Insight into the molecular basis of pathogen abundance: group A Streptococcus inhibitor of complement inhibits bacterial adherence and internalization into human cells

Streptococcal inhibitor of complement (Sic) is a secreted protein made predominantly by serotype M1 Group A Streptococcus (GAS), which contributes to persistence in the mammalian upper respiratory tract and epidemics of human disease. Unexpectedly, an isogenic sic-negative mutant adhered to human epithelial cells significantly better than the wild-type parental strain. Purified Sic inhibited the adherence of a sic negative serotype M1 mutant and of non-Sic-producing GAS strains to human epithelial cells. Sic was rapidly internalized by human epithelial cells, inducing cell flattening and loss of microvilli. Ezrin and moesin, human proteins that functionally link the cytoskeleton to the plasma membrane, were identified as Sic-binding proteins by affinity chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis. Sic colocalized with ezrin inside epithelial cells and bound to the F-actin-binding site region located in the carboxyl terminus of ezrin and moesin. Synthetic peptides corresponding to two regions of Sic had GAS adherence-inhibitory activity equivalent to mature Sic and inhibited binding of Sic to ezrin. In addition, the sic mutant was phagocytosed and killed by human polymorphonuclear leukocytes significantly better than the wild-type strain, and Sic colocalized with ezrin in discrete regions of polymorphonuclear leukocytes. The data suggest that binding of Sic to ezrin alters cellular processes critical for efficient GAS contact, internalization, and killing. Sic enhances bacterial survival by enabling the pathogen to avoid the intracellular environment. This process contributes to the abundance of M1 GAS in human infections and their ability to cause epidemics.     

Markers of inflammation and microvascular complications in type 1 diabetes

Aims

Long-term hyperglycemia, characteristic for type 1 diabetes, causes enhanced oxidative stress, chronic inflammation and endothelial dysfunction which are the key events in the development of vascular complications. On the other hand, some data shows that existence of chronic degenerative complications may cause increased inflammatory marker levels in diabetic patients, mainly as a repercussion of malfunctioned endothelial repair process. Our study aims to determinate a degree of inflammation in type 1 diabetes patients and to investigate its relation to development of the chronic microvascular complications.

Methods

General information, anthropometric, glucose metabolism, lipid and lipoprotein parameters, levels of C reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were analyzed and screening tests for detection of the chronic microvascular complications were conducted in 76 type 1 diabetes patients.

Results

Forty six patients had at least one of the complications. They were older and had longer duration of diabetes (p=0.015; p<0.0001) and higher values of total (p=0.021), LDL-cholesterol (p=0.048) and triglycerides (p=0.002). Levels of CRP (p=0.004) and TNF-α (p=0.048) were higher in patients with chronic microvascular complications in regard to patients without diagnosed microangiopathy.

Conclusion

Low grade chronic inflammation is characteristic for type 1 diabetes patients with developed chronic microvascular complications.     

Necrotizing fasciitis caused by group A streptococcus

The first case of the confirmed necrotizing fasciitis caused by Group A Streptococcus in Yugoslavia was presented. Male patient, aged 28, in good health, suddenly developed symptoms and signs of severe infective syndrome and intensive pain in the axillary region. Parenteral antibiotic, substitutional and supportive therapy was conducted along with the radical surgical excision of the necrotizing tissue. The patient did not develop streptococcal toxic shock syndrome thanks to the early established diagnosis and timely applied aggressive treatment. He was released from the hospital as completely cured two months after the admission.     

New Public Health education in the Republic of Macedonia: expectations, experiences and perspectives

Development of a strategy in public health (PH) education is crucial for Macedonia in providing modern education for actual PH practice. Establishing a School of Public Health (SPH) is vital for a country in a health transition with high rates of preventable diseases. The main strategic goals in modern PH education in Macedonia should be capacity building, improving the competencies of PH professionals, serving communities, participating in the policy, and partnership development. Expectations were expressed through two key points: strengthening institutional capacity in the area of PH and institutional development of SPH. The organizational structure of the new Center of Public Health is based on existing human resources and infrastructure. Medical Faculty initiated development of a postgraduate PH teaching program [Master of Public Health (MPH)] provided by the newly formed Center of Public Health within the Medical Faculty Skopje. The Macedonian MPH program has been developed with modular-type courses as a part-time teaching program in four semesters within a 2-year period. This program is designed to cover all the basics of PH sciences and practice, including basic and elective courses, workshops, research forum. and master's thesis with a credit transfer system in PH education. The main assets for SPH development are knowledge and skills of the constantly improving teaching staff. Successful preliminary evaluation of the Macedonian SPH project, being qualified “as a model for SPH development,” led to full Association of Schools of Public Health in the European Region (ASPHER) membership. Sustainability of this program will require continuing support although a remarkable beginning has been achieved. The next strategic goal is continuing development of SPH with fiscal and academic autonomy and preparing formal ASPHER Public Health Education European Review (PEER). This SPH recognized the main communicating message of the New Public Health: “Moving with the time.” New Public Health is determined by a dual approach: to be modern, and to grow and to build the tradition in PH education. The development of Macedonian SPH represents a new orientation toward science, philosophy, culture, and life and promotes new spirit and movement in PH in this region of Europe.     

Key role of poly-gamma-DL-glutamic acid in immune evasion and virulence of Staphylococcus epidermidis

Coagulase-negative staphylococci, with the leading species Staphylococcus epidermidis, are the predominant cause of hospital-acquired infections. Treatment is especially difficult owing to biofilm formation and frequent antibiotic resistance. However, virulence mechanisms of these important opportunistic pathogens have remained poorly characterized. Here we demonstrate that S. epidermidis secretes poly-gamma-DL-glutamic acid (PGA) to facilitate growth and survival in the human host. Importantly, PGA efficiently sheltered S. epidermidis from key components of innate host defense, namely antimicrobial peptides and neutrophil phagocytosis, and was indispensable for persistence during device-related infection. Furthermore, PGA protected S. epidermidis from high salt concentration, a key feature of its natural environment, the human skin. Notably, PGA was synthesized by all tested strains of S. epidermidis and a series of closely related coagulase-negative staphylococci, most of which are opportunistic pathogens. Our study presents important novel biological functions for PGA and indicates that PGA represents an excellent target for therapeutic maneuvers aimed at treating disease caused by S. epidermidis and related staphylococci.     

Familial presenile dementia with bitemporal atrophy

This study describes the clinical, neuropsychological, neuroimaging and genetic characteristics in two generations of a Swedish family affected by presenile dementia. The pedigree includes 5 cases (mother and 4 of 5 children) of progressive dementia with onset between 54 and 62 years. The clinical picture is characterized by insidious onset and progressive decline in episodic memory without spatial impairment or dyspraxia, followed by changes in personality and behaviour, with signs of disinhibition, irritability, impulsivity and loss of social awareness. Three siblings, examined after 10 years of duration, showed moderate language deficits but preserved spatial function and praxis. CT and MRI showed progressive bilateral temporal atrophy and moderate frontal white matter changes. Regional cerebral blood flow measurements showed hypoperfusion in temporal areas bilaterally. Quantitative EEG was normal within 5 years after symptom onset and thereafter showed a moderate increase in relative theta power. Sequencing of the tau gene (chromosome 17) revealed the previously described R406W mutation in exon 13 as a likely cause of the disease. This mutation was identified in all affected cases. The clinical picture of this family shows striking similarities not only to frontotemporal dementia but also to Alzheimer's disease.     

Controlled release of lipase from Candida rugosa loaded into hydrogels of N-isopropylacrylamide and itaconic acid

The series of poly(N-isopropylacrylamide-co-itaconic acid) hydrogels, with lipase from Candida rugosa as a model protein, were synthesized by free radical copolymerization. The composition of hydrogels was varied by monomers ratio, crosslinking agent concentration and amounts of lipase, which was loaded by in situ polymerization. All samples were characterized regarding morphology. The investigation of hydrogel swelling properties revealed their pH and temperature sensitive character. Protein loading efficiency, release profiles and the specific activity yield of the released lipase were also investigated as a function of hydrogel composition, protein content and pH, at the physiological temperature of 37°C. Copolymers of N-isopropylacrylamide and itaconic acid presented high lipase loading efficiency. Another very important feature of these copolymers was that the protein release kinetic strongly depended on the pH value of the medium. The diffusion exponents values around 1 denoted that these hydrogel compositions could be adjusted to follow near zero-order kinetics. Namely, hydrogel formulations released low amounts of lipase at pH 2.20, but much higher released protein quantities were observed at pH 6.80 enabling these copolymers to be attractive candidates as site specific protein oral drug delivery systems.     

Staphylococcal superantigen-like 5 binds PSGL-1 and inhibits P-selectin-mediated neutrophil rolling

Staphylococcus aureus secretes several virulence factors interfering with host-cell functions. Staphylococcal superantigen-like (SSL) proteins are a family of 11 exotoxins with structural homology to superantigens but with generally unknown functions. Recently, we described that chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS(31-121)), a potent inhibitor of C5a-induced responses, is structurally homologous to the C-terminal domain of SSL5. Here, we identify P-selectin glycoprotein ligand-1 (PSGL-1), involved in the initial rolling of neutrophils along the endothelium, as a target for SSL5. SSL5 specifically bound to Chinese hamster ovary cells stably expressing PSGL-1 (CHO-PSGL-1), which was dependent of sulfation and sialylation. Furthermore, SSL5 bound to PSGL-1/Ig fusion protein immobilized on a biosensor chip. SSL5 affected binding of soluble P-selectin/Fc chimera, the principle ligand of PSGL-1, to CHO-PSGL-1 cells and inhibited adhesion of neutrophils to immobilized P-selectin under static conditions. Under flow conditions SSL5 strongly decreased neutrophil rolling on immobilized P-selectin/Fc and activated human endothelial cells. In conclusion, SSL5 interferes with the interaction between PSGL-1 and P-selectin, suggesting that S aureus uses SSL5 to prevent neutrophil extravasation toward the site of infection. This makes SSL5 a potential lead for the development of new anti-inflammatory compounds for disorders characterized by excessive recruitment of leukocytes.