Aspirin Attenuates Cardiac Allograft Rejection by Inhibiting the Maturation of Dendritic Cells via the NF-κB Signaling Pathway

Acetylsalicylic acid use and development of cardiac allograft vasculopathy: A national prospective study using highly automated 3-D optical coherence tomography analysis

BACKGROUND

There is conflicting evidence on the role of acetylsalicylic acid (ASA) use in the development of cardiac allograft vasculopathy (CAV).

METHODS

A nationwide prospective two-center study investigated changes in the coronary artery vasculature by highly automated 3-D optical coherence tomography (OCT) analysis at 1 month and 12 months after heart transplant (HTx). The influence of ASA use on coronary artery microvascular changes was analyzed in the overall study cohort and after propensity score matching for selected clinical CAV risk factors.

RESULTS

In total, 175 patients (mean age 52 ± 12 years, 79% male) were recruited. During the 1-year follow-up, both intimal and media thickness progressed, with ASA having no effect on its progression. However, detailed OCT analysis revealed that ASA use was associated with a lower increase in lipid plaque (LP) burden (p = .013), while it did not affect the other observed pathologies. Propensity score matching of 120 patients (60 patient pairs) showed similar results, with ASA use associated with lower progression of LPs (p = .002), while having no impact on layered fibrotic plaque (p = .224), calcification (p = .231), macrophage infiltration (p = .197), or the absolute coronary artery risk score (p = .277). According to Kaplan-Meier analysis, ASA use was not associated with a significant difference in survival (p = .699) CONCLUSION: This study showed a benefit of early ASA use after HTx on LP progression. However, ASA use did not have any impact on the progression of other OCT-observed pathologies or long-term survival.

Sinomenine promotes differentiation of induced pluripotent stem cells into immature dendritic cells with high induction of immune tolerance

BACKGROUND

Immature dendritic cells (imDCs) play an important role in the induction of donor-specific transplant immunotolerance. However, these cells have limitations, such as rapid maturation and a short lifespan in vivo. In previous studies, induced pluripotent stem cells (iPSCs) differentiated into imDCs, and sinomenine (SN) was used to inhibit the maturation of imDCs.

AIM

To study the capacity of SN to maintain iPSC-derived imDCs (SN-iPSCs-imDCs) in an immature state and the mechanism by which SN-iPSCs-imDCs induce immunotolerance.

METHODS

In this study, mouse iPSCs were induced to differentiate into imDCs in culture medium without or with SN (iPSCs-imDCs and SN-iPSCs-imDCs). The imDC-related surface markers, endocytotic capacity of fluorescein isothiocyanate-Dextran and apoptosis were analyzed by flow cytometry. The effects of iPSCs-imDCs and SN-iPSCs-imDCs on T-cell stimulatory function, and regulatory T (Treg) cell proliferative function in vitro were analyzed by mixed lymphocyte reaction. Cytokine expression was detected by ELISA. The apoptosis-related proteins of iPSCs-DCs and SN-iPSCs-DCs were analyzed by western blotting. The induced immunotolerance of SN-iPSCs-DCs was evaluated by treating recipient Balb/c skin graft mice. Statistical evaluation of graft survival was performed using Kaplan–Meier curves.

RESULTS

Both iPSCs-imDCs and SN-iPSCs-imDCs were successfully obtained, and their biological characteristics and ability to induce immunotolerance were compared. SN-iPSCs-imDCs exhibited higher CD11c levels and lower CD80 and CD86 levels compared with iPSCs-imDCs. Reduced major histocompatibility complex II expression, worse T-cell stimulatory function, higher Treg cell proliferative function and stronger endocytotic capacity were observed with SN-iPSCs-imDCs (P < 0.05). The levels of interleukin (IL)-2, IL-12, interferon-γ in SN-iPSCs-imDCs were lower than those in iPSCs-imDCs, whereas IL-10 and transforming growth factor-β levels were higher (P < 0.05). The apoptosis rate of these cells was significantly higher (P < 0.05), and the expression levels of cleaved caspase3, Bax and cleaved poly(ADP-ribose) polymerase were higher after treatment with lipopolysaccharides, but Bcl-2 was reduced. In Balb/c mice recipients immunized with iPSCs-imDCs or SN-iPSCs-imDCs 7 d before skin grafting, the SN-iPSCs-imDCs group showed lower ability to inhibit donor-specific CD4⁺ T-cell proliferation (P < 0.05) and a higher capacity to induce CD4⁺CD25⁺FoxP3⁺ Treg cell proliferation in the spleen (P < 0.05). The survival span of C57bl/6 skin grafts was significantly prolonged in immunized Balb/c recipients with a donor-specific pattern.

CONCLUSION

This study demonstrated that SN-iPSCs-imDCs have potential applications in vitro and in vivo for induction of immunotolerance following organ transplantation.

Proof-of-Concept Preclinical Use of Drosophila melanogaster in the Initial Screening of Immunomodulators

Drug discovery is a complex process, and the use of a comprehensive approach is deemed necessary to discover new chemical entities with novel mechanisms of action. This research was carried out to determine whether Drosophila melanogaster can serve as an appropriate model organism in the initial screening of drug candidates with immunomodulatory activities. To test this, we performed phenotypic assay and molecular analysis to investigate the immunomodulatory activities of aspirin, dexamethasone, curcumin, and epigallocatechin gallate (EGCG), that have been reported to yield such effects in the mammalian model system. In vivo survival analysis demonstrated that all drugs/compounds were relatively safe at the tested concentrations. In the infection assay, curcumin and EGCG showed a protective signature to bacterial infection in flies lacking Toll-mediated immune responses. Furthermore, dexamethasone and aspirin, drugs with immunosuppressive activity, could improve the survival of PGRP-LBΔ mutant flies with hyperactivated immune system. These phenotypes were supported by RT-qPCR-based molecular analysis, revealing that drugs/compounds used in this study could modulate the expression level of genes related to the immune system. In conclusion, while curcumin and EGCG could promote the improvement of fly survival against infection, aspirin and dexamethasone were able to suppress overactivation of immune responses in D. melanogaster. These results are in line with the ones observed in the mammalian model system, further emphasizing the notion that flies would serve as a prospective model organism in the initial screening of drug candidates for their immunomodulatory activities prior to further checking in the mammalian animal models. In the end, this will reduce the use of mammalian animal models for preliminary experiments in an effort to discover/repurpose drugs with immunomodulatory activity.