The dichotomy of pathogens and allergens in vaccination approaches

Vogt-Koyanagi-Harada Disease and COVID

Vogt-Koyanagi-Harada (VKH) is a rare multisystem inflammatory disease affecting the eyes, ears, brain, skin, and hair. The Coronavirus Disease 2019 (COVID-19) is a new contagious infection that might trigger the onset of VKH disease, as previously proposed for other viruses. Moreover, after the mass vaccination against SARS-CoV-2 worldwide, cases of VKH disease associated with COVID-19 vaccination have been reported. We present an overview of VKH and a comprehensive literature revision of all the VKH cases described after COVID-19 infection and vaccination, adding our experience. No differences have been found considering epidemiology and clinical findings of the disease compared to those reported in the no-COVID era. All of the patients promptly responded to systemic and local corticosteroid therapy with a good final visual prognosis. Different possible pathogenetic mechanisms underlying the onset of VKH after COVID-19 vaccination are discussed, while the presence of the HLA DR4 antigen as a genetic predisposition for the onset of the disease after COVID-19 infection and vaccination is proposed. VKH disease is one of the most frequently reported uveitic entities after COVID-19 vaccination, but a good response to therapy should not discourage vaccination. Nevertheless, ophthalmologists should be alerted to the possibility of VKH occurrence or relapse after COVID-19 vaccination, especially in genetically predisposed subjects.

A Comprehensive Review of the Protein Subunit Vaccines Against COVID-19

Two years after severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), in December 2019, the first infections were identified in Wuhan city of China. SARS-CoV-2 infection caused a global pandemic and accordingly, 5.41 million deaths worldwide. Hence, developing a safe and efficient vaccine for coronavirus disease 2019 (COVID-19) seems to be an urgent need. Attempts to produce efficient vaccines inexhaustibly are ongoing. At present time, according to the COVID-19 vaccine tracker and landscape provided by World Health Organization (WHO), there are 161 vaccine candidates in different clinical phases all over the world. In between, protein subunit vaccines are types of vaccines that contain a viral protein like spike protein or its segment as the antigen assumed to elicit humoral and cellular immunity and good protective effects. Previously, this technology of vaccine manufacturing was used in a recombinant influenza vaccine (RIV4). In the present work, we review protein subunit vaccines passing their phase 3 and 4 clinical trials, population participated in these trials, vaccines manufactures, vaccines efficiency and their side effects, and other features of these vaccines.

Under the superficial dichotomy pathogen and allergen are two manifestations of same immune activation and pathogenesis mechanisms

Pathogens and allergens are deemed as two contrasting facets of host immune status, deficiency and exuberant. In silico domain analysis of a diverse panel of pathogen and allergen proteins has revealed the shortcoming of this notion. Both the pathogen and allergen proteins elicit immune activation, with the outcome of immune agitation depending on the pathogen strain, allergen exposure duration, and host factors. Pathogens can replicate within the host and constantly irritate the immune system, leading to blood coagulation, respiratory collapse and death. Allergens, being non-viable, can only provoke the immune system transiently; however, depending on the allergen dose and extent exposed to, inflammation and fatality can occur. In silico analysis of pathogen and allergen proteins showed the conserved domains to be AAA, WR1, VKc, Kelch, Hr1, HAMP, HELICc, Dak2, CHAD, CHASE2, Galanin, PKS_TE, Robl_LC7, Excalibur, DISIN, etc. This exciting discovery can have far-reaching effects in drug target identification approaches.

Effects of immunomodulators on the response induced by vaccines against autoimmune diseases

A promising treatment for T-cell-mediated autoimmune diseases is the induction of immune tolerance by modulating the immune response against self-antigens, an objective that may be achieved by vaccination. There are two main types of vaccines currently under development. The tolerogenic vaccines, composed of proteins formed by a cytokine fused to a self-antigen, which usually induce tolerance by eliminating the T-cells that are immune reactive against the self-antigen. The immunogenic vaccines, comprised of a self-antigen plus a sole Th2 adjuvant either free or conjugated, that alleviate autoimmunity by switching the immune response against the self-antigen, from a damaging pro-inflammatory Th1/Th17 to an anti-inflammatory Th2 immunity. Another type of vaccines is the DNA vaccines, where cells transiently express the self-antigen encoded by DNA, which induces a Th2 immunity. Actually, DNA vaccines can benefit from the presence of an adjuvant that elicits a systemic sole Th2 immunity to enhance the initially weak immune response characteristic of these vaccines. While in the tolerogenic vaccines, cytokines are the endogenous immunomodulators, in the immunogenic vaccines, the adjuvants are exogenous agents that elicit Th2 immunity with a production of anti-inflammatory cytokines and antibodies against the self-antigen. Because the commonly used Th2 adjuvant alum, fails to induce an effective immunity in the elderly population, it is unlikely that it would be widely used. Another Th2 adjuvant, the oil/water emulsions mixed with the antigen, while effective in vaccines against infectious agents, due to potential aldehydes in their formulation may be not suitable for autoimmune vaccines. A unique compound is glatiramer, which seems to be both a random polypeptide antigen and an immune modulator that biases the response to Th2 immunity. Its mechanism of action seems to implicate binding to MHC-II, which alters the outcome of T-cell signaling, leading to anergy. Glatiramer, while effective in the treatment of multiple sclerosis has not shown efficacy in other autoimmune diseases. An important new group of promising sole Th2 adjuvants are the fucosylated glycans, which by binding to DC-SIGN bias dendritic cells to Th2 immunity while inhibiting Th1/Th7 immunities. These glycans are similar to those produced by parasitic helminths to prevent inflammatory responses by mammalian hosts. A novel group of sole Th2 adjuvants are some plant-derived fucosylated triterpene glycosides, which share the immune modulatory properties from the fucosylated glycans. These glycosides have also an aldehyde group that delivers an alternative co-stimulatory signal to T-cells, averting the anergy associated with aging due to the loss of the CD28 receptor on T-cells. Hence, the development of vaccines to treat and/or prevent autoimmune conditions and some proteopathies, will significantly benefit from the availability of new sole Th2 adjuvants that while inducing an anti-inflammatory immunity, they do not abrogate pro-inflammatory Th1/Th17 immunities.

A review on emerging frontiers of house dust mite and cockroach allergy research

Currently, mankind is afflicted with diversified health issues, allergies being a common, yet little understood malady. Allergies, the outcome of a baffled immune system encompasses myriad allergens and causes an array of health consequences, ranging from transient to recurrent and mild to fatal. Indoor allergy is a serious hypersensitivity in genetically-predisposed people, triggered by ingestion, inhalation or mere contact of allergens, of which mite and cockroaches are one of the most-represented constituents. Arduous to eliminate, these aeroallergens pose constant health challenges, mostly manifested as respiratory and dermatological inflammations, leading to further aggravations if unrestrained. Recent times have seen an unprecedented endeavour to understand the conformation of these allergens, their immune manipulative ploys and other underlying causes of pathogenesis, most importantly therapies. Yet a large section of vulnerable people is ignorant of these innocuous-looking immune irritants, prevailing around them, and continues to suffer. This review aims to expedite this field by a concise, informative account of seminal findings in the past few years, with particular emphasis on leading frontiers like genome-wide association studies (GWAS), epitope mapping, metabolomics etc. Drawbacks linked to current approaches and solutions to overcome them have been proposed.

Nucleic acid vaccination strategies against infectious diseases

INTRODUCTION

Gene vaccines are an interesting and emerging alternative for the prevention of infectious diseases, as well as in the treatment of other pathologies including cancer, allergies, autoimmune diseases, or even drug dependencies. When applied to the target organism, these vaccines induce the expression of encoded antigens and elicit the corresponding immune response, with the potential ability of being able to induce antibody-, helper T cell-, and cytotoxic T cell-mediated immune responses.

AREAS COVERED

Special attention is paid to the variety of adjuvants that may be co-administered to enhance and/or to modulate immune responses, and to the methods of delivery. Finally, this article reviews the efficacy data of gene vaccines against infectious diseases released from current clinical trials.

EXPERT OPINION

Taken together, this approach will have a major impact on future strategies for the prevention of infectious diseases. Better-designed nucleic acid constructs, novel delivery technologies, as well as the clarification of the mechanisms for antigen presentation will improve the potential applications of this vaccination strategy against microbial pathogens.