Dear Colleagues,

The Immune system is an intricate network of proteins, cells, and various organs that acts as a potent host defense against pathogens, toxins, allergens, and tumor cells. Our immune system gradually matures during infancy. Subsequently, it undergoes major development during a lifetime of exposure to environmental antigens, hence, inducing a rapid evolution of the immune responses. A functioning immune system protects the host from foreign agents either by producing antibodies or recruiting various immune cells. The innate immune system, including neutrophils, monocytes, macrophages, and dendritic cells, provides the first line of defense against pathogens. It generates rapid, non-specific inflammatory responses to bacteria, viruses, and other pathogens. Innate immunity plays an important role in shaping the antigen-specific responses, also known as adaptive immunity. The ability of humans to survive in a world where they are re-exposed to pathogens throughout their lifetimes is due to memory T and B cells, which are the hallmark of adaptive immunity. A balanced interplay between various components in the immune system is important, otherwise it leads to immunological abnormalities. The abnormalities in the innate and adaptive immune system can lead to immunological deficiencies, allergies, or autoimmune diseases. Furthermore, age and sex have been reported to modulate immune responses differently against pathogens. For instance, males experienced severe outcomes compared to females during the recent SARS-CoV-2 pandemic. Moreover, growing evidence in the last few decades has shown that microbiota associated with organisms play a significant role in shaping immune responses and, thus, overall health. The use of immunotherapeutic treatment to treat cancer and immunological disorders is rapidly evolving. In order to achieve the desired outcome from these treatments, it is critical that we fully understand the host immune mechanism. Much has been learnt in this area, but there is still much to be understood. This Special Issue plans to give an overview of the most recent advances in the field of host immune mechanisms in infectious and non-infectious diseases in humans. We encourage reviews, research papers, and perspectives that provide a detailed report of the molecular and cellular variables at play across a variety of innate and adaptive cell types, signaling pathways, and responses in the context of infectious and non-infectious disorders. This Special Issue is also aimed at providing selected contributions on recent advances in our understanding of the relationship between sex, age, and immune functions, as well as the impact of gut microbiota in shaping the immunological responses.

Potential topics include, but are not limited to:

• Innate immunity and inflammation
• Gene regulation and recombination
• Lymphocyte development and migration
• Cell signaling
• Autoimmune diseases
• Effect of age and sex on the immune mechanisms
• Role of gut microbiota in shaping immune system

Dr. Georges Khoury
Dr. Akil Akhtar
Dr. Rajesh Valanparambil
Guest Editors

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