The immunomodulatory role of carbon monoxide during transplantation

The number of organ and tissue transplants has increased worldwide in recent decades. However, graft rejection, infections due to the use of immunosuppressive drugs and a shortage of graft donors remain major concerns. Carbon monoxide (CO) had long been regarded solely as a poisonous gas. Ultimately, physiological studies unveiled the endogenous production of CO, particularly by the heme oxygenase (HO)-1 enzyme, recognizing CO as a beneficial gas when used at therapeutic doses. The protective properties of CO led researchers to develop uses for it, resulting in devices and molecules that can deliver CO in vitro and in vivo. The resulting interest in clinical investigations was immediate. Studies regarding the CO/HO-1 modulation of immune responses and their effects on various immune disorders gave rise to transplantation research, where CO was shown to be essential in the protection against organ rejection in animal models. This review provides a perspective of how CO modulates the immune system to improve transplantation and suggests its use as a therapy in the field.

Liver transplantation and expanded Milan criteria: does it really work?

CONTEXT: Orthotopic liver transplantation is an excellent treatment approach for hepatocellular carcinoma in well-selected candidates. Nowadays some institutions tend to Expand the Milan Criteria including tumor with more than 5 cm and also associate with multiple tumors none larger than 3 cm in order to benefit more patients with the orthotopic liver transplantation. METHODS: The data collected were based on the online database PubMED. The key words applied on the search were "expanded Milan criteria" limited to the period from 2000 to 2009. We excluded 19 papers due to: irrelevance of the subject, lack of information and incompatibility of the language (English only). We compiled patient survival and tumor recurrence free rate from 1 to 5-years in patients with hepatocellular carcinoma submitted to orthotopic liver transplantation according to expanded the Milan criteria from different centers. RESULTS: Review compiled data from 23 articles. Fourteen different criteria were found and they are also described in detail, however the University of California - San Francisco was the most studied one among them. CONCLUSION: Expanded the Milan criteria is a useful attempt for widening the preexistent protocol for patients with hepatocellular carcinoma in waiting-list for orthotopic liver transplantation. However there is no significant difference in patient survival rate and tumor recurrence free rate from those patients that followed the Milan criteria.

Thrombotic obstruction of the central venous catheter in patients undergoing hematopoietic stem cell transplantation

This is an integrative literature review with the aim of summarizing the prevention measures and treatment of thrombotic obstruction of long-term semi-implanted central venous catheters, in patients undergoing hematopoietic stem cell transplantation. The sample consisted of seven studies, being two randomized controlled clinical trials, three cohort studies and two case series. Regarding the prevention measures, one single study demonstrated effectiveness, which was a cohort study on the oral use of warfarin. In relation to the treatment measures, three studies evidenced effectiveness, one highlighted the efficacy of streptokinase or urokinase, one demonstrated the benefit of using low-molecular-weight heparin and the other treated the obstruction with heparin or urokinase. Catheter patency research shows a restricted evolution that does not follow the evolution of transplantations, mainly regarding nursing care.

A mathematical model for optimizing the indications of liver transplantation in patients with hepatocellular carcinoma

Abstract Background The criteria for organ sharing has developed a system that prioritizes liver transplantation (LT) for patients with hepatocellular carcinoma (HCC) who have the highest risk of wait-list mortality. In some countries this model allows patients only within the Milan Criteria (MC, defined by the presence of a single nodule up to 5 cm, up to three nodules none larger than 3 cm, with no evidence of extrahepatic spread or macrovascular invasion) to be evaluated for liver transplantation. This police implies that some patients with HCC slightly more advanced than those allowed by the current strict selection criteria will be excluded, even though LT for these patients might be associated with acceptable long-term outcomes. Methods We propose a mathematical approach to study the consequences of relaxing the MC for patients with HCC that do not comply with the current rules for inclusion in the transplantation candidate list. We consider overall 5-years survival rates compatible with the ones reported in the literature. We calculate the best strategy that would minimize the total mortality of the affected population, that is, the total number of people in both groups of HCC patients that die after 5 years of the implementation of the strategy, either by post-transplantation death or by death due to the basic HCC. We illustrate the above analysis with a simulation of a theoretical population of 1,500 HCC patients with tumor size exponentially. The parameter λ obtained from the literature was equal to 0.3. As the total number of patients in these real samples was 327 patients, this implied in an average size of 3.3 cm and a 95% confidence interval of [2.9; 3.7]. The total number of available livers to be grafted was assumed to be 500. Results With 1500 patients in the waiting list and 500 grafts available we simulated the total number of deaths in both transplanted and non-transplanted HCC patients after 5 years as a function of the tumor size of transplanted patients. The total number of deaths drops down monotonically with tumor size, reaching a minimum at size equals to 7 cm, increasing from thereafter. With tumor size equals to 10 cm the total mortality is equal to the 5 cm threshold of the Milan criteria. Conclusion We concluded that it is possible to include patients with tumor size up to 10 cm without increasing the total mortality of this population.

Liver transplantation for transthyretin amyloidosis: experience of a single center in Italy

Liver transplantation is the only definitive treatment for transthyretin amyloidosis, with an excellent 5-year survival in endemic countries where the Met30 mutation is predominant. We report our experience of liver transplantation for transthyretin amyloidosis. We reviewed the clinical records of 17 transplanted patients (11 males, 6 females; age at liver transplant: 45.7±11.7 years). We had a wide spectrum of non-Met30 mutations (52.9%), with a predominance of Gln89 (23.5%). Five-year survival after transplantation was 43.8%; at multivariate analysis, both non-Met30 mutations (HR 17.3, 95% CI 1.03-291.7) and modified BMI (HR 0.50, 95% CI 0.29-0.87) showed significant and independent prognostic roles (P=0.048 and P=0.015, respectively). Five out of the 9 non-Met30 carriers received combined heart transplantation because of severe cardiomyopathy; they showed a trend towards a better prognosis vs. the 4 patients who did not receive combined heart transplantation (although not statistically significant; P=0.095). At follow-up, no significant improvement of transthyretin amyloidosis manifestations was observed. The results of liver transplantation for transthyretin amyloidosis in our population are poorer than those reported in the literature probably because of the high prevalence of non-Met30 mutations.

Role of SP-A gene polymorphism in lung transplantation

Lung transplantation is a widely accepted therapeutic option for end stage lung disease. Clinical outcome is yet challenged by primary graft failure responsible for the majority of the early mortality, by chronic allograft dysfunction and chronic rejection accounting for more than 30% of deaths after the third postoperative year. Pulmonary surfactant proteins (SP) A, B, C and D are one of the first host defense mechanisms the lung can mount. SP-A in particular, produced by the type II pneumocytes, is active in the innate and adaptive immune system being an opsonin, but also regulating the macrophage and lymphocyte response. The main hypothesis for this project is that pulmonary surfactant protein A polymorphism may determine the early and long term lung allograft survival. Of note SP-A biologic activity seems to be genetically determined and SP-A polymorphisms have been associated to various lung disease. The two SP-A genes SP-A1 and SP-A2 have several polymorphisms within the coding region, SP-A1 (6A, 6A2-20), and SP-A2(1A, 1A0-13). The SP-A gene expression is regulated by cAMP, TTF-1 and glucocorticoids. In vitro studies have indicated that SP-A1 and SP-A2 gene variants may have a variable response to glucocorticoids. We proposed to determine if SP-A gene polymorphism predicts primary graft dysfunction and/or chronic lung allograft dysfunction and if SP-A may serve as a biomarker of lung allograft dysfunction. We also proposed to study the interaction between immunosuppressive drugs and SP-A expression and determine whether this is dependent on SP-A polymorphisms. This study will generate novel information improving our understanding of lung allograft dysfunction. It is conceivable that the information will stimulate the interest for a multi centre study to investigate if SP-A polymorphism may be integrated in the donor lung selection criteria and/or to implement post transplant tailored immunosuppression.

Interactions between the gut microbiota, short-chain fatty acids and the immune system in pediatric patients undergoing hematopoietic stem cell transplantation

The gut microbiota (GM) is essential for human health and contributes to several diseases; indeed it can be considered an extension of the self and, together with the genetic makeup, determines the physiology of an organism. In this thesis has been studied the peripheral immune system reconstitution in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (aHSCT) in the early phase; in parallel, have been also explored the gut microbiota variations as one of the of primary factors in governing the fate of the immunological recovery, predisposing or protecting from complications such as the onset of acute graft-versus-host disease (GvHD). Has been demonstrated, to our knowledge for the first time, that aHSCT in pediatric patients is associated to a profound modification of the GM ecosystem with a disruption of its mutualistic asset. aGvHD and non-aGvHD subjects showed differences in the process of GM recovery, in members abundance of the phylum Bacteroidetes, and in propionate fecal concentration; the latter are higher in the pre-HSCT composition of non-GvHD subjects than GvHD ones. Short-chain fatty acids (SCFAs), such as acetate, butyrate and propionate, are end-products of microbial fermentation of macronutrients and distribute systemically from the gut to blood. For this reason, has been studied their effect in vitro on human DCs, the key regulators of our immune system and the main player of aGvHD onset. Has been observed that propionate and, particularly, butyrate show a strong and direct immunomodulatory activity on DCs reducing inflammatory markers such as chemokines and interleukins. This study, with the needed caution, suggests that the pre-existing GM structure can be protective against aGvHD onset, exerting its protective role through SCFAs. They, indeed, may regulate cell traffic within secondary lymphoid tissues, influence T cell development during antigen recognition, and, thus, directly shape the immune system.

In vitro characterisation and expansion of human regulatory T cells for their in vivo application in the induction of tolerance in haematopoietic stem cell and solid organ transplantation

Solid organ transplantation (SOT) is considered the treatment of choice for many end-stage organ diseases. Thus far, short term results are excellent, with patient survival rates greater than 90% one year post-surgery, but there are several problems with the long term acceptance and use of immunosuppressive drugs. Hematopoietic Stem Cells Transplantation (HSCT) concerns the infusion of haematopoietic stem cells to re-establish acquired and congenital disorders of the hematopoietic system. The main side effect is the Graft versus Host Disease (GvHD) where donor T cells can cause pathology involving the damage of host tissues. Patients undergoing acute or chronic GvHD receive immunosuppressive regimen that is responsible for several side effects. The use of immunosuppressive drugs in the setting of SOT and GvHD has markedly reduced the incidence of acute rejection and the tissue damage in GvHD however, the numerous adverse side effects observed boost the development of alternative strategies to improve the long-term outcome. To this effect, the use of CD4+CD25+FOXP3+ regulatory T cells (Treg) as a cellular therapy is an attractive approach for autoimmunity disease, GvHD and limiting immune responses to allograft after transplantation. Treg have a pivotal role in maintaining peripheral immunological tolerance, by preventing autoimmunity and chronic inflammation. Results of my thesis provide the characterization and cell processing of Tregs from healthy controls and patients in waiting list for liver transplantation, followed by the development of an efficient expansion-protocol and the investigation of the impact of the main immunosuppressive drugs on viability, proliferative capacity and function of expanded cells after expansion. The conclusion is that ex vivo expansion is necessary to infuse a high Treg dose and although many other factors in vivo can contribute to the success of Treg therapy, the infusion of Tregs during the administration of the highest dose of immunosuppressants should be carefully considered.

Refractory Hematuria in an Oliguric Patient After Pancreas Transplantation with Exocrine Pancreas Bladder Drainage

A 52-yr-old man presented with hematuria and clot retention. He had undergone simultaneous pancreas-kidney transplantation with exocrine pancreas bladder drainage 16 yr ago. The patient suffered from progressive transplant kidney failure with gradually decreasing urine output and needed hemodialysis every other day. Gross hematuria persisted after removal of all blood clots. Cystoscopy showed multiple small, flat ulcers of the bladder mucosa. Some bled discretely and were coagulated cautiously. However, hematuria was refractory to multiple urological interventions, which eventually necessitated an enteric diversion of the exocrine pancreas. Hematuria ceased following an uneventful postoperative course.

Three-dimensional electroanatomic entrainment map in atypical atrial flutter late after heart transplantation

Atrial flutter in the donor part of orthotopic heart transplants has been reported and successfully treated by radiofrequency ablation of the cavotricuspid isthmus, but mapping and ablation of atypical flutter circuits may be challenging.(1) Entrainment mapping has been used in combination with activation mapping to define the mechanism of atypical atrial flutter. Here, we report a case where colour-coded three-dimensional (3D) entrainment mapping allowed us to accurately determine and visualize the 3D location of the reentrant circuit and to plan the ablation of a left atrial flutter without the need for activation mapping.