Biofilm exopolysaccharides alter sensory-neuron-mediated sickness during lung infection.

Infections of the lung cause observable sickness thought to be secondary to inflammation. Signs of sickness are crucial to alert others via behavioral-immune responses to limit contact with contagious individuals. Gram-negative bacteria produce exopolysaccharide (EPS) that provides microbial protection; however, the impact of EPS on sickness remains uncertain. Using genome-engineered Pseudomonas aeruginosa (P. aeruginosa) strains, we compared EPS-producers versus non-producers and a virulent Escherichia coli (E. coli) lung infection model in male and female mice. EPS-negative P. aeruginosa and virulent E. coli infection caused severe sickness, behavioral alterations, inflammation, and hypothermia mediated by TLR4 detection of the exposed lipopolysaccharide (LPS) in lung TRPV1+ sensory neurons. However, inflammation did not account for sickness. Stimulation of lung nociceptors induced acute stress responses in the paraventricular hypothalamic nuclei by activating corticotropin-releasing hormone neurons responsible for sickness behavior and hypothermia. Thus, EPS-producing biofilm pathogens evade initiating a lung-brain sensory neuronal response that results in sickness.

Bps polysaccharide of Bordetella pertussis resists antimicrobial peptides by functioning as a dual surface shield and decoy and converts Escherichia coli into a respiratory pathogen.

Infections and disease caused by the obligate human pathogen Bordetella pertussis (Bp) are increasing, despite widespread vaccinations. The current acellular pertussis vaccines remain ineffective against nasopharyngeal colonization, carriage, and transmission. In this work, we tested the hypothesis that Bordetella polysaccharide (Bps), a member of the poly-ß-1,6-N-acetyl-D-glucosamine (PNAG/PGA) family of polysaccharides promotes respiratory tract colonization of Bp by resisting killing by antimicrobial peptides (AMPs). Genetic deletion of the bpsA-D locus, as well as treatment with the specific glycoside hydrolase Dispersin B, increased susceptibility to AMP-mediated killing. Bps was found to be both cell surface-associated and released during laboratory growth and mouse infections. Addition of bacterial supernatants containing Bps and purified Bps increased B. pertussis resistance to AMPs. By utilizing ELISA, immunoblot and flow cytometry assays, we show that Bps functions as a dual surface shield and decoy. Co-inoculation of C57BL/6J mice with a Bps-proficient strain enhanced respiratory tract survival of the Bps-deficient strain. In combination, the presented results highlight the critical role of Bps as a central driver of B. pertussis pathogenesis. Heterologous production of Bps in a non-pathogenic E. coli K12 strain increased AMP resistance in vitro, and augmented bacterial survival and pathology in the mouse respiratory tract. These studies can serve as a foundation for other PNAG/PGA polysaccharides and for the development of an effective Bp vaccine that includes Bps.

The role of exopolysaccharides Psl and Pel in resistance of Pseudomonas aeruginosa to the oxidative stressors sodium hypochlorite and hydrogen peroxide.

Pseudomonas aeruginosa is well-known for its antimicrobial resistance and the ability to survive in harsh environmental conditions due to an abundance of resistance mechanisms, including the formation of biofilms and the production of exopolysaccharides. Exopolysaccharides are among the major components of the extracellular matrix in biofilms and aggregates of P. aeruginosa. Although their contribution to antibiotic resistance has been previously shown, their roles in resistance to oxidative stressors remain largely elusive. Here, we studied the function of the exopolysaccharides Psl and Pel in the resistance of P. aeruginosa to the commonly used disinfectants and strong oxidizing agents NaOCl and H2O2. We observed that the simultaneous inactivation of Psl and Pel in P. aeruginosa PAO1 mutant strain ∆pslA pelF resulted in a significant increase in susceptibility to both NaOCl and H2O2. Further analyses revealed that Pel is more important for oxidative stress resistance in P. aeruginosa and that the form of Pel (i.e., cell-associated or cell-free) did not affect NaOCl susceptibility. Additionally, we show that Psl/Pel-negative strains are protected against oxidative stress in co-culture biofilms with P. aeruginosa PAO1 WT. Taken together, our results demonstrate that the EPS matrix and, more specifically, Pel exhibit protective functions against oxidative stressors such as NaOCl and H2O2 in P. aeruginosa. IMPORTANCE: Biofilms are microbial communities of cells embedded in a self-produced polymeric matrix composed of polysaccharides, proteins, lipids, and extracellular DNA. Biofilm bacteria have been shown to possess unique characteristics, including increased stress resistance and higher antimicrobial tolerance, leading to failures in bacterial eradication during chronic infections or in technical settings, including drinking and wastewater industries. Previous studies have shown that in addition to conferring structure and stability to biofilms, the polysaccharides Psl and Pel are also involved in antibiotic resistance. This work provides evidence that these biofilm matrix components also contribute to the resistance of Pseudomonas aeruginosa to oxidative stressors including the widely used disinfectant NaOCl. Understanding the mechanisms by which bacteria escape antimicrobial agents, including strong oxidants, is urgently needed in the fight against antimicrobial resistance and will help in developing new strategies to eliminate resistant strains in any environmental, industrial, and clinical setting.

Lesión miocárdica en una paciente con lupus eritematoso sistémico: Un reto diagnóstico / Myocardial lesion in a patient with systemic lupus erythematosus: A diagnostic challenge

Resumen Mujer de 37 años con antecedentes de lupus eritematoso sistémico (LES), tromboembolia pulmonar y trombosis venosa profunda, quien consultó por dolor torácico, con hallazgos de elevación de la troponina, disfunción sistólica del ventrículo izquierdo y alteraciones de la contractilidad segmentaria, además de anti-DNA elevado y complemento consumido. La angiografía coronaria mostró estenosis grave en el tercio medio de la arteria descendente anterior, que fue intervenida con angioplastia más stent medicado. La resonancia magnética cardiaca reveló infarto agudo de miocardio extenso en el territorio de la arteria descendente anterior, sin miocarditis. Se descartó compromiso cardiaco por LES, se continuó igual terapia inmunosupresora, se añadió manejo para enfermedad coronaria y egresó por buena evolución. El enfoque de las causas de lesión miocárdica en un paciente con LES supone un reto, dadas las múltiples posibilidades en el espectro de compromiso cardiaco, ya que varias estructuras se pueden ver afectadas. La miocarditis y la pericarditis se consideran las más frecuentes, pero el compromiso coronario no puede descartarse, independientemente de la edad y de la presencia de factores de riesgo tradicionales, puesto que el componente inflamatorio de la patología autoinmunitaria confiere un desarrollo acelerado de ateroesclerosis. La multimodalidad diagnóstica y el enfoque interdisciplinario son necesarios para aclarar el mecanismo de la lesión y así brindar un tratamiento dirigido.

Abstract A 37-year-old woman with a history of systemic lupus erythematosus (SLE), pulmonary thromboembolism and deep vein thrombosis consulted for chest pain, with findings of elevated troponin, left ventricular systolic dysfunction, and segmental contractility abnormalities, as well as elevated anti-DNA and complement consumption. Coronary angiography showed severe stenosis of the middle third of the anterior descending artery, which was treated with angioplasty plus a medicated stent. Cardiac magnetic resonance imaging revealed an extensive acute myocardial infarction in the area supplied by the anterior descending artery, without myocarditis. Cardiac involvement in SLE was ruled out, immunosuppressive treatment was maintained, coronary disease treatment was added, and she was discharged due to improvement. Identifying the causes of myocardial insult in a patient with SLE is challenging, given the multiple possibilities across the cardiac involvement spectrum, in which several structures may be affected. Myocarditis and pericarditis are considered to be the most frequent, but coronary involvement cannot be ruled out, regardless of age or the presence of traditional risk factors, since the inflammatory component of the autoimmune disease accelerates the development of atherosclerosis. Multimodal diagnostics and an interdisciplinary approach are necessary to clarify the mechanism of injury and provide targeted treatment.