Immunobiology of transplantation: impact on targets for large and small molecules

Oral health status after hematopoietic stem cell transplantations: Outcomes from an adult Italian population

AIM

To describe oral cavity changes in patients who underwent a hematopoietic stem cell transplantation (HSCT).

METHODS AND RESULTS

A group of 32 patients was studied after a mean period of 48.8 months (±11.22) from HSCT; oral, dental, and periodontal status were collected and compared with those of healthy matched controls. Unstimulated whole salivary flow (UWS) and salivary pH were also measured. A validated questionnaire (EORTC QLQH&N-35) was used for reported quality of life. Fifty-nine percent of patients were affected by chronic graft-versus-host disease (cGVHD). Dental health and periodontal status were statistically worse than in controls (P = .003 and P = .008, respectively). Regarding the HSCT group, UWS was statistically lower, and EORTC QLQH&N-35 significantly higher than those reported in controls (P = .000 for both). There was no statistical correlation between hypo-salivation and conditioning, presence of cGVHD, type of medication used before and after transplantation, and time of follow-up. A reduction in salivary pH has been noted only for patients with erosive oral lesions.

CONCLUSION

The oral cavity of HSCT patients appeared to undergo substantial modifications and the quality of life was deeply compromised.

Uterine Tissue Engineering: Where We Stand and the Challenges Ahead

Tissue engineering is an innovative approach to develop allogeneic tissues and organs. The uterus is a very sensitive and complex organ, which requires refined techniques to properly regenerate and even, to rebuild itself. Many therapies were developed in 20th century to solve reproductive issues related to uterus failure and, more recently, tissue engineering techniques provided a significant evolution in this issue. Herein we aim to provide a broad overview and highlights of the general concepts involved in bioengineering to reconstruct the uterus and its tissues, focusing on strategies for tissue repair, production of uterine scaffolds, biomaterials and reproductive animal models, highlighting the most recent and effective tissue engineering protocols in literature and their application in regenerative medicine. In addition, we provide a discussion about what was achieved in uterine tissue engineering, the main limitations, the challenges to overcome and future perspectives in this research field.

Regenerative Medicine Approaches in Bioengineering Female Reproductive Tissues

Diseases, disorders, and dysfunctions of the female reproductive tract tissues can result in either infertility and/or hormonal imbalance. Current treatment options are limited and often do not result in tissue function restoration, requiring alternative therapeutic approaches. Regenerative medicine offers potential new therapies through the bioengineering of female reproductive tissues. This review focuses on some of the current technologies that could address the restoration of functional female reproductive tissues, including the use of stem cells, biomaterial scaffolds, bio-printing, and bio-fabrication of tissues or organoids. The use of these approaches could also be used to address issues in infertility. Strategies such as cell-based hormone replacement therapy could provide a more natural means of restoring normal ovarian physiology. Engineering of reproductive tissues and organs could serve as a powerful tool for correcting developmental anomalies. Organ-on-a-chip technologies could be used to perform drug screening for personalized medicine approaches and scientific investigations of the complex physiological interactions between the female reproductive tissues and other organ systems. While some of these technologies have already been developed, others have not been translated for clinical application. The continuous evolution of biomaterials and techniques, advances in bioprinting, along with emerging ideas for new approaches, shows a promising future for treating female reproductive tract-related disorders and dysfunctions.

Reconstruction of functional uterine tissues through recellularizing the decellularized rat uterine scaffolds by MSCs in vivo and in vitro

Infertile people who suffered from loss of uterine structures and/or functions can be treated through gestational surrogacy or uterus transplantation, which remains challenging due to the ethical and social issues, the lack of donor organs as well as technical and safety risks. One promising solution is to regenerate and reconstruct a bioartificial uterus for transplantation through the engineering of uterine architecture and appropriate cellular constituents. Here, we developed a well-defined system to regenerate a functional rat uterine through recellularization of the decellularized uterine matrix (DUM) patches reseeded with human mesenchymal stem cells (hMSCs). Engraftment of the recellularized DUMs on the partially excised uteri yielded a functional rat uterus with a pregnancy rate and number of fetuses per uterine horn comparable to that of the control group with an intact uterus. Particularly, the recellularized DUMs enhanced the regeneration of traumatic uterine in vivo because of MSC regulation. The established system here will shed light on the treatment of uterine infertility with heterogeneous DUMs/cell resources through tissue engineering in the future.

Is dental caries associated with liver transplantation? A systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis was to evaluate the experience of dental caries in individuals pre- or postliver transplant.

MATERIALS AND METHODS

Searches in PubMed, Scopus, Web of Science, Ovid, and Lilacs from databases' inception date up to April 2020 were undertaken. Gray literature and manual searches were also conducted. Observational studies were eligible. The retrieved references were evaluated by two independent reviewers. Meta-analysis and risk of bias assessment using the University of Adelaide tool were conducted. The strength of the evidence was assessed with GRADE.

RESULTS

The search retrieved 1990 references. Twenty-four cross-sectional studies were included. One subgroup analysis demonstrated no significant difference in the number of teeth with dental caries between pre-liver transplant and healthy individuals (mean difference = 1.65, confidence interval = -0.87 to 4.17). The prevalence of dental caries among pre-liver transplant individuals was 73.82% and in the post-transplant individuals was 72.83%. In the included studies, the main concern regarding risk of bias was the absence of control for confounding variables. The strength of the evidence was very low.

CONCLUSIONS

Dental caries may be a relevant issue in pre- and postliver transplant individuals. Oral health counseling should be included in the care of pre- and/or postliver transplant individuals.

Targeted and global pharmacometabolomics in everolimus-based immunosuppression: association of co-medication and lysophosphatidylcholines with dose requirement

INTRODUCTION

The immunosuppressive therapy with everolimus (ERL) after heart transplantation is characterized by a narrow therapeutic window and a substantial variability in dose requirement. Factors explaining this variability are largely unknown.

OBJECTIVES

Our aim was to evaluate factors affecting ERL metabolism and to identify novel metabolites associated with the individual ERL dose requirement to elucidate mechanisms underlying ERL dose response variability.

METHOD

We used liquid chromatography coupled with mass spectrometry for quantification of ERL metabolites in 41 heart transplant patients and evaluated the effect of clinical and genetic factors on ERL pharmacokinetics. Non-targeted plasma metabolic profiling by ultra-performance liquid chromatography and high resolution quadrupole-time-of-flight mass spectrometry was used to identify novel metabolites associated with ERL dose requirement.

RESULTS

The determination of ERL metabolites revealed differences in metabolite patterns that were independent from clinical or genetic factors. Whereas higher ERL dose requirement was associated with co-administration of sodium-mycophenolic acid and the CYP3A5 expressor genotype, lower dose was required for patients receiving vitamin K antagonists. Global metabolic profiling revealed several novel metabolites associated with ERL dose requirement. One of them was identified as lysophosphatidylcholine (lysoPC) (16:0/0:0). Subsequent targeted analysis revealed that high levels of several lysoPCs were significantly associated with higher ERL dose requirement.

CONCLUSION

For the first time, this study describes distinct ERL metabolite patterns in heart transplant patients and detected potentially new drug-drug interactions. The global metabolic profiling facilitated the discovery of novel metabolites associated with ERL dose requirement that might represent new clinically valuable biomarkers to guide ERL therapy.

Uterus transplantation and beyond

Uterus transplantation is today the only available treatment for absolute uterine factor infertility which is caused by either congenital/surgical uterine absence or that a present uterus is non-functioning. Structured animal-based research, from rodents to nonhuman primates, was the scientific basis for a successful introduction of uterus transplantation as a clinical procedure. The patient groups for uterus transplantation, the preclinical research and data from the published human cases will be covered herein. During recent years the concept of bioengineering of organs and tissues has emerged. Creation of a bioengineered uterus is in the initial research state, with experiments performed in rodents. The research that has been performed to create a bioengineered uterus will be summarized. In conclusion, uterus transplantation is now a clinical experimental procedure for treatment of uterine factor infertility. In parallel to the establishment of this combined assisted reproduction technique and transplantation procedure as a routine clinical procedure, we predict that uterus bioengineering will develop further towards introduction within the human setting, but that this process will take several years.

Bioengineering the Uterus: An Overview of Recent Advances and Future Perspectives in Reproductive Medicine

Since the initial in vitro attempts to more complex models, research on uterine regeneration is moving towards the creation of a functional bioengineered uterus with possible clinical applications. We describe here the most relevant advances in bioengineering of the uterus published in the last decades considering the use of stem cells and biomaterials as well as future developing techniques in Regenerative Medicine.

Uterine Tissue Engineering and the Future of Uterus Transplantation

The recent successful births following live donor uterus transplantation are proof-of-concept that absolute uterine factor infertility is a treatable condition which affects several hundred thousand infertile women world-wide due to a dysfunctional uterus. This strategy also provides an alternative to gestational surrogate motherhood which is not practiced in most countries due to ethical, religious or legal reasons. The live donor surgery involved in uterus transplantation takes more than 10 h and is then followed by years of immunosuppressive medication to prevent uterine rejection. Immunosuppression is associated with significant adverse side effects, including nephrotoxicity, increased risk of serious infections, and diabetes. Thus, the development of alternative approaches to treat absolute uterine factor infertility would be desirable. This review discusses tissue engineering principles in general, but also details strategies on how to create a bioengineered uterus that could be used for transplantation, without risky donor surgery and any need for immunosuppression. We discuss scaffolds derived from decellularized organs/tissues which may be recellularized using various types of autologous somatic/stem cells, in particular for uterine tissue engineering. It further highlights the hurdles that lay ahead in developing an alternative to an allogeneic source for uterus transplantation.

Towards the development of a bioengineered uterus: comparison of different protocols for rat uterus decellularization

Uterus transplantation (UTx) may be the only possible curative treatment for absolute uterine factor infertility, which affects 1 in every 500 females of fertile age. We recently presented the 6-month results from the first clinical UTx trial, describing nine live-donor procedures. This routine involves complicated surgery and requires potentially harmful immune suppression to prevent rejection. However, tissue engineering applications using biomaterials and stem cells may replace the need for a live donor, and could prevent the required immunosuppressive treatment. To investigate the basic aspects of this, we developed a novel whole-uterus scaffold design for uterus tissue engineering experiments in the rat. Decellularization was achieved by perfusion of detergents and ionic solutions. The remaining matrix and its biochemical and mechanical properties were quantitatively compared from using three different protocols. The constructs were further compared with native uterus tissue composition. Perfusion with Triton X-100/dimethyl sulfoxide/H2O led to a compact, weaker scaffold that showed evidence of a compromised matrix organization. Sodium deoxycholate/dH2O perfusion gave rise to a porous scaffold that structurally and mechanically resembled native uterus better. An innovative combination of two proteomic analyses revealed higher fibronectin and versican content in these porous scaffolds, which may explain the improved scaffold organization. Together with other important protocol-dependent differences, our results can contribute to the development of improved decellularization protocols for assorted organs. Furthermore, our study shows the first available data on decellularized whole uterus, and creates new opportunities for numerous in vitro and in vivo whole-uterus tissue engineering applications.

A high-throughput phenotypic screen of cytotoxic T lymphocyte lytic granule exocytosis reveals candidate immunosuppressants

We screened the National Institutes of Health's Molecular Libraries Small Molecule Repository for inhibitors of cytotoxic T lymphocyte (CTL) lytic granule exocytosis by measuring binding of an antibody in the extracellular solution to a lysosomal membrane protein (LAMP-1) that is transferred to the plasma membrane by exocytosis. We used TALL-104 human leukemic CTLs stimulated with soluble chemicals. Using high-throughput cluster cytometry to screen 364,202 compounds in a 1536-well plate format, we identified 2404 initial hits: 161 were confirmed on retesting, and dose-response measurements were performed. Seventy-five of those compounds were obtained, and 48 were confirmed active. Experiments were conducted to determine the molecular mechanism of action (MMOA) of the active compounds. Fifteen blocked increases in intracellular calcium >50%. Seven blocked phosphorylation of extracellular signal-regulated kinase (ERK) by upstream mitogen-activated protein kinase kinases >50%. One completely blocked the activity of the calcium-dependent phosphatase calcineurin. None blocked ERK catalytic activity. Eight blocked more than one pathway. For 8 compounds, we were unable to determine an MMOA. The activity of 1 of these compounds was confirmed from powder resupply. We conclude that a screen based on antibody binding to CTLs is a good means of identifying novel candidate immunosuppressants with either known or unknown MMOAs.

Limited efficacy of immunosuppressive drugs on CD8+ T cell-mediated and natural killer cell-mediated lysis of human renal tubular epithelial cells

BACKGROUND

Although CD8+ T cell-mediated and natural killer (NK) cell-mediated cytotoxicity against renal tubular epithelial cells (TECs) plays a crucial role during rejection, the degree of inhibition of these lytic immune responses by immunosuppressive drugs is unknown. We investigated the CD8 T-cell and NK cell responses induced by TECs in vitro and questioned how these processes are affected by immunosuppressive drugs.

METHODS

Donor-derived TECs were co-cultured with recipient peripheral blood monocyte cells. Proliferation of CD8+ T cells and NK cell subsets was assessed using PKH dilution assay. CD107a degranulation and europium release assay were performed to explore CD8+-mediated and NK cell-mediated TEC lysis. Experiments were conducted in the absence or presence of tacrolimus (10 ng/mL), everolimus (10 ng/mL), and prednisolone (200 ng/mL).

RESULTS

Tubular epithelial cells induce significant CD8+ T-cell and NK cell proliferation. All immunosuppressive drugs significantly inhibited TEC-induced CD8+ T-cell proliferation. Interestingly, prednisolone was the most powerful inhibitor of NK cell proliferation. CD8-mediated and NK cell-mediated early lytic responses were marked by strong degranulation after an encounter of unstimulated TECs, represented by a high cell surface expression of CD107a. However, with the use of interferon-γ-activated and tumor necrosis factor-α-activated TECs, the NK degranulation response was significantly reduced and CD8 degranulation response was even more enhanced (P<0.05). Tubular epithelial cell-induced CD8 degranulation and CD8-mediated TEC lysis were preferentially inhibited by tacrolimus and prednisolone, and not by everolimus. Although tacrolimus showed the most inhibitory effect on the degranulation of NK cells, NK cell-mediated TEC lysis was efficiently inhibited by prednisolone (P<0.05).

CONCLUSION

Overall, our data point to a limited efficacy of immunosuppressive drugs on CD8+ T cell-mediated and NK cell-mediated lysis of human renal TECs.

Substantial proliferation of human renal tubular epithelial cell-reactive CD4+CD28null memory T cells, which is resistant to tacrolimus and everolimus

BACKGROUND

In spite of maintenance treatment with immunosuppressive drugs, tubulitis still occurs and can lead to structural kidney graft damage. We hypothesize that human renal tubular epithelial cells (TECs) trigger selective proliferation of recipient T-cell subsets with variable sensitivity to immunosuppressive drugs.

METHODS

Recipient peripheral blood mononuclear cells were cocultured with donor-derived TECs for 7 days. The proliferation of the total CD4 T-cell pool was assessed. Next, we analyzed which CD4 T-cell subset proliferated and how this response was affected by tacrolimus, everolimus, prednisolone, and mycophenolic acid (MPA) in clinically relevant concentrations.

RESULTS

CD4 T-cell proliferation upon TEC encounter was mainly executed by memory T cells. Interestingly, 38%±7% of the proliferating CD4 T-cell pool showed a CD28 phenotype. These proliferating CD4CD28 memory T cells produced high levels of interferon-γ, tumor necrosis factor-α, and the cytolitic protease granzyme B. TEC-reactive CD4 T-cell proliferation was significantly suppressed by tacrolimus, everolimus, prednisolone, and MPA (P<0.05). Surprisingly and in contrast to prednisolone and MPA, neither tacrolimus nor everolimus could inhibit the CD4CD28 T-cell proliferative response.

CONCLUSION

Our data show substantial proliferation of TEC-reactive CD4CD28 memory T cells, which are resistant to tacrolimus and everolimus. This phenomenon might play an important mechanistic role during cellular rejection under full immunosuppression.

Endothelium and Regulatory Inflammatory Mechanisms During Organ Rejection

Endothelial integrity is mandatory for physiologic organ function; however, endothelium dysfunction can be caused by systemic inflammation, occurring during sepsis or organ rejection after transplantation. This article will address our current understanding of endothelial involvement in organ transplantation and rejection. Overall, more detailed studies focusing on the endothelial modulation after organ transplantation would be necessary to investigate the role of endothelium activation during organ rejection.

The pharmacokinetics of prednisolone and prednisone in adult liver transplant recipients early after transplantation

BACKGROUND

Glucocorticoids represent a cornerstone in the immunosuppressive therapy after solid organ transplantation. Interconversion between active and inactive states of glucocorticoids (ie, prednisolone and prednisone) is catalyzed by the enzymes 11β-hydroxysteroid dehydrogenases 1 and 2.

MATERIALS

This study investigated the pharmacokinetics of prednisolone and prednisone in 16 liver transplant recipients. Blood samples were collected in four 12-hour dosing intervals during the first 3 weeks posttransplant, including samples drawn at 13 time points.

RESULTS

Area under the time-concentration curve of prednisolone was 3-13 μg·h·mL·mg·kg with maximum concentrations (Cmax) between 0.37 and 2.5 μg·mL·mg·kg and trough concentrations (C0) between 0.13 and 1.1 μg·mL·mg·kg. The elimination half-lives were 1.9-10.3 hours. Apparent volume of distribution (VD/F) and apparent clearance (Cl/F) were 23-159 L and 4.7-28.7 L/h, respectively.

CONCLUSIONS

This study demonstrated large intraindividual and interindividual variabilities in glucocorticoid pharmacokinetics. The results suggest that current prednisolone dosing early after liver transplantation might be too high, in particular when coadministered with methylprednisolone. These findings indicate a potential for improvement by personalized dosing of glucocorticoids in organ transplantation.

Advances in targeting cell surface signalling molecules for immune modulation

The past decade has witnessed a surge in the development of immunomodulatory approaches to combat a broad range of human diseases, including cancer, viral infections, autoimmunity and inflammation as well as in the prevention of transplant rejection. Immunomodulatory approaches mostly involve the use of monoclonal antibodies or recombinant fusion proteins that target cell surface signalling molecules on immune cells to drive immune responses towards the desired direction. Advances in our understanding of the human immune system, along with valuable lessons learned from the first generation of therapeutic biologics, are aiding the design of the next generation of immunomodulatory biologics with better therapeutic efficacy, minimized adverse effects and long-lasting clinical benefit. The recent encouraging results from antibodies targeting programmed cell death protein 1 (PD1) and B7 homolog 1 (B7H1; also known as PDL1) for the treatment of various advanced human cancers show that immunomodulatory therapy has come of age.

Heme oxygenase, inflammation, and fibrosis: the good, the bad, and the ugly?

Upon injury, prolonged inflammation and oxidative stress may cause pathological wound healing and fibrosis, leading to formation of excessive scar tissue. Fibrogenesis can occur in most organs and tissues and may ultimately lead to organ dysfunction and failure. The underlying mechanisms of pathological wound healing still remain unclear, and are considered to be multifactorial, but so far, no efficient anti-fibrotic therapies exist. Extra- and intracellular levels of free heme may be increased in a variety of pathological conditions due to release from hemoproteins. Free heme possesses pro-inflammatory and oxidative properties, and may act as a danger signal. Effects of free heme may be counteracted by heme-binding proteins or by heme degradation. Heme is degraded by heme oxygenase (HO) that exists as two isoforms: inducible HO-1 and constitutively expressed HO-2. HO generates the effector molecules biliverdin/bilirubin, carbon monoxide, and free iron/ferritin. HO deficiency in mouse and man leads to exaggerated inflammation following mild insults, and accumulating epidemiological and preclinical studies support the widely recognized notion of the cytoprotective, anti-oxidative, and anti-inflammatory effects of the activity of the HO system and its effector molecules. In this review, we address the potential effects of targeted HO-1 induction or administration of HO-effector molecules as therapeutic targets in fibrotic conditions to counteract inflammatory and oxidative insults. This is exemplified by various clinically relevant conditions, such as hypertrophic scarring, chronic inflammatory liver disease, chronic pancreatitis, and chronic graft rejection in transplantation.

Orofacial diseases in solid organ and hematopoietic stem cell transplant recipients

OBJECTIVE

Solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients are at risk of several diseases, principally attributable to immunosuppression. This global overview of SOT/HSCT-associated orofacial diseases is aimed at providing a practical instrument for the oral healthcare management of SOT/HSCT recipients.

METHODS

Literature search was made through MEDLINE. The associations between orofacial diseases and SOT/HSCT were assessed using observational studies and case series and were classified into 'association', 'no association', and 'unclear association'.

RESULTS

Lip/oral cancers, drug-induced gingival overgrowth (DIGO), infections, including hairy leukoplakia and, less frequently, post-transplantation lymphoproliferative disorders (PTLDs) and oral lichenoid lesions of graft-versus-host disease (GVHD), were associated with SOT. Lip/oral cancers, GVHD, mucositis, DIGO, infections and, less frequently, PTLDs were associated with HSCT. Associations of orofacial granulomatosis-like lesions and oral mucosa-associated lymphoid tissue-type lymphoma with SOT, and of pyogenic granuloma and hairy leukoplakia with HSCT were unclear. Periodontal disease and dental caries were not associated with SOT/HSCT. For none of the local treatments was there a strong evidence of effectiveness.

CONCLUSIONS

Solid organ transplant/HSCT recipients are at risk of orofacial diseases. Adequate management of these patients alleviates local symptoms responsible for impaired eating, helps prevent systemic and lethal complications, and helps where dental healthcare has been neglected.