Preventive and therapeutic effects of tacrolimus in an interleukin-10-deficient mouse model of colitis

The Effect of Tacrolimus and Mycophenolic Acid on CD14+ Monocyte Activation and Function

Monocytes and macrophages play key roles in many disease states, including cellular and humoral rejection after solid organ transplantation (SOT). To suppress alloimmunity after SOT, immunosuppressive drug therapy is necessary. However, little is known about the effects of the immunosuppressive drugs tacrolimus and mycophenolic acid (MPA) on monocyte activation and function. Here, the effect of these immunosuppressants on monocytes was investigated by measuring phosphorylation of three intracellular signaling proteins which all have a major role in monocyte function: p38MAPK, ERK and Akt. In addition, biological functions downstream of these signaling pathways were studied, including cytokine production, phagocytosis and differentiation into macrophages. To this end, blood samples from healthy volunteers were spiked with diverse concentrations of tacrolimus and MPA. Tacrolimus (200 ng/ml) inhibited phosphorylation of p38MAPK by 30% (mean) in CD14+ monocytes which was significantly less than in activated CD3+ T cells (max 60%; p < 0.05). This immunosuppressive agent also partly inhibited p-AKT (14%). MPA, at a therapeutic concentration showed the strongest effect on p-AKT (27% inhibition). p-ERK was inhibited with a maximum of 15% after spiking with either tacrolimus or MPA. The production of IL-1β and phagocytosis by monocytes were not affected by tacrolimus concentrations, whereas MPA did inhibit IL-1β production by 50%. Monocyte/macrophage polarization was shifted to an M2-like phenotype in the presence of tacrolimus, while MPA increased the expression of M2 surface markers, including CD163 and CD200R, on M1 macrophages. These results show that tacrolimus and MPA do not strongly affect monocyte function, apart from a change in macrophage polarization, to a clinically relevant degree.

Tacrolimus induction followed by maintenance monotherapy is useful in selected patients with moderate-to-severe ulcerative colitis refractory to prior treatment

BACKGROUND

Tacrolimus in refractory ulcerative colitis often serves as a bridge to long-term maintenance therapy with thiopurines. Our aim was to review efficacy and safety of tacrolimus in active ulcerative colitis resistant to conventional therapies, including anti-tumour necrosis factor.

METHODS

Charts of consecutive outpatients with refractory ulcerative colitis, in whom tacrolimus was orally administered as a 12 week-induction (target trough levels 10-15ng/mL) followed by a maintenance therapy (target trough levels 5-10ng/mL), were retrospectively reviewed. Clinical remission and response at weeks 4, 12 and 52 as well as adverse events within 1-year therapy were reported.

RESULTS

Twelve (40%) and six (20%) of the 30 patients included (14 males, mean age 37.1±1.4 years) achieved a clinical remission and response, respectively, at week 12. Three responders to tacrolimus initiation experienced drug-related adverse events requiring discontinuation. Among the 18 remaining initial responders who tolerated tacrolimus, 8 (27%) were in clinical remission at week 52, whereas the remainder either experienced adverse events requiring drug withdrawal (n=4) or relapsed (n=6). Overall adverse events were recorded in 14 patients (46%), mainly finger tremor and urinary infections.

CONCLUSION

Oral monotherapy with tacrolimus may be a valuable long-term therapeutic option in selected patients with moderate-to-severe active refractory ulcerative colitis.

Angiotensin converting enzyme-inhibitor reduces colitis severity in an IL-10 knockout model

BACKGROUND

We previously demonstrated angiotensin converting enzymes (ACE) over-expression in a dextran-sodium sulfate colitis model; ACE inhibitor (ACE-I) treatment reduced colitis severity in this model. However, ACE-I has not been tested in more immunologically relevant colitis models.

AIM

We hypothesized that ACE-I would decrease disease severity in an IL-10 knockout (-/-) colitis model.

METHODS

Colitis was induced by giving 10-week old IL-10-/- mice piroxicam (P.O.) for 14 days. The ACE-I enalaprilat was given transanally at a dose of 6.25 mg/kg for 21 days. Prednisolone (PSL) with or without enalaprilat were used as therapeutic, comparative groups. All groups were compared to a placebo treated group. Outcome measures were clinical course, histology, abundance of pro-inflammatory cytokines/chemokines, and epithelial barrier function.

RESULTS

Enalaprilat exhibited better survival (91 %) versus other treatment groups (PSL: 85.7 %, PSL + ACE-I: 71.4 %, placebo: 66.6 %). The ACE-I and PSL + ACE-I groups showed significantly better histological scores versus placebo mice. ACE-I and the PSL groups significantly reduced several pro-inflammatory cytokines versus placebo mice. FITC-dextran permeability was reduced in the ACE-I and PSL + ACE-I groups. Blood pressure was not affected in ACE-I treated mice compared to placebo mice.

CONCLUSIONS

ACE-I was effective in reducing severity of colitis in an IL-10-/- model. The addition of prednisolone minimally augmented this effect. The findings suggest that appropriately dosed ACE-I with or without steroids may be a new therapeutic agent for colitis.