Week 3 Flashcards
Tolerance
Regulatory immune response
- Necessary to prevent: Allergic disease & Auto-immune disease
Why is neonatal immunology and immune ontogeny important to study?
- Early life is a period of high susceptibility to diseases that depend on immune function: Infectious disease and allergic disease
- Early life health conditions long term health
- Knowing the specificities of the immune system in early life is necessary for efficient prevention/cure of disease in early life
The developmental origins of health and disease concept
Some epidemiological and biological observations supporting this concept:
• Malnutrition during foetal life is inducing metabolic adaptation leading to increased risk of cardiovascular disease in adult exposed to rich diet1. Metabolic disease such as cardiovascular disease and Diabetes are caused by low grade inflammation • Living in a farm during first year of life is a major protective factor against asthma • Gut microbiota composition during first 100 days determines risk of asthma in childhood
- The identification of protective and risk factors in early life that condition long term susceptibility to chronic diseases is required for prevention
Why is the neonatal immune system important?
Babies have specific requirements
- propose preventative and therapeutic approach that are adapted and efficient for this period of life
What are the specificities of the neonatal immune system?
- Early life specific limitations: immune system still developing / gut microbiota still getting established
- Early life specific constraints : growth : avoid excessive inflammation/ trend to allergy
- Early life specific immune challenges : numerous new antigens ( food, microbes)
- Early life specific immune reactivity: low dose of antigen as an example- no memory
- Early life specific help
Early life specific constraints: growth and development
- tissue growth and development is associated with the secretion of molecules, which also play a role in allergic immune responses
- strong inflammatory responses should be avoided as this may interfere with tissue development (scars): in general neonates do not mount strong inflammatory responses and this can explain susceptibility to infection
- immune responses in early life tend to be biased towards allergy and poorly inflammatory
Neonates are susceptible to infection: what can be done for prevention?
• Fragile barriers :
Skin: keep vernix caseosa, avoid soaps, use cream,…
Gut: breastfeeding
Avoid high exposure to pathogens: Hygiene
• Developing immune system
Breastfeeding
Avoid high exposure to pathogens: Hygiene
Maternal and child vaccination
What can be done to prevent allergy?
- Need to know what are the mechanisms underlying allergic disease development
- Need to identify factors that are protective or that increase susceptibility
Allergy is due to …
Regulatory immune response towards non dangerous antigens in the environment
What happens during an allergic immune response?
- Sensitisation
- Allergic reaction
Allergic immune response: Sensitisation
- Exposure to a source of allergen (= an antigen that induces allergic reaction)
- Transfer of the allergen across a body barrier (skin, lung, gut) and production of danger signals
- Activation of the immune system and expansion of Th2 lymphocytes
- Activation of B lymphocytes and synthesis of IgE that are specific for the allergen and that bind to mastocytes
Allergic immune response: Allergic reaction
- Exposure of an already sensitised individual to an allergen
- Transfer of an allergen across a barrier
- Binding of the allergen to mastocytes covered with IgE
- Instantaneous liberation of inflammatory mediators causing symptoms
What happens in a non-allergic individual?
- Exposure to a source of allergen (=an antigen that can induce allergic reaction)
- Low transfer of the allergen across a body barrier (skin, lung, gut) - no/few danger signal produced
- Activation of the immune system and expansion
