Cyclosporin A reduces airway mucus secretion and mucociliary clearance in rats

Tacrolimus impairs airway mucociliary clearance of rats

OBJECTIVES

Tacrolimus (TAC) is the most widely used immunosuppressive agent after lung transplantation. Considering that the ciliary beat frequency (CBF) mainly depends on the cytoplasmic calcium concentration and that TAC can affect this due to its binding with the intracellular immunophilin FKBP12, we hypothesized that TAC could also impair the airway mucociliary clearance of rats.

METHODS

Sixty rats were divided into two groups (n = 30 each): Control = water; TAC = tacrolimus. After 7, 15 or 30 days of treatment, ten animals from each group were euthanized and the following parameters were studied: mucus transportability, CBF, mucociliary transport velocity (MCTV), and neutral and acid mucus production.

RESULTS

There was a significant decrease in CBF (Control vs TAC: 7 days, p = 0.008; 15 days, p = 0.007; 30 days, p = 0.001) and MCTV (Control vs TAC: 7 days, p = 0.004; 15 days, p < 0.001; 30 days, p < 0.001) in all immunosuppressed animals. TAC therapy also caused an increase in acid mucus production at all treatment times (Control vs TAC: 7 days, p = 0.001; 15 days, p = 0.043; 30 days, p = 0.001).

CONCLUSIONS

TAC impairs airway mucociliary clearance of rats.

Basiliximab Does Not Impair Airway Mucociliary Clearance of Rats

Previous studies have shown that immunosuppressive drugs impair the airway mucociliary clearance of rats. However, considering the high specificity of basiliximab (BSX) and the absence of studies reporting its side effects, our aim was to investigate whether BSX, associated or not with triple therapy, impairs the mucociliary system. Forty rats were divided into 4 groups: Control, BSX, Triple, and BSX + Triple. After 15 days of treatment, animals were euthanized and the ciliary beating frequency (CBF), mucociliary transport velocity (MCTV), neutral and acid mucin production, Muc5ac and Muc5b gene expression, inflammatory cell number, and interleukin (IL)-6 concentration were analyzed. CBF and MCTV were lower in Triple and BSX + Triple groups (p < 0.05). Neutral mucin percentage was higher in Triple group (p < 0.05), and acid mucin percentage was higher in Triple and BSX + Triple groups (p < 0.05). The Muc5ac and Muc5b gene expression was higher in Triple and BSX + Triple groups (p < 0.05). Animals from Triple and BSX + Triple groups presented fewer mononuclear cells (p < 0.05). The number of polymorphonuclear cells was higher in the Triple group (p < 0.05). In the analysis of inflammatory cells in the blood, there was a decrease in lymphocytes and an increase in neutrophils in the Triple and BSX + Triple groups (p < 0.05). The concentration of IL-6 significantly increased in the animals of the Triple and BSX + Triple groups (p < 0.05). BSX did not change the mucociliary apparatus of rats.

Adverse effects of immunosuppressant drugs upon airway epithelial cell and mucociliary clearance: implications for lung transplant recipients

Optimal post-transplantation immunosuppression is critical to the survival of the graft and the patient after lung transplantation. Immunosuppressant agents target various aspects of the immune system to maximize graft tolerance while minimizing medication toxicities and side effects. The vast majority of patients receive maintenance immunosuppressive therapy consisting of a triple-drug regimen including a calcineurin inhibitor, a cell cycle inhibitor and a corticosteroid. Although these immunosuppressant drugs are frequently used after transplantation and to control inflammatory processes, limited data are available with regard to their effects on cells other than those from the immunological system. Notably, the airway epithelial cell is of interest because it may contribute to development of bronchiolitis obliterans through production of pro-inflammatory cytokines. This review focuses the current armamentarium of immunosuppressant drugs used after lung transplantation and their main side effects upon airway epithelial cells and mucociliary clearance.

Immunosuppression effects on airway mucociliary clearance: comparison between two triple therapies

BACKGROUND

Tacrolimus and mycophenolate have now become the most widely used combination for maintenance immunosuppressive regimens after lung transplantation in comparison with cyclosporine and azathioprine. However, limited information is available with respect to their effects on cells, other than those from the immunologic compartment. We hypothesized that different triple therapies could have different effects on airway mucociliary clearance, playing an important role in respiratory infections observed after lung transplantation.

METHODS

Ninety rats were assigned to three groups (n = 30 each): control = vehicle, therapy 1 = tacrolimus + mycophenolate + prednisone, and therapy 2 = cyclosporine + azathioprine + prednisone. After 7, 15, or 30 days of treatment by gavage, the animals were killed and the following parameters were studied: mucus transportability, ciliary beating frequency, mucociliary transport velocity, and neutral and acid mucus production.

RESULTS

There was a significant decrease in ciliary beating frequency, mucociliary transport velocity, and neutral mucus production in all immunosuppressed animals; indeed, both therapies, mainly therapy 1, caused an increase in acid mucus production for as long as 15 days of treatment.

CONCLUSIONS

Both triple therapies impaired airway mucociliary clearance of rats, but therapy 1 had a more deleterious effect. These data suggest that these undesirable effects can contribute to the high incidence of respiratory infections observed in patients undergoing lung transplantation.

Effects of prednisone on mucociliary clearance in a murine model

All transplant patients are at increased risk of developing pulmonary infections, a significant cause of morbidity and mortality. Immunosuppressants increase the incidence of lung infection by acting not only directly on the inflammatory cells, but also on the native immune system. Experimental studies have shown corticosteroid therapy, which is used in most immunosuppressive protocols after transplantation, to suppress mucus production by inhibiting calceiform. The objective of this study was to evaluate the effects of prednisone on mucociliary clearance. A total of 120 male Wistar rats were distributed into 4 groups. Animals in P1, P2, and P3 groups received daily doses of prednisone (0.625, 1.25, and 2.5 mg/kg/d), and hosts in the Sal group underwent gavage with saline solution (2.5 mL/d). After 7, 15, and 30 days, treatment, animals were killed. We assessed ciliary beating frequency (CBF), mucociliary transport velocity (MCTV), and mucus transportability (MT). There was no significant difference for CBF regarding dose (P = .089) or treatment duration (P = .175). MCTV values of 0.60 ± 0.14 in group P1, 0.59 ± 0.13 in group P2, 0.51 ± 0.19 in group P3, and 0.61 ± 0.08 Group Sal, showed P3 to significantly differ from P1 (P = .048) and Sal (P = .007) groups. Regardless of the prednisone dose, all groups displayed impaired MT compared with the Sal group: P1 (P = .02); P2 (P = .02) P3 (P = .03). There was no interaction between the therapy and the treatment time for CBF (P = .10), MCTV (P = .71), and MT (P = .64). Prednisone reduced the transportability of mucus even when administered at low doses; however, this change was not sufficient to alter the mucociliary clearance. Only high doses of prednisone impaired mucociliary clearance.

A pilot study to examine the effect of chronic treatment with immunosuppressive drugs on mucociliary clearance in a vagotomized murine model

BACKGROUND

Previously, we have demonstrated that mucociliary clearance (MCC) is diminished within the first months after surgery in lung transplant patients and the explanation for the reduction in MCC is unknown. We hypothesized that chronic treatment with a commonly prescribed regimen of immunosuppressive drugs significantly impairs MCC. We tested this hypothesis in a murine model of lung transplantation.

METHODS

Fifteen C57BL/6 mice underwent vagotomy on the right side to simulate denervation associated with lung transplantation in humans. For 6 days, seven mice (controls) were intraperitoneally injected with three 100 µL doses of phosphate buffered saline and eight mice (immunosuppressed) were injected with three 100 µL injections of tacrolimus (1 mg/kg), mycophenolate mofetil (30 mg/kg), and prednisone (2 mg/kg) once daily. Then, mice inhaled the radioisotope (99m)technetium and underwent gamma camera imaging of their lungs for 6.5 hrs. Counts in the right lung at 1-1.5 hrs and at 6-6.5 hrs were first background-corrected and then decay-corrected to time 0 counts. Decay-corrected counts were then divided by time 0 counts. Retention at each time point was subtracted from 1.00 and multiplied by 100% to obtain percent removed by mucociliary clearance.

RESULTS

Although there was a slowing of MCC at 1-1.5 hrs for the immunosuppressed mice, there was no statistical difference in MCC measured at 1-1.5 hrs for the two groups of mice. At 6-6.5 hrs, MCC was significantly slower in the immunosuppressed mice, compared to controls, with 7.78±5.9% cleared versus 23.01±11.7% cleared, respectively (p = 0.006).

CONCLUSIONS

These preliminary results suggest that chronic treatment with immunosuppressive medications significantly slows MCC in vagotomized C57BL/6 mice. These findings could shed light on why MCC is reduced in lung transplant patients whose lungs are denervated during surgery and who are chronically treated with immunosuppressive drugs post surgery.

The effects on mucociliary clearance of prednisone associated with bronchial section

OBJECTIVE

Infections have been and remain the major cause of morbidity and mortality after lung transplantation. Because mucociliary clearance plays an important role in human defense mechanisms, the influence of drugs on the mucociliary epithelium of patients undergoing lung transplantation must be examined. Prednisone is the most important corticosteroid used after lung transplantation. The aim of this study was to evaluate the effects of bronchial transection and prednisone therapy on mucociliary clearance.

METHODS

A total of 120 rats were assigned to 4 groups according to surgical procedure or drug therapy: prednisone therapy (1.25 mg/kg/day); bronchial section and anastomosis + prednisone therapy (1.25 mg/kg/day); bronchial section + saline solution (2 ml/day); and saline solution (2 ml/day). After 7, 15, or 30 days, the animals were sacrificed, and the lungs were removed from the thoracic cavity. The in situ mucociliary transport velocity, ciliary beat frequency and in vitro mucus transportability were evaluated.

RESULTS

Animals undergoing bronchial section surgery and anastomosis had a significant decrease in the ciliary beat frequency and mucociliary transport velocity 7 and 15 days after surgery (p<0.001). These parameters were normalized 30 days after the surgical procedure. Prednisone improved mucous transportability in the animals undergoing bronchial section and anastomosis at 15 and 30 days (p<0.05).

CONCLUSION

Bronchial section and anastomosis decrease mucociliary clearance in the early postoperative period. Prednisone therapy improves mucus transportability in animals undergoing bronchial section and anastomosis.

Effects of mycophenolate sodium on mucociliary clearance using a bronchial section and anastomosis rodent model

OBJECTIVE

To study the effects of mycophenolate sodium on mucociliary clearance.

INTRODUCTION

Mycophenolate is one of the most commonly used immunosuppressive drugs in lung transplantation. Although its pharmacokinetic properties are well defined, its side effects on mucociliary clearance have not yet been studied.

METHODS

Sixty rats were subjected to left bronchial section and anastomosis. The right bronchus was used as a control. After surgery, the rats were assigned to two groups based on whether they received saline solution (n = 30) or mycophenolate sodium (n = 30). After 7, 15, or 30 days of treatment, 10 animals from each group were sacrificed, and in vitro mucus transportability, in situ mucociliary transport velocity and ciliary beat frequency were measured.

RESULTS

The analysis of mucus transportability revealed that neither mycophenolate nor bronchial section altered any transportability related property for up to 30 days of treatment after surgery (p>0.05). With regard to ciliary beat frequency, the operated left bronchi from the mycophenolate group showed a significant decrease on post-surgical day 30 (p = 0.003). In addition, we found a significant reduction in the in situ mucociliary transport velocity in the mycophenolate-treated group (p = 0.0001).

DISCUSSION

These data add important information regarding mucociliary clearance dysfunction following mycophenolate therapy and suggest that mycophenolate might contribute to the high incidence of respiratory tract infections in lung transplant patients. Further studies are needed to investigate the combined action of mycophenolate with other immunosuppressive drugs and to establish methods to protect and recover mucociliary clearance, an important airway defense mechanism.

Prevalence of gastroesophageal reflux in lung transplant candidates with advanced lung disease

OBJECTIVE

To assess the esophageal function profile and the prevalence of gastro-esophageal reflux (GER) in lung transplant candidates.

METHODS

From July of 2005 to November of 2006, a prospective study was conducted involving 55 candidates for lung transplantation at the Santa Casa de Misericórdia Hospital in Porto Alegre, Brazil. Prior to transplantation, patients underwent outpatient stationary esophageal manometry and 24-h esophageal pH-metry using one and two electrodes.

RESULTS

Abnormal esophageal manometry was documented in 80% of the patients, and 24% of the patients presented pathological acid reflux. Digestive symptoms presented sensitivity and specificity for GER of 50% and 61%, respectively. Of the patients with chronic obstructive pulmonary disease, 94% presented abnormal esophageal manometry, and 80% presented lower esophageal sphincter hypotonia, making it the most common finding. Patients with bronchiectasis presented the highest prevalence of GER (50%).

CONCLUSIONS

In patients with advanced lung disease, GER is highly prevalent. In the population studied, digestive symptoms of GER were not predictive of pathological acid reflux. The role that GER plays in chronic rejection should be examined and clarified in future studies.

Influence of cyclosporine A on mucociliary system after lung transplantation in rats

PURPOSE

To investigate the function of the bronchial mucociliary system in transplanted rat lungs with and without the influence of immunosuppression.

METHODS

Thirty-six rats underwent single-lung transplantation and were divided into two groups, one of which received cyclosporine treatment, and the control group which did not. Cyclosporine was administered subcutaneously in doses of 10 mg/kg daily. The rats were sacrificed 2, 15 or 30 days after transplantation. In situ bronchial mucociliary transport (MCT) and ciliary beat frequency (CBF) were determined proximal and distal to the bronchial anastomosis.

RESULTS

Significant progressive improvement on MCT, proximal and distal to the anastomotic site, was also found in the cyclosporine-treated group at 15 and 30 days (p<0.01). No significant change in MCT was found in the control group. CBF behavior in the two groups. Histological analysis showed that rejection was significantly higher in the control group (p<0.05).

CONCLUSION

Cyclosporine has a positive influence on bronchial mucociliary transport but not on CBF due to the effect of the rejection mechanism.

Effects of azathioprine on mucociliary clearance after bronchial section and anastomosis in a rat experimental model

OBJECTIVE

To evaluate the effects of azathioprine on the mucociliary system in a model of bronchial section and anastomosis in rats.

METHODS

Thirty-six male Wistar-Furth rats were submitted to left bronchial section and anastomosis and divided into two groups to receive either saline solution or azathioprine. After 7, 15 and 30 days of treatment, six animals from each group were killed, after which in situ mucociliary transport velocity, in vitro mucus transportability, and contact angle of mucus in the right (intact) and left (sectioned) bronchi were measured.

RESULTS

In situ mucociliary transport velocity was significantly lower in the sectioned bronchi than in the intact bronchi (p < 0.001). In situ mucociliary transport velocity was lower in the intact bronchi of the animals treated with azathioprine for 7 days (p < 0.05), and those bronchi presented full recovery after 30 days of treatment. The contact angle was higher in the mucus samples collected from the sectioned bronchi of the animals treated with saline solution for 30 days (p < 0.001), which is in accordance with the decreased in vitro mucus transportability observed in the same animals (p < 0.001).

CONCLUSIONS

We conclude that, in the sectioned bronchi of rats, treatment with azathioprine causes only transitory impairment of mucociliary transport, whereas administration of saline solution impairs mucociliary transport for up to 30 days. In addition, azathioprine protects against alterations in mucus surface properties.