Interventional studies on immunological balance in IBD and allergic asthma.

We have studied a role of immunological balance in connection to allergen challenge in asthma
patients and in connection to apheresis treatment in inflammatory bowel disease (IBD) patients.
It has been suggested that T-helper type 2 cells become recruited into the bronchial mucosa and
regulate allergic asthma reaction. Patients who mounted a late-phase reaction in connection to
allergen challenge were designated dual responders opposite to single responders. Our finding that
IL4+CD4+ cells decreased in the patient group and IFN-γ + CD4+ cells decreased in the single
responders after allergen challenge suggests the active traffic of both Th1 and Th2 cells into
bronchial mucosa. A diminished capacity to down-regulate the Th2 response by recruitment of
sufficient number of IFN-γ positive CD4+ lymphocytes was suggested as explanation to the late
phase symptoms in the dual responders.
A previously proposed mechanism of granulocyte- and monocyte adsorbing apheresis (GMA) is
that in removing activated granulocytes and monocytes the production of pro-inflammatory
cytokines, predominantly TNF-α will be reduced. Following GMA in patients with chronic, active
IBD, IFN-γ-positive lymphocytes decreased in post-treatment biopsies in responders and appeared
to predict the maintenance of long-term remission or response after 12 months.
The finding of down regulation of IFN-γ+CD4+ cells in post-treatment blood samples and
IFN-γ+ cells in post-treatment biopsies indicates that the mechanisms of GMA are complex and may
influence the Th-balance.
Given that FoxP3+ T regulatory cells and Toll Like Receptor (TLR) expression are key actors in
mucosal immunoregulation we extended the previous study to identify the dynamics of these actors
in the intestinal mucosa in relation to clinical improvement following GMA. The number of FoxP3+
cells and TLR-2 expression significantly decreased in post-treatment biopsies. The down regulation
of FoxP3+ cells and TLR-2 expression mirrored clinical improvement in patients with active IBD
after GMA. The results suggest a potential role of these cells in the pathogenesis of IBD and the
induction of immunological tolerance in the mucosa.
The effect of apheresis system lines on soluble regulatory molecules (which are important for the
immunological balance) has not been studied before, but was assessed on selected regulatory
molecules during a safety study on a modified Cellsorba (device for leukacytapheresis (LCAP)). An
important observation was that LL-37 increased at all apheresis sessions within the apheresis plastic
lines. LL-37 is a major constituent of neutrophil granules. The peptide mediates a wide range of
immunomodulatory actions (microbicidal and chemokine for granulocytes, monocytes, mastcells
and T lymphocytes, it suppresses TLR-induced secretion of proinflammatory cytokines) and may
therefore have a positive impact on the immunological tolerance and which may contribute to LCAP
efficacy on UC.
In summary: We have suggested that differences in response to allergen can depend on different
capacity to maintain and restore the immunological balance in bronchial mucosa, the Th-balance.
Diminished capacity to recruit IFN-γ+ CD4+ lymphocytes is associated with development of an
additional so called late-phase reaction. We have demonstrated that one plausible mechanism of
GMA are immunomodulating involving down regulation of IFN-γ+ lymphocytes hereby influencing
the Th-balance. The clinical improvement in IBD after GMA was associated with improved
immunological tolerance mirrored by down regulation of FoxP3+ cells and TLR-2 expression. And
finally, we have described generation of LL-37 in the plastic lines of apheresis system, which may
also have a positive effect on the immunologic tolerance.
The results emphasize that the restoration of the immunological tolerance can be a key to future
successful therapeutic strategy