Physiology and Pathology of Innate Immune Response Against Pathogens

Abstract

Pathogen infections are recognized by the immune system, which consists of two types of responses: an innate immune response and an antigen-specific adaptive immune response. The innate response is characterized by being the first line of defense that occurs rapidly in which leukocytes such as neutrophils, monocytes, macrophages, eosinophils, mast cells, dendritic cells, etc., are involved. These cells recognize the pathogen-associated molecular patterns (PAMPs), which have been evolutionarily conserved by the diversity of microorganisms that infect humans. Recognition of these pathogen-associated molecular patterns occurs through pattern recognition receptors such as Toll-like receptors and some other intracellular receptors such as nucleotide oligomerization domain (NOD), with the aim of amplifying the inflammation and activating the adaptive cellular immune response, through the antigenic presentation. In the present chapter, we will review the importance of the main components involved in the innate immune response, such as different cell types, inflammatory response, soluble immune mediators and effector mechanisms exerted by the immune response against bacteria, viruses, fungi, and parasites; all with the purpose of eliminating them and eradicating the infection of the host.

Avocado–Soybean Unsaponifiables: A Panoply of Potentialities to Be Exploited

“…The human immune system is known to protect the body against the foreign invaders that basically exert a wide variety of deleterious effects [95]. Sometimes the optimal functioning mechanism of the immune system is said to act as a 'double-edged sword', either by healing the physiological state or by damaging it.…”

Pathogenesis of Periodontal Disease

“…Inflammation is a process of the innate immune system activation, in response to exogenous and endogenous factors, such as infection by microorganisms, tissue stress, and injuries. Inflammation is a protective response, characterized by its cardinal signs, such as redness, swelling, heat, pain, and disrupted function [19]. The inflammatory response consists of four main components: (1) endogenous or exogenous factors, such as molecular patterns associated with pathogens (PAMP) and damage (DAMP), which are derived from bacteria, viruses, fungi, parasites, and cell damage, as well as toxic cellular components or any other harmful condition; (2) cellular receptors that recognize these molecular patterns (PRR), for example, Toll-like receptors (TLR); (3) proinflammatory mediators, such as cytokines, chemokines, the complement system, etc.…”

Cytokine Profiling Plays a Crucial Role in Activating Immune System to Clear Infectious Pathogens

“…Cytokines compromise leukocytes to respond to a microbial stimulus. Cytokines can be classified into six groups: (1) L1 superfamily, (2) TNF superfamily, (3) IL-17 family, (4) IL-6 superfamily, (5) type I superfamily, and (6) type II superfamily [5].…”