scholarly journals In Vitro and In Vivo Antibiotic Capacity of Two Host Defense Peptides

2020 ◽  
Vol 64 (7) ◽  
Author(s):  
Iván Arenas ◽  
Marco Antonio Ibarra ◽  
Felix L. Santana ◽  
Elba Villegas ◽  
Robert E. W. Hancock ◽  
...  
Keyword(s):  
Host Defense ◽  
Foot Ulcer ◽  
Diabetic Foot Ulcer ◽  
Immunomodulatory Activity ◽  
Host Defense Peptides ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Infective Activity

ABSTRACT Two nonamidated host defense peptides named Pin2[G] and FA1 were evaluated against three types of pathogenic bacteria: two (Staphylococcus aureus UPD13 and Pseudomonas aeruginosa UPD3) isolated from diabetic foot ulcer patients, and another (Salmonella enterica serovar Typhimurium [ATCC 14028]) from a commercial collection. In vitro experiments showed that the antimicrobial performance of the synthetic peptides Pin2[G] and FA1 was modest, although FA1 was more effective than Pin2[G]. In contrast, Pin2[G] had superior in vivo anti-infective activity to FA1 in rabbit wound infections by the diabetic foot ulcer pathogens S. aureus UPD13 and P. aeruginosa UPD3. Indeed, Pin2[G] reduced bacterial colony counts of both S. aureus UPD13 and P. aeruginosa UPD3 by >100,000-fold after 48 to 72 h on skin wounds of infected rabbits, while in similar infected wounds, FA1 had no major effects at 72 to 96 h of treatment. Ceftriaxone was equally effective versus Pseudomonas but less effective versus S. aureus infections. Additionally, the two peptides were evaluated in mice against intragastrically inoculated S. enterica serovar Typhimurium (ATCC 14028). Only Pin2[G] at 0.56 mg/kg was effective in reducing systemic (liver) infection by >67-fold, equivalent to the effect of treatment with levofloxacin. Pin2[G] showed superior immunomodulatory activity in increasing chemokine production by a human bronchial cell line and suppressing polyinosinic-polycytidylic acid (poly[I:C])-induced proinflammatory IL-6 production. These data showed that the in vitro antimicrobial activity of these peptides was not correlated with their in vivo anti-infective activity and suggest that other factors such as immunomodulatory activity were more important.

scholarly journals Toll-Like Receptor 2 (TLR2) and TLR9 Play Opposing Roles in Host Innate Immunity against Salmonella enterica Serovar Typhimurium Infection

2015 ◽  
Vol 83 (4) ◽  
pp. 1641-1649 ◽  
Author(s):  
Renhui Zhan ◽  
Qiuju Han ◽  
Cai Zhang ◽  
Zhigang Tian ◽  
Jian Zhang
Keyword(s):  
Innate Immunity ◽  
Host Defense ◽  
Salmonella Enterica ◽  
Nk Cell ◽  
Bacterial Load ◽  
Content Type ◽  
Serovar Typhimurium ◽  
High Bacterial Load

Toll-like receptors (TLRs) are evolutionarily conserved host proteins that are essential for effective host defense against pathogens. However, recent studies suggest that some TLRs can negatively regulate immune responses. We observed here that TLR2 and TLR9 played opposite roles in regulating innate immunity against oral infection ofSalmonella entericaserovar Typhimurium in mice. WhileTLR9−/−mice exhibited shortened survival, an increased cytokine storm, and more severeSalmonellahepatitis than wild-type (WT) mice,TLR2−/−mice exhibited the opposite phenomenon. Further studies demonstrated that TLR2 deficiency and TLR9 deficiency in macrophages both disrupted NK cell cytotoxicity againstS. Typhimurium-infected macrophages by downregulating NK cell degranulation and gamma interferon (IFN-γ) production through decreased macrophage expression of the RAE-1 NKG2D ligand. But more importantly, we found thatS. Typhimurium-infectedTLR2−/−macrophages upregulated inducible nitric oxide synthase (iNOS) expression, resulting in a lower bacterial load than that in WT macrophagesin vitroand liversin vivoas well as low proinflammatory cytokine levels. In contrast,TLR9−/−macrophages showed decreased reactive oxygen species (ROS) expression concomitant with a high bacterial load in the macrophages and in livers ofTLR9−/−mice.TLR9−/−macrophages were also more susceptible than WT macrophages toS. Typhimurium-induced necroptosisin vitro, likely contributing to bacterial spread and transmissionin vivo. Collectively, these findings indicate that TLR2 negatively regulates anti-S. Typhimurium immunity, whereas TLR9 is vital to host defense and survival againstS. Typhimurium invasion. TLR2 antagonists or TLR9 agonists may thus serve as potential anti-S. Typhimurium therapeutic agents.

scholarly journals Mechanistic Fingerprinting Reveals Kinetic Signatures of Resistance to Daptomycin and Host Defense Peptides in Streptococcus mitis-oralis

Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 404
Author(s):  
Michael R. Yeaman ◽  
Liana C. Chan ◽  
Nagendra N. Mishra ◽  
Arnold S. Bayer
Keyword(s):  
Flow Cytometry ◽  
Host Defense ◽  
Durable Resistance ◽  
Cross Resistance ◽  
Streptococcus Mitis ◽  
Host Defense Peptides ◽  
Strain Pair ◽  
Defense Peptides

Streptococcus mitis-oralis (S. mitis-oralis) infections are increasingly prevalent in specific populations, including neutropenic cancer and endocarditis patients. S. mitis-oralis strains have a propensity to evolve rapid, high-level and durable resistance to daptomycin (DAP-R) in vitro and in vivo, although the mechanism(s) involved remain incompletely defined. We examined mechanisms of DAP-R versus cross-resistance to cationic host defense peptides (HDPs), using an isogenic S. mitis-oralis strain-pair: (i) DAP-susceptible (DAP-S) parental 351-WT (DAP MIC = 0.5 µg/mL), and its (ii) DAP-R variant 351-D10 (DAP MIC > 256 µg/mL). DAP binding was quantified by flow cytometry, in-parallel with temporal (1–4 h) killing by either DAP or comparative prototypic cationic HDPs (hNP-1; LL-37). Multicolor flow cytometry was used to determine kinetic cell responses associated with resistance or susceptibility to these molecules. While overall DAP binding was similar between strains, a significant subpopulation of 351-D10 cells hyper-accumulated DAP (>2–4-fold vs. 351-WT). Further, both DAP and hNP-1 induced cell membrane (CM) hyper-polarization in 351-WT, corresponding to significantly greater temporal DAP-killing (vs. 351-D10). No strain-specific differences in CM permeabilization, lipid turnover or regulated cell death were observed post-exposure to DAP, hNP-1 or LL-37. Thus, the adaptive energetics of the CM appear coupled to the outcomes of interactions of S. mitis-oralis with DAP and selected HDPs. In contrast, altered CM permeabilization, proposed as a major mechanism of action of both DAP and HDPs, did not differentiate DAP-S vs. DAP-R phenotypes in this S. mitis-oralis strain-pair.

scholarly journals Needle-Free Delivery of Acetalated Dextran-Encapsulated AR-12 Protects Mice from Francisella tularensis Lethal Challenge

2016 ◽  
Vol 60 (4) ◽  
pp. 2052-2062 ◽  
Author(s):  
Ky V. Hoang ◽  
Heather Curry ◽  
Michael A. Collier ◽  
Hassan Borteh ◽  
Eric M. Bachelder ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Lethal Challenge ◽  
Content Type ◽  
Human Macrophages ◽  
Gentamicin Treatment ◽  
Significant Toxicity ◽  
Serovar Typhimurium ◽  
Spectrum Activity

ABSTRACTFrancisella tularensiscauses tularemia and is a potential biothreat. Given the limited antibiotics for treating tularemia and the possible use of antibiotic-resistant strains as a biowarfare agent, new antibacterial agents are needed. AR-12 is an FDA-approved investigational new drug (IND) compound that induces autophagy and has shown host-directed, broad-spectrum activityin vitroagainstSalmonella entericaserovar Typhimurium andF. tularensis. We have shown that AR-12 encapsulated within acetalated dextran (Ace-DEX) microparticles (AR-12/MPs) significantly reduces host cell cytotoxicity compared to that with free AR-12, while retaining the ability to controlS.Typhimurium within infected human macrophages. In the present study, the toxicity and efficacy of AR-12/MPs in controlling virulent type AF. tularensisSchuS4 infection were examinedin vitroandin vivo. No significant toxicity of blank MPs or AR-12/MPs was observed in lung histology sections when the formulations were given intranasally to uninfected mice. In histology sections from the lungs of intranasally infected mice treated with the formulations, increased macrophage infiltration was observed for AR-12/MPs, with or without suboptimal gentamicin treatment, but not for blank MPs, soluble AR-12, or suboptimal gentamicin alone. AR-12/MPs dramatically reduced the burden ofF. tularensisin infected human macrophages, in a manner similar to that of free AR-12. However,in vivo, AR-12/MPs significantly enhanced the survival ofF. tularensisSchuS4-infected mice compared to that seen with free AR-12. In combination with suboptimal gentamicin treatment, AR-12/MPs further improved the survival ofF. tularensisSchuS4-infected mice. These studies provide support for Ace-DEX-encapsulated AR-12 as a promising new therapeutic agent for tularemia.

scholarly journals Terminal Deoxynucleotidyl Transferase Is Not Required for Antibody Response to Polysaccharide Vaccines againstStreptococcus pneumoniaeandSalmonella entericaSerovar Typhi

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Vivek Belde ◽  
Matthew P. Cravens ◽  
Dania Gulandijany ◽  
Justin A. Walker ◽  
Isabel Palomo-Caturla ◽  
...  
Keyword(s):  
Antibody Response ◽  
B Cell ◽  
Salmonella Enterica ◽  
Passive Immunization ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Human Infants ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTB cell antigen receptor (BCR) diversity increases by several orders of magnitude due to the action of terminal deoxynucleotidyl transferase (TdT) during V(D)J recombination. Unlike adults, infants have limited BCR diversity, in part due to reduced expression of TdT. Since human infants and young mice respond poorly to polysaccharide vaccines, such as the pneumococcal polysaccharide vaccine Pneumovax23 and Vi polysaccharide (ViPS) ofSalmonella entericaserovar Typhi, we tested the contribution of TdT-mediated BCR diversity in response to these vaccines. We found that TdT+/−and TdT−/−mice generated comparable antibody responses to Pneumovax23 and survivedStreptococcus pneumoniaechallenge. Moreover, passive immunization of B cell-deficient mice with serum from Pneumovax23-immunized TdT+/−or TdT−/−mice conferred protection. TdT+/−and TdT−/−mice generated comparable levels of anti-ViPS antibodies and antibody-dependent, complement-mediated bactericidal activity againstS. Typhiin vitro. To test the protective immunity conferred by ViPS immunizationin vivo, TdT+/−and TdT−/−mice were challenged with a chimericSalmonella entericaserovar Typhimurium strain expressing ViPS, since mice are nonpermissive hosts forS. Typhi infection. Compared to their unimmunized counterparts, immunized TdT+/−and TdT−/−mice challenged with ViPS-expressingS. Typhimurium exhibited a significant reduction in the bacterial burden and liver pathology. These data suggest that the impaired antibody response to the Pneumovax23 and ViPS vaccines in the young is not due to limited TdT-mediated BCR diversification.

scholarly journals B Cell Activating Factor Inhibition Impairs Bacterial Immunity by Reducing T Cell-Independent IgM Secretion

2013 ◽  
Vol 81 (12) ◽  
pp. 4490-4497 ◽  
Author(s):  
Derek D. Jones ◽  
Maura Jones ◽  
Gregory A. DeIulio ◽  
Rachael Racine ◽  
Katherine C. MacNamara ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
T Cell ◽  
B Cell ◽  
Host Defense ◽  
B Cell Differentiation ◽  
Content Type ◽  
Surface Marker Expression ◽  
B Cell Activating Factor

ABSTRACTB cell activating factor of the tumor necrosis factor family (BAFF) is an essential survival factor for B cells and has been shown to regulate T cell-independent (TI) IgM production. DuringEhrlichia murisinfection, TI IgM secretion in the spleen was BAFF dependent, and antibody-mediated BAFF neutralization led to an impairment of IgM-mediated host defense. The failure of TI plasmablasts to secrete IgM was not a consequence of alterations in their generation, survival, or early differentiation, since all occurred normally in infected mice following BAFF neutralization. Gene expression characteristic of plasma cell differentiation was also unaffected by BAFF neutralizationin vivo, and except for CD138, plasmablast cell surface marker expression was unaffected. IgM was produced, since it was detected intracellularly, and impaired secretion was not due to a failure to express the IgM secretory exon. Addition of BAFF to plasmablastsin vitrorescued IgM secretion, suggesting that BAFF signaling can directly regulate secretory processes. Our findings indicate that BAFF signaling can modulate TI host defense by acting at a late stage in B cell differentiation, via its regulation of terminal plasmablast differentiation and/or IgM secretion.

scholarly journals Efficacy of Synthetic Peptides RP-1 and AA-RP-1 against Leishmania SpeciesIn VitroandIn Vivo

2011 ◽  
Vol 56 (2) ◽  
pp. 658-665 ◽  
Author(s):  
Marie Crisel B. Erfe ◽  
Consuelo V. David ◽  
Cher Huang ◽  
Victoria Lu ◽  
Ana Claudia Maretti-Mira ◽  
...  
Keyword(s):  
Intravenous Administration ◽  
Synthetic Peptides ◽  
Antileishmanial Activity ◽  
Host Defense Peptides ◽  
Content Type ◽  
Causative Agents ◽  
Antileishmanial Activities ◽  
Conventional Antibiotics

ABSTRACTHost defense peptides are naturally occurring molecules that play essential roles in innate immunity to infection. Based on prior structure-function knowledge, we tested two synthetic peptides (RP-1 and AA-RP-1) modeled on the conserved, microbicidal α-helical domain of mammalian CXCL4 platelet kinocidins. These peptides were evaluated for efficacy againstLeishmaniaspecies, the causative agents of the group of diseases known as leishmaniasis.In vitroantileishmanial activity was assessed against three distinctLeishmaniastrains by measuring proliferation, metabolic activity and parasite viability after exposure to various concentrations of peptides. We demonstrate that micromolar concentrations of RP-1 and AA-RP-1 caused dose-dependent growth inhibition ofLeishmaniapromastigotes. This antileishmanial activity correlated with rapid membrane disruption, as well as with a loss of mitochondrial transmembrane potential. In addition, RP-1 and AA-RP-1 demonstrated distinct and significantin vivoantileishmanial activities in a mouse model of experimental visceral leishmaniasis after intravenous administration. These results establish efficacy of RP-1 lineage synthetic peptides againstLeishmaniaspeciesin vitroand after intravenous administrationin vivoand provide further validation of proof of concept for the development of these and related systemic anti-infective peptides targeting pathogens that are resistant to conventional antibiotics.

Valsartan solid lipid nanoparticles integrated hydrogel: A challenging repurposed use in the treatment of diabetic foot ulcer, in-vitro/in-vivo experimental study

2021 ◽  
Vol 592 ◽  
pp. 120091
Author(s):  
Noha S. El-Salamouni ◽  
Mennatallah A. Gowayed ◽  
Nevine L. Seiffein ◽  
Rehab A. Abdel- Moneim ◽  
Maher A. Kamel ◽  
...  
Keyword(s):  
Experimental Study ◽  
Diabetic Foot ◽  
Solid Lipid Nanoparticles ◽  
Foot Ulcer ◽  
Diabetic Foot Ulcer ◽  
Lipid Nanoparticles ◽  
Solid Lipid

scholarly journals Role of B Cells in Host Defense against Primary Coxiella burnetii Infection

2015 ◽  
Vol 83 (12) ◽  
pp. 4826-4836 ◽  
Author(s):  
Laura Schoenlaub ◽  
Alexandra Elliott ◽  
Danielle Freches ◽  
William J. Mitchell ◽  
Guoquan Zhang
Keyword(s):  
B Cells ◽  
Host Defense ◽  
Coxiella Burnetii ◽  
Critical Role ◽  
Interleukin 10 ◽  
Content Type ◽  
B1a Cells

DespiteCoxiella burnetiibeing an obligate intracellular bacterial pathogen, our recent study demonstrated that B cells play a critical role in vaccine-induced immunity toC. burnetiiinfection by producing protective antibodies. However, the role of B cells in host defense against primaryC. burnetiiinfection remains unclear. In this study, we investigated whether B cells play an important role in host defense against primaryC. burnetiiinfection. The results showed that peritoneal B cells were able to phagocytose virulentC. burnetiibacteria and formCoxiella-containing vacuoles (CCVs) and thatC. burnetiican infect and replicate in peritoneal B1a subset B cellsin vitro, demonstrating a potential role for peritoneal B cells in host defense againstC. burnetiiinfectionin vivo. In addition, the results showing that B1a cells secreted a high level of interleukin-10 (IL-10) in response toC. burnetiiinfectionin vitrosuggest that B1a cells may play an important role in inhibiting theC. burnetiiinfection-induced inflammatory response. The observation that adoptive transfer of peritoneal B cells did not significantly affect the severity ofC. burnetiiinfection-induced diseases in both severe combined immunity-deficient (SCID) and μMT mice indicates that peritoneal B cells alone may not be able to controlC. burnetiiinfection. In contrast, our finding thatC. burnetiiinfection induced more-severe splenomegaly and a higher bacterial burden in the spleens of B1a cell-deficient Bruton's tyrosine kinase x-linked immunity-deficient (BTKxid) mice than in their wild-type counterparts further suggests that B1a cells play an important role in host defense against primaryC. burnetiiinfection.

scholarly journals In Salmonella enterica, the Gcn5-Related Acetyltransferase MddA (Formerly YncA) Acetylates Methionine Sulfoximine and Methionine Sulfone, Blocking Their Toxic Effects

2014 ◽  
Vol 197 (2) ◽  
pp. 314-325 ◽  
Author(s):  
Kristy L. Hentchel ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Salmonella Enterica ◽  
Physiological Role ◽  
Methionine Sulfoximine ◽  
Amino Acid Transporters ◽  
Content Type ◽  
Methionine Sulfone ◽  
Serovar Typhimurium ◽  
Acylation Reactions

Protein and small-molecule acylation reactions are widespread in nature. Many of the enzymes catalyzing acylation reactions belong to theGcn5-relatedN-acetyltransferase (GNAT; PF00583) family, named after the yeast Gcn5 protein. The genome ofSalmonella entericaserovar Typhimurium LT2 encodes 26 GNATs, 11 of which have no known physiological role. Here, we providein vivoandin vitroevidence for the role of the MddA (methioninederivativedetoxifier; formerly YncA) GNAT in the detoxification of oxidized forms of methionine, including methionine sulfoximine (MSX) and methionine sulfone (MSO). MSX and MSO inhibited the growth of anS. entericaΔmddAstrain unless glutamine or methionine was present in the medium. We used anin vitrospectrophotometric assay and mass spectrometry to show that MddA acetylated MSX and MSO. AnmddA+strain displayed biphasic growth kinetics in the presence of MSX and glutamine. Deletion of two amino acid transporters (GlnHPQ and MetNIQ) in a ΔmddAstrain restored growth in the presence of MSX. Notably, MSO was transported by GlnHPQ but not by MetNIQ. In summary, MddA is the mechanism used byS. entericato respond to oxidized forms of methionine, which MddA detoxifies by acetyl coenzyme A-dependent acetylation.

scholarly journals The Host Defense Peptide Beta-Defensin 1 Confers Protection against Bordetella pertussis in Newborn Piglets

2006 ◽  
Vol 74 (4) ◽  
pp. 2338-2352 ◽  
Author(s):  
Shokrollah Elahi ◽  
Rachelle M. Buchanan ◽  
Sam Attah-Poku ◽  
Hugh G. G. Townsend ◽  
Lorne A. Babiuk ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Host Defense ◽  
Bordetella Pertussis ◽  
Respiratory Infections ◽  
Upper Respiratory Tract ◽  
Host Defense Peptides ◽  
Newborn Piglets ◽  
Defense Peptides

ABSTRACT Innate immunity plays an important role in protection against respiratory infections in humans and animals. Host defense peptides such as beta-defensins represent major components of innate immunity. We recently developed a novel porcine model of pertussis, an important respiratory disease of young children and infants worldwide. Here, we investigated the role of porcine beta-defensin 1 (pBD-1), a porcine defensin homologue of human beta-defensin 2, in conferring protection against respiratory infection with Bordetella pertussis. In this model, newborn piglets were fully susceptible to infection and developed severe bronchopneumonia. In contrast, piglets older than 4 weeks of age were protected against infection with B. pertussis. Protection was associated with the expression of pBD-1 in the upper respiratory tract. In fact, pBD-1 expression was developmentally regulated, and the absence of pBD-1 was thought to contribute to the increased susceptibility of newborn piglets to infection with B. pertussis. Bronchoalveolar lavage specimens collected from older animals as well as chemically synthesized pBD-1 displayed strong antimicrobial activity against B. pertussis in vitro. Furthermore, in vivo treatment of newborn piglets with only 500 μg pBD-1 at the time of challenge conferred protection against infection with B. pertussis. Interestingly, pBD-1 displayed no bactericidal activity in vitro against Bordetella bronchiseptica, a closely related natural pathogen of pigs. Our results demonstrate that host defense peptides play an important role in protection against pertussis and are essential in modulating innate immune responses against respiratory infections.

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