• Dr Joanne Delange

Immunobiotics Role in Malnutrition and Immunity


Malnutrition and the Immune System


Malnutrition is a serious condition that happens when your diet does not contain the right amount of nutrients resulting in disordered nutrient assimilation. Malnutrition is diagnosed as either undernutrition or overnutrition. Furthermore, it is characterised by recurrent infections and chronic inflammation, which implies an underlying immune defect.


The immunodeficiency associated with malnutrition is characterised by a weakened immune response against infectious diseases. As such, respiratory infections are among the leading causes of increased morbidity and mortality, especially in immunosuppressed patients.


Dr Claire Bourke, a postdoctoral research fellow in the Centre for Genomics and Child Health at Queen Mary University of London said: 'Those height and weight defects that we see are the tip of the iceberg - there are a whole range of pro-inflammatory conditions, impaired gut function, weakened responses to new infections, and a resulting high metabolic burden underlying them.' Publishing her findings in Trends in Immunology.


How malnutrition and immune function are linked is still poorly understood, but it is known that malnutrition is associated with a range of immune problems. White blood cells that fight infections from bacteria, viruses, fungi, and other pathogens, are reduced. Lymph nodes that function as filters, trapping pathogens before they can infect other parts of the body do not work properly. The mucosal membranes of the skin and gut, which defend against pathogens, are leaky which makes it easier for the pathogens to break through.


Immunobiotics and the Respiratory System


The crosstalk between immunobiotics and the immune cells of the respiratory mucosa has been examined by scientists at the Reference Centre for Lactobacilli and the National University of Tucuman, San Miguel de Tucuman, Argentina. In their paper, published in Frontiers in Nutrition they discuss how this cross talk affects the maintenance of a normal generation of immune cells, which is crucial for the establishment of protective innate and adaptive immune responses.


Many clinical and animal model studies have shown that immunobiotics can beneficially modulate the respiratory immune response. As such, the oral or nasal administration of some immunobiotic strains or their postbiotics (the beneficial molecules produced by probiotic bacteria) have been shown to improve the immune response against bacterial and viral infections in healthy and immunosuppressed patients. Dr Susana Salva, who led the study, hypothesised that 'immunobiotic bacteria can be used in therapies aimed at modulating the immunity of the respiratory mucosa, especially in populations at risk.'


Immunobiotics have been proposed as dietary supplements to improve immunity and aid the fight against infections. These supplements are usually administered orally, however, nasal administration has been highlighted as the preferred route to induce systemic immunity, providing an advantage in protecting against respiratory infections. This is believed to be due to a stronger stimulation of the immune cells of the airways in the nasal cavity and the upper respiratory tract.


Lactobacillus rhamnosus CRL1505


Lactobacillus rhamnosus is one of the most widely used immunobiotic probiotic strains that is known to aid in the prevention and treatment of gastrointestinal infections and diarrhoea, and to improve immune responses in both healthy and immunosuppressed patients.


The peptidoglycan from L. rhamnosus CRL1505 has been shown to be the key cellular component involved in improving immune responses, which cannot be found in other L. rhamnosus or probiotic strains. Therefore, L. rhamnosus CRL1505 is proposed as a mucosal adjuvant to improve the immune response of immunosuppressed patients.


The nasal administration of L. rhamnosus CRL1505, or its postbiotic, is able to accelerate the improvement of the number and functionality of respiratory myeloid, B and T cells. Furthermore, this immunobiotic or postbiotic is able to accelerate the recovery of bone marrow, thymus and spleen damaged by malnutrition.


Nasal administration with the L. rhamnosus CRL1505 immunobiotic or postbiotic has been shown to increase resistance against respiratory infections and stimulate and effective innate and specific immune response against the pathogen.


Gut-Lung Axis


The microbiome, commonly known as intestinal flora, consists of trillions of microorganisms. The gut microbiota maintains the immune defence mechanisms in the respiratory tract. Furthermore, the lung microbiota contributes significantly to airway tolerance and immune responses to respiratory infections. This bi-directional cross-talk that occurs between the gut and the lung has been termed the gut-lung axis. The gut and lung microflora are clearly linked by nutrition, the immune system and digestive and respiratory health, through mutual communication linking this intricate system.


As certain probiotics have shown beneficial effects on lung health and the treatment of respiratory diseases, the influence of the lung microbiota on the immune system deserves further investigation.


Further research is currently aimed at advancing our understanding of the microorganisms that make up the lung microbiota in patients with respiratory diseases, and also healthy people. It is vital to understand the immune response that is modulated. Nasally administered immunobiotics or postbiotics could act as mediators to modulate the immune responses triggered by respiratory pathogens. In this way, they could contribute to restoring and maintaining lung health.


Conclusion


Oral and nasal immunobiotic treatments have been shown effective to improve resistance to infection in immunosuppressed patients. However, nasal administration has been determined as the optimal route to modulate the local response against respiratory infections.


Further studies are required to investigate the immune pathways effected by malnutrition, however research to date does provide evidence for a causal role for immune dysfunction in malnutrition.


References:


Salva S, et al (2021). The Role of Immunobiotics and Postbiotics in the Recovery of Immune Cell Populations From Respiratory Mucosa of Malnourished Hosts: Effect on the Resistance Against Respiratory Infections. Frontiers in Nutrition. Aug 12;8:704868. Available at https://doi.org/10.3389/fnut.2021.704868


Bourke CD, et al (2016). Immune Dysfunction as a Cause and Consequence of Malnutrition.

Volume 37, Issue 6, June, Pages 386-398. Available at https://doi.org/10.1016/j.it.2016.04.003


Nutritional Insight - In-Depth: Links Between Microbiota and the Gut-Lung Axis.

Available at https://www.nutritional-insight.co.uk/post/in-depth-links-between-microbiota-and-the-gut-lung-axis

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