Introduction
Hello and welcome to the World Asthma Foundation blog, where we share the latest news and information on asthma and related topics. We are a non-profit organization that pursues our mission and vision with a strategy to support the asthma community with educational resources. Our goal is to foster improved outcomes, better doctor-patient relationships, and support joint decision-making. In this way, asthmatics can take charge of their own health.
One of our main areas of focus is Infectious Asthma, which is a term that describes asthma that is triggered or worsened by infections, such as bacteria, viruses, fungi or parasites. Infectious Asthma can affect anyone, but it is more common and severe in children, elderly, immunocompromised or low-income populations. Infectious Asthma can cause more frequent and severe asthma attacks, lung damage, chronic sinusitis, nasal polyps and other complications.
In this article, we will review the current knowledge on one of the most common and potentially harmful triggers of Infectious Asthma: Staphylococcus aureus (S. aureus), a bacterium that can colonize the skin and mucous membranes of humans. S. aureus can produce various toxins, such as staphylococcal enterotoxins (SE), that can act as superantigens and induce an intense immune response in the airways. This can result in increased production of immunoglobulin E (IgE), a type of antibody that mediates allergic reactions, and activation of eosinophils, a type of white blood cell that causes inflammation and tissue damage.
We will also discuss how measuring SE specific IgE (SE-IgE) may help to identify a subgroup of patients with severe asthma who may benefit from specific interventions. Finally, we will provide some key takeaways and recommendations for asthmatics and clinicians.
We hope that this article will be informative and helpful for you. If you have any questions or comments, please feel free to contact us. Thank you for reading.
Summary
In this article, we have reviewed the current knowledge on the role of S. aureus and its enterotoxins in asthma, especially severe asthma. We have summarized the main findings from five recent studies that have investigated the association between SE sensitization and asthma severity, phenotype and inflammation. We have also discussed how measuring SE-IgE may help to phenotype asthmatics and guide treatment decisions. We have provided some key takeaways and recommendations for asthmatics and clinicians. Here are the main points:
• S. aureus and its enterotoxins are important factors in the pathogenesis of asthma, especially severe asthma.
• SE can act as superantigens and induce an intense T cell activation causing local production of polyclonal IgE and resultant eosinophil activation.
• SE can also manipulate the airway mucosal immunology at various levels via other proteins, such as serine-protease-like proteins (Spls) or protein A (SpA), and trigger the release of IL-33, type 2 cytokines, mast cell mediators and eosinophil extracellular traps.
• SE sensitization is associated with increased risk of asthma, more asthma exacerbations, nasal polyps, chronic sinusitis, lower lung function and more intense type-2 inflammation.
• SE sensitization is also linked to allergic poly-sensitization and allergic multimorbidity, such as rhinitis, eczema and food allergy, indicating a possible role of S. aureus in the development of allergic diseases.
• Measuring SE-IgE may help to identify a subgroup of patients with severe asthma who may benefit from specific interventions, such as anti-IgE therapy or antibiotics.
Key Takeaways
• Asthmatics should be aware of the potential role of S. aureus and its enterotoxins in triggering and worsening their asthma symptoms and seek medical advice if they suspect an infection or colonization.
• Asthmatics should avoid contact with S. aureus carriers or sources of contamination, such as contaminated food or water, and practice good hygiene and wound care to prevent infection or colonization.
• Asthmatics should ask their doctors about testing for SE-IgE as part of their asthma phenotyping and management, as it may help to identify a subgroup of patients with severe asthma who may benefit from specific interventions.
• Clinicians should consider measuring SE-IgE in asthmatics, especially those with severe asthma, nasal polyps, chronic sinusitis or allergic multimorbidity, as it may provide valuable information on the underlying mechanisms and phenotypes of asthma and suggest novel therapeutic targets and strategies.
• Clinicians should also monitor the SE-IgE levels and response to treatment in asthmatics who are receiving anti-IgE therapy or antibiotics, as it may help to evaluate the efficacy and safety of these interventions.
Conclusion
Asthma is a complex and heterogeneous disease that can be influenced by various factors, such as allergens, irritants, infections and stress. Among these factors, S. aureus and its enterotoxins have emerged as important triggers and modulators of asthma, especially severe asthma. SE can act as superantigens and induce an intense immune response in the airways, resulting in increased production of IgE and activation of eosinophils. SE can also manipulate the airway mucosal immunology at various levels via other proteins, such as Spls or SpA, and trigger the release of IL-33, type 2 cytokines, mast cell mediators and eosinophil extracellular traps. These mechanisms can lead to more severe asthma phenotype and type-2 inflammation.
SE sensitization is associated with increased risk of asthma, more asthma exacerbations, nasal polyps, chronic sinusitis, lower lung function and more intense type-2 inflammation. SE sensitization is also linked to allergic poly-sensitization and allergic multimorbidity, such as rhinitis, eczema and food allergy, indicating a possible role of S. aureus in the development of allergic diseases. Measuring SE-IgE may help to identify a subgroup of patients with severe asthma who may benefit from specific interventions, such as anti-IgE therapy or antibiotics.
In this article, we have reviewed the current knowledge on the role of S. aureus and its enterotoxins in asthma, especially severe asthma. We have summarized the main findings from five recent studies that have investigated the association between SE sensitization and asthma severity, phenotype and inflammation. We have also discussed how measuring SE-IgE may help to phenotype asthmatics and guide treatment decisions. We have provided some key takeaways and recommendations for asthmatics and clinicians.
We hope that this article has been informative and helpful for you. If you have any questions or comments, please feel free to contact us. Thank you for reading.
References
: Bachert C., Humbert M., Hanania N.A., Zhang N., Holgate S., Buhl R., Bröker B.M. Staphylococcus aureus and its IgE-inducing enterotoxins in asthma: current knowledge. Eur Respir J. 2020;55(4):1901592. doi: 10.1183/13993003.01592-2019.
: Kanemitsu Y., Taniguchi M., Nagano H., Matsumoto T., Kobayashi Y., Itoh H. Specific IgE against Staphylococcus aureus enterotoxins: an independent risk factor for asthma. J Allergy Clin Immunol. 2012;130(2):376–382.e3. doi: 10.1016/j.jaci.2012.04.027.
: Soh J.Y., Lee B.W., Goh A. Staphylococcal enterotoxin specific IgE and asthma: a systematic review and meta-analysis. Pediatr Allergy Immunol. 2013;24(3):270–279.e1-4. doi: 10.1111/pai.12056.
: Schleich F., Brusselle G.G., Louis R., Vandenplas O., Michils A., Van den Brande P., Lefebvre W.A., Pilette C., Gangl M., Cataldo D.D., et al. Asthmatics only sensitized to Staphylococcus aureus enterotoxins have more exacerbations, airflow limitation, and higher levels of sputum IL-5 and IgE. J Allergy Clin Immunol Pract. 2023;11(5):1658–1666.e4. doi: 10.1016/j.jaip.2023.01.021.
: James A., Gyllfors P., Henriksson E.L., Lundahl J., Nilsson G., Alving K., Nordvall L.S., van Hage M., Cardell L.O. Staphylococcus aureus enterotoxin sensitization is associated with allergic poly-sensitization and allergic multimorbidity in adolescents. Clin Exp Allergy. 2015;45(6):1099–1107. doi: 10.1111/cea.12519.
Sidebar: What is Staphylococcus aureus?
Staphylococcus aureus is a type of bacteria that can cause various infections in humans and animals. It is found in the environment and also in the normal flora of the skin and mucous membranes of most healthy individuals. It can colonize the anterior nares (the front part of the nose), the throat, the skin, and the gastrointestinal tract. It is estimated that up to half of all adults are colonized by S. aureus, and approximately 15% of them persistently carry it in their noses.
S. aureus can cause infections when it breaches the skin or mucosal barriers and enters the bloodstream or internal tissues. These infections can range from mild skin infections, such as boils or impetigo, to more serious infections, such as pneumonia, endocarditis, osteomyelitis, septic arthritis, or sepsis. S. aureus can also produce toxins that can cause food poisoning, toxic shock syndrome, or scalded skin syndrome.
S. aureus is a very adaptable and versatile bacterium that can acquire resistance to various antibiotics. The most notorious example is methicillin-resistant S. aureus (MRSA), which is resistant to most beta-lactam antibiotics, such as penicillins and cephalosporins. MRSA can cause infections both in community-acquired and hospital-acquired settings and poses a major public health challenge.
S. aureus is believed to have originated in Central Europe in the mid-19th century and has since evolved and diversified into many different strains or clones. Some of these strains are more virulent or resistant than others and have spread globally through human migration and travel. One of these strains is ST8, which includes the USA300 clone that is responsible for most community-acquired MRSA infections in the United States.
S. aureus is one of the most common and potentially harmful triggers of Infectious Asthma, especially severe asthma. It can produce various toxins, such as staphylococcal enterotoxins (SE), that can act as superantigens and induce an intense immune response in the airways. This can result in increased production of immunoglobulin E (IgE), a type of antibody that mediates allergic reactions, and activation of eosinophils, a type of white blood cell that causes inflammation and tissue damage.
References
: Staphylococcus aureus Infection – StatPearls – NCBI Bookshelf
: Global Epidemiology and Evolutionary History of Staphylococcus aureus ST45
: Origin, evolution, and global transmission of community-acquired … – PNAS
: Staphylococcus aureus Infections: Epidemiology, Pathophysiology