Severe diarrhoea during Campath-1H treatment for refractory cutaneous T-cell lymphoma

The intestinal barrier in multiple sclerosis: implications for pathophysiology and therapeutics

Biological barriers are essential for the maintenance of homeostasis in health and disease. Breakdown of the intestinal barrier is an essential aspect of the pathophysiology of gastrointestinal inflammatory diseases, such as inflammatory bowel disease. A wealth of recent studies has shown that the intestinal microbiome, part of the brain-gut axis, could play a role in the pathophysiology of multiple sclerosis. However, an essential component of this axis, the intestinal barrier, has received much less attention. In this review, we describe the intestinal barrier as the physical and functional zone of interaction between the luminal microbiome and the host. Besides its essential role in the regulation of homeostatic processes, the intestinal barrier contains the gut mucosal immune system, a guardian of the integrity of the intestinal tract and the whole organism. Gastrointestinal disorders with intestinal barrier breakdown show evidence of CNS demyelination, and content of the intestinal microbiome entering into the circulation can impact the functions of CNS microglia. We highlight currently available studies suggesting that there is intestinal barrier dysfunction in multiple sclerosis. Finally, we address the mechanisms by which commonly used disease-modifying drugs in multiple sclerosis could alter the intestinal barrier and the microbiome, and we discuss the potential of barrier-stabilizing strategies, including probiotics and stabilization of tight junctions, as novel therapeutic avenues in multiple sclerosis.

Effect of alemtuzumab on intestinal intraepithelial lymphocytes and intestinal barrier function in cynomolgus model

Background:

Alemtuzumab has been used in organ transplantation and a variety of hematologic malignancies (especially for the treatment of B-cell chronic lymphocytic leukemia). However, serious infectious complications frequently occur after treatment. The reason for increased infections postalemtuzumab treatment is unknown at this stage. We explore the effect of alemtuzumab on intestinal intraepithelial lymphocytes (IELs) and intestinal barrier function in cynomolgus model to explain the reason of infection following alemtuzumab treatment.

Methods:

Twelve male cynomolguses were randomly assigned to either a treatment or control group. The treatment group received alemtuzumab (3 mg/kg, intravenous injection) while the control group received the same volume of physiological saline. Intestinal IELs were isolated from the control group and the treatment group (on day 9, 35, and 70 after treatment) for counting and flow cytometric analysis. Moreover, intestinal permeability was monitored by enzymatic spectrophotometric technique and enzyme-linked immunosorbent assay.

Results:

The numbers of IELs were decreased significantly on day 9 after treatment compared with the control group (0.35 ± 0.07 × 10⁸ and 1.35 ± 0.09 × 10⁸, respectively; P < 0.05) and were not fully restored until day 70 after treatment. There were significant differences among four groups considering IELs subtypes. In addition, the proportion of apoptotic IELs after alemtuzumab treatment was significantly higher than in the control group (22.01 ± 3.67 and 6.01 ± 1.42, respectively; P < 0.05). Moreover, the concentration of D-lactate and endotoxin was also increased significantly on day 9 after treatment.

Conclusions:

Alemtuzumab treatment depletes lymphocytes in the peripheral blood and intestine of cynomolgus model. The induction of apoptosis is an important mechanism of lymphocyte depletion after alemtuzumab treatment. Notably, intestinal barrier function may be disrupted after alemtuzumab treatment.

A CD52 antibody impairs mouse-transplanted intestinal tight junctions

BACKGROUND

Induction immunosuppression strategies using a CD52 monoclonal antibody (mAb) have been introduced for small bowel transplantation, resulting in improved outcomes. However, little information is known about the effects of the antibody on the microstructure of the intestinal barrier, which functions to prevent bacterial translocation. In this study, we used a murine orthotopic small bowel transplantation model to investigate the impact of a CD52 mAb on tight junctions (TJs), which are considered a central part of the intestinal barrier, of the transplanted intestine.

MATERIALS AND METHODS

C57BL/6 mice were used as recipients. The grafts were harvested from BALB/c mice in allogeneic groups and C57BL/6 mice in syngeneic groups. The anti-mouse CD52 mAb was applied as a surrogate antibody. Transmission electron microscopy was used to evaluate the TJ ultrastructure. The expression of the TJ proteins occludin and ZO-1 was analyzed by Western blot. The distribution of TJ proteins was observed by immunofluorescence, and the permeability of the transplanted intestine was assessed in vivo using FITC-dextran.

RESULTS

After CD52 mAb application, a compromised TJ ultrastructure was observed. In addition, TJ protein expression (occludin and ZO-1) decreased and the intestinal permeability increased.

CONCLUSIONS

The anti-mouse CD52 mAb impaired the transplanted intestinal TJ and barrier.

Effect of anti-mouse CD52 monoclonal antibody on mouse intestinal intraepithelial lymphocytes

BACKGROUND

CD52 monoclonal antibody (mAb) has been used therapeutically in lymphocytic leukemia, autoimmune disease, and organ transplantation. But the effect of CD52 mAb on intestinal intraepithelial lymphocytes (IELs) was unknown. The aim of this study was to assess the influence of anti-mouse CD52 mAb on IELs.

METHODS

Twenty male C57BL/6 mice were randomly assigned to a treatment or a control group. The treatment group received anti-mouse CD52 mAb (20 mug, subcutaneously), whereas the control group received the same volume of phosphate-buffered solution. On the seventh day after treatment, mice were killed, and ileum and colon were obtained for histopathology and immunohistochemistry examination, IELs were isolated for flow cytometric analysis and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis. Furthermore, the intestinal permeability was measured by lactulose-mannitol test.

RESULTS

The number and viability of IELs were decreased significantly in treatment compared with the control group. There were significant differences between the two groups considering IELs phenotypes. In addition, the proportion of apoptotic IELs in CD52 mAb treatment group was significantly higher than the control group (19.59%+/-3.13% and 2.02%+/-0.33%, respectively; P<0.05). Furthermore, lactulose-mannitol test showed a marked increase intestinal permeability after CD52 treatment (90.38%+/-5.96% and 46.02%+/-6.40%, respectively; P<0.05).

CONCLUSION

Anti-mouse CD52 mAb could induce more IELs to apoptosis and result in reducing the number of IELs, which may disrupt intestinal barrier function.