Lentivirus IL-10 gene therapy down-regulates IL-17 and attenuates mouse orthotopic lung allograft rejection

Flexible bronchoscopy in pediatric lung transplantation

Pediatric lung transplantation represents a treatment option for children with advanced lung disease or pulmonary vascular disorders who are deemed an appropriate candidate. Pediatric flexible bronchoscopy is an important and evolving field that is highly relevant in the pediatric lung transplant population. It is thus important to advance our knowledge to better understand how care for children after lung transplant can be maximally optimized using pediatric bronchoscopy. Our goals are to continually improve procedural skills when performing bronchoscopy and to decrease the complication rate while acquiring adequate samples for diagnostic evaluation. Attainment of these goals is critical since allograft assessment by bronchoscopic biopsy is required for histological diagnosis of acute cellular rejection and is an important contributor to establishing chronic lung allograft dysfunction, a common complication after lung transplant. Flexible bronchoscopy with bronchoalveolar lavage and transbronchial lung biopsy plays a key role in lung transplant graft assessment. In this article, we discuss the application of bronchoscopy in pediatric lung transplant evaluation including historical approaches, our experience, and future directions not only in bronchoscopy but also in the evolving pediatric lung transplantation field. Pediatric flexible bronchoscopy has become a vital modality for diagnosing lung transplant complications in children as well as assessing therapeutic responses. Herein, we review the value of flexible bronchoscopy in the management of children after lung transplant and discuss the application of novel techniques to improve care for this complex pediatric patient population and we provide a brief update about new diagnostic techniques applied in the growing lung transplantation field.

Creating superior lungs for transplantation with next-generation gene therapy during ex vivo lung perfusion

Engineering donor organs to better tolerate the harmful non-immunological and immunological responses inherently related to solid organ transplantation would improve transplant outcomes. Our enhanced knowledge of ischemia-reperfusion injury, alloimmune responses and pathological fibroproliferation after organ transplantation, and the advanced toolkit available for gene therapies, have brought this goal closer to clinical reality. Ex vivo organ perfusion has evolved rapidly especially in the field of lung transplantation, where clinicians routinely use ex vivo lung perfusion (EVLP) to confirm the quality of marginal donor lungs before transplantation, enabling safe transplantation of organs originally considered unusable. EVLP would also be an attractive platform to deliver gene therapies, as treatments could be administered to an isolated organ before transplantation, thereby providing a window for sophisticated organ engineering while minimizing off-target effects to the recipient. Here, we review the status of lung transplant first-generation gene therapies that focus on inducing transgene expression in the target cells. We also highlight recent advances in next-generation gene therapies, that enable gene editing and epigenetic engineering, that could be used to permanently change the donor organ genome and to induce widespread transcriptional gene expression modulation in the donor lung. In a future vision, dedicated organ repair and engineering centers will use gene editing and epigenetic engineering, to not only increase the donor organ pool, but to create superior organs that will function better and longer in the recipient.

Donor IL-17 receptor A regulates LPS-potentiated acute and chronic murine lung allograft rejection

Chronic lung allograft dysfunction (CLAD) is a major complication after lung transplantation that results from a complex interplay of innate inflammatory and alloimmune factors, culminating in parenchymal and/or obliterative airway fibrosis. Excessive IL-17A signaling and chronic inflammation have been recognized as key factors in these pathological processes. Herein, we developed a model of repeated airway inflammation in mouse minor alloantigen-mismatched single-lung transplantation. Repeated intratracheal LPS instillations augmented pulmonary IL-17A expression. LPS also increased acute rejection, airway epithelial damage, and obliterative airway fibrosis, similar to human explanted lung allografts with antecedent episodes of airway infection. We then investigated the role of donor and recipient IL-17 receptor A (IL-17RA) in this context. Donor IL-17RA deficiency significantly attenuated acute rejection and CLAD features, whereas recipient IL-17RA deficiency only slightly reduced airway obliteration in LPS allografts. IL-17RA immunofluorescence positive staining was greater in human CLAD lungs compared with control human lung specimens, with localization to fibroblasts and myofibroblasts, which was also seen in mouse LPS allografts. Taken together, repeated airway inflammation after lung transplantation caused local airway epithelial damage, with persistent elevation of IL-17A and IL-17RA expression and particular involvement of IL-17RA on donor structural cells in development of fibrosis.

Immunomodulation of the donor lung with CRISPR-mediated activation of IL-10 expression

BACKGROUND

Inflammatory injury in the donor lung remains a persistent challenge in lung transplantation that limits donor organ usage and post-transplant outcomes. Inducing immunomodulatory capacity in donor organs could address this unsolved clinical problem. We sought to apply clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) technologies to the donor lung to fine-tune immunomodulatory gene expression, exploring for the first time the therapeutic use of CRISPR-mediated transcriptional activation in the whole donor lung.

METHODS

We explored the feasibility of CRISPR-mediated transcriptional upregulation of interleukin 10 (IL-10), a key immunomodulatory cytokine, in vitro and in vivo. We first evaluated the potency, titratability, and multiplexibility of the gene activation in rat and human cell lines. Next, in vivo CRISPR-mediated IL-10 activation was characterized in rat lungs. Finally, the IL-10-activated donor lungs were transplanted into recipient rats to assess the feasibility in a transplant setting.

RESULTS

The targeted transcriptional activation induced robust and titrable IL-10 upregulation in vitro. The combination of guide RNAs also facilitated multiplex gene modulation, that is, simultaneous activation of IL-10 and IL1 receptor antagonist. In vivo profiling demonstrated that adenoviral delivery of Cas9-based activators to the lung was feasible with the use of immunosuppression, which is routinely applied to organ transplant recipients. The transcriptionally modulated donor lungs retained IL-10 upregulation in isogeneic and allogeneic recipients.

CONCLUSIONS

Our findings highlight the potential of CRISPR epigenome editing to improve lung transplant outcomes by creating a more favorable immunomodulatory environment in the donor organ, a paradigm that may be extendable to other organ transplants.

Multifunctional hydrogel modulates the immune microenvironment to improve allogeneic spinal cord tissue survival for complete spinal cord injury repair

Transplantation of allogeneic adult spinal cord tissues (aSCTs) to replace the injured spinal cord, serves as a promising strategy in complete spinal cord injury (SCI) repair. However, in addition to allograft immune rejection, damage-associated molecular pattern (DAMP)-mediated inflammatory microenvironments greatly impair the survival and function of transplants. In this study, we aimed to regulate the immune microenvironment after aSCT implantation by developing a functional hybrid gelatin and hyaluronic acid hydrogel (F-G/H) modified with cationic polymers and anti-inflammatory cytokines that can gelatinize at both ends of the aSCT to glue the grafts for perfect matching at defects. The F-G/H hydrogel exhibited the capacities of DAMP scavenging, sustainably released anti-inflammatory cytokines, and reduced lymphocyte accumulation, thereby modulating the immune response and enhancing the survival and function of aSCTs. When the hydrogel was used in combination with a systemic immunosuppressive drug treatment, the locomotor functions of SCI rats were significantly improved after aSCTs and F-G/H transplantation. This biomaterial-based immunomodulatory strategy may provide the potential for spinal cord graft replacement for treating SCI. STATEMENT OF SIGNIFICANCE: In this study, we aimed to regulate the immune microenvironment by developing a functional hybrid gelatin and hyaluronic acid hydrogel (F-G/H) modified with cationic polymers and anti-inflammatory cytokines that can gelatinize at both ends of the aSCT to glue the grafts for perfect matching at defects. We found that with the treatment of F-G/H hydrogel, the aSCT survival and function was significantly improved, as a result of reducing recruitment and activation of immune cells through TLR- and ST-2- related signaling. With the combination of immunosuppressive drug treatment, the locomotor functions of SCI rats were significantly improved after aSCTs and F-G/H transplantation. Findings from this work suggest the potential application of the F-G/H as a biomaterial-based immunoregulatory strategy for improving the therapeutic efficiency of the transplanted spinal cord graft for spinal cord injury repair.

Gene Therapy: Will the Promise of Optimizing Lung Allografts Become Reality?

Lung transplantation is the definitive therapy for patients living with end-stage lung disease. Despite significant progress made in the field, graft survival remains the lowest of all solid organ transplants. Additionally, the lung has among the lowest of organ utilization rates-among eligible donors, only 22% of lungs from multi-organ donors were transplanted in 2019. Novel strategies are needed to rehabilitate marginal organs and improve graft survival. Gene therapy is one promising strategy in optimizing donor allografts. Over-expression or inhibition of specific genes can be achieved to target various pathways of graft injury, including ischemic-reperfusion injuries, humoral or cellular rejection, and chronic lung allograft dysfunction. Experiments in animal models have historically utilized adenovirus-based vectors and the majority of literature in lung transplantation has focused on overexpression of IL-10. Although several strategies were shown to prevent rejection and prolong graft survival in preclinical models, none have led to clinical translation. The past decade has seen a renaissance in the field of gene therapy and two AAV-based in vivo gene therapies are now FDA-approved for clinical use. Concurrently, normothermic ex vivo machine perfusion technology has emerged as an alternative to traditional static cold storage. This preservation method keeps organs physiologically active during storage and thus potentially offers a platform for gene therapy. This review will explore the advantages and disadvantages of various gene therapy modalities, review various candidate genes implicated in various stages of allograft injury and summarize the recent efforts in optimizing donor lungs using gene therapy.

Inducible Pluripotent Stem Cells as a Potential Cure for Diabetes

Over the last century, diabetes has been treated with subcutaneous insulin, a discovery that enabled patients to forego death from hyperglycemia. Despite novel insulin formulations, patients with diabetes continue to suffer morbidity and mortality with unsustainable costs to the health care system. Continuous glucose monitoring, wearable insulin pumps, and closed-loop artificial pancreas systems represent an advance, but still fail to recreate physiologic euglycemia and are not universally available. Islet cell transplantation has evolved into a successful modality for treating a subset of patients with ‘brittle’ diabetes but is limited by organ donor supply and immunosuppression requirements. A novel approach involves generating autologous or immune-protected islet cells for transplant from inducible pluripotent stem cells to eliminate detrimental immune responses and organ supply limitations. In this review, we briefly discuss novel mechanisms for subcutaneous insulin delivery and define their shortfalls. We describe embryological development and physiology of islets to better understand their role in glycemic control and, finally, discuss cell-based therapies for diabetes and barriers to widespread use. In response to these barriers, we present the promise of stem cell therapy, and review the current gaps requiring solutions to enable widespread use of stem cells as a potential cure for diabetes.

Identification and Modulation of Microenvironment Is Crucial for Effective Mesenchymal Stromal Cell Therapy in Acute Lung Injury

Rationale: There are controversial reports on applications of mesenchymal stromal cells (MSCs) in patients with acute respiratory distress syndrome (ARDS). Objectives: We hypothesized that lung microenvironment was the main determinant of beneficial versus detrimental effects of MSCs during ARDS. Methods: Lung proteome was profiled in three models of injury induced by acid instillation and/or mechanical ventilation in mice. Human gene of glutathione peroxidase-1 was delivered before MSC administration; or MSCs carrying human gene of IL-10 or hepatocyte growth factor were administered after lung injury. An inhibitory cocktail against IL-6, fibronectin, and oxidative stress was used in in vitro studies using human small airway epithelial cells and human MSCs after exposure to plasma of patients with ARDS. Measurements and Main Results: Distinct proteomic profiles were observed in three lung injury models. Administration of MSCs protected lung from ventilator-induced injury, whereas it worsened acid-primed lung injuries associated with fibrotic development in lung environment that had high levels of IL-6 and fibronectin along with low antioxidant capacity. Correction of microenvironment with glutathione peroxidase-1, or treatment with MSCs carrying human gene of IL-10 or hepatocyte growth factor after acid-primed injury, reversed the detrimental effects of native MSCs. Proteomic profiles obtained in the mouse models were also similarly observed in human ARDS. Treatment with the inhibitory cocktail in samples of patients with ARDS retained protective effects of MSCs in small airway epithelial cells. Conclusions: MSCs can be beneficial or detrimental depending on microenvironment at the time of administration. Identification of potential beneficiaries seems to be crucial to guide MSC therapy in ARDS.

A B cell-dependent pathway drives chronic lung allograft rejection after ischemia-reperfusion injury in mice

Chronic lung allograft dysfunction (CLAD) limits long-term survival after lung transplant (LT). Ischemia-reperfusion injury (IRI) promotes chronic rejection (CR) and CLAD, but the underlying mechanisms are not well understood. To examine mechanisms linking IRI to CR, a mouse orthotopic LT model using a minor alloantigen strain mismatch (C57BL/10 [B10, H-2^b ] → C57BL/6 [B6, H-2^b ]) and isograft controls (B6→B6) was used with antecedent minimal or prolonged graft storage. The latter resulted in IRI with subsequent airway and parenchymal fibrosis in prolonged storage allografts but not isografts. This pattern of CR after IRI was associated with the formation of B cell-rich tertiary lymphoid organs within the grafts and circulating autoantibodies. These processes were attenuated by B cell depletion, despite preservation of allograft T cell content. Our observations suggest that IRI may promote B cell recruitment that drives CR after LT. These observations have implications for the mechanisms leading to CLAD after LT.

Spectrum of chronic lung allograft pathology in a mouse minor-mismatched orthotopic lung transplant model

Chronic lung allograft dysfunction (CLAD) is a fatal condition that limits survival after lung transplantation (LTx). The pathological hallmark of CLAD is obliterative bronchiolitis (OB). A subset of patients present with a more aggressive CLAD phenotype, called restrictive allograft syndrome (RAS), characterized by lung parenchymal fibrosis (PF). The mouse orthotopic single LTx model has proven relevant to the mechanistic study of allograft injury. The minor-alloantigen-mismatched strain combination using C57BL/10(B10) donors and C57BL/6(B6) recipients reportedly leads to OB. Recognizing that OB severity is a spectrum that may coexist with other pathologies, including PF, we aimed to characterize and quantify pathologic features of CLAD in this model. Left LTx was performed in the following combinations: B10→B6, B6→B10, B6→B6. Four weeks posttransplant, blinded pathologic semi-quantitative assessment showed that OB was present in 66% of B10→B6 and 30% of B6→B10 grafts. Most mice with OB also had PF with a pattern of pleuroparenchymal fibroelastosis, reminiscent of human RAS-related pathology. Grading of pathologic changes demonstrated variable severity of airway fibrosis, PF, acute rejection, vascular fibrosis, and epithelial changes, similar to those seen in human CLAD. These assessments can make the murine LTx model a more useful tool for further mechanistic studies of CLAD pathogenesis.

T Helper Cell Subsets in Experimental Lung Allograft Rejection

BACKGROUND

Human lung transplantation has evolved to an established treatment for pulmonary diseases in their end stages; however, the long-term outcome is worse when compared to all other solid transplantable organs. The major reason for this unfavorable outcome is rejection, either in its acute or chronic form, the latter termed as chronic lung allograft dysfunction.

METHODS

A systematic review search was performed.

RESULTS

One of the most important immune cells responsible for rejection are T cells. Beside alloreactive CD8+ T cells, CD4+ T cells play a key role during the evolvement of allograft rejection. Certain subsets of these allograft CD4+ T cells have been identified which have been shown to exert either transplant-protective or transplant-injuring properties. These effects have been proven in various experimental models, mainly in rats and mice, and allowed for the gain of important insights into these proinflammatory and anti-inflammatory characteristics including their targetability: while the subsets Th1, Th17, Th22, and Tfh cells have been shown to act in a rather proinflammatory way, Tregs, Th2, and Th9 subsets exert anti-inflammatory effects. Chronic airway obstruction is mainly induced by IL17 as shown across models.

CONCLUSIONS

This review shall summarize and provide an overview of the current evidence about the role and effects of proinflammatory and anti-inflammatory CD4-+ T helper cell subsets during lung allograft rejection in experimental rodent models.

A novel combined ex vivo and in vivo lentiviral interleukin-10 gene delivery strategy at the time of transplantation decreases chronic lung allograft rejection in mice

OBJECTIVE

Our objective was to develop a rapid-onset and durable gene-delivery strategy that is applicable at the time of transplant to determine its effects on both acute rejection and chronic lung allograft fibrosis using a mouse orthotopic lung transplant model.

METHODS

C57BL/6 mice received an orthotopic left lung transplant from syngeneic donors or C57BL/10 donors. By using syngeneic lung transplantation, we established a novel gene transfer protocol with lentivirus luciferase intrabronchial administration to the donor lung ex vivo before transplantation. This strategy was applied in allogeneic lung transplantation with lentivirus engineering expression of human interleukin-10 or lentivirus luciferase (control).

RESULTS

Bioluminescent imaging revealed that the highest early transgene expression was achieved when lentivirus luciferase was administered both directly into the donor lung graft ex vivo before implantation and subsequently to the recipient in vivo daily on post-transplant days 1 to 4, compared with post-transplant in vivo administration only (days 0 to 4). Our previous work with adenoviral interleukin-10 gene therapy indicates that early interleukin-10 expression in the allograft is desirable. Therefore, we selected the combined protocol for human interleukin-10 encoding lentiviral vector therapy. In the allogeneic transplant setting, ex vivo and in vivo human interleukin-10 encoding lentiviral vector therapy reduced acute rejection grade (2.0 vs 3.0, P < .05) at day 28. The percentage of fibrotic obliterated airways was reduced in the human interleukin-10 encoding lentiviral vector-treated group (10.9% ± 7.7% vs 40.9% ± 9.3%, P < .05).

CONCLUSIONS

Delivery of lentiviral interleukin-10 gene therapy, using a novel combined ex vivo and in vivo delivery strategy, significantly improves acute and chronic rejection in the mouse lung transplant model.

Study of differential expression of miRNAs in lung tissue of mice submitted to experimental infection by Paracoccidioides brasiliensis

MicroRNAs (miRNAs) are small single stranded RNA sequences involved in post-transcriptional regulation of different biological and physiological processes. Paracoccidioidomycosis (PCM) is an infection caused by Paracoccidioides brasiliensis, and it is a major cause of mortality due to systemic mycoses in Brazil. To date, there have been few reports on the role of miRNAs in the immune response against fungi, especially PCM. The objective of this study was to evaluate the differential expression of miRNAs related to the inflammatory response associated with pulmonary infection by P. brasiliensis. For this purpose, lungs from BALB/c mice, intravenously infected with P. brasiliensis (2.7×107 yeast cells/ml, n = 12) and noninfected BALB/c mice (n = 8), were collected at the 28 and 56 day after infection. The lung parenchyma presented a great number of yeast cells, granulomas, and edema at 28 days and a framework of resolution of the inflammatory process after 56 days. The mRNAs gata-3, ror-γt, foxp3, and IL-6 were positively regulated at the moment at the 56 day, while the TGF-β1 mRNA was positively regulated at both moments. The miRNAs 126a-5p, 340-5p, 30b-5p, 19b-3p, 221-3p, 20a-5p, 130a-3p, and 301a-3p, 466k presented the greatest increase in expression levels 28 days after infection, and the miRNAs let-7f-5p, let-7a-5p, 5p-26b, let-7e-5p and 369-3p, 466k presented a greater increase in levels of expression 56 days after infection. This study shows a set of differentially expressed miRNAs possibly involved in the immune response in mice during pulmonary infection by P. brasiliensis.

Transplantation of Hearts Donated after Circulatory Death

Cardiac transplantation has become limited by a critical shortage of suitable organs from brain-dead donors. Reports describing the successful clinical transplantation of hearts donated after circulatory death (DCD) have recently emerged. Hearts from DCD donors suffer significant ischemic injury prior to organ procurement; therefore, the traditional approach to the transplantation of hearts from brain-dead donors is not applicable to the DCD context. Advances in our understanding of ischemic post-conditioning have facilitated the development of DCD heart resuscitation strategies that can be used to minimize ischemia-reperfusion injury at the time of organ procurement. The availability of a clinically approved ex situ heart perfusion device now allows DCD heart preservation in a normothermic beating state and minimizes exposure to incremental cold ischemia. This technology also facilitates assessments of organ viability to be undertaken prior to transplantation, thereby minimizing the risk of primary graft dysfunction. The application of a tailored approach to DCD heart transplantation that focuses on organ resuscitation at the time of procurement, ex situ preservation, and pre-transplant assessments of organ viability has facilitated the successful clinical application of DCD heart transplantation. The transplantation of hearts from DCD donors is now a clinical reality. Investigating ways to optimize the resuscitation, preservation, evaluation, and long-term outcomes is vital to ensure a broader application of DCD heart transplantation in the future.

IL-17A Blockade Attenuates Obliterative Bronchiolitis and IFN-γ Cellular Immune Response in Lung Allografts

Obliterative bronchiolitis (OB), characterized by fibrous obliteration of the small airways, is a major impediment to long-term survival in lung allograft recipients. We found previously that IL-17A is produced primarily by CD4⁺ T cells and γδ T cells after lung transplant in a mouse model of orthotopic lung transplant. The absence of either subset of T cells was compensated for by expansion of the other subset, which suggested that systemic blockade of IL-17A was necessary. To determine the specific role of IL-17A in the development of OB, we treated lung allograft recipients with an IL-17A antagonistic antibody. After IL-17A blockade, the incidence of OB was significantly reduced in lung allografts. IL-17A blockade also significantly attenuated the severity of acute rejection and overall lung fibrosis. The decreased OB incidence was associated with reduced lymphocyte recruitment, particularly CD8⁺ T cells and other IFN-γ-producing lymphocytes, to the lung allograft. Interestingly, IL-17A blockade led to an increase in the frequency of IL-17A-producing T-helper cell type 17 cells and γδ T cells in lung allografts, suggesting that IL-17A is a negative regulator of these T cells. Our data suggest that blocking IL-17A after lung transplant reduces the overall IFN-γ-mediated lymphocyte response and decreases the development of OB.

Interferon-τ increases BoLA-I for implantation during early pregnancy in dairy cows

Interferon-τ (IFN-τ) signals pregnancy recognition in ruminants. We investigated the effects of IFN-τ produced by embryo trophoblastic cells (ETCs) on expression of bovine leukocyte antigen-I (BoLA-I), a bovine analogue of human MHC-I, in endometrial luminal epithelial cells (EECs) during early pregnancy in dairy cows. Expression of IFN-τ and BoLA-I was increased in endometrial tissues during early pregnancy. Expression of the anti-inflammatory cytokine IL-10 was increased in endometrial tissues, while expression of the pro-inflammatory cytokine IL-6 was decreased, indicating immunosuppression. Progesterone increased IFN-τ expression in EECs. IFN-τ increased p-STAT1 and p-STAT3 levels in EECs, but reduced TRAF3 levels. In addition, IFN-τ increased expression of BoLA-I and IL-10, but decreased expression of IL-6 in EECs. These results indicate that IFN-τ enables stable implantation in dairy cows by increasing expression of BoLA-I, and by immunosuppression mediated by increased IL-10 and decreased IL-6 expression.

Primary graft dysfunction: pathophysiology to guide new preventive therapies

INTRODUCTION

Primary graft dysfunction (PGD) is a common complication of lung transplantation characterized by acute pulmonary edema associated with bilateral pulmonary infiltrates and hypoxemia in the first 3 post-operative days. Development of PGD is a predictor of poor short- and long-term outcomes after lung transplantation, but there are currently limited tools to prevent its occurrence. Areas covered: Several potentially modifiable donor, recipient, and operative risk factors for PGD have been identified. In addition, basic and translational studies in animals and ex vivo lung perfusion systems have identified several biomarkers and mechanisms of injury in PGD. In this review, we outline the clinical and genetic risk factors for PGD and summarize experimental data exploring PGD mechanisms, with a focus on strategies to reduce PGD risk and on potential novel molecular targets for PGD prevention. Expert commentary: Because of the clinical importance of PGD, development of new therapies for prevention and treatment is critically important. Improved understanding of the pathophysiology of clinical PGD provides a framework to explore novel agents to prevent or reverse PGD. Ex vivo lung perfusion provides a new opportunity for rapid development of therapeutics that target this devastating complication of lung transplantation.

The Critical Role of Induced CD4+ FoxP3+ Regulatory Cells in Suppression of Interleukin-17 Production and Attenuation of Mouse Orthotopic Lung Allograft Rejection

BACKGROUND

Lung transplantation is the only definitive therapy for many forms of end-stage lung disease. Studies have demonstrated the critical role of interleukin (IL)-17 in the development of lung rejection. Regulatory T cells (Tregs) are essential for the establishment and maintenance of immune tolerance.

METHODS

We established mouse orthotopic lung transplantation models to investigate the importance of IL-17 and IL-17-producing cell types in acute lung allograft rejection and the efficacy of the adoptive transfer of induced Tregs (iTregs) in attenuating pathologic lesions of lung allografts.

RESULTS

We found that the IL-17 produced by Th17 cells and γδ T cells might make the primary contributions to the progression of acute lung allograft rejection. Interleukin-17 deficiency decreased lung allograft lesions. Exogenous iTregs maintained their FoxP3 expression levels in lung allograft recipients. Induced Tregs therapy downregulated the expressions of Th17 and IL-17 γδ T cells and increased IL-10 production in the mouse orthotopic lung transplantation models. Moreover, the adoptive transfer of iTregs prolonged the survivals of the lung allografts and attenuated the progression of acute rejection.

CONCLUSION

These data suggested that the adoptive transfer of iTregs could suppress the Th17 cells and IL-17 γδ cells of the recipients, decrease the expression of IL-17, and attenuate the pathology of acute lung allograft rejection. Exogenous iTregs upregulated immunosuppressive factors, such as IL-10 and suppressed IL-17-producing cells, which was one of the pathways to play a role in protecting lung allografts.

CD26 costimulatory blockade improves lung allograft rejection and is associated with enhanced interleukin-10 expression

BACKGROUND

The ectoenzyme CD26/dipeptidyl peptidase 4 (DPP4) has costimulatory activity that contributes to T cell activation and proliferation. Here, we aimed to target this costimulatory activity for the attenuation of the alloreactive Th17-cell response during acute rejection after mouse lung transplantation.

METHODS

To test the CD26-costimulatory blockade in vitro, mixed lymphocyte reaction was performed between major histocompatibility complex class I and II fully mismatched cells (CD4(+) splenocytes, C57BL/6, responders, and antigen-presenting cells, BALB/c, stimulators) by adding the CD26 inhibitor vildagliptin (0-15 μg). Lung transplantation between BALB/c (donor) and C57BL/6 (recipient) mice was performed, including controls, CD26-inhibited (CD26-I, daily administration of vildagliptin [GLSynthesis, Worcester, MA], 10 mg/kg subcutaneous), and CD26 knockout (CD26KO) mice was performed. Analysis on Day 1 and 5 after transplant included immunohistochemistry, fluorescence-activated cell sorting, and enzyme-linked immunosorbent assay (ELISA) for immune cell detection and their key cytokines.

RESULTS

In vitro, there was a significant reduction of the Th17 cytokines interleukin (IL)-17 and IL-21. In vivo, CD26-I-treated and CD26KO mice showed significantly preserved macroscopic and histologic characteristics on Day 5 (p < 0.01), a higher partial pressure of arterial oxygen/fraction of inspired oxygen ratio (p ≤ 0.05), fewer infiltrating CD3(+) T cells (p < 0.01), but more interstitial macrophages on Day 1 (p < 0.01) compared with control. Fewer IL-17(+) cells were found in CD26-I allografts on Day 1 (p = 0.05). Higher levels of IL-10 in CD26-I and CD26KO allografts on day 5 were seen (p < 0.05). IL-10/CD206 double-staining (alternative macrophages) revealed more positive cells in CD26-I and CD26KO on Day 1 and 5 (p < 0.01).

CONCLUSIONS

CD26 costimulatory blockade promotes lung allograft acceptance via reduced T cell infiltration, less expression of IL-17, and increased expression of IL-10, likely to be derived from alternatively activated macrophages.

CD4 T Cells but Not Th17 Cells Are Required for Mouse Lung Transplant Obliterative Bronchiolitis

Lung transplant survival is limited by obliterative bronchiolitis (OB), but the mechanisms of OB development are unknown. Previous studies in a mouse model of orthotopic lung transplantation suggested a requirement for IL-17. We have used this orthotopic mouse model to investigate the source of IL-17A and the requirement for T cells producing IL-17A. The major sources of IL-17A were CD4(+) T cells and γδ T cells. Depletion of CD4(+) T cells led to a significantly decreased frequency and number of IL-17A(+) lymphocytes and was sufficient to prevent acute rejection and OB. However, mice with STAT3-deficient T cells, which are unable to differentiate into Th17 cells, rejected lung allografts and developed OB similar to control mice. The frequency of IL-17A(+) cells was not decreased in mice with STAT3-deficient T cells due mainly to the presence of IL-17A(+) γδ T cells. Deficiency of γδ T cells also did not affect the development of airway fibrosis. Our data suggest that CD4(+) T cells are required for OB development and expansion of IL-17A responses in the lung, while Th17 and γδ T cells are not absolutely required and may compensate for each other.

Modulation of Alloimmune Responses by Interleukin-10 Prevents Rejection of Implanted Allogeneic Smooth Muscle Cells and Restores Postinfarction Ventricular Function

Interleukin-10 (IL-10) gene transduction into allogeneic smooth muscle cells (SMCs) was evaluated to improve the long-term benefits of allogeneic cell transplantation into infarcted myocardium. Allogeneic cells, including SMCs, have been demonstrated to restore cardiac function and repair the infarcted myocardium, but late rejection of the transplanted cells by the host immune system may reverse the benefits of cell therapy. In a rat myocardial infarction model, three groups of rats were injected with either unmodified autologous, unmodified allogeneic, or allogeneic + IL-10 SMCs into the infarct region. Three weeks later, most of the allogeneic cells were rejected, whereas autologous cells were engrafted in the myocardium. IL-10 gene transduction of the allogeneic SMCs significantly improved the cell survival. To understand the mechanism of this improved survival, we evaluated the host immune responses against the SMCs. Allogeneic SMCs expressing IL-10 decreased leukocyte-mediated cytotoxicity in coculture, decreased the number of cytotoxic CD8+ T-cells, and increased the number of CD4+CD25+ regulatory T-cells in vitro and in vivo. Furthermore, IL-10 prevented the production of antidonor antibodies by the recipients against the allogeneic SMCs. Transplantation of unmodified autologous SMCs, but not unmodified allogeneic SMCs, significantly improved fractional shortening and left ventricular dimensions compared to the media-injected control group. However, IL-10 gene-enhanced allogeneic SMCs improved ventricular function, increased wall thickness, and decreased scar length in association with their enhanced survival. We conclude that IL-10 gene-enhanced cell therapy with allogeneic SMCs prevents detrimental alloimmune responses in the recipient, thereby increasing the survival of transplanted allogeneic SMCs and more effectively restoring cardiac function.

Sphingosine-1-phosphate receptor 1 agonist SEW2871 prolongs heterotopic heart allograft survival in mice

Sphingosine-1-phosphate (S1P) is a biologically active metabolite of plasma-membrane sphingolipids that is essential for immune cell trafficking. Recent studies have revealed immunomodulatory functions of S1P and its receptors (S1PR1-S1PR5) in many inflammatory conditions, such as asthma and autoimmunity. Here, we explore the efficacy of SEW2871, a selective S1PR1 agonist, in the prevention of acute allograft rejection in a murine cardiac transplantation model. Treatment of recipient mice with SEW2871 significantly prolongs cardiac allograft survival as compared to those recipients treated with control vehicle. The enhanced graft survival is associated with reduced circulating lymphocytes and allograft inflammatory cell infiltration. The cytokine analysis showed decreased allograft expression of TNF-α, IFN-γ and IL-2 in the SEW2871-treated mice. Moreover, administration of SEW2871 increases the percentage of CD4(+) T regulatory cells and FoxP3 expression in spleen of allograft recipients. Therefore, SEW2871 plays a critical role in regulation of lymphocyte trafficking and development, which directly contributes to prolongation of the allograft survival.

Thioredoxin priming prolongs lung allograft survival by promoting immune tolerance

Tolerance to allograft antigen is the major challenge and final goal of transplant medicine. Our previous study demonstrated that thioredoxin-1 (Trx) priming of donor lung significantly protected allogeneic lung graft. To determine whether Trx priming of donor lung inhibits allograft rejection, extends allograft survival and induces immune tolerance, orthotopic left lung transplantation was performed from Lewis to Sprague-Dawley rats without immunosuppression. Donor lungs were primed with Trx at 4°C for 4 hr prior to transplantation. After up to 37 days post-transplantation, allograft lung morphology, recipient T cell and humoral alloantigen-specific immune responses were examined. We found that Trx-primed lungs exhibited much reduced acute rejection and associated lung injuries resulting in loss of graft functional area at 5-37 days post-transplant in contrast to the control groups. CD4⁺ T cells from the recipients with Trx-primed grafts responded to the stimulation of dendritic cells (DCs) of donor origin, in contrast to DCs from the third party, with significantly reduced proliferation. Consistent with above findings, we observed that CD4⁺Foxp3⁺ regulatory T cells in spleen cells from the recipients with Trx-primed grafts were significantly increased compared to controls, and CD4⁺ T cells from the recipients with Trx-primed grafts produced much higher levels of immunosuppressive cytokine, IL-10 when stimulated with allogeneic donor DCs. In addition, humoral immune tolerance was also induced as there was no significant increase levels of serum antibodies against donor antigens in Trx-lung recipients when re-challenged with allogeneic donor antigens. Our results demonstrate that one-time Trx-priming of donor lung grafts prior to transplantation significantly prolongs the survival of the grafts through inducing or promoting cellular and humoral alloantigen-specific immune tolerance, which might be associated with the induction of immunosuppressive regulatory T cells.

Could Ex Vivo Lung Perfusion Be a Platform to Decrease the Incidence of Chronic Lung Allograft Dysfunction?

The number of patients requiring lung transplantation is increasing, with a significant unmet demand for grafts. Ex vivo lung perfusion has been developed to increase graft recruitment. The major complications of lung transplantation include chronic allograft dysfunction (CLAD) whose cumulative incidence ranges from 43-80% within the first 5 years of transplantation. Many risk factors are listed for development of CLAD and almost all of those risk factors would involve activation of Toll-like receptors. This paper represents the author's overview regarding the development of CLAD as a complication of lung transplantation and the possible protective potential of ex vivo lung perfusion in this regard.

Echinococcus granulosus infection reduces airway inflammation of mice likely through enhancing IL-10 and down-regulation of IL-5 and IL-17A

BACKGROUND

Cystic echinococcosis (CE) is a near cosmopolitan zoonosis caused by the larval stage of the dog tapeworm Echinococcus granulosus. E. granulosus infection induces a polarized T-helper type 2 (Th2) systematic immune response in its intermediate hosts. However, it is not known whether the infection modulates lung inflammation by regulating local immune response. In this study, we examined the effects of E. granulosus infection on mouse ovalbumin (OVA)-induced asthma model.

METHODS

BALB/c mice were intraperitoneally transplanted with 50 small E. granulosus cysts cultured in vitro. At 3 months post-inoculation, the mice were sensitized and challenged with ovalbumin (OVA). For histopathological studies, hematoxylin eosin and periodic acid schiff staining was used to examine the inflammatory cells infiltration and goblet cells hyperplasia, respectively. Cytokine levels were measured by mouse cytometric bead array (CBA) Kit and quantitative RT-PCR and other molecular biological approaches. Airway hyperresponsiveness was assessed in response to increasing doses of methacholine. Serum immunoglobulins were determined by ELISA.

RESULTS

E. granulosus infection significantly increased Th2 and Treg cytokine levels in serum and lung tissues, but down-regulated the expression of IL-5 in the lungs and IL-17A in serum and lung tissues of asthmatic mice sensitized and challenged with OVA. Histological staining of lung tissues showed that E. granulosus infection significantly reduced the severity of OVA-induced airway inflammation including reduction of eosinophil cell infiltration and mucus production. The E. granulosus infection also reduced eosinophil accumulation induced by OVA in bronchoalveolar lavage fluid (BALF) and also ameliorated airway hyperresponsiveness, a hallmark symptom of asthma.

CONCLUSIONS

E. granulosus infection remarkably reduces the severity of OVA-induced airway inflammation likely through enhancing IL-10 and down-regulation of IL-5 and IL-17A.

Imaging mouse lung allograft rejection with (1)H MRI

PURPOSE

To demonstrate that longitudinal, noninvasive monitoring via MRI can characterize acute cellular rejection in mouse orthotopic lung allografts.

METHODS

Nineteen Balb/c donor to C57BL/6 recipient orthotopic left lung transplants were performed, further divided into control-Ig versus anti-CD4/anti-CD8 treated groups. A two-dimensional multislice gradient-echo pulse sequence synchronized with ventilation was used on a small-animal MR scanner to acquire proton images of lung at postoperative days 3, 7, and 14, just before sacrifice. Lung volume and parenchymal signal were measured, and lung compliance was calculated as volume change per pressure difference between high and low pressures.

RESULTS

Normalized parenchymal signal in the control-Ig allograft increased over time, with statistical significance between day 14 and day 3 posttransplantation (0.046→0.789; P < 0.05), despite large intermouse variations; this was consistent with histopathologic evidence of rejection. Compliance of the control-Ig allograft decreased significantly over time (0.013→0.003; P < 0.05), but remained constant in mice treated with anti-CD4/anti-CD8 antibodies.

CONCLUSION

Lung allograft rejection in individual mice can be monitored by lung parenchymal signal changes and by lung compliance through MRI. Longitudinal imaging can help us better understand the time course of individual lung allograft rejection and response to treatment.

Profiles of serum cytokines in acute drug-induced liver injury and their prognostic significance

Drug-induced liver injury (DILI) is the most common cause of acute liver failure in the United-States. The aim of the study was to describe serum immune profiles associated with acute DILI, to investigate whether there are profiles associated with clinical features or types of DILI and/or with prognosis, and to assess temporal changes in levels. Twenty-seven immune analytes were measured in the sera of 78 DILI subjects in the Drug-Induced Liver Injury Network (DILIN) and compared with 40 healthy controls. Immune analytes (14 cytokines, 7 chemokines and 6 growth factors) were measured by BioPlex multiplex ELISA at DILI onset and after 6 months. A modeling process utilizing immune principles was used to select a final set of variables among 27 immune analytes and several additional clinical lab values for prediction of early death (within 6 months of DILI onset). Nineteen of the 27 immune analytes were differentially expressed among healthy control, DILI onset and 6-month cohorts. Disparate patterns of immune responses, especially innate and adaptive cellular (mostly TH17) immunity were evident. Low values of four immune analytes (IL-9, IL-17, PDGF-bb and RANTES) and serum albumin are predictive of early death [PPV = 88% (95% CI, 65%-100%), NPV = 97% (95% CI, 93%-100%), accuracy = 96% (95% CI, 92%-100%)].