Discussion
The aim of the present meta-analysis was to investigate possible
differences between CD or UC patients and healthy controls in serum
resistin levels. The result confirmed that higher resistin levels in CD,
UC patients than in healthy individuals. In subgroup analyses stratified
by region, we observed that the serum resistin levels of CD and UC
patients in Europe were higher, indicating region may be associated with
serum resistin concentrations. Moreover, meta-regression for serum
resistin levels indicated that publication year may be an explanation
for the high heterogeneity across the
studies.
Adipokines appear to drive metabolic alterations, pro-inflammatory as
well as anti-inflammatory, and human resistin can stimulate the
pro-inflammatory cytokines by
NF-kappaB
(NF-k B) pathway25 . Resistin was
extensively studied in rheumatoid arthritis, ankylosing spondylitis,
systemic lupus erythematosus, psoriasis and osteoarthritis26-28 . It can
bind toll-like receptor 4 (TLR4) on human leukocytes and increase the
producing of pro-inflammatory cytokines, such as interleukin(IL)-6,
IL-12 and IL-1β, in turn, these cytokines also enhance resistin
expression 29 .
It also can stimulate tumor necrosis factor(TNF)-α secretion and
activate NF-k B25 . Furthermore,
resistin is associated with disease activity, drug use, blood glucose
level, glucose tolerance and insulin resistance30 ,31 . Taken together,
the
resistin has been comfirmed to play a crucially role in autoimmune
diseases, inflammatory as well as various metabolic.
The causes of the aberrant immune response in IBD patients is unclear,
CD might result from the interaction between enetic predisposition,
environmental factors, and altered gut microbiota, leading to
hyperactive gut-associated immune response32 . In contrast
with CD, the UC inflammation is limited to the colonic mucosa and
genetic, dietary, and environmental risk factors may also play an
pivotal role in the etiology33 . IBD patient
is typically characterized hypertrophy of the mesenteric adipose tissue
and alterations in local or serum adipokine concentrations34 . Our result
confirmed that higher resistin concentrations in CD, UC patients.
Although the etiology of IBD remains unkonwn, resistin may act as a new
serological biomarkers of IBD.
Subgroup analyses stratified by region showed elevated serum resistin
levels in CD and UC patients in the studies conducted in Europe,
indicating the presence of regional differences. However, heterogeneity
was high in the meta-analysis that compared serum resistin levels
between CD and UC patients and healthy controls. Meta-regression and
subgroup analysis were performed to detect the potential reasons of
heterogeneity. Studies have demonstrated positive relationships between
obesity and IBD risk35 . In
meta-regression analysis, year of publication, size of sample, age of
cases, BMI of cases were incorporated as covariates, the results
suggested that the source of heterogeneity may come from publication
year.
To our knowledge, the current study shows the first meta-analysis that
combines all published studies and presents the differences of resistin
concentrations in CD, UC patients. Several limitations deserve to be
considered in our study. Firstly, the heterogeneity among studies was
high. Secondly, studies evaluating resistin in CD and UC are limited and
insufficient data might account for the high heterogeneity among these
studies. Future studies examining the resistin concentrations in a
larger number of CD and UC patients are required.
In summary, the levels of resistin are significantly elevated in CD and
UC patients compared with healthy controls, suggesting
a
pivotal role of resistin in IBD pathogenesis.