Mechanisms of toxicity mediated by neutrophil and eosinophil granule proteins.

Neutrophils and eosinophils are granulocytes which are characterized by the presence of granules in the cytoplasm. Granules provide a safe storage site for granule proteins that play important roles in the immune function of granulocytes. Upon granulocytes activation, diverse proteins are released from the granules into the extracellular space and contribute to the fight against infections. In this article, we describe granule proteins of both neutrophils and eosinophils able to kill pathogens and review their anticipated mechanism of antimicrobial toxicity. It should be noted that an excess of granules protein release can lead to tissue damage of the host resulting in chronic inflammation and organ dysfunction

Autophagy and Skin Diseases.

Autophagy is a highly conserved lysosomal degradation system that involves the creation of autophagosomes, which eventually fuse with lysosomes and breakdown misfolded proteins and damaged organelles with their enzymes. Autophagy is widely known for its function in cellular homeostasis under physiological and pathological settings. Defects in autophagy have been implicated in the pathophysiology of a variety of human diseases. The new line of evidence suggests that autophagy is inextricably linked to skin disorders. This review summarizes the principles behind autophagy and highlights current findings of autophagy's role in skin disorders and strategies for therapeutic modulation

Physiological and Pathophysiological Roles of Metabolic Pathways for NET Formation and Other Neutrophil Functions.

Neutrophils are the most numerous cells in the leukocyte population and essential for innate immunity. To limit their effector functions, neutrophils are able to modulate glycolysis and other cellular metabolic pathways. These metabolic pathways are essential not only for energy usage, but also for specialized effector actions, such as the production of reactive oxygen species (ROS), chemotaxis, phagocytosis, degranulation, and the formation of neutrophil extracellular traps (NETs). It has been demonstrated that activated viable neutrophils can produce NETs, which consists of a DNA scaffold able to bind granule proteins and microorganisms. The formation of NETs requires the availability of increased amounts of adenosine triphosphate (ATP) as it is an active cellular and therefore energy-dependent process. In this article, we discuss the glycolytic and other metabolic routes in association with neutrophil functions focusing on their role for building up NETs in the extracellular space. A better understanding of the requirements of metabolic pathways for neutrophil functions may lead to the discovery of molecular targets suitable to develop novel anti-infectious and/or anti-inflammatory drugs

Nanoparticles With a Specific Size and Surface Charge Promote Disruption of the Secondary Structure and Amyloid-Like Fibrillation of Human Insulin Under Physiological Conditions

Nanoparticles attract much interest as fluorescent labels for diagnostic and therapeutic tools, although their applications are often hindered by size- and shape-dependent cytotoxicity. This cytotoxicity is related not only to the leak of toxic metals from nanoparticles into a biological solution, but also to molecular cytotoxicity effects determined by the formation of a protein corona, appearance of an altered protein conformation leading to exposure of cryptic epitopes and cooperative effects involved in the interaction of proteins and peptides with nanoparticles. In the last case, nanoparticles may serve, depending on their nature, as centers of self-association or fibrillation of proteins and peptides, provoking amyloid-like proteinopathies, or as inhibitors of self-association of proteins, or they can self-assemble on biopolymers as on templates. In this study, human insulin protein was used to analyze nanoparticle-induced proteinopathy in physiological conditions. It is known that human insulin may form amyloid fibers, but only under extreme experimental conditions (very low pH and high temperatures). Here, we have shown that the quantum dots (QDs) may induce amyloid-like fibrillation of human insulin under physiological conditions through a complex process strongly dependent on the size and surface charge of QDs. The insulin molecular structure and fibril morphology have been shown to be modified at different stages of its fibrillation, which has been proved by comparative analysis of the data obtained using circular dichroism, dynamic light scattering, amyloid-specific thioflavin T (ThT) assay, transmission electron microscopy, and high-speed atomic force microscopy. We have found important roles of the QD size and surface charge in the destabilization of the insulin structure and the subsequent fibrillation. Remodeling of the insulin secondary structure accompanied by remarkable increase in the rate of formation of amyloid-like fibrils under physiologically normal conditions was observed when the protein was incubated with QDs of exact specific diameter coated with slightly negative specific polyethylene glycol (PEG) derivatives. Strongly negatively or slightly positively charged PEG-modified QDs of the same specific diameter or QDs of bigger or smaller diameters had no effect on insulin fibrillation. The observed effects pave the way to the control of amyloidosis proteinopathy by varying the nanoparticle size and surface charge

Identification of Phylogenetic Position in the Chlamydiaceae Family for Chlamydia Strains Released from Monkeys and Humans with Chlamydial Pathology

Based on the results of the comparative analysis concerning relatedness and evolutional difference of the 16S–23S nucleotide sequences of the middle ribosomal cluster and 23S rRNA I domain, and based on identification of phylogenetic position for Chlamydophila pneumoniae and Chlamydia trichomatis strains released from monkeys, relatedness of the above stated isolates with similar strains released from humans and with strains having nucleotide sequences presented in the GenBank electronic database has been detected for the first time ever. Position of these isolates in the Chlamydiaceae family phylogenetic tree has been identified. The evolutional position of the investigated original Chlamydia and Chlamydophila strains close to analogous strains from the Gen-Bank electronic database has been demonstrated. Differences in the 16S–23S nucleotide sequence of the middle ribosomal cluster and 23S rRNA I domain of plasmid and nonplasmid Chlamydia trachomatis strains released from humans and monkeys relative to different genotype groups (group B-B, Ba, D, Da, E, L1, L2, L2a; intermediate group-F, G, Ga) have been revealed for the first time ever. Abnormality in incA chromosomal gene expression resulting in Chlamydia life development cycle disorder, and decrease of Chlamydia virulence can be related to probable changes in the nucleotide sequence of the gene under consideratio

Allergen-Specific Antibodies Regulate Secondary Allergen-Specific Immune Responses

Immunoglobulin E (IgE)-associated allergy is the most common immunologically-mediated hypersensensitivity disease. It is based on the production of IgE antibodies and T cell responses against per se innocuous antigens (i.e., allergens) and subsequent allergen-induced inflammation in genetically pre-disposed individuals. While allergen exposure in sensitized subjects mainly boosts IgE production and T cell activation, successful allergen-specific immunotherapy (AIT) induces the production of allergen-specific IgG antibodies and reduces T cell activity. Under both circumstances, the resulting allergen-antibody complexes play a major role in modulating secondary allergen-specific immune responses: Allergen-IgE complexes induce mast cell and basophil activation and perpetuate allergen-specific T cell responses via presentation of allergen by allergen presenting cells to T cells, a process called IgE-facilitated antigen presentation (FAP). In addition, they may induce activation of IgE memory B cells. Allergen-induced production of specific IgGs usually exerts ameliorating effects but under certain circumstances may also contribute to exacerbation. Allergen-specific IgG antibodies induced by AIT which compete with IgE for allergen binding (i.e., blocking IgG) inhibit formation of IgE-allergen complexes and reduce activation of effector cells, B cells and indirectly T cells as FAP is prevented. Experimental data provide evidence that by binding of allergen-specific IgG to epitopes different from those recognized by IgE, allergen-specific IgG may enhance IgE-mediated activation of mast cells, basophils and allergen-specific IgE+ B cells. In this review we provide an overview about the role of allergen-specific antibodies in regulating secondary allergen-specific immune responses

Positive experience with TNF-α inhibitor in toxic epidermal necrolysis resistant to high-dose systemic corticosteroids

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare, potentially life-threatening syndromes characterized by the development of necrotic epidermal and mucosal lesions. The most common etiologic cause of SJS/TEN is drug-induced mechanisms. The group of drugs with high potential risk includes sulfonamides, anticonvulsants, non-steroidal anti-inflammatory drugs (NSAIDs), allopurinol, phenobarbital, etc. There is no gold standard treatment algorithm for SJS/TEN. In medical practice, systemic glucocorticosteroids (sGCS), intravenous immunoglobulin (IVIG), plasmapheresis, and cyclosporine are used empirically and in various combinations. Recently published studies have demonstrated the efficacy of TNF-α inhibitors as a promising approach in SJS/TEN, including cases resistant to high-dose sGCS, with etanercept and infliximab being the most commonly used drugs. In a large multicenter study by Zhang J et al. (XXXX), 242 patients treated with etanercept, sGCS, or a combination of both had lower mortality compared to the control group. A shorter skin healing time was documented compared to sGCS monotherapy, thus reducing the risk of secondary infections. The published data show a high efficacy with THF-α inhibitor blockade, but the safety of TNF-α inhibitors in patients with SJS/TEN is still questionable due to the paucity of available information. As all clinical research data should be accumulated to provide reliable evidence that the use of TNF-α inhibitors may be beneficial in SJS/TEN, we report a case of etoricoxib-associated SJS with progression to TEN in a 50-year-old woman who was refractory to high-dose sGCS therapy

Pre-exposure prophylaxis of new COVID-19 coronavirus infection with tixagevimab/cilgavimab in adult Moscow patients with primary immunodeficiencies

Background. Primary immunodeficiencies (PIDs), now known as inborn errors of immunity, are a group of inherited diseases caused by defects in the genes that control the immune response. Patients with PIDs have risks of developing a severe course and/or death in COVID-19. Passive immunization with long-acting monoclonal antibodies (MABs) to SARS-CoV-2 should be considered as pre-exposure prophylaxis in patients with PIDs. Tixagevimab/cilgavimab is a combination of MABs that bind to the SARS-CoV-2 spike protein. Aim. To evaluate the efficacy and safety of pre-exposure prophylaxis of new SARS-CoV-2 infection in PIDs with the combination of tixagevimab/cilgavimab. Materials and methods. Forty eight patients diagnosed with PIDs were included in the study. Median follow-up after drug administration was 174 days. The total number of confirmed coronavirus infections in patients with PIDs as well as 6 months before and after administration of MAT were assessed. Results. In the analyzed cohort, the overall incidence of COVID-19 from pandemic onset to MABs administration was 75% (36/48), with 31% (11/36) of over-infected patients having had the infection more than once. The incidence of COVID-19 immediately 6 months before the introduction of tixagevimab/cilgavimab was 40%. All patients who had COVID-19 after pre-exposure prophylaxis had a mild infection. The incidence of COVID-19 6 months after tixagevimab/cilgavimab administration significantly decreased compared to the incidence 6 months before administration (7 and 40%, respectively; p0.001). Conclusion. The use of tixagevimab/cilgavimab in patients with PIDs is effective as pre-exposure prophylaxis and reduces the risk of severe COVID-19

Strategies to Prevent SARS-CoV-2-Mediated Eosinophilic Disease in Association with COVID-19 Vaccination and Infection.

A vaccine to protect against COVID-19 is urgently needed. Such a vaccine should efficiently induce high-affinity neutralizing antibodies which neutralize SARS-CoV-2, the cause of COVID-19. However, there is a concern regarding both vaccine-induced eosinophilic lung disease and eosinophil-associated Th2 immunopotentiation following infection after vaccination. Here, we review the anticipated characteristics of a COVID-19 vaccine to avoid vaccine-associated eosinophil immunopathology

Anionic dicarbollyl complexes of germanium(II) and tin(II) — missing links in a series of [pi]-complexes with Group 14 elements as central atoms

Jutzi P, Wegener D, Stammler H-G, Karaulov A, Hursthouse MB. Anionic dicarbollyl complexes of germanium(II) and tin(II) — missing links in a series of [pi]-complexes with Group 14 elements as central atoms. Inorganica Chimica Acta. 1992;198-200:369-375.On the basis of the isolobal concept, comparable series of structurally different [pi]-complexes with Group 14 elements as central atoms and with cyclopentadienyl or dicarbollyl systems as ligands can be organized. We describe for the first time anionic [pi]-complexes in which one or two dicarbollyl (B9H9C2Me2) ligands are coordinated to a divalent germanium or tin centre. Thus, reaction of the phosphonium salt Ph3MeP+TlB9H9C2Me2- (4) with the element dichlorides GeCl2 and SnCl2, respectively, in a 1:1 ratio leads to the ionic compounds Ph3MeP+ClGeB9H9C2Me2- (5) and Ph3MeP+ClSnB9H9C2Me2- (6), respectively. In a 2:1 ratio of the same reactants, the ionic compounds (Ph3MeP+)2Ge(B9H9C2Me2)22- (7) and (Ph3MeP+)2Sn(B9H9C2Me2)22- (8), respectively, are formed. Some further chemistry of the starting material Tl+TlB9H9C2Me2- is also described. The characterization of the new complexes is based on 1H, 13C, 11B and 119Sn NMR data and on X-ray crystal structure investigations (5 and 7)