Immunology: Current Research
Open Access

Innate immunity; Immune system; Pattern recognition receptors; Phagocytes; Natural killer cells; Complement system; Inflammation; Fever; Interferon’s; Cytokines; Adaptive immunity

Introduction

Innate immunity, often referred to as the body's first line of defence, is an essential aspect of our immune system. It serves as a critical shield against various invading pathogens, providing a rapid and immediate response to protect our bodies from harmful microorganisms. Unlike adaptive immunity, which develops over time and targets specific pathogens, innate immunity is an ancient and evolutionarily conserved system that is always ready to take action. In this article, we will explore the fascinating world of innate immunity, its components, mechanisms, and its vital role in preserving our health [1, 2].

The Foundation of Innate Immunity: Innate immunity is a complex network of cellular and molecular processes that come into play instantly when the body is faced with a potential threat. This innate system is present from birth and is encoded in our genes. It provides a level of protection that does not require prior exposure to the specific pathogen, making it the first line of defence before adaptive immunity comes into action [3,4].

Components of innate immunity

Physical and chemical barriers

The first line of defense comprises external barriers like the skin and mucous membranes that create a physical barrier, preventing pathogens from entering the body. Additionally, these barriers secrete antimicrobial peptides and chemicals that can neutralize or kill potential invaders [5].

Pattern recognition receptors (PRRs):

Within our cells, specialized receptors known as Pattern Recognition Receptors (PRRs) recognize conserved structures found on pathogens called Pathogen-Associated Molecular Patterns (PAMPs). Examples of PAMPs include lipopolysaccharides on bacterial cell walls or viral nucleic acids. PRRs trigger a cascade of immune responses upon detecting these foreign molecules, alerting the immune system of the presence of pathogens [6].

Phagocytes: Phagocytes, such as macrophages and neutrophils, play a crucial role in innate immunity. They engulf and destroy pathogens and infected cells, effectively eliminating the threat. These cells also produce cytokines, signalling molecules that modulate immune responses [7].

Natural killer (NK) cells: NK cells are a type of lymphocyte that recognizes and kills virus-infected and tumor cells. They act swiftly to eliminate these abnormal cells, preventing further infection or uncontrolled cell growth.

Complement system: The complement system is a group of proteins that, when activated, enhances the ability of antibodies and phagocytic cells to clear pathogens. It can directly destroy pathogens through a process called the membrane attack complex [8].

Innate immune responses: When a pathogen breaches the body's barriers and activates the PRRs, a series of immune responses occur: Inflammation: Inflammation is a fundamental response to infection or injury. It serves to localize and eliminate pathogens, as well as initiate tissue repair. Signs of inflammation include redness, heat, swelling, and pain.

Fever: Fever is a systemic response that occurs in response to infection. Elevated body temperature helps to inhibit the growth of certain pathogens and enhances the effectiveness of immune responses.

Interferon: interferon are proteins released by infected cells to warn neighbouring cells about a viral infection, activating antiviral defences and preventing the virus from spreading [9].

Cytokines: Cytokines are signalling molecules released by various immune cells to orchestrate immune responses, such as recruiting more immune cells to the site of infection.

The coordination of innate and adaptive immunity: While innate immunity provides an immediate response to pathogens, adaptive immunity complements and strengthens this defence. Innate immunity informs adaptive immunity about the presence of a pathogen, helping initiate a targeted and specific immune response. Dendritic cells, for example, bridge the gap between these two systems by presenting antigens from pathogens to T cells, which are central to adaptive immunity [10].

Conclusion

Innate immunity is a remarkable system that serves as the body's first line of defence against a wide range of pathogens. Its rapid response and broad specificity play a crucial role in preventing infections and maintaining overall health. Understanding the intricacies of innate immunity allows scientists and medical professionals to develop innovative therapies and interventions to enhance its effectiveness. By continuing to unravel the mysteries of this ancient defence system, we move closer to a future with better protection against infectious diseases and improved healthcare outcomes for all. Innate immunity serves as an essential cornerstone of our overall health and well-being. From the physical and chemical barriers that form our body's first line of defence to the intricate pattern recognition receptors, phagocytes, natural killer cells, and the complement system, each component plays a crucial role in identifying and eliminating potential threats. The innate immune responses, such as inflammation, fever, interferon release, and cytokine signalling, further showcase the system's intricacies and efficiency in combating pathogens. The coordination between innate and adaptive immunity highlights the interconnectedness of the immune system, ensuring a comprehensive and formidable response to infections. As our understanding of innate immunity grows, it continues to pave the way for ground-breaking advancements in immunological research and the development of innovative therapies to combat infectious diseases. By nurturing and strengthening our innate immune system, we can enhance our body's ability to fend off various pathogens, leading us towards a healthier and more resilient future. Embracing the wisdom of innate immunity allows us to appreciate the intricacies of our biological defences, fostering a deeper appreciation for the innate power of our bodies to protect and preserve our health.

1. Taguchi T, Mukai K (2019) Innate immunity signalling and membrane trafficking. Curr Opin Cell Biol 59: 1-7.

Indexed at, Google Scholar, Crossref

2. Cao X (2016) Self-regulation and cross-regulation of pattern-recognition receptor signalling in health and disease. Nat Rev Immunol 16:35-50.

Indexed at, Google Scholar, Crossref

3. Cui J, Chen Y, Wang HY, Wang RF (2014) Mechanisms and pathways of innate immune activation and regulation in health and cancer. Hum Vaccin Immunother 10:3270-3285.

Indexed at, Google Scholar, Crossref

4. Cianciola NL, Chung S, Manor D, Carlin CR (2017) Adenovirus Modulates Toll-Like Receptor 4 Signaling by Reprogramming ORP1L-VAP Protein Contacts for Cholesterol Transport from Endosomes to the Endoplasmic Reticulum. J Virol 91:e01904-1916.

Indexed at, Google Scholar, Crossref

5.  Kumar S, Ingle H, Prasad DV, Kumar H (2013) Recognition of bacterial infection by innate immune sensors. Crit Rev Microbiol 39:229-460.

Indexed at, Google Scholar, Crossref

6. Gleeson PA (2014) The role of endosomes in innate and adaptive immunity. Semin Cell Dev Biol 31:64-72.

Indexed at, Google Scholar, Crossref

7. Kedziora S, Słotwiński R (2009) Molecular mechanisms associated with recognition of pathogens by receptors of innate immunity. Postepy Hig Med Dosw 63:30-80.

Indexed at, Google Scholar, Crossref

8. Liu X, Wang C (2016) The emerging roles of the STING adaptor protein in immunity and diseases. Immunology 147:285-91.

Indexed at, Google Scholar, Crossref

9. Kimura T, Endo S, Inui M, Saitoh S, Miyake K, et al. (2015) Endoplasmic Protein Nogo-B (RTN4-B) Interacts with GRAMD4 and Regulates TLR9-Mediated Innate Immune Responses. J Immunol 194:5426-36.

Indexed at, Google Scholar, Crossref

10. Kumar H, Kawai T, Akira S (2009) Pathogen recognition in the innate immune response. Biochem J 420:1-16.

Indexed at, Google Scholar, Crossref