Science and Health

Human Defense System for Survival and Longevity

A simplified overview of the human biological defense system by leveraging recent scientific studies and reviews

Introduction

There has been a constant war inside us since our inception in human form. Our body has an army of highly complex defense systems with many integrated and well-functioning components.

Even the quietest of us, including zen masters, experience this biological war non-stop. It is human nature.

Working on autonomous systems developing immunity methods in artificial intelligence technology, I am also interested in self-healing mechanisms for the human body and the brain as a sensible transhumanist.

I have a strong interest in immunotherapy which is growing and evolving rapidly. It creates hope in dealing with deadly diseases, thus increasing our lifespan, also known as longevity.

An awareness of our bodily enemies — viruses, bacteria, fungi, parasites — and an understanding of the importance and mechanism of this system can help design our lifestyle choices, health, fitness, and well-being goals.

In this story, I provide you with a 30,000-foot view of our defense system. Details of this ultra-complex system are not possible in voluminous books, let alone a simple article.

Thus, based on my medical literature reviews, I categorize our self-healing systems under five major categories: core immune system, genome, stem cells, lymphatic system & blood vessels, and the gut microbiota.

1 — Core Immune System

The human immune system comprises various components such as cytokines, lymphoid organs, and humoral factors. These components protect us from harmful organisms and toxins entering the body by inhaling, drinking, and eating.

Our skin, the most significant protective organ, is also exposed to many external microorganisms and toxins.

When harmful organisms and toxic materials threaten our health, our immune system is activated to defend our bodies from detrimental effects.

As I mentioned in this article, in the cancer prevention and treatment context, we all have cancer cells. However, our immune system recognizes them and stops them from growing and turning into large tumors or spreading to other organs.

Our immune system is strengthened by using various lifestyle choices such as breathing clean air, drinking pure water, eating healthy food, reducing stress by sleeping and resting, moving the body through chores, hobbies, and exercise, and detoxifying by various methods.

The immune system can overreact. For example, it creates extra inflammation due to allergies and food intolerances. This condition is commonly known as an autoimmune response. There are many autoimmune conditions such as rheumatoid arthritis, ALS, Multiple sclerosis, lupus, dermatomyositis, pernicious anemia, Sjogren syndrome, Hashimoto, celiac, Addison disease, and type I diabetes.

Immunological factors are only one facet of autoimmune disease. There are also other factors, such as environmental, genetic, and hormonal. We also know that stress triggers autoimmunity.

As confirmed in this scientific paper, “physical and psychological stress has been implicated in the development of autoimmune disease. Moreover, many retrospective studies found that a high proportion of patients reported uncommon emotional stress before disease onset. Unfortunately, not only does stress cause disease, but the disease itself also causes significant stress in the patients, creating a vicious cycle.”

As pointed out in this paper, “the importance of autoimmunity and the mechanisms that lead to clinical disease were first recognized about 50 years ago following the pioneering studies of Macfarlane Burnett and his Nobel Prize-winning hypothesis of the ‘forbidden clone’. Such pioneering efforts led to a better understanding not only of autoimmunity but also of lymphoid cell development, thymic education, apoptosis, and deletion of autoreactive cells.”

One of the most exciting development is related to PDLs. For example, this study in Oncotarget highlights the importance of “checkpoint programmed death-1 (PD-1)/programmed cell death ligands (PD-Ls) for being identified as negative immunoregulatory molecules that promote immune evasion of tumor cells. Furthermore, the interaction of PD-1 and PD-Ls inhibits the function of T cells and tumor-infiltrating lymphocytes (TIL) while increasing the function of immunosuppressive regulatory T cells (Tregs).”

2 — Genome

Similar to the immune system, our DNA plays a role as a defense system. It continually fixes itself from the damage of toxins. For example, our DNA is adversely affected by ultraviolet light from the sun.

As mentioned in this paper, “an increase in oxidation levels is a universal feature of genomic DNA of irradiated or aged or even malignant cells. In case of apoptotic death of stressed cells, oxidized DNA can be released in circulation. According to the results of the studies, the oxidized cfDNA serves as a biomarker for a stress signal transmitted from the “stressed” area, i.e., irradiated cells or cells with deficient anti-oxidant defenses to distant cells.

As the study mentions, “the diversified virion morphotypes and genome contents of archaeal viruses result in a highly complex array of archaea-virus interactions.”

The results of this study published in Nature Communications indicate that “DndCDEA-PbeABCD is a new type of PT-based virus resistance system, expanding the known arsenal of defense systems and our understanding of host-virus interactions.”

Studies on DNA started with its discovery as a chemical substance by Friedrich Miescher in the mid-1800s. There is a significant focus on DNA as a defense mechanism for the human body. The details of the ongoing research are recorded in this paper.

3 — Stem Cells

Our bodies have a mechanism to regenerate. As a result, some organs can grow even if they are damaged. For example, the liver can produce after cutting a certain amount in a required surgical operation.

Stem cells are critical components of our defense system. Scientific literature classifies stem cells under four major categories: embryonic, tissue-specific, Mesenchymal, and pluripotent stem cells. The role of stem cells is to generate new tissues. You can find the details of each stem cell type in this article.

As mentioned in this article, “stem cells act as reservoirs of cells that divide to produce new stem cells, as well as a myriad of different types of specialized cells, required to secure tissue renewal and function. The hematopoietic stem cells (HSC) are nestled in the bone marrow, the soft tissue in the center of large bones. Their role is to renew the repertoire of blood cells, including cells of the immune system which are crucial to fight infections and other diseases.”

This book chapter in Immunobiology informs that “a pluripotent hematopoietic stem cell gives rise to the lymphocytes responsible for adaptive immunity, and also to myeloid lineages that participate in both innate and adaptive immunity. Neutrophils, eosinophils, and basophils are collectively known as granulocytes; they circulate in the blood unless recruited to act as effector cells at sites of infection and inflammation.”

It is important to point out cancer stem cells (CSCs). As this paper informs, “CSCs have important roles in tumor development, relapse, and metastasis. The intrinsic self-renewal characteristics and tumorigenic properties of these cells provide them with unique capabilities to resist diverse forms of anticancer therapy, seed recurrent tumors, and disseminate to and colonize distant tissues. The findings of several studies indicate that CSCs originate from a non-malignant stem or progenitor cells.”

4 — Lymphatic System & Blood Vessels

The lymphatic system is our first line of defense against toxins. As mentioned in this LGDA resource, “the lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections. It is made up of a complex network of lymphoid organs, lymph nodes, lymph ducts, lymph tissues, lymph capillaries, and a network of lymphatic vessels that carry lymph and other substances throughout the body.”

As part of the lymphatic system, the spleen and thymus protect the body by clearing defective red blood cells and foreign bodies from the bloodstream. So, the spleen and thymus are essential organs monitoring the activities in the bloodstream fighting against pathogens and malignant cells, and preventing us from infection.

This paper published in Trend in Immunology informs that “the blood vessel wall is largely composed of three cell types: endothelial cells lining the entire vascular tree, pericytes supporting the endothelium of microvessels, and smooth muscle cells forming the bulk of large vessel walls. Each of these cell types interacts with and alters the behavior of infiltrating T cells in different ways, making these cells active participants in the processes of immune-mediated inflammation.”

The formation of new blood vessels is known as angiogenesis in science. According to the National Cancer Institute, “angiogenesis plays a critical role in the growth of cancer because solid tumors need a blood supply if they are to grow beyond a few millimeters in size. Tumors can actually cause this blood supply to form by giving off chemical signals that stimulate angiogenesis. Tumors can also stimulate nearby normal cells to produce angiogenesis signaling molecules.”

5 —The Gut Microbiota

Our microbiome has many functions, and we still don’t know much about this mysterious colonization in our gut. However, the research on microbiota, especially its relation to our immune system, is intense.

This paper informs that “the gut microbiota, the largest symbiotic ecosystem with the host, has been shown to play important roles in maintaining intestinal homeostasis. Dysbiosis of the gut microbiome is caused by the imbalance between the commensal and pathogenic microbiomes. The commensal microbiome regulates the maturation of the mucosal immune system, while the pathogenic microbiome causes immunity dysfunction, resulting in disease development.”

This scientific review points out that “a gut-muscle axis may regulate muscle protein deposition and muscle function. In older individuals, this axis may be involved in the pathogenesis of muscle wasting disorders through multiple mechanisms, involving the transduction of pro-anabolic stimuli from dietary nutrients, modulation of inflammation, and insulin sensitivity. The immune system plays a fundamental role in these processes, being influenced by microbiome composition and at the same time contributing to shaping microbial communities.”

Another paper highlights that “the gut microbiome can modulate the host immune system both locally and systemically. Cancer immunotherapy has emerged as a promising way in the treatment of patients with cancer. Accumulating evidence supports that microbiome affects the therapeutic efficacy of cancer immunotherapy, particularly immune checkpoint inhibitors.”

Even though we don’t know the details yet, the microbiome is part of the defense system. It relates to our mental health as well. For example, as pointed out in this study, the gut microbiome plays a facilitating role between stress response, inflammation, depression, and anxiety.

The study documented multiple pathways by which stress-induced inflammation harms brain function and ultimately affects mental health. In addition, researchers reviewed how probiotic and prebiotic treatments have shown to be beneficial. The study also provides an overview of gut microbiome-derived compounds such as short-chain fatty acids, tryptophan catabolites, microbial pattern recognition, and related mechanisms involved in mediating the gut microbiome’s influence on mental health.

Conclusions

We all experience a constant and silent war inside our bodies, even though we might not be aware of the ongoing battle. However, an astonishing army of complex defense systems protects us from internal and external invaders constantly.

I provided a high-level view of our defense system under five categories: immune system, genetics, stem cells, lymphatic system & blood vessels, and the gut microbiota. An awareness of our defense system is valuable in designing our lifestyle choices and making decisions for our health, fitness, and well-being.

In addition to our defense system, we have other mechanisms dealing with internal and external invaders in another layer. The function of this layer is the self-eating (cannibalizing) of damaged cells, known as autophagy and mitophagy.

Thank you for reading my perspectives. I wish you a healthy and happy life.

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