Array 22 - Irritable Bowel/SIBO Screen

Bacterial Cytotoxins refer to the cytolethal distending toxin, subunit B (CdtB) that is released by Escherichia coli, Salmonella, Shigella and Campylobacter jejuni. Utilizing subunits A and C, gram-negative bacteria can bind to human cells, allowing CdtB to infiltrate the cell. Inside the cell, CdtB contributes to cytoskeletal damage, which may induce apoptosis (cell death). CdtB is the first bacterial toxin known to act in the nucleus of a target cell. Associated With: - Irritable bowels - SIBO - Gut dysbiosis - Chronic functional bowel changes - Localized aggressive periodontitis -------------------- Cyrex Array 22 measures IgA, IgG and IgM antibodies against bacterial cytotoxins and cytoskeletal proteins in human blood. This is based on the scientific fact that bacteria from the colon move up to the upper gut, and their concentrations become elevated. By producing cytotoxins, these bacteria affect the delicate environment of the small intestine, and then gain entry into the cell, where, by binding to the cellular DNA, they induce apoptosis (cell death). They then find their way to the submucosa, regional lymph nodes, and into the circulation. Immune response against the bacterial cytotoxins may result in the production of IgA, IgM and IgG antibodies against them. Due to the antigenic similarity between E. coli, Salmonella, Shigella toxins, Campylobacter jejuni and human cytoskeletal proteins such as vinculin and talin, these antibodies cross-react with the cytoskeletal proteins, causing depolymerization of and release of these proteins from the epithelial cells, with subsequent antibody production against the cytoskeletal proteins vinculin, talin, and actinin. These IgA, IgM and IgG antibodies against bacterial cytotoxins and cytoskeletal proteins are detected in the blood with high accuracy and reproducibility. Thus, bacterial over-growth can be an instigator of extra-intestinal autoimmunity (autoimmune reactivity outside of the gastrointestinal tract). Cytotoxins are lethal xenobiotics released by commensal coliform bacteria. Bacterial cytotoxins can destroy epithelial cells of the intestinal barrier. Therefore, Cyrex also assesses antibodies to cytoskeletal proteins. Once this epithelial cell damage occurs, bacterial cytotoxins can freely enter circulation. Like systemic lipopolysaccharides, when bacterial cytotoxins enter the blood stream, they produce chronic inflammation and can permeate the blood brain barrier.

Overview The Cytoskeletal Proteins IgA marker measures immune reactivity to certain structural proteins that are part of the intestinal lining. These cytoskeletal proteins—most notably vinculin, talin, and alpha-actinin—help maintain the integrity of the gut's epithelial cells and tight junctions. These junctions are critical in regulating what passes from the inside of the gut into the bloodstream. When functioning properly, they help maintain a healthy, selective barrier that keeps out unwanted substances like toxins, bacteria, and partially digested food particles. This test specifically measures Immunoglobulin A (IgA), an antibody type predominantly found in mucosal surfaces such as the gut. Elevated levels of IgA against cytoskeletal proteins can indicate that the immune system is responding to damage or stress at the intestinal lining, which may be the result of bacterial overgrowth, chronic inflammation, or previous gastrointestinal infections. Why it’s tested In conditions like Small Intestinal Bacterial Overgrowth (SIBO) or post-infectious Irritable Bowel Syndrome (IBS), certain pathogens—such as Campylobacter jejuni, E. coli, and Salmonella—can produce toxins that damage the epithelial cells lining the gut. One of the well-documented toxins involved in this process is the cytolethal distending toxin (Cdt), which can trigger an autoimmune-like immune response. When epithelial cells are injured, their cytoskeletal proteins are exposed to the immune system in abnormal ways. This may cause the immune system to treat those internal proteins as foreign, generating antibodies like IgA against them. The presence of these antibodies reflects mucosal immune activation and may indicate a loss of immune tolerance to structural components of the gut lining. In other words, the immune system starts attacking the body's own tissue at the site of damage—an early sign of a more complex immune or inflammatory process that may not be limited to the digestive system. Clinical relevance of elevated IgA Elevated Cytoskeletal Proteins IgA levels suggest there may be ongoing damage or dysfunction in the intestinal barrier. This is important for several reasons: Gut permeability (leaky gut): The integrity of the intestinal lining may be compromised, allowing bacteria, toxins, and food antigens to enter the bloodstream. This can lead to widespread inflammation and symptoms that go beyond the gut, such as joint pain, fatigue, or brain fog. Post-infectious IBS and SIBO: Elevated antibodies to cytoskeletal proteins are commonly found in individuals with diarrhea-predominant IBS (IBS-D), especially after a gastrointestinal infection. In these cases, the immune response is driven by the aftermath of infection and can lead to long-term changes in gut motility and sensitivity. Autoimmune risk: Persistent immune responses against self-proteins in the gut may contribute to the development of autoimmune conditions over time. The immune system's targeting of these proteins could spread to other tissues, particularly in individuals with genetic or environmental predispositions. Barrier system cross-reactivity: Damage to the intestinal barrier may also affect other body systems that rely on similar barrier mechanisms, such as the blood-brain barrier or the lung epithelium. Cross-reactivity to structural proteins in multiple tissues is a growing area of research in immune-mediated diseases. What this means for your health If your Cytoskeletal Proteins IgA level is elevated, it suggests your immune system is reacting to structural proteins in your gut lining, likely in response to damage or chronic irritation. While this marker alone does not confirm a diagnosis, it provides useful insight when viewed in the context of other markers on the Array 22 panel—such as bacterial toxin antibodies (e.g., CdtB or LPS)—as well as your symptoms, history of infections, and digestive complaints. Healthcare practitioners may use this information to support a diagnosis of post-infectious IBS, SIBO, or to guide personalized treatment strategies aimed at reducing immune activation, repairing the intestinal lining, and restoring a healthy microbial balance. This often includes dietary modifications, targeted antimicrobial therapy, probiotics, gut-healing nutrients like glutamine and zinc carnosine, and lifestyle changes to reduce systemic inflammation. Summary Cytoskeletal Proteins IgA is a powerful marker for identifying mucosal immune reactions in the gut. When elevated, it signals that your immune system may be targeting structural elements of the intestinal lining due to prior or ongoing damage—often related to SIBO, post-infectious IBS, or other inflammatory gut conditions. Addressing this immune reactivity early through targeted interventions can help support gut repair, prevent progression to broader immune dysregulation, and alleviate both digestive and systemic symptoms.

Known Cross-Reactions: Alpha-actinin with anti-ssDNA