Layperson Version
When "Self" Becomes the Villain
Blog #18:Autoimmune disease (Part 1) – Causes
When, for some unknown reason, the body incorrectly identifies itself (i.e., self) as foreign (i.e., non-self), effectively, the body becomes an “antigen” and generates a process referred to as “autoantigenicity.” This process initiates an adaptive immune response directed at itself. Stated another way, the immune system has the potential to produce an “autoimmune response.”
There are several theories as to the cause(s) of this unusual autoimmune response, but whatever the cause(s), the response has created an entirely separate disease category referred to as “autoimmune disease.” Despite the fact that the cause (etiology) of this disease category remains unknown or at least open to multiple hypotheses, its development and thus, its therapeutic strategies, are similar to those of chronic inflammation (CI) in that CI is the immunological basis and the biological process responsible for this category of immune disease is in fact, CI.
The etiologies of autoimmune diseases and those of CI are virtually identical (see Blog #14 and 18), thus making the two entities synonymous, one with a clinical label (autoimmune disease) and one as a biological or pathological classification (CI). The first cause is “a prolonged inflammatory process from failure to eliminate an antigen.” Continued or unabated antigen stimulus will lead to CI and its clinical sequalae as discussed in Blog #14 and 18, and stress antigenicity as described in Blog #3 and elsewhere.
The second cause of autoimmune disease is abnormalities (inherent or mutational) in the patient’s genome that can make it susceptible to dysregulation. Complicated interactions between neural, genetic variants, genetic mutations, and epigenetics (non-altered DNA modifications of phenotype gene expression) can produce a multitude of pathways that lead to autoimmune diseases.
The third cause is environmental factor(s) or stress eliciting an autoimmune response. Combined with inherited gene alterations (alleles) that an individual might possess for a specific gene, a given environmental factor can produce a “trigger,” something to produce the clinical manifestations of autoimmune disease. Consider the person who has smoked all their life without ever experiencing the classic, associated diseases (respiratory, cardiovascular, carcinogenic). One (like an aging, inveterate smoker) would use this as an argument that smoking is not a risk factor. On the contrary, that individual “rolled the dice” (unknowingly) on not having the specific gene(s) and alleles to induce a smoke-related disorder, and he/she won the gamble. But epidemiologic studies have unequivocally concluded that there is a greater risk of having one or more “triggers” for smoking-induced disorders than not. The free-will choices we make regarding what we will or will not expose ourselves to (i.e., risks) range from people’s common sense (or lack thereof) to practicing good personal and public health measures (e.g., smoking, or of late, wearing a mask, and vaccination during an infectious pandemic). Maybe routine DNA screening in the future will help us make better decisions.
The fourth cause of autoimmune disease is the increasing release and accumulation of proinflammatory cytokines or endogenous (internal) autoantigens, including such “self things” as metabolic and immune byproducts. This phenomenon was described in some detail back in Blogs #3 and 14 in our discussion of the “clinical autoimmune cycle” or “death hypothesis.”
Finally, the fifth (and probably not the last) cause of autoimmune disease is “rogue B cells” and epitope spreading. Antigens have small sites on their surfaces called epitopes or “antigenic determinants” that bind to a genetically predetermined corresponding receptor on the surface of the B cell (from the “antibody-encoding gene” introduced in Blog #7). These B-cell receptors and epitopes are programmed genetically through the major histocompatibility complex (MHC) on the T cells, again, as described in Blog #10. When toll-like receptors (TLRs or the “sentry cells”) send immune signal to MHCs, the B cells undergo changes in their genes to produce antibodies that create strong attachments to the antigens’ epitopes and generate plasma cells that proceed to produce large amounts of antibodies. During this rapid proliferation and dispersion (or “spreading”) of antibodies, some B cells become genetically (aberrantly) altered and begin to mistake “self” as antigenic. These autoantibody B cells are called “rogue B cells” and their migration is called “epitope spreading.” This spreading is what produces the clinical picture of the many autoimmune diseases whose signs and symptoms “spread” insidiously (Machiavellian-like) or gradually over time, from one organ to another. It is theorized that this “rogue B-cell-epitope spreading” phenomenon is a product of dual genetic influences (messages) to the immune system, some of which incite, but other which silence the immune system, thus reducing autoantigenic effects (yet another immune paradox).
Blog #19: Autoimmune disease (Part 2)- Female bias)
It’s time to revisit female bias in immunology, “for better and for worse,” in this case, more “for worse.” The prevalence of autoimmune diseases in females is an area of intense research and speculation as to its causes. This blog will briefly address some of the most popular theories from the evolutionary, individual development, disease occurrence, and immunologic explanations.
Autoimmune immune diseases occur in females at a rate of two to one over males (6.4% of women vs. 2.7% of men). In fact, it is estimated that 78% of people affected by autoimmune diseases are women. There is an abundance of theories as to why there is such a strong female predilection for autoimmune diseases. Some are based on speculation, but most on evidence-based science. A listing (and labeling) of some (not all) of the possible causes, some of which we have discussed already in numerous blogs and some not yet presented:
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Male testosterone protection (speculation);
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Pregnancy factors (evidence-based science);
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Genetic expression (evidence-based science);
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Embryologically, women confer first immunity to their babies suggesting a stronger immune system than the father (evidence-based science);
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“Pregnancy brain” where fetal cells from the embryo transfer to the mother during pregnancy and remain in her brain for life producing a “potential” autoantigenic effect (evidence-based science and speculation);
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Women, as traditional caregivers, suggest a kind of evolutionary development wherein women seems to produce more absolute lifelong antibody levels than men, thus producing a stronger immune system but increased risk for innate immune dysregulation (speculation);
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Females tend to have more body fat than males, thus more immune cells (evidence-based science);
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Women live longer, thus producing more antibodies that contribute to a longer life, but also create a greater potential risk for dysregulation and loss of homeostasis or abnormal balance pf physiologic forces (speculation);
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The “hygiene hypothesis” that compromises the microbiome and increases the risk of autoimmune disease (greater in females due to inherent differences between males and females or “sexual dimorphism”) (evidence-based and speculation);
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Probably more theories abound, including any you might identify in other blog discussions.
I mentioned way back in Blog #12 that we would be revisiting X Chromosome Inactivation (XCI) with some frequency in subsequent discussions. Well, here is the first revisit and it’s a big one. Beyond the 10 possible explanations for autoimmune disease being most prevalent in females, XCI may just be the most credible and validated science-based theory. It all has to do with XCI’s and its intimate relationship with microRNA.
It is well understood that sex hormones are an enormous factor in the regulation and dysregulation of immunity. Predominant influences of female estrogen and progesterone both increase and decrease immune chemistry and are believed to be responsible for autoantibody development, autoimmune stimulation, and corresponding autoimmune diseases. More so, perhaps, estrogens regulate microRNAs (miRNA), the noncoding RNA gene (not involved in protein synthesis process) abundant on the female X chromosome and essential in how genes produce the organism’s (person’s) physical characteristics (as mentioned in Blog #10). Also, about 15% of genes escape the XCI process, called “escapees”, all of which recent research has confirmed as primary contributors to the female bias for autoimmune diseases, especially SLE. Paradoxically, the relationship of the X chromosome, in combination with XCI and XCI “escape” provides the basis of “protection” (vs. risk) for females against certain cancers and an increased risk for males. The escapees play a significant role in oncogenesis (cancer production) and will be further discussed in the later blogs on cancer. But after all is said and done regarding definitive causes of autoimmune diseases (and cancers), understanding their etiologies remain relatively nascent and will require an enormous amount of continuing research.
Other interesting associations in the disease producing or protective causes of autoimmune disease include the effects of the microbiome (remember that from Blog #13?). Its unrelenting effort to control CI becomes a mitigating force against autoimmune diseases, even cancers as it modulates the immune system. Dysbiosis or imbalance in the gut microbiome is another important environmental factor that has been linked to the onset of different autoimmune diseases. The “gut microbiota-innate immunity axis” and “symbiotic bacteria” (short-chain fatty acids or SFCA) present in the microbiome upregulate interleukins and TNF-a and further contribute to the causes of autoimmune diseases. Finally, the modification of gene expression from SCFA metabolism and its byproducts and interactions between gut microbiota and the innate immune system disrupt homeostasis and also contribute to the disease process in autoimmunity. Confusing? Don't worry, you're not alone.
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Blog #20: Autoimmune disease (Part 3)- Clinical considerations)
When discussing autoimmune diseases in the previous blog (#19), we identified the phenomenon of epitope spreading contributing to the nature of autoimmune diseases as being specific to a bodily organ or tissue, or conversely being distributed, diffusely among multiple organ systems or tissues throughout the body. This “rogue B-cell” effect combined with the pervasive focal and diffuse vascular effects of chronic inflammation are the highly likely causes of the multisystem organ/tissue-specific clinical manifestations (also diagnosed as multisystem inflammation syndrome in children or MIS-C) synonymous with autoimmune diseases. It should also be noted that multiple autoimmune diseases, organ-specific and/or diffuse, can occur simultaneously in the same patient making the diagnosis of autoimmune diseases infinitely more difficult. So, the diagnosis of autoimmune disease can be challenging for two reasons. First, many of the associated diseases share similar symptoms. Second, as described previously, the disease process may be organ-specific or disseminated among multiple body systems. The diagnostic evaluation includes a thorough history, physical examination, laboratory testing, and imaging based on suspected tissue or organ-system involvement(s).
Regarding the array of autoimmune diseases, there have been more than 80 identified affecting more than 50 million Americans (according to the American Autoimmune Disease Related Association, AARDA, 2019), 78% of whom are women. Relative to the specific conditions, symptoms range from no symptoms at all to general malaise to severe illness and risk of death. Let’s list the top 10 autoimmune diseases, but because of the limitations of these blog presentations, we’ll have to limit the discussion of their clinical signs and symptoms (Table 5.3); diagnostic criteria; and treatments, including immunotherapeutic agents (Table 5.4), all of which are comprehensively outlined and discussed in “The Paradox of the Immune System” book, of which this entire blog is an abridged version. However, we will be providing an expanded discussion in the next blog (#21) on immunotherapies including those identified in the 10 most common conditions listed below (plus Table 5.2 of 40 additional prevalent autoimmune diseases from among the 80+ identified by NIH).
1. Rheumatoid arthritis (RA)
2. Systemic lupus erythematosus (SLE)
3. Inflammatory bowel disease (IBD)
4. Crohn’s Disease
5. Multiple sclerosis (MS)
6. Type 1 diabetes mellitus
7. Guillain-Barre syndrome
8. Psoriasis
9. Graves’ disease
10. Myasthenia gravis
As we have discussed multiple times throughout these blogs, the nature of CI and autoimmune diseases may be localized, as in specific to a bodily organ or tissue, and/or distributed diffusely among multiple organ systems or tissues throughout the body. As such, CI and autoimmune diseases often require “localized” treatment directed at the tissue(s) and organ system(s) or more “generalized” treatment falling under the categories of immunosuppressive and immunomodulating (suppressing or stimulating) therapies, sometimes referred to as “nonspecific therapies.” Because of the parallel nature of CI and autoimmune diseases, as we have identified and elaborated on their causes and development in the previous 7 blogs, we’ll devote the next 2 blogs (#21 “Immunotherapies” and #22 “Therapeutic [cellular and genetic] procedures”) to the generic classifications and some specific considerations regarding treatment options (many of which will also be revisited in Blog #23 and #24 on cancer and #25 on infectious disease). This last sentence on treatment considerations in subsequent blogs speaks to the nature of immunotherapies as “nonspecific therapies” as previously mentioned.
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Among all the topics discussed in these blogs, the next three (immunotherapies, cancers, and infectious diseases) will probably be out of date sooner than all the others, and that’s good. The research in these three areas is undoubtedly the most prolific and productive in all of the medical biosciences. So, while we’ll try to give the most recent information, consider these following discussions more baseline (circa 2023) than the most recent science. As we continue this blog (hopefully for years to come), updates on these 3 areas will be the principal focus of our discussions (hopefully from the researchers involved).
The immunotherapeutics, i.e., pharmacologic agents that modulate the immune system), do so by targeting the cells, chemicals and biological processes occurring in chronic inflammation (CI). These processes include those involved in autoimmune diseases (localized and diffuse), cancers and the wide range of other CI-related diseases. The basis of immunotherapies is to utilize the chemicals, molecules and proteins of the immune system, the ones we’ve been talking about in all the previous blogs (Table 4.2), to elicit desired therapeutic effects by immunomodulation, meaning amplifications, supplementation or suppression of the chemical and molecular components identified in the inflammatory cascade, the adaptive immune response precipitating the inflammatory phenomenon from back in Blog #9. The immunotherapies are generally considered “non-specific” therapies, that means they can have multiple therapeutic effects by targeting the biological processes in diseases. These non-specific therapies are subdivided into “monoclonal antibodies” and “biologics.”
Monoclonal antibodies
Sometimes the actual cells and chemicals involved in a bodily process are used to supplement the body’s own defense mechanisms. Monoclonal antibodies (any drug with the suffix, “… mab” in the generic name, most listed in Tables 5.4 and 5.5) are laboratory antibodies or even the patients’ own antibodies, bioengineered and used to mimic the immune system’s own antibody response to a specific antigen and the potential autoimmune disease or CI it can produce. These antibodies are made by identical immune cells that are all replicated (cloned) from a unique parent cell from the patient. Monoclonal antibodies produced naturally by your body are classified as biologics and help the immune system recognize antigens and pathogens that cause disease. They then mark them and destroy them through the innate and adaptive immune response. Like your body’s own antibodies, engineered monoclonal antibodies recognize specific “evil” targets and function similarly to our bodies’ natural antibodies. These engineered monoclonal antibodies are often generated by isolating or transforming antibody-producing cells taken directly from the patient or immunized animals. They then transplant the antibody-encoding genes (remember those amazing
Blog #21: Immunotherapeutics (Monoclonal antibodies and biologics)
genes?) of these monoclonal (natural of engineered) cells into reproducing cell lines which generate large amounts of identical antibodies.
Checkpoint inhibitors (drug names ending in "...ib") are monoclonal antibody drugs that target and attach to certain specific proteins on T cells and some cancer cells. This binding action can inhibit those proteins and boost the immune response against cancer cells (more on this in exciting therapy in Blog #24 on cancer treatments).
Along with other outstanding researchers, Dr. Anthony Fauci identified antibodies on B cells that could make endless copies of themselves. These “cloned” monoclonal antibodies could then be categorized by which antibodies respond to which antigens (pathogens, carcinogens, etc.). From this information, immunopharmaceutical drugs have been designed with specific types of monoclonal antibodies that can attack specific identified antigens. This accomplishment by Dr. Fauci and his team has changed the face of health care as monoclonal antibodies have revolutionized disease care in the 21st century.
Biologic drugs
Beyond monoclonal antibody drugs or “biologic drugs” (Table 5.6) there’s an additional category termed “ DMARDs,” disease-modifying anti-rheumatic drugs. These include drugs such as hydroxychloroquine (you’ve heard of that one, I’m sure!), methotrexate, sulfasalazine, and leflunomide. This second category of biologics attempts to regulate, increase or decrease, the immune response. These nonspecific, generic biologics treat a range of autoimmune (CI) diseases by processes that act on their diseases’ biochemistry to inhibit inflammatory generating agents or promoting inhibitory agents to those inflammatory generating agents. Other popular nonspecific, biologic immunotherapeutic agents include chemicals in the adaptive immune process like cytokines, interferons, interleukins, and anti-TNFs agents, that strong proinflammatory cytokine discussed previously in Blog #15 and 16). Of course, as with corticosteroids and any immunosuppressive agents, the risk of secondary infection must always be considered.
The reason for the large variety of immunotherapeutic drugs is due to the extensive diversity of chemicals (mediators) that stimulate inflammation producing chronic inflammatory and autoimmune processes. To wit, research in immunotherapeutic drugs reaches back into the chemistry of the innate and adaptive immune system as well. While the biologics include a large number of drug options, all are attempting to regulate the immune response. Each has a distinct biochemical effect on different mediators. This gives treating physicians the ability to get a maximal drug effect (and sometimes a definitive diagnosis) by “experimenting” with the response(s) to a variety of biologics. This also confuses the hell out of the public when they watch a TV commercial promoting a biologic drug for a specific autoimmune condition, e.g., rheumatoid arthritis, on one station. Then they change channels and see the same drug being promoted for an entirely different condition (e.g., Crohn’s Disease). The drugs are specific for individual chemical mediators that occur in multiple autoimmune diseases, and thus, they are nonspecific for any one disease. Make sense?