veNTIlATIoN - Green Cross Publishing

probiotics
38
immune cells. Further evidence that an increase in salivary
sIgA may be a beneficial mode of immune modulation for this
probiotic, came from an open-label study in nine healthy adults
(20-45 years), who consumed two bottles of the drink (each
with 6.5 x 10 9 live cells of L. casei Shirota) daily for four weeks.
Saliva samples were collected and analysed at baseline, during
the intervention and two weeks later. This showed that there
was a significant increase in the mean sIgA secretion rate after
four weeks, in comparison to baseline levels (Fig 1). Secretion
of both subtypes of IgA (types one and two) was also increased
at week four and remained elevated two weeks after cessation
of L. casei Shirota consumption (Fig 2). Consumption of certain
probiotic strains may be linked to a reduced duration and
severity of winter respiratory infections, therefore from this
study one mechanism involved may be a probiotic-associated
increase in IgA and IFN-γ secretion. 19
Figure 1
Mean Secretion Rate (mg/minute)
Mean Secretion Rate (µg/minute)
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Figure 2
20
15
10
5
0
sIgA
IgA1 & IgA2
P=0.02
Week 0 Week 1 Week 2 Week 4 Week 6
P=0.03
P=0.03
P=0.02
P=0.01
IgA1
IgA2
Week 0 Week 1 Week 2 Week 4 Week 6
ProbIoTIcs ANd AllergIc resPoNses
The composition of the gut flora of infants who later develop
allergy has been reported to differ from infants who do not
develop allergy. These differences are evident very early in life
before any clinical signs of atopy 20 (a disease characterised
by a tendency to be hyperallergic). There appears to be a
strong hereditary component to this: one study concluded
that the general risk of developing atopic dermatitis and
atopy increases by a factor of two with each first-degree
family member already atopic. 21 Disturbances of the gut flora
have also been documented in patients with asthma and
allergic rhinitis. 22 These studies indicate that the gut flora may
influence allergy. 23 Allergic responses are linked to T-helper
glossary
cytokines are proteins that act as chemical messengers in
the immune system.
IFN-γ is a cytokine made by T-cells. It has antiviral activity,
is able to activate macrophages and has many other
immune effects
IgA is the major antibody produced at mucosal lymphoid
surfaces; it can be sub-divided in to IgA1 and IgA2.
Interleukins (IL) are cytokines produced by leukocytes.
Il-12 is a cytokine produced by antigen-presenting cells
that induces differentiations of virgin T-cells into Th1 cells
and activates NK cells.
sIgA is the secretory form of IgA and is the main
immunoglobulin in mucus secretions.
Th1 secretes IL-4, IL-5, IL-10 and IL-13. Th1 cells are mainly
involved in activating macrophages and defending against
intracellular pathogens.
Th2 secretes IL-4, IL-5, IL-10 and IL-13. Th2 cells are mainly
involved in stimulating B cells to produce antibodies, but
also important in the allergic response
type 2 (Th2) lymphocytes that produce high levels of IL-4, IL-5
and IL-6 that promote IgE synthesis.24 Probiotics have the
potential to re-direct this response back to a healthy regulated
balance.
Hay fever is an allergic reaction to pollen or fungal spores,
most commonly grass pollen. The immune system mistakes the
spores for harmful invaders and produces excessive amounts
of the antibody IgE to bind to them and fight them off. IgE
stimulates the release of histamine to flush out the spores,
and this irritates the airways making them swell and produce
the symptoms of hay fever. A placebo-controlled probiotic
study was conducted during the hay fever season in 20 people
with a history of seasonal allergic rhino-conjunctivitis. All had
detectable levels of pollen-specific IgE antibodies in the blood
before the start of the pollen season. The volunteers drank
a daily drink with or without live probiotic bacteria (L. casei
Shirota) over five months. Blood samples were taken before
the grass pollen season, then again when it was at its peak
(June), and four weeks after the end of season. There were no
significant differences in levels of IgE in the blood between the
two groups at the start of the study, but IgE levels were lower in
the probiotic group both at the peak season and afterwards. At
the same time, levels of IgG were higher; this antibody plays a
protective role against allergic reactions. 25
ProbIoTIcs IN resPIrATory TrAcT ANd
gAsTroINTesTINAl TrAcT INFecTIoNs
Thirty million working hours are lost every winter in Ireland
due to sickness when the weather gets colder and the days
get shorter. Statistics released earlier this year show that nearly
60% of the Irish workforce will miss work days though winterrelated
health issues and that 85% of Irish people suffer from
the winter blues. 26
A study in Sweden which recruited 181 day and shift workers