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Background: Clostridioides difficile infections have become more frequently diagnosed and associated with greater disease severity, which has resulted in an increase burden on the healthcare system. These increases are attributed to the increased prevalence of hypervirulent strains encompassing select ribotypes. These epidemic ribotypes were characterized as hypervirulent due to higher in vitro spore and toxin production, as well as increased incidence, severity and mortality within patients. However, it is unclear whether epidemic ribotypes are truly more virulent than non-epidemic ribotypes in vivo. Furthermore, there is conflicting evidence about the ability of a strain's in vitro phenotype to be predictive of their in vivo virulence. The goals of the current studies were to determine if epidemic ribotypes are more virulent than other ribotypes in animal models, and whether the in vitro virulence phenotype of an isolate or ribotype predict in vivo virulence. Results: To determine if epidemic strains were truly more virulent than other non-epidemic strains, the in vivo virulence of 13 C. difficile isolates (7 non-epidemic and 6 epidemic ribotype isolates) were determined in murine and hamster models of CDI. The isolates of epidemic ribotype of C. difficile were found to be more virulent in both the murine and hamster models than non-epidemic isolates. In particular, the group of epidemic ribotypes of C. difficile had lower LD50 values in hamsters. The increased severity of disease was associated with higher levels of Toxin A and Toxin B production found in fecal samples, but not numbers of organisms recovered. The isolates were further characterized for their in vitro virulence phenotypes, e.g. toxin production, growth rates, spore formation and adherence of spores to intestinal epithelial cell lines. Although there were higher levels of toxins produced and greater adherence for the group of epidemic ribotypes, the in vitro profiles of individual isolates were not always predictive of their in vivo virulence. Conclusions: Overall, the group of epidemic ribotypes of C. difficile were more virulent in vivo despite individual isolates having similar phenotypes to the non-epidemic isolates in vitro. [ABSTRACT FROM AUTHOR]

A hallmark of effective cancer treatment is the prevention of tumor reoccurrence and metastasis to distal organs, which are responsible for most cancer deaths. However, primary tumor resection is expected to be curative as most solid tumors have been shown both experimentally and clinically to accelerate metastasis to distal organs including the lungs. In this study, we evaluated the efficacy of our engineered nasal nano-vaccine (CpG-NP-Tag) in reducing accelerated lung metastasis resulting from primary tumor resection. Cytosine–phosphate–guanine oligonucleotide [CpG ODN]-conjugated nanoparticle [NP] encapsulating tumor antigen [Tag] (CpG-NP-Tag) was manufactured and tested in vivo using a syngeneic mouse mammary tumor model following intranasal delivery. We found that our nasal nano-vaccine (CpG-NP-Tag), compared to control NPs administered after primary mammary tumor resection, significantly reduced lung metastasis in female BALB/c mice subjected to surgery (surgery mice). An evaluation of vaccine efficacy in both surgery and non-surgery mice revealed that primary tumor resection reduces CD11b+ monocyte-derived suppressor-like cell accumulation in the lungs, allowing increased infiltration of vaccine-elicited T cells (IFN-γ CD8+ T cells) in the lungs of surgery mice compared to non-surgery mice. These findings suggest that the combination of the target delivery of a nasal vaccine in conjunction with the standard surgery of primary tumors is a plausible adjunctive treatment against the establishment of lung metastasis. [ABSTRACT FROM AUTHOR]

C. difficile is an endospore-forming pathogen, which is becoming a common cause of microbial health-care associated gastrointestinal disease in the United States. Both healthy and symptomatic patients can shed C. difficile spores into the environment, which can survive for long periods, being resistant to desiccation, heat, and disinfectants. In healthcare facilities, environmental contamination with C. difficile is a major concern as a potential source of exposure to this pathogen and risk of disease in susceptible patients. Although hospital-acquired infection is recognized, community-acquired infection is an increasingly recognized health problem. Primary care clinics may be a significant source of exposure to this pathogen; however, there are limited data about presence of environmental C. difficile within clinics. To address the potential for primary care clinics as a source of environmental exposure to virulent C. difficile, we measured the frequency of environmental contamination with spores in clinic examination rooms and hospital rooms in Dallas-Fort Worth (DFW) area of Texas. The ribotypes and presence of toxin genes from some environmental isolates were compared. Our results indicate primary care clinics have higher frequencies of contamination than hospitals. After notification of the presence of C. difficile spores in the clinics and an educational discussion to emphasize the importance of this infection and methods of infection prevention, environmental contamination in clinics was reduced on subsequent sampling to that found in hospitals. Thus, primary care clinics can be a source of exposure to virulent C. difficile, and recognition of this possibility can result in improved infection prevention, potentially reducing community-acquired C. difficile infections and subsequent disease. [ABSTRACT FROM AUTHOR]

Lung metastasis is a leading cause of cancer-related deaths. Here, we show that intranasal delivery of our engineered CpG-coated tumor antigen (Tag)-encapsulated nanoparticles (NPs)—nasal nano-vaccine—significantly reduced lung colonization by intravenous challenge of an extra-pulmonary tumor. Protection against tumor-cell lung colonization was linked to the induction of localized mucosal-associated effector and resident memory T cells as well as increased bronchiolar alveolar lavage-fluid IgA and serum IgG antibody responses. The nasal nano-vaccine-induced T-cell-mediated antitumor mucosal immune response was shown to increase tumor-specific production of IFN-γ and granzyme B by lung-derived CD8+ T cells. These findings demonstrate that our engineered nasal nano-vaccine has the potential to be used as a prophylactic approach prior to the seeding of tumors in the lungs, and thereby prevent overt lung metastases from existing extra pulmonary tumors. [ABSTRACT FROM AUTHOR]

Mycoplasmas are a common cause of pneumonia in humans and animals, and attempts to create vaccines have not only failed to generate protective host responses, but they have exacerbated the disease. Mycoplasma pulmonis causes a chronic inflammatory lung disease resulting from a persistent infection, similar to other mycoplasma respiratory diseases. Using this model, Th1 subsets promote resistance to mycoplasma disease and infection, whereas Th2 responses contribute to immunopathology. The purpose of the present study was to evaluate the capacity of cytokine-differentiated dendritic cell (DC) populations to influence the generation of protective and/or pathologic immune responses during M. pulmonis respiratory disease in BALB/c mice. We hypothesized that intratracheal inoculation of mycoplasma Ag-pulsed bone marrow-derived DCs could result in the generation of protective T cell responses during mycoplasma infection. However, intratracheal inoculation (priming) of mice with Ag-pulsed DCs resulted in enhanced pathology in the recipient mice when challenged with mycoplasma. Inoculation of immunodeficient SCID mice with Ag-pulsed DCs demonstrated that this effect was dependent on lymphocyte responses. Similar results were observed when mice were primed with Ag-pulsed pulmonary, but not splenic, DCs. Lymphocytes generated in uninfected mice after the transfer of either Ag-pulsed bone marrow-derived DCs or pulmonary DCs were shown to be IL-13+ Th2 cells, known to be associated with immunopathology. Thus, resident pulmonary DCs most likely promote the development of immunopathology in mycoplasma disease through the generation of mycoplasma-specific Th2 responses. Vaccination strategies that disrupt or bypass this process could potentially result in a more effective vaccination. [ABSTRACT FROM AUTHOR]

Abstract: Stress responses have been associated with altered immunity and depending upon the type of stressor, can have diverse effects on disease outcomes. As the first line of defense against potential pathogens, alterations in cellular immune responses along the respiratory tract can have a significant impact on the manifestation of local and systemic disease. Utilizing a murine model of respiratory pneumonia, the current study investigated the effects of restraint stress on the induction of primary and secondary immunity along the respiratory tract, influencing host susceptibility. Female CD-1 mice were subjected to three hours of restraint stress over a period of four days followed by primary and secondary Streptococcus pneumoniae infection via intranasal route. Stress exposure led to increased retention of bacterial carriage in the lungs, enhanced polymorphonuclear cells and a preferential decrease in pulmonary CD11c+ MHC II+ cells resulting in delayed lethality during primary infection but significant impairment of acquired immune protection after secondary infection. We also provide evidence to support a role for lung-associated corticotropin releasing hormone regulation through peripheral CRH and diverse CRH receptor expression by MHC II+ antigen presenting cells (APCs). We conclude that repeated restraint stress has distinct influences on immune cell populations that appear to be important in the generation of innate and adaptive immune responses along the respiratory tract with the potential to influence local and systemic protection against disease pathogenesis. [Copyright &y& Elsevier]

Coadministration of human secretory IgA (sIgA) together with subtherapeutic vancomycin enhanced survival in the Clostridioides difficile infection (CDI) hamster model. Vancomycin (5 or 10 mg/kg × 5 days) plus healthy donor plasma sIgA/monomeric IgA (TID × 21 days) or hyperimmune sIgA/monomeric IgA (BID × 13 days) enhanced survival. Survival was improved compared to vancomycin alone, P = .018 and .039 by log-rank Mantel-Cox, for healthy and hyperimmune sIgA, respectively. Passive immunization with sIgA (recombinant human secretory component plus IgA dimer/polymer from pooled human plasma) can be administered orally and prevents death in a partially treated CDI hamster model. [ABSTRACT FROM AUTHOR]

Lantibiotics continue to offer an untapped pipeline for the development of novel antibiotics. We report here the discovery of a novel lantibiotic for the treatment of C. difficile infection (CDI). The leads were selected from a library of over 300 multiple substitution variants of the lantibiotic Mutacin 1140 (MU1140). Top performers were selected based on testing for superior potency, solubility, manufacturability, and physicochemical and/or metabolic stability in biologically-relevant systems. The best performers in vitro were further evaluated orally in the Golden Syrian hamster model of CDAD. In vivo testing ultimately identified OG716 as the lead compound, which conferred 100% survival and no relapse at 3 weeks post infection. MU1140-derived variants are particularly attractive for further clinical development considering their novel mechanism of action. [ABSTRACT FROM AUTHOR]

Toxin-induced Clostridium difficile infection (CDI) is a major disease characterized by severe diarrhea and high morbidity rates. The aim with this study was to develop an alternative drug for the treatment of CDI. Cows were repeatedly immunized to establish specific immunoglobulin G and A titers against toxins A (TcdA) and B (TcdB) and against C. difficile cells in mature milk or colostrum. The effect of three different concentrations of anti-C. difficile whey protein isolates (anti-CD-WPI) and the standard of care antibiotic vancomycin were investigated in an animal model of CD infected hamsters (6 groups, with 10 hamsters each). WPI obtained from the milk of exactly the same cows pre-immunization and a vehicle group served as negative controls. The survival of hamsters receiving anti-CD-WPI was 50, 80 and 100% compared to 10 and 0% for the control groups, respectively. Vancomycin suppressed the growth of C. difficile and thus protected the hamsters at the time of administration, but 90% of these hamsters nevertheless died shortly after discontinuation of treatment. In contrast, the surviving hamsters of the anti-CD-WPI groups survived the entire study period, although they were treated for only 75 h. The specific antibodies not only inactivated the toxins for initial suppression of CDI, but also provoked the inhibition of C. difficile growth after discontinuation, thus preventing recurrence. Oral administration of anti-CD-WPI is a functional therapy of CDI in infected hamsters for both primary treatment and prevention of recurrence. Thus, anti-CD-WPI could address the urgent unmet medical need for treating and preventing recurrent CDI in humans. [ABSTRACT FROM AUTHOR]

Abstract: Utilizing a murine model of S. pneumoniae infection and restraint stress, we determined how corticotropin releasing hormone (CRH-R) receptors impacts disease. CRH-R1 (antalarmin) and CRH-R2 (astressin2B) antagonists were administered intraperitoneally prior to restraint stress followed by pulmonary S. pneumoniae infection. CRH-R1 inhibition is not protective against pneumococcal disease induced by stress. Conversely, CRH-R2 inhibition attenuates stress-induced bacterial growth and significantly prevented severe sepsis. Neutrophillic responses were associated with CRH receptor-specific disease outcome providing a potential cellular target for stress-induced susceptibility to the development of severe pneumococcal disease. CRH receptor-mediated effects on immune responses could prove valuable for novel therapeutics. [Copyright &y& Elsevier]

Abstract: The aim of this study was to develop a specific and sensitive liquid chromatography mass spectrometry (LC/MS) method for the determination of rifampicin and levofloxacin concentrations from infected tissues within teflon catheter segments which were subcutaneously implanted in mice. A solid-phase extraction procedure was used to extract analytes from tissue homogenates of the catheter segments and reverse-phase HPLC combined with positive electrospray ionization mass spectrometry was used for analyte separation and quantification. The assay was found to be linear over the concentration range of 0.02–2μg/g for rifampicin and levofloxacin in tissues and provided good validation data for accuracy and precision. The intra-day accuracy as determined by the relative error was −1.3% for levofloxacin and 6.1% for rifampicin, and precision was evaluated by R.S.D.s with a maximum of 5.1% for levofloxacin and 8.1% for rifampicin. The inter-day accuracy was −3.3% for levofloxacin and −4.6% for rifampicin, and precision was 8.6% for levofloxacin and 7.1% for rifampicin. The assay uses less tissue than previously described methods and can be applied to determine the penetration of rifampicin and the fluoroquinolone in catheter segments from a mouse model of a device-related infection. Finally, the HPLC–MS assay should be applicable to studies of rifamycin+quinolone combination therapies in other animal models of bacterial infection. [Copyright &y& Elsevier]

Abstract: A novel series of spirorifamycins was synthesized and their antibacterial activity evaluated both in vitro and in vivo. This new series of rifamycins shows excellent activity against Staphylococcus aureus that is equivalent to rifabutin. However, some compounds of the series exhibit lower MICs than rifabutin against rifampin-resistant strains of S. aureus. Further, compound 2e exhibits comparable efficacy in vivo in a murine model of S. aureus septicemia model following administration by either oral or parenteral dosing routes. [Copyright &y& Elsevier]