent on TLR-4, while B. parapertussis activation was MyD88 and TLR-4 independent. However, the bacteria alone did not induce IL-12p70 synthesis, requiring IFN-g as an additional signal. Evidences indicated MAPK p38, ERK1/2 and PI3K during B. pertussis and B. parapertussis activation, as well as the exogenous addition of PT to B. parapertussis activated MfDM, was critical for the up regulation of IL-12p70. This finding indicates that different TLR-4 dependent and independent signaling pathways may control the production of IL-12 in this model.
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Addressing Gaps in Immunization Rates in a Family Medicine Residency ClinicPatel, Amit, Veerman, Richard, Polaha, Jodi, Johnson, Leigh, Flack, Gina, Goodman, Michelle, McAllister, Leona, Briggs, Monaco 05 April 2018 (has links)
Adult immunizations effectively reduce morbidity, mortality, and transmission rates of multiple diseases; however, outpatient providers often a struggle to convince patients to accept vaccinations. This project’s aim is to address vaccination rates in our adult population, focusing first on the influenza vaccine in year one (2016), and then on pneumococcal vaccine in year two (2017), by 1) using a strong quality improvement strategy (known as a Champion Team) and 2) implementing a clinic program consisting of provider training, improved documentation, and informative posters targeted at patients. A quality improvement strategy known as a “Champion Team” provided a strong mechanism through which we developed and implemented the interventions across both years. Specifically, the Champion Team consisted of key stakeholders (nurses, residents, physician faculty, and informatics expert) who identified, developed, and evaluated the program. Programming included an annual health care professional training session for each vaccine (early fall of 2016 and 2017 for flu, spring 2017 for pneumococcal), improved documentation strategies and nursing uptake, and informative posters in the clinic. We assayed data from our patient electronic health record to evaluate: the percentage of our patient population for whom an immunization was documented relative to the number of unique patients seen in our clinic during that time frame. This approach in year one showed a marked increase in influenza vaccination rates in our clinic. During the 2014/2015 and 2015/2016 flu seasons our clinic vaccination rates were 39.98% and 42.05% respectively. After implementation of our champion team and clinic wide program to increase rates in 2016 our vaccination rates for the 2016/2017 flu seasons was 50.88%. Pneumonia data for a full year are under analyses and will be included in this presentation. We anticipate a similar increase in rates for our pneumococcal vaccinations. Our Champion Team and clinic wide program were perceived as relatively low-effort interventions yet appeared to increase vaccinations over the course of this study. The replication of these findings across pneumonia data (pending) and, in future work, with the herpes zoster vaccine (planned for Year 3), will increase our confidence that increases in rates were attributable to these very accessible interventions.
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Elizabethkingia Meningoseptica Bacteremia associated with Infective Endocarditis in an Intravenous Drug AbuserSriramoju, Vindhya, M.D., Arikapudi, Sowminya, M.D., Arif, Sarah, M.D., Ali, Muazzam, M.D., Madhavaram, Suhitha, M.D., Zhang, Michael, M.D, Hannan, Abdul, M.D., Cook, Christopher T, M.D. 05 April 2018 (has links)
Elizabethkingia Meningoseptica (E. Meningoseptica) an oxidase-positive gram-negative aerobic rod.1-2 Although ubiquitous in nature and widely distributed in soil and water, it is not a part of normal human flora. Cases of outbreaks of meningitis in premature neonates or infants have been reported, however, very few cases have been reported in adults.3 Infection is primarily nosocomial, or hospital acquired and has been implicated in bacteremia, meningitis, pneumonia, endocarditis especially in immunocompromised individuals.2-4 We report a 29-year-old male with past medical history significant for intravenous drug abuse, hepatitis C, oxymorphone induced hemolytic uremic syndrome, who presented to hospital with altered mental status. On admission, patient was unresponsive to vocal commands, febrile (102.3 F), tachycardic and tachypneic. He had pinpoint pupils and diffuse petechiae. In addition, he had erythematous flat macular lesions on his palms and dorsum of hands as well as injection marks in left cubital fossa. Cardiac examination was significant for a grade III systolic murmur at apical region and diastolic murmur at left second intercostal space. Laboratory studies revealed thrombocytopenia (43,000m/microL), lactic acidosis (4.9mmol/L), serum creatinine (Cr) of 6.6 mg/dL, glomerular filtration rate (GFR) of 10 ml/min. Transthoracic echocardiogram (TTE) revealed large mobile vegetation on aortic valve measuring 3.6 x 0.72 cm. Patient’s presentation was consistent with infective endocarditis with the vegetation seen on TTE and patient’s physical findings. Magnetic Resonance Imaging of the brain showed numerous small hemorrhagic infarcts, likely secondary to emboli from aortic valve vegetation. Patient required intubation for airway protection and started on hemodialysis. He was initially started on Meropenem and Vancomycin for infective endocarditis and later switched to Ciprofloxacin based on blood cultures and sensitivities which revealed methicillin sensitive staphylococcus aureus and multi-drug resistant E. Meningoseptica. Patient was transferred to long term care facility after acute care at the hospital. The increasing incidence of polymicrobial infective endocarditis and increasing resistance to antibiotic therapy pose challenges to the rapid assessment and treatment to mitigate the multi-organ involvement with septic emboli. Reports of pathogenicity associated with native valve endocarditis with this organism is scarce and exist primarily in a very few case reports and is resistant to many traditional antibiotics.5,6 E. Meningoseptica has shown antimicrobial susceptibility to the newer quinolones, rifampin, trimethoprim/sulfamethoxazole and ciprofloxacin with reasonable activity.7 Due to the unusual pattern of antibiotic resistance, early switching to appropriate antibiotics based on sensitivities is crucial for survival in patients with E. Meningoseptica.
References
1..Kim KK, Kim MK, Lim JH, Park HY, Lee ST. Transfer of Chryseobacterium meningosepticum and Chryseobacterium miricola to Elizabethkingia gen. nov. as Elizabethkingia meningoseptica comb. nov. and Elizabethkingia miricola comb. nov. Int J Syst Evol Microbiol.2005 May;55(Pt 3):1287-93.
2:Shinha T, Ahuja R. Bacteremia due to Elizabethkingia meningoseptica. IDCases. 2015 Jan 17;2(1):13-5. doi: 10.1016/j.idcr.2015.01.002. eCollection 2015.
3..Jung SH, Lee B, Mirrakhimov AE, Hussain N. Septic shock caused by Elizabethkingia meningoseptica: a case report and review of literature. BMJ Case Rep. 2013 Apr 3;2013. pii: bcr2013009066. doi: 10.1136/bcr-2013-009066.
4.Ratnamani MS, Rao R. Elizabethkingia meningoseptica: Emerging nosocomial pathogen in bedside hemodialysis patients. Indian J Crit Care Med. 2013 Sep;17(5):304-7.
5.Bomb K, Arora A, Trehan N. Endocarditis due to Chryseobacterium meningosepticum. Indian J Med Microbiol. 2007 Apr;25(2):161-2.
6.Yang J, Xue W, Yu X. Elizabethkingia meningosepticum endocarditis: A rare case and special therapy. Anatol J Cardiol. 2015 May;15(5):427-8.
7. Hsu MS, Liao CH, Huang YT, Liu CY, Yang CJ, Kao KL, Hsueh PR. Clinical features, antimicrobial susceptibilities, and outcomes of Elizabethkingia meningoseptica (Chryseobacterium meningosepticum) bacteremia at a medical center in Taiwan,1999-2006. Eur J Clin Microbiol Infect Dis. 2011 Oct;30(10):1271-8.
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S100A9 Sustains Myeloid-Derived Suppressor Expansion and Immunosuppression During Chronic Murine SepsisAlkhateeb, Tuqa, PharmD, Kumbhare, Ajinkya, MD, Bah, Isatou, BS, Elgazzar, Mohamed, PhD 12 April 2019 (has links)
Myeloid-derived suppressor cells (MDSC) expand during sepsis, suppress both innate and adaptive immunity, and promote chronic immunosuppression, which characterizes the late/chronic phase of sepsis. We previously reported that the transcription factors Stat3 and C/EBPb synergize to induces the expression of microRNA (miR)-21 and miR-181b to promote MDSC expansion in a mouse model of polymicrobial sepsis that progresses from an early/acute proinflammatory phase to a late/chronic immunosuppressive stage. We also showed that Gr1+CD11b+ cells, the precursors of MDSCs, from mice genetically deficient in the inflammatory protein S100A9 lack miR-21 or miR-181b in late sepsis, and are not immunosuppressive. In the present study, we show that S100A9 induces miR-21 and miR-181b during the late sepsis phase. We find that S100A9 associates with and stabilizes the Stat3-C/EBPb protein complex that activates the miRNA promoters. Reconstituting Gr1+CD11b+ cells from the S100A9 knockout mice with late sepsis with S100A9 protein restores the Stat3-C/EBPb protein complex and miRNA expressions, and switches the Gr1+CD11b+ cells into the immunosuppressive, MDSC phenotype. Importantly, we find that this process requires IL-10 mediated signaling, which induces S100A9 translocation from the cytosol to the nucleus. These results demonstrate that S100A9 promotes MDSC expansion and immunosuppression in late/chronic sepsis by inducing the expression of miR-21 and miR-181b.
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PhoP-regulated genes contribute to Mycobacteria tuberculosis-induced burst size necrosis in macrophagesKativhu, Chido L. 01 February 2021 (has links)
Tuberculosis (TB) is primarily a pulmonary disease caused by Mycobacterium tuberculosis (Mtb). Mtb is highly infectious, but studies have shown that only 5–15% of Mtb-infected individuals develop TB disease. The Bacille Calmette-Gu.rin (BCG) vaccine is the only commercially available Mtb vaccine, but its efficacy varies based on the strain used. The Mtb PhoPR-mutant variant, MTBVAC, has been tested as a possible attenuated live vaccine against Mtb. Although it has successfully conferred durable CD4+ T-cell responses in infants, it has also resulted in adverse effects. Our goal is to identify PhoPR-regulated gene(s) that mediate Mtb-induced burst size necrosis in infected cells. PhoPR is a two-component system in mycobacteria. PhoR responds to environmental cues, such as changes in pH, and phosphorylates the PhoP transcription factor, which then activates or suppresses the expression of approximately 40 Mtb genes. The Mtb PhoPR-mutant strain is able to replicate in infected macrophages, but it does not induce the horizontal spread of Mtb to other immune cells. Our lab has previously shown that virulent, cytopathic strains of Mtb, such as H37Rv, suppress early apoptosis, have faster replication rates in macrophages, and trigger cell death at a lethal load threshold of approximately 25 bacteria. Cell death of infected macrophages primarily occurs via necrosis, which involves nuclear pyknosis without DNA fragmentation and general disruption of lipid bilayer membranes. Viable bacilli are released to infect other macrophages and neutrophils recruited to the developing TB lesion. Here, we show that PhoP contributes to burst size necrosis in macrophages and that the PhoP-regulated genes, fadD21 and pks3, are potential drivers of this necrosis. FadD21 and pks3 are involved in the generation of diacyl trehalose/penta-acyl trehalose (DAT/PAT) for cell wall synthesis, suggesting that Mtb cell wall composition may determine virulence. Therefore, we have uncovered potential targets for early intervention or vaccinations to avoid granuloma formation or tissue damage in response to Mtb-induced macrophage necrosis.
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