Low-dose recombinant properdin provides substantial protection against Streptococcus pneumoniae and Neisseria meningitidis infection

Modern medicine has established three central antimicrobial therapeutic concepts: vaccination, antibiotics, and, recently, the use of active immunotherapy to enhance the immune response toward specific pathogens. The efficacy of vaccination and antibiotics is limited by the emergence of new pathogen strains and the increased incidence of antibiotic resistance. To date, immunotherapy development has focused mainly on cytokines. Here we report the successful therapeutic application of a complement component, a recombinant form of properdin (P_n), with significantly higher activity than native properdin, which promotes complement activation via the alternative pathway, affording protection against N. menigitidis and S. pneumoniae. In a mouse model of infection, we challenged C57BL/6 WT mice with N. menigitidis B-MC58 6 h after i.p. administration of P_n (100 µg/mouse) or buffer alone. Twelve hours later, all control mice showed clear symptoms of infectious disease while the P_n treated group looked healthy. After 16 hours, all control mice developed sepsis and had to be culled, while only 10% of P_n treated mice presented with sepsis and recoverable levels of live Meningococci. In a parallel experiment, mice were challenged intranasally with a lethal dose of S. pneumoniae D39. Mice that received a single i.p. dose of P_n at the time of infection showed no signs of bacteremia at 12 h postinfection and had prolonged survival times compared with the saline-treated control group (P < 0.0001). Our findings show a significant therapeutic benefit of P_n administration and suggest that its antimicrobial activity could open new avenues for fighting infections caused by multidrug-resistant neisserial or streptococcal strains.Pneumococcal and meningococcal infectious diseases remain a serious threat to public health. Streptococcus pneumoniae is the leading cause of community-acquired pneumonia and a major cause of otitis media, septicemia, and meningitis (1, 2). S. pneumoniae is responsible for ∼1.2 million deaths per year worldwide, with young children and immunocompromised patients at particular risk (3). Neisseria meningitidis causes epidemic bacterial meningitis and septicemia, with high mortality in children and young adults (4). The impact of meningococcal disease on human health is defined by both the risk and the severity of invasive meningococcal infections, with unacceptably high mortality rates, ranging from 10% in patients under optimal clinical therapy with the latest generation of antibiotics to up to 40% in patients with untreated septicemia. Almost one-third of those who survive invasive infections are left with long-term disabilities and long-term morbidity. Globally, the World Health Organization estimates that ∼1.2 million cases of invasive meningococcal infections occur annually, leading to more than 135,000 fatalities (5).Vaccination programs have reduced the rates of infection in developed countries, but neonates and elderly adults remain especially vulnerable (6, 7). The efficacy of vaccination is further limited by the emergence of new strains of S. pneumoniae and N. meningitidis.The complement system plays a major role in the host resistance to both pathogens (8–13). Complement is activated via three routes: the classical pathway, the lectin pathway, and the alternative pathway. Activation of the classical and lectin pathways is mediated by specific recognition molecules. Binding of C1q to the bacterial surface or the Fc region of antibody initiates the classical pathway. The lectin pathway is initiated by carbohydrate recognition molecules, including mannan-binding lectin, ficolins, and collectin 11, which bind directly to bacterial polysaccharides. Activation of the classical or lectin pathway leads to the formation of a C3 convertase (C4b2a), which splits C3 into the biologically active fragments, C3b and C3a. C3b can bind covalently to an activating surface, and hundreds of molecules of C3b can be deposited in close proximity to the C3 convertase complex. Accumulation of C3b close to C4b2a forms the classical pathway C5 convertase C4b2a(3b)_n, in which C4b and C3b form a binding site for C5, orienting it for cleavage by C2a (14, 15).The mechanisms initiating the alternative pathway are less well understood. It is widely accepted that the alternative pathway maintains a continuous state of low-rate activation, which is held in check by potent negative regulators of activation on nonactivating surfaces, such as the surface of host cells. Turnover of the alternative pathway is initiated either by the provision of C3b via the classical pathway, the lectin pathway, or complement-independent proteolysis of C3 or by the spontaneous hydrolysis of C3 to form C3(H₂O). C3b or C3(H₂O) bind factor B to form either the C3bB or C3(H₂O)B zymogen complex. In this complex, factor B is cleaved by factor D, releasing a Ba fragment. The activated C3bBb or C3(H₂O)Bb fragments are themselves C3 convertases, which in turn cleave more C3 into C3a and C3b. Unchecked, the accumulation of C3b rapidly leads to the formation of more alternative pathway convertase complexes, resulting in a physiologically critical positive feedback mechanism—the amplification loop of complement activation (16). The alternative pathway thus amplifies complement activation initiated by any of the three pathways, making it an attractive target for therapeutic intervention designed to modulate complement-mediated immunity and/or inflammatory processes (17).Deposition of C3b and iC3b on the bacterial surface is a key step in the immune response against S. pneumoniae, because complement-mediated opsonisation is essential for clearance of S. pneumoniae through phagocytosis (8). Lysis of bacteria, owing to formation of the membrane attack complex complex, is the critically important biological activity of complement in the defense against N. meningitidis (10). Inherited or acquired deficiencies of the alternative pathway are associated with a high risk of recurrent bacterial infection. Factor B deficiencies significantly increase the risk of S. pneumoniae and Pseudomonas aeruginosa infection (9, 18). In a mouse model of properdin deficiency, the severity of polymicrobial peritonitis was significantly greater in deficient mice compared with their WT littermates (19). Properdin deficiency in humans has been associated with a high risk of meningococcal infections, especially with unusual infective serotypes, such as W-135 and Y (10, 20, 21). In addition, opsonophagocytosis of S. pneumoniae was found to be severely compromised in properdin-deficient sera, and reconstitution of properdin-deficient sera with purified properdin restored the opsonic activity and killing of S. pneumoniae by polymorphonuclear leukocytes (22, 23).Properdin is the only known positive physiological regulator of complement activation. It stabilizes and extends the half-life of the surface-bound C3 convertase C3bBb, and inhibits its degradation by factor I (24–26). In their pioneering 1954 work, Pillemer et al. (26) first described properdin as a serum protein that mediates complement activation and antimicrobial activity in absence of antibodies.Properdin is present in serum at a concentration of ∼5–15 μg/mL (27). Unlike most other complement components, properdin is not synthesized in the liver but rather is expressed by other cells, including monocytes, T cells, mast cells, and granulocytes (19, 28–30). Properdin monomers can assemble into dimers (P₂), trimers (P₃), and tetramers (P₄), formed by head-to-tail association of monomers (each ∼53 kDa) (31, 32). Properdin aggregates, so-called “activated” properdin (P_n), are considered artificial higher-order oligomers formed during the purification of properdin from plasma or during subsequent freeze–thaw cycles (33). The functional activity of properdin increases with the size of the polymers formed (34). By increasing the half-life of the alternative pathway C3 convertase, properdin antagonizes the functional activity of complement factor H, an abundantly expressed plasma component, which promotes inactivation of the alternative pathway C3 convertase and of all C5 convertases of complement by accelerating the decay of these enzyme complexes through binding to complex-bound C3b and by serving as a cofactor in the factor I-mediated conversion of C3b to its inactive form, termed iC3b (35). Interestingly, the two pathogens used in this study were previously shown to express distinct microbial surface components that sequester factor H from host plasma, leading to resistance to the complement-mediated immune clearance of these pathogens (36, 37).In the present study, we addressed the role of the alternative pathway and the effect of administration of recombinant properdin as a tool for boosting alternative pathway activity to augment the immune response against S. pneumoniae or N. meningitidis.     

Assessment of health-related quality of life among hypertensive patients: a cross-sectional study from Palestine

Aim

The ability to identify indicators of poor health-related quality of life (HRQoL) is crucial for both improving clinical care and determining targets of intervention for the prevention and treatment of disease. The main objectives of this study were to assess the HRQoL profile of the hypertensive population from Palestine, and to determine the socio-demographic and clinical characteristics associated with poor HRQoL.

Subject and methods

A cross sectional study was conducted, adopting the EuroQoL-5 Dimensions scale (EQ-5D-5 L) for the assessment of HRQoL. Hypertensive patients attending outpatients’ clinics at Al-Makhfyah primary health care clinic and from Alwatani Hospital, Nablus, Palestine were approached for study.

Results

Four hundred and ten hypertensive patients were enrolled in the study. Of these, 213 patients (52 %) were female. The average age of the study population was 58.38?±?10.65 years. HRQoL was good, with a mean EQ-5D-5 L index value and EQ visual analogue scale (EQ-VAS) score of 0.80?±?0.16 and 74.1?±?15.6 respectively. There was a significant positive correlation (r?=?0.56; p?<?0.001) between the EQ-5D-5 L index values and the reported EQ-VAS scores. A significant difference in EQ-5D-5 L index values was found among participants when grouped according to age, occupation, marital status, income, educational level, duration of disease, total number of chronic diseases, and total number of medications (Kruskal–Wallis test; p-value?<?0.05), as well as gender and therapy type (Mann–Whitney test, p-value?<?0.05).

Conclusions

This study highlighted that specific socio-demographic and disease-related characteristics of hypertensive patients as well as treatment factors were strongly associated with HRQoL. The study findings could be helpful in clinical practice, mainly in the early treatment of hypertensive patients, at a point where improving HRQoL is still possible.     

Anaphylaxis: an update for dental practitioners

Anaphylaxis is an acutely presenting life‐threatening medical emergency. Surveys indicate that dentists feel inadequately able to recognize and treat anaphylaxis. This paper reviews the terminology and pathophysiology of anaphylaxis, and describes the recognition and initial management of anaphylaxis for dentists. Dentists should be able to administer intramuscular adrenaline during anaphylaxis at the appropriate dose. The role of further medical care is also explained. Six cases of anaphylaxis arising from dental oral maxillofacial surgery practice are discussed.     

Is there an association between anxiety/depression and temporomandibular disorders in college students?

Objective

Considering the high incidence of Temporomandibular Disorders (TMD) in the population aged 15-30 years and the fact that students are exposed to stressful psychosocial factors, the purposes of this study were: to verify clinical symptoms and jaw functionality in college students with TMD according to the anxiety/depression (A/D) level and to evaluate the correlation between A/D and functionality, maximum mouth opening (MMO) and pain and muscle activity.

Material and Methods

Nineteen students with TMD diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders underwent two assessments during an academic semester. The evaluations were based on questionnaires (MFIQ - Mandibular Function Impairment Questionnaire; HADS - Hospital Anxiety and Depression Scale), clinical measurements (MMO without pain, MMO and assisted MMO; palpation of joint and masticatory muscles), and electromyography. The HADS scores obtained in the two assessments were used to classify all data as either "high" or "low" A/D. Data normality, differences and correlations were tested with the Shapiro-Wilk test, Student''s t-test (or the Wilcoxon test), and Spearman test, respectively. The alpha level was set at 0.05.

Results

None of the clinical variables were significantly different when comparing low and high A/D data. In low A/D there was a significant correlation between HADS score and: MFIQ (P=0.005, r=0.61), and MMO without pain (P=0.01, r=-0.55).

Conclusions

Variation in A/D level did not change clinical symptoms or jaw functionality in college students with TMD. Apparently, there is a correlation between TMJ functionality and A/D level, which should be further investigated, taking into account the source of the TMD and including subjects with greater functional limitation.     

Effectiveness and safety of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate single-tablet combination among HIV-infected patients in Turkey: results from a real world setting

BackgroundEfficacy of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil (E/C/F/TDF) in treatment-naïve and experienced patients with HIV infection was demonstrated in phase 3 trials. The primary objective of this study was to evaluate effectiveness and safety of E/C/F/TDF in real world settings.MethodsRetrospective, observational data collected by the Turkish ACTHIV-IST study group between May 2015 and December 2016 were analysed.ResultsA total of 387 patients were prescribed E/C/F/TDF; 210 patients with available data at 6th month were eligible; 91.5% were male, and mean age was 35.2 (SD: 10.8) years; 54.0% of males identified themselves as MSM. Sixty-three percent (133) of the study population were treatment-naïve patients, and 37% (77) were treatment experienced. HIV RNA level was below 100 copies/mL in 78.9% of treatment-naïve patients and 89.9% of treatment experienced patients at month 6. Median increase in CD4 T lymphocyte count was 218 copies/mL in treatment-naïve patients and remained stable or increased in treatment experienced patients. Adverse events were observed in 15% of the patients, and the regimen was discontinued in only six patients.ConclusionReal world data on the effectiveness and safety of E/C/F/TDF is comparable with the phase 3 trial results Adverse events are uncommon and manageable.     

Copper oxide integrated perylene diimide self-assembled graphitic pencil for robust non-enzymatic dopamine detection

Exploring a robust, extremely sensitive, cost-effective and reliable assay platform for the precise analysis of dopamine (DA) has become a big challenge predominantly at the clinical level. To participate in this quest, herein, we fabricated a perylene diimide (PDI) self-assembled graphitic surface of the graphitic pencil electrode (GPE) anchored copper oxide (CuO). The self-assembled N-rich PDI led to the fast movement of ions by decreasing the bandgap and improved the electron transport kinetics with more exposed catalytic active sites, thus resulting in the robust electrochemical sensing of DA. The designed sensor exhibited good sensitivity (4 μM⁻¹ cm⁻²), high structural stability, repeatability and excellent reproducibility with an RSD value of 2.9%. Moreover, the developed system showed a wide linear range (5 μM to 500 μM) and reliable selectivity even in the presence of co-existing interferants, such as ascorbic acid and uric acid. The fabricated nanohybrid was eventually employed to analyze DA in spiked physiological fluids and provided satisfactory recoveries. The designed PDI-CuO based interface also showed a very low detection limit of 6 nM (S/N = 3), consequently confirming its suitability for clinical and biological applications.

Exploring a robust, extremely sensitive, cost-effective and reliable assay platform for the precise analysis of dopamine (DA) has become a big challenge predominantly at the clinical level.