Dr Paris Tavakoli, Longitudinal course of IBDs on 12 months of follow up, JGENCA July 2017

due to intestinal damage resulting from the exaggerated
inflammatory response. Complications from these immunemediated
diseases include anaemia, malnutrition, bowel
obstruction, fistula, infection and an increased risk of colon
cancer. Extraintestinal manifestations may also develop,
such as joint problems (arthralgia, arthritis, and ankylosing
spondylitis), rashes and skin conditions (erythema nodosum),
chronic liver disease (primary sclerosing cholangitis) and
eye conditions (such as uveitis).
There is an accumulating body of research exploring
potential factors thought to contribute to the aetiology and
pathophysiology of IBD. These include genetics, microbiome,
dietary, environmental and psychosocial factors.
The genetics of IBD highlight considerable heterogeneity
between, and within, UC and CD, with some genes
common to both and some separate. More than 200 gene
polymorphisms have been identified that are associated with
IBD (Liu et al., 2015). Many of these genes increase the risk
of the development of disease by only a very small amount.
One-third of loci described confer susceptibility to both CD
and UC (Lees et al., 2011). In twin studies of CD and UC, a
strong familial aggregation has been observed (Brant, 2011).
Recent population-based sibling risk is 26-fold greater for
CD and 9-fold greater for UC (Bengtson, 2009). Many risk
alleles are associated with host responses to bacteria,
innate and adaptive immunity, autophagy, phagocytosis and
mucosal barrier function (Xavier & Podolsky, 2007).
It is well documented that any chronic disease is associated
with a greater burden of psychological stress, depression
and anxiety (Knowles & Mikocka-Walus, 2015). IBD follows
the same model of neuropsychiatric co-morbidities, which
are more prevalent with active disease when the disease
is difficult to control (Mikocka-Walus et al., 2007). It could
be projected that illness leads to psychological problems
through a unidirectional effect on patients’ wellbeing and
quality of life. A bidirectional interplay, however, between
disease factors including inflammatory activities in the
body (systemically) and/or in the gut (locally), and the
brain is more likely. Psychological state can influence
patients’ behaviour and their perception of disease. The
role of stress — conceptualised both as an environmental/
psychosocial challenge, as well as an internal stressor such
as an evolving illness, has been substantially investigated
in the course of IBD. It has been shown that stress can
aggravate physiological, psychological and environmental
vulnerabilities, leading to emotional distress and potentially
the onset of mental and physical disorders (Knowles &
Mikocka-Walus, 2015).
In the middle of the nineteenth century, the discovery of
the “enteric nervous system — ENS” was considered a
scientific breakthrough in understanding the interaction
between the nervous system and the digestive system
(Furness, 2006). Even before that, though, and for centuries,
psychologists and physiologists had recognised the
significance of interactions between the brain and the body,
here the digestive system. Early investigators have reported
top-down (brain to gastrointestinal function) modulation,
as well as bottom-up signalling via visceral afferents to the
brain and the gastrointestinal regulatory control by emotion/
stress. The sympathetic innervations in the gastrointestinal
tract modulate GI function and its immune regulation by
their close proximity to immune cells such as dendritic cells,
B-lymphocytes and mast cells (Lyte, Vulchanova & Brown,
2011). The parasympathetic innervations of the GI tract
(vagal and sacral parasympathetic divisions) are thought
to have an anti-inflammatory modulatory role (Knowles
& Mikocka-Walus, 2015). Extensive modification in the
autonomic nervous system and its dysfunction (perhaps
related to stress, anxiety and depression), alters autonomic
output to the gut and is likely to affect brain-gut signalling,
gut function and its immune regulation (Knowles & Mikocka-
Walus, 2015).
There is no cure for IBD, so the aim of treatment is to control
the symptoms, to maintain mucosal integrity and promote
healing. A recent breakthrough in controlling the disease has
been achieved using biologic therapies that target specific
components of the immune system, for example, by using
anti-tumour necrosis factor (anti-TNF) to suppress the
exaggerated immune response. The aim is to keep patients
in remission and asymptomatic, with a primary aim of
reducing inflammation during relapse and a secondary aim
of prolonging the time spent in remission (Shanahan, 2000).
Intestinal microbiome
Immediately after birth, environmentally exposed surfaces
such as skin, respiratory tract, mouth, vagina and gut are
introduced to and colonised by foreign microorganisms
(Ley, Peterson & Gordon, 2006). A large and dynamic
community of different bacteria is considered a natural
inhabitant of the human gut with well-documented effects
on human physiology and pathology arising from the
interaction between resident bacteria and the mucosal
immune system. However, the nature of this mutualisation
is not very well understood. The human intestine’s immune
system coexists and interacts with more than 400 different
species of bacteria (mostly in the large intestine), almost 10 14
bacteria/g faeces or 10 times more than the number of body
cells (Turnbaugh et al., 2007). This microbiota portfolio can
be affected by factors such as genetics, birth route, diet,
hygiene, psychological distress, infections and medications,
including antibiotics. The gut microflora are important in
inducing tolerance towards this natural habitat and they
are thought to out-compete pathogens. Important roles of
intestinal microorganisms in the colon’s physiology include
their influence on epithelial cell differentiation (Guarner &
Melagelada, 2003).
Gut-bacteria metabolism accounts for the conversion of
many substances into metabolites. These metabolites can
be absorbed and used by the host for processes such
as vitamin synthesis (Guarner & Melagelada, 2003), and
absorption of calcium, magnesium and iron (Miyazawa,
Iwabuchi & Yoshida, 1996). In the large intestine, anaerobic
bacteria ferment undigested carbohydrates to short-chain
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