Histamine H4 Receptor: A Novel Target for Inflammation Therapy

Circulating miRNAs drive personalized medicine based on subgroup classification in myasthenia gravis patients

Myasthenia gravis (MG) is a classic autoimmune neuromuscular disease with strong clinical heterogeneity. The concept of subgroup classification was proposed to guide the precise treatment of MG. Subgroups based on serum antibodies and clinical features include ocular MG, early-onset MG with AchR antibodies, late-onset MG with AchR antibodies, thymoma-associated MG, MuSK-associated MG, LRP4-associated MG, and seronegative MG. However, reliable objective biomarkers are still needed to reflect the individualized response to therapy. MicroRNAs (miRNAs) are small non-coding RNA molecules which can specifically bind to target genes and regulate gene expression at the post-transcriptional level, and then influence celluar biological processes. MiRNAs play an important role in the pathogenesis of autoimmune diseases, including MG. Several studies on circulating miRNAs in MG have been reported. However, there is rare systematic review to summarize the differences of these miRNAs in different subgroups of MG. Here, we summarize the potential role of circulating miRNAs in different subgroups of MG to promote personalized medicine.

Treatment of allergy: Overview of synthetic anti-allergy small molecules in medicinal chemistry

The prevalence of allergic diseases has been continuously increasing over the past few decades, affecting approximately 20-30% of the global population. Allergic reactions to infection of respiratory tract, digestive tract, and skin system involve multiple different targets. The main difficulty of anti-allergy research is how to develop drugs with good curative effect and less side effects by adopting new multi-targets and mechanisms according to the clinical characteristics of different allergic populations and different allergens. This review focuses on information concerning potential therapeutic targets as well as the synthetic anti-allergy small molecules with respect to their medicinal chemistry. The structure-activity relationship and the mechanism of compound-target interaction were highlighted with perspective to histamine-1/4 receptor antagonists, leukotriene biosynthesis, Th2 cytokines inhibitors, and calcium channel blockers. We hope that the study of chemical scaffold modification and optimization for different lead compounds summarized in this review not only lays the foundation for improvement of success rate and efficiency of virtual screening of antiallergic drugs, but also can provide valuable reference for the drug design of related promising research such as allergy, inflammation, and cancer.

Therapeutic Targets in Allergic Conjunctivitis

Allergic conjunctivitis (AC) is a common condition resulting from exposure to allergens such as pollen, animal dander, or mold. It is typically mediated by allergen-induced crosslinking of immunoglobulin E attached to receptors on primed conjunctival mast cells, which results in mast cell degranulation and histamine release, as well as the release of lipid mediators, cytokines, and chemokines. The clinical result is conjunctival hyperemia, tearing, intense itching, and chemosis. Refractory and chronic cases can result in ocular surface complications that may be vision threatening. Patients who experience even mild forms of this disease report an impact on their quality of life. Current treatment options range from non-pharmacologic therapies to ocular and systemic options. However, to adequately control AC, the use of multiple agents is often required. As such, a precise understanding of the immune mechanisms responsible for this ocular surface inflammation is needed to support ongoing research for potential therapeutic targets such as chemokine receptors, cytokine receptors, non-receptor tyrosine kinases, and integrins. This review utilized several published articles regarding the current therapeutic options to treat AC, as well as the pathological and immune mechanisms relevant to AC. This review will also focus on cellular and molecular targets in AC, with particular emphasis on potential therapeutic agents that can attenuate the pathology and immune mechanisms driven by cells, receptors, and molecules that participate in the immunopathogenesis and immunopathology of AC.

Chemical Probes for Histamine Receptor Subtypes

Ligands with different properties and different selectivity are highly needed for in vitro and in vivo studies on the (patho)physiological influence of the chemical mediator histamine and its receptor subtypes. A selection of well-described ligands for the different receptor subtypes and different studies is shown with a particular focus on affinity and selectivity. In addition, compounds with radioactive or fluorescence elements will be presented with their beneficial use for other species or different investigations.

Immunopathology of Allergic Conjunctivitis

Allergic conjunctivitis is predominantly an immunoglobulin E-mediated hypersensitivity reaction to environmental allergens. Allergic diseases affect >30% of the world’s population, of which 40% report associated ocular manifestations. Cellular and soluble mediators play a major role in the pathophysiology of allergic conjunctivitis. Mast cells, which are major effector cells of allergic conjunctivitis, undergo activation and degranulation to release histamine, tryptase, prostaglandins, leukotrienes, and cytokines. These mediators play important roles in immunopathological mechanisms that generate the clinical manifestations of allergic conjunctivitis. These clinical features include conjunctival hyperaemia, chemosis, tearing, itching, papillae, mucus discharge, and eyelid oedema. Histamine mediates the early phase of the allergic immune response, whereas lipid mediators and cytokines are involved in the late phase of the immunopathology of allergic conjunctivitis. Current management of allergic conjunctivitis includes non-pharmacological approaches such as allergen avoidance and palliative therapy, whereas pharmacological therapeutic modalities may include antihistamine–mast cell stabiliser combination ophthalmic formulations and allergen-specific immunotherapy. Furthermore, as cellular and soluble mediators play a pivotal role in the immunopathogenesis and immunopathology of allergic conjunctivitis, development of immunotherapeutic and pharmacotherapeutic agents specific to these mediators can enhance the therapeutic index and safety profile of anti-allergy treatment.

Update and clinical utility of alcaftadine ophthalmic solution 0.25% in the treatment of allergic conjunctivitis

Allergic disorders of the ocular surface are primarily characterized as IgE- and/or T-lymphocyte-mediated disorders that affect the cornea, conjunctiva, and eyelid. Approximately 40% of individuals in the developed countries have allergic conjunctivitis, and as such, it is the most common form of ocular allergy. Seasonal allergic conjunctivitis is the most prevalent type of allergic conjunctivitis that impacts the quality of life of patients. This article reviews the pharmacology, pharmacodynamics, pharmacokinetics, clinical trials, clinical efficacy, and safety of alcaftadine. Histamine and the pathological mechanism of ocular allergy will be briefly reviewed with the intent of providing a background for the detailed discussion on the clinical utility of alcaftadine in allergic conjunctivitis. The Medline PubMed, Elsevier Science Direct, and Google Scholar databases were used to search for evidence-based literature on histamine and immunopathological mechanism of allergic conjunctivitis, as well as on pharmacology, pharmacodynamics, pharmacokinetics, clinical trials, and clinical efficacy of alcaftadine. The treatment and management goals of allergic conjunctivitis are to prevent or minimize the inflammatory cascade associated with allergic response in the early stages of the pathological mechanism. It is of note that activation of histamine receptors on immune and nonimmune cells are associated with allergen-induced inflammation of the conjunctiva and its associated ocular allergic manifestations, including itching, edema, hyperemia, and tearing. Alcaftadine is an efficacious multiple action antiallergic therapeutic agent with inverse agonist activity on H1, H2, and H4 receptors, as well as anti-inflammatory and mast cell stabilizing effects that could provide therapeutic benefits to patients with allergic conjunctivitis.