Significance Staphylococcus aureus is an opportunistic pathogen of the normal human flora. It is among the most frequent causes of cutaneous abscesses, leading to life-threatening invasive infection. ...Incomplete understanding of host defenses against S. aureus skin or invasive infection has hindered development of effective vaccines to address these issues. NDV-3 is a unique cross-kingdom vaccine targeting S. aureus and Candida albicans . The present studies offer important new evidence: ( i ) NDV-3 protects against methicillin-resistant S. aureus skin and skin structure infection largely through IL-22– and IL-17A–mediated host defense peptide and neutrophil induction, ( ii ) vaccine-mediated IL-22 and IL-17A play distinct roles in protection against cutaneous versus invasive infection, and ( iii ) NDV-3 vaccine efficacy in this model involves a coordinated induction of innate and adaptive immunity.
Increasing rates of life-threatening infections and decreasing susceptibility to antibiotics urge development of an effective vaccine targeting Staphylococcus aureus . This study evaluated the efficacy and immunologic mechanisms of a vaccine containing a recombinant glycoprotein antigen (NDV-3) in mouse skin and skin structure infection (SSSI) due to methicillin-resistant S. aureus (MRSA). Compared with adjuvant alone, NDV-3 reduced abscess progression, severity, and MRSA density in skin, as well as hematogenous dissemination to kidney. NDV-3 induced increases in CD3+ T-cell and neutrophil infiltration and IL-17A, IL-22, and host defense peptide expression in local settings of SSSI abscesses. Vaccine induction of IL-22 was necessary for protective mitigation of cutaneous infection. By comparison, protection against hematogenous dissemination required the induction of IL-17A and IL-22 by NDV-3. These findings demonstrate that NDV-3 protective efficacy against MRSA in SSSI involves a robust and complementary response integrating innate and adaptive immune mechanisms. These results support further evaluation of the NDV-3 vaccine to address disease due to S. aureus in humans.
Staphylococcus aureus is the leading cause of skin and skin structure infections (SSSI) in humans. Moreover, the high frequency of recurring SSSI due to S. aureus, particularly methicillin-resistant ...S. aureus (MRSA) strains, suggests that infection induces suboptimal anamnestic defenses. The present study addresses the hypothesis that interleukin-17A (IL-17A) and IL-22 play distinct roles in immunity to cutaneous and invasive MRSA infection in a mouse model of SSSI. Mice were treated with specific neutralizing antibodies against IL-17A and/or IL-22 and infected with MRSA, after which the severity of infection and host immune response were determined. Neutralization of either IL-17A or IL-22 reduced T cell and neutrophil infiltration and host defense peptide elaboration in lesions. These events corresponded with increased abscess severity, MRSA viability, and CFU density in skin. Interestingly, combined inhibition of IL-17A and IL-22 did not worsen abscesses but did increase gamma interferon (IFN-γ) expression at these sites. The inhibition of IL-22 led to a reduction in IL-17A expression, but not vice versa. These results suggest that the expression of IL-17A is at least partially dependent on IL-22 in this model. Inhibition of IL-17A but not IL-22 led to hematogenous dissemination to kidneys, which correlated with decreased T cell infiltration in renal tissue. Collectively, these findings indicate that IL-17A and IL-22 have complementary but nonredundant roles in host defense against cutaneous versus hematogenous infection. These insights may support targeted immune enhancement or other novel approaches to address the challenge of MRSA infection.
Recent discoveries suggest cysteine-stabilized toxins and antimicrobial peptides have structure-activity parallels derived by common ancestry. Here, human antimicrobial peptide hBD-2 and rattlesnake ...venom-toxin crotamine were compared in phylogeny, 3D structure, target celi specificity, and mechanisms of action. Results indicate a striking degree of structural and phylogenetic congruence. Importantly, these polypeptides also exhibited functional reciprocity: (i) they exerted highly similar antimicrobial pH optima and spectra; (ii) both altered membrane potential consistent with ion channel-perturbing activities; and (iii) both peptides induced phosphatidylserine accessibility in eukaryotic cells. However, the $Na_v $ channel-inhibitor tetrodotoxin antagonized hBD-2 mechanisms, but not those of crotamine. As crotamine targets eukaryotic ion Channels, computational docking was used to compare hBD-2 versus crotamine interactions with prototypic bacterial, fungal, or mammalian $K_v $ Channels. Models support direct interactions of each peptide with $K_v $ Channels. However, while crotamine localized to occlude $K_v $ Channels in eukaryotic but not prokaryotic cells, hBD-2 interacted with prokaryotic and eukaryotic $K_v $ Channels but did not occlude either. Together, these results support the hypothesis that antimicrobial and cytotoxic polypeptides have ancestral structurefunction homology, but evolved to preferentially target respective microbial versus mammalian ion Channels via residue-specific interactions. These insights may accelerate development of antiinfective or therapeutic peptides that selectively target microbial or abnormal host cells.
ABSTRACT Objective: To investigate whether empiric carbapenem therapy, compared to empiric non-carbapenem therapy, was associated with improved clinical outcomes among hospitalized, non-intensive ...care unit (ICU) patients with extended-spectrum β-lactamase (ESBL)-producing Enterobacterales infections. Methods: We performed a retrospective cohort study of adult, non-ICU patients admitted with ESBL-producing Enterobacterales infections. Primary outcome was time to clinical stability from the first empiric antibiotic dose. Secondary outcomes were early clinical response and 30-day all-cause hospital readmission. We used multivariate regression methods to examine time to clinical stability. Results: Of the 142 patients, 59 (42%) received empiric carbapenems and 83 (58%) received empiric non-carbapenems, most commonly ceftriaxone (49/83, 59%). Median age was 59 years. The most common infection source was urinary (71%). The carbapenem group had a higher proportion of patients who received antibiotics within 6 months of admission (55% vs 28%, P < .01) and history of ESBL (57% vs 17%, P < .01). There were no significant differences in hours until clinical stability between the carbapenem and non-carbapenem groups (22 (IQR: 0, 85) vs 19 (IQR: 0, 69), P = .54). Early clinical response (88% vs 90%, P = .79) and 30-day all-cause hospital readmission (17% vs 8%, P = .13) were similar between groups. Conclusion: Among hospitalized non-ICU patients with ESBL-producing Enterobacterales infection, we found no difference in time to clinical stability after the first empiric antibiotic dose between those receiving carbapenems and those who did not. Our data suggest that empiric carbapenem use may not be an important driver of clinical response in patients with less severe ESBL-producing Enterobacterales infection.
SARS-CoV-2 is the etiologic agent of coronavirus disease 2019 (COVID-19). Questions remain regarding correlates of risk and immune protection against COVID-19.
We prospectively enrolled 200 ...participants with a high risk of SARS-CoV-2 occupational exposure at a U.S. medical center between December 2020 and April 2022. Participant exposure risks, vaccination/infection status, and symptoms were followed longitudinally at 3, 6, and 12 months, with blood and saliva collection. Serological response to the SARS-CoV-2 spike holoprotein (S), receptor binding domain (RBD) and nucleocapsid proteins (NP) were quantified by ELISA assay.
Based on serology, 40 of 200 (20%) participants were infected. Healthcare and non-healthcare occupations had equivalent infection incidence. Only 79.5% of infected participants seroconverted for NP following infection, and 11.5% were unaware they had been infected. The antibody response to S was greater than to RBD. Hispanic ethnicity was associated with 2-fold greater incidence of infection despite vaccination in this cohort.
Overall, our findings demonstrate: 1) variability in the antibody response to SARS-CoV-2 infection despite similar exposure risk; 2) the concentration of binding antibody to the SARS-CoV-2 S or RBD proteins is not directly correlated with protection against infection in vaccinated individuals; and 3) determinants of infection risk include Hispanic ethnicity despite vaccination and similar occupational exposure.
Objectives:
Vaccine hesitancy among essential workers remains a significant public health challenge. We examined psychological constructs of perceived susceptibility, threat, and self-efficacy and ...their associations with COVID-19 vaccine hesitancy among a racially and ethnically diverse essential workforce population.
Methods:
We performed a cross-sectional survey of essential workers from September-December 2020 at a large Los Angeles safety-net medical center as part of a program offering free COVID-19 serology testing. Program participants completed a standardized survey at the time of phlebotomy. Hierarchical logistic regression was utilized to determine factors independently associated with vaccine hesitancy.
Results:
Among 1327 persons who had serology testing, 1235 (93%) completed the survey. Of these, 958 (78%) were healthcare workers. Based on expressed intent, 22% were vaccine-hesitant 78% were vaccine acceptors. In our multivariate model, vaccine hesitancy was associated with female gender aOR = 2.09; 95% CI (1.44-3.05), African American race aOR = 4.32; (2.16-8.62), LatinX ethnicity aOR = 2.47; 95% CI (1.51-4.05) and history of not/sometimes receiving influenza vaccination aOR = 4.39; 95% CI (2.98-6.48). Compared to nurses, vaccine hesitancy was lower among physicians aOR = 0.09; 95% CI (0.04-0.23), non-nursing/non-physician healthcare workers aOR = 0.55; 95% CI (0.33-0.92), and non-healthcare care workers aOR = 0.53; 95% CI (0.36-0.78).
Conclusions:
Among a racially/ethnically diverse group of safety net medical center essential workers, COVID-19 vaccine hesitancy was associated with racial/ethnic minority groups, employment type, and prior influenza vaccination hesitancy. Interestingly, we found no association with the Health Belief Model construct measures of perceived susceptibility, threat, and self-efficacy. Psychological constructs not assessed may be drivers of vaccine hesitancy in our population.
Platelets (PLTs) act in antimicrobial host defense by releasing PLT microbicidal proteins (PMPs) or PLT kinocidins (PKs). Receptors mediating staphylocidal efficacy and PMP or PK release versus ...isogenic PMP-susceptible (ISP479C) and -resistant (ISP479R) Staphylococcus aureus strains were examined in vitro. Isolated PLTs were incubated with ISP479C or ISP479R (PLT/S. aureus ratio range, 1:1 to 10,000:1) in the presence or absence of a panel of PLT inhibitors, including P2X and P2Y receptor antagonists of increasingly narrow specificity, and PLT adhesion receptors (CD41, CD42b, and CD62P). PLT-to-S. aureus exposure ratios of greater-than-or-equal10:1 yielded significant reductions in the viability of both strains. Results from reversed-phase high-performance liquid chromatography indicated that staphylocidal PLT releasates contained PMPs and PKs. At ratios below 10:1, the PLT antistaphylococcal efficacy relative to the intrinsic S. aureus PMP-susceptible or -resistant phenotype diminished. Apyrase (an agent of ADP degradation), suramin (a general P2 receptor antagonist), pyridoxal 5'-phosphonucleotide derivative (a specific P2X₁ antagonist), and cangrelor (a specific P2Y₁₂ antagonist) mitigated the PLT staphylocidal response against both strains, correlating with reduced levels of PMP and PK release. Specific inhibition occurred in the presence and absence of homologous plasma. The antagonism of the thromboxane A₂, cyclooxygenase-1/cyclooxygenase-2, or phospholipase C pathway or the hindrance of surface adhesion receptors failed to impede PLT anti-S. aureus responses. These results suggest a multifactorial PLT anti-S. aureus response mechanism involving (i) a PLT-to-S. aureus ratio sufficient for activation; (ii) the ensuing degranulation of PMPs, PKs, ADP, and/or ATP; (iii) the activation of P2X₁/P2Y₁₂ receptors on adjacent PLTs; and (iv) the recursive amplification of PMP and PK release from these PLTs.
Mammalian platelets contain an array of antimicrobial peptides, termed platelet microbicidal proteins (PMPs). Human and rabbit PMPs include known chemokines, such as platelet factor-4 (hPF-4); PMP-1 ...is the rabbit orthologue of hPF-4. Chemokines that also exert direct antimicrobial activity have been termed kinocidins. A consensus peptide domain library representing mammalian PF-4 family members was analyzed to define structural domains contributing to antimicrobial activity against a panel of human pathogens. Secondary conformations were assessed by circular dichroism spectrometry, and molecular modeling was employed to investigate structural correlates of antimicrobial efficacy. Antimicrobial activity against isogenic peptide-susceptible or -resistant
Staphylococcus aureus,
Salmonella typhimurium, and
Candida albicans strain pairs mapped to the C-terminal hemimer (38–74) and modular domains thereof (49–63 and 60–74). Increasing electrostatic charge and steric bulk were general correlates of efficacy. Structural data corroborated spatial distribution of charge, steric bulk and putative secondary structure with organism-specific efficacy. Microbicidal efficacies of the cPMP antimicrobial hemimer and C-terminal peptide (60–74) were retained in a complex human-blood biomatrix assay. Collectively, these results suggest that modular determinants arising from structural components acting independently and cooperatively govern the antimicrobial functions of PF-4 family kinocidins against specific target pathogens.
Structure-mechanism relationships are key determinants of host defense peptide efficacy. These relationships are influenced by anatomic, physiologic and microbiologic contexts. Structure-mechanism ...correlates were assessed for the synthetic peptide RP-1, modeled on microbicidal domains of platelet kinocidins. Antimicrobial efficacies and mechanisms of action against susceptible ((S)) or resistant ((R)) Salmonella typhimurium (ST), Staphylococcus aureus (SA), and Candida albicans (CA) strain pairs were studied at pH 7.5 and 5.5. Although RP-1 was active against all study organisms, it exhibited greater efficacy against bacteria at pH 7.5, but greater efficacy against CA at pH 5.5. RP-1 de-energized SA and CA, but caused hyperpolarization of ST in both pH conditions. However, RP-1 permeabilized ST(S) and CA strains at both pH, whereas permeabilization was modest for ST(R) or SA strain at either pH. Biochemical analysis, molecular modeling, and FTIR spectroscopy data revealed that RP-1 has indistinguishable net charge and backbone trajectories at pH 5.5 and 7.5. Yet, concordant with organism-specific efficacy, surface plasmon resonance, and FTIR, molecular dynamics revealed modest helical order increases but greater RP-1 avidity and penetration of bacterial than eukaryotic lipid systems, particularly at pH 7.5. The present findings suggest that pH- and target-cell lipid contexts influence selective antimicrobial efficacy and mechanisms of RP-1 action. These findings offer new insights into selective antimicrobial efficacy and context-specificity of antimicrobial peptides in host defense, and support design strategies for potent anti-infective peptides with minimal concomitant cytotoxicity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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