Conformational States of a Bacterial α2-Macroglobulin Resemble Those of Human Complement C3

α2 macroglobulins (α2Ms) are broad-spectrum protease inhibitors that play essential roles in the innate immune system of eukaryotic species. These large, multi-domain proteins are characterized by a broad-spectrum bait region and an internal thioester, which, upon cleavage, becomes covalently associated to the target protease, allowing its entrapment by a large conformational modification. Notably, α2Ms are part of a larger protein superfamily that includes proteins of the complement system, such as C3, a multi-domain macromolecule which is also characterized by an internal thioester-carrying domain and whose activation represents the pivotal step in the complement cascade. Recently, α2M/C3-like genes were identified in a large number of bacterial genomes, and the Escherichia coli α2M homolog (ECAM) was shown to be activated by proteases. In this work, we have structurally characterized ECAM by electron microscopy and small angle scattering (SAXS) techniques. ECAM is an elongated, flexible molecule with overall similarities to C3 in its inactive form; activation by methylamine, chymotrypsin, or elastase induces a conformational modification reminiscent of the one undergone by the transformation of C3 into its active form, C3b. In addition, the proposed C-terminus of ECAM displays high flexibility and different conformations, and could be the recognition site for partner macromolecules. This work sheds light on a potential bacterial defense mechanism that mimics structural rearrangements essential for activation of the complement cascade in eukaryotes, and represents a possible novel target for the development of antibacterials

Indicativos de resiliência familiar em famílias de crianças com síndrome de Down

Resumo Este estudo objetiva caracterizar e analisar a resiliência familiar em famílias de crianças com síndrome de Down. Participaram cinco famílias compostas por pai, mãe e filhos, tendo um deles a síndrome. Os instrumentos utilizados foram o Questionário de Caracterização do Sistema Familiar, o qual foi respondido pela mãe; o Inventário de Estratégias de Coping, o qual ambos os genitores responderam separadamente; e entrevistas com genitores e filhos com desenvolvimento típico. As famílias foram visitadas em três momentos. Os resultados indicam que diante de eventos ruins, principalmente, dos problemas de saúde relacionados à síndrome de Down, as famílias apresentam capacidade de extrair sentido da adversidade, bem como de se organizar de forma cooperativa, com diálogo e estreitamento dos vínculos. Em todas as famílias foram identificados indicativos de resiliência familiar. A estratégia de coping mais utilizada é a reavaliação positiva, enquanto a menos utilizada é fuga-esquiva

A New Class of Safe Oligosaccharide Polymer Therapy To Modify the Mucus Barrier of Chronic Respiratory Disease

The host- and bacteria-derived extracellular polysaccharide coating of the lung is a considerable challenge in chronic respiratory disease and is a powerful barrier to effective drug delivery. A low molecular weight 12–15-mer alginate oligosaccharide (OligoG CF-5/20), derived from plant biopolymers, was shown to modulate the polyanionic components of this coating. Molecular modeling and Fourier transform infrared spectroscopy demonstrated binding between OligoG CF-5/20 and respiratory mucins. Ex vivo studies showed binding induced alterations in mucin surface charge and porosity of the three-dimensional mucin networks in cystic fibrosis (CF) sputum. Studies in Humans showed that OligoG CF-5/20 is safe for inhalation in CF patients with effective lung deposition and modifies the viscoelasticity of CF-sputum. OligoG CF-5/20 is the first inhaled polymer therapy, represents a novel mechanism of action and therapeutic approach for the treatment of chronic respiratory disease, and is currently in Phase IIb clinical trials for the treatment of CF

A low-molecular-weight alginate oligosaccharide disrupts pseudomonal microcolony formation and enhances antibiotic effectiveness

In chronic respiratory disease the formation of dense, 3-dimensional ‘micro colonies' by Pseudomonas aeruginosa within the airway plays an important role in contributing to resistance to treatment. An in vitro biofilm model of pseudomonal microcolony formation using artificial sputum (AS) medium was established to study the effects of low molecular weight alginate oligomers (OligoG CF-5/20) on pseudomonal growth, microcolony formation and the efficacy of colistin. The studies employed clinical cystic fibrosis (CF) isolates (n=3) and reference non-mucoid and mucoid multi-drug resistant (MDR) CF isolates (n=7). Bacterial growth, biofilm development and disruption were studied using cell-viability assays and image analysis using scanning electron- and confocal laser scanning microscopy. Pseudomonal growth in AS medium was associated with increased ATP production (p10 μm) microcolonies. In conventional growth medium, colistin retained an ability to inhibit growth of planktonic bacteria, although the MIC was increased (0.1 to 0.4 μg/ml) in AS medium versus. In contrast, in an established biofilm model in the AS medium, the efficacy of colistin was decreased. OligoG CF-5/20 (≥2%) treatment however, induced dose-dependent biofilm disruption (p0.2%; p<0.05) reductions in pseudomonal quorum sensing signaling. These findings reinforce the potential clinical significance of microcolony formation in the CF lung, and highlight a novel approach to treat MDR pseudomonal infections