Studies of circulating microparticle release in peripheral blood after pancreatic islet transplantation

In Vitro Impact of Pro-Senescent Endothelial Microvesicles on Isolated Pancreatic Rat Islets Function

BACKGROUND

Ischemia-driven islet isolation procedure is one of the limiting causes of pancreatic islet transplantation. Ischemia-reperfusion process is associated with endothelium dysfunction and the release of pro-senescent microvesicles. We investigated whether pro-senescent endothelial microvesicles prompt islet senescence and dysfunction in vitro.

MATERIAL AND METHODS

Pancreatic islets were isolated from male young rats. Replicative endothelial senescence was induced by serial passaging of primary porcine coronary artery endothelial cells, and microvesicles were isolated either from young passage 1 (P1) or senescent passage 3 (P3) endothelial cells. Islet viability was assessed by fluorescence microscopy, apoptosis by flow cytometry, and Western blot. Function was assessed by insulin secretion and islet senescence markers p53, p21, and p16 by Western blot. Microvesicles were stained by the PKH26 lipid fluorescent probe and their islet integration assessed by microscopy and flow cytometry.

RESULTS

Regardless of the passage, half microvesicles were integrated in target islets after 24 hours incubation. Insulin secretion significantly decreased after treatment by senescent microvesicles (P3: 1.7 ± 0.2 vs untreated islet: 2.7 ± 0.2, P < .05) without altering the islet viability (89.47% ± 1.69 vs 93.15% ± 0.97) and with no significant apoptosis. Senescent microvesicles significantly doubled the expression of p53, p21, and p16 (P < .05), whereas young microvesicles had no significant effect.

CONCLUSION

Pro-senescent endothelial microvesicles specifically accelerate the senescence of islets and alter their function. These data suggest that islet isolation contributes to endothelial driven islet senescence.

Significance of neutrophil microparticles in ischaemia-reperfusion: Pro-inflammatory effectors of endothelial senescence and vascular dysfunction

Endothelial senescence is an emerging cause of vascular dysfunction. Because microparticles are effectors of endothelial inflammation and vascular injury after ischaemia-reperfusion, we examined leucocyte-derived microparticles of spleen origin as possible contributors. Microparticles were generated from primary rat splenocytes by either lipopolysaccharide or phorbol-myristate-acetate/calcium ionophore, under conditions mimicking innate and adaptive immune responses. Incubation of primary porcine coronary endothelial cells with either type of microparticles, but not with those from unstimulated splenocytes, leads to a similar threefold raise in senescence-associated β-galactosidase activity within 48 hours, indicating accelerated senescence, to endothelial oxidative stress, and a fivefold and threefold increase in p21 and p16 senescence markers after 24 hours. After 12-hour incubation, the endothelial-dependent relaxation of coronary artery rings was reduced by 50%, at distinct optimal microparticle concentration. In vitro, microparticles were pro-thrombotic by up-regulating the local angiotensin system, by prompting tissue factor activity and a secondary generation of pro-coagulant endothelial microparticles. They initiated an early pro-inflammatory response by inducing phosphorylation of NF-κB, MAP kinases and Akt after 1 hour, and up-regulated VCAM-1 and ICAM-1 at 24 hours. Accordingly, VCAM-1 and COX-2 were also up-regulated in the coronary artery endothelium and eNOS down-regulated. Lipopolysaccharide specifically favoured the shedding of neutrophil- and monocyte-derived microparticles. A 80% immuno-depletion of neutrophil microparticles reduced endothelial senescence by 55%, indicating a key role. Altogether, data suggest that microparticles from activated splenocytes prompt early pro-inflammatory, pro-coagulant and pro-senescent responses in endothelial cells through redox-sensitive pathways. The control of neutrophil shedding could preserve the endothelium at site of ischaemia-reperfusion-driven inflammation and delay its dysfunction.

Epithelial-mesenchymal transition and membrane microparticles: Potential implications for bronchiolitis obliterans syndrome after lung transplantation

Long term survival post lung transplantation (LTx) is limited by the occurrence of bronchiolitis obliterans syndrome (BOS). One mechanism involved is the epithelial-mesenchymal transition (EMT). Membrane microparticles (MPs) are known to be involved in some respiratory diseases and in other organs allograft rejection episodes. We hypothesized that leukocyte-derived MPs likely contribute to EMT. To emphasize this physiological concept, our objectives were to: (1) confirm the presence of EMT on explanted lungs from patients who underwent a second LTx for BOS; 2) characterize circulating MPs in transplanted patients, with or without BOS; (3) evaluate in vitro the effect of monocyte-derived MPs in EMT of human bronchial epithelial cells. Our IHC analysis on explanted graft lungs revealed significant pathological signs of EMT with an inhomogeneous destruction of the bronchial epithelium, with decreased expression of the epithelial protein E-cadherin and increased expression of the mesenchymal protein Vimentin. The immunophenotyping of MPs demonstrated that the concentration of MPs carrying E-cadherin was lower in patients affected by BOS (p = .007). In vitro, monocyte-derived MPs produced with LPS were associated with decreased E-cadherin expression (p < .05) along with significant morphological and functional cell modifications. MPs may play a role in EMT onset in bronchial epithelium following LTx.

Assessment of plasma microvesicles to monitor pancreatic islet graft dysfunction: Beta cell- and leukocyte-derived microvesicles as specific features in a pilot longitudinal study

Markers of early pancreatic islet graft dysfunction and its causes are lacking. We monitored 19 type 1 diabetes islet-transplanted patients for up to 36 months following last islet injection. Patients were categorized as Partial (PS) or complete (S) Success, or Graft Failure (F), using the β-score as an indicator of graft function. F was the subset reference of maximum worsened graft outcome. To identify the immune, pancreatic, and liver contribution to the graft dysfunction, the cell origin and concentration of circulating microvesicles (MVs) were assessed, including MVs from insulin-secreting β-cells typified by polysialic acid of neural cell adhesion molecule (PSA-NCAM), and data were compared with values of the β-score. Similar ranges of PSA-NCAM⁺ -MVs were found in healthy volunteers and S patients, indicating minimal cell damage. In PS, a 2-fold elevation in PSA-NCAM⁺ -MVs preceded each β-score drop along with a concomitant rise in insulin needs, suggesting β-cell damage or altered function. Significant elevation of liver asialoglycoprotein receptor (ASGPR)⁺ -MVs, endothelial CD105⁺ -MVs, neutrophil CD66b⁺ -MVs, monocyte CD 14⁺ -MVs, and T4 lymphocyte CD4⁺ -MVs occurred before each β-score drop, CD8⁺ -MVs increased only in F, and B lymphocyte CD19⁺ -MVs remained undetectable. In conclusion, PSA-NCAM⁺ -MVs are noninvasive early markers of transplant dysfunction, while ASGPR⁺ -MVs signal host tissue remodeling. Leukocyte MVs could identify the cause of graft dysfunction.

Extracellular Vesicles in Type 1 Diabetes: Messengers and Regulators

PURPOSE OF REVIEW

Theories about the pathogenesis of type 1 diabetes (T1D) refer to the potential of primary islet inflammatory signaling as a trigger for the loss of self-tolerance leading to disease onset. Emerging evidence suggests that extracellular vesicles (EV) may represent the missing link between inflammation and autoimmunity. Here, we review the evidence for a role of EV in the pathogenesis of T1D, as well as discuss their potential value in the clinical sphere, as biomarkers and therapeutic agents.

RECENT FINDINGS

EV derived from β cells are enriched in diabetogenic autoantigens and miRNAs that are selectively sorted and packaged. These EV play a pivotal role in antigen presentation and cell to cell communication leading to activation of autoimmune responses. Furthermore, recent evidence suggests the potential of EV as novel tools in clinical diagnostics and therapeutic interventions. In-depth analysis of EV cargo using modern multi-parametric technologies may be useful in enhancing our understanding of EV-mediated immune mechanisms and in identifying robust biomarkers and therapeutic strategies for T1D.

[Membranous microparticles and respiratory disease]

Microparticles (MP) are plasmic membrane fragments released from cells after physiological stimulation or stress conditions like inflammation or infection. Their production is correlated to the rate of cell apoptosis. All types of cells can produce MP but they are produced mainly by platelets, endothelial cells, and leukocytes. They carry many bio-active molecules on their surface, specific to the parental cell, giving them the ability to be biomarkers and bio-effectors. MP are present in circulating blood, tissues and many biological fluids. Circulating MP levels can change during the course of many diseases. They have been the subject of many studies in the fields of cardiovascular disease and oncology. In the lungs, they are present in circulating blood and in the airways. They seem to have a role in pulmonary homeostasis in physiological situations and also in the expression of several disease processes. In this review of the literature, we were interested in the quantitative and qualitative variations in MP and their impact in airway diseases like chronic obstructive pulmonary disease (COPD) and asthma, pulmonary fibrosis and pulmonary hypertension.

The value of microparticles in detecting acute rejection episodes after liver transplantation

CONTEXT

Non-invasive markers for diagnosis of acute rejection (AR) following liver transplantation have not been developed, yet.

OBJECTIVE

We analyzed the correlation of plasma microparticle levels (MP) with AR.

MATERIALS AND METHODS

MP (CD4, CD8, CD25, CD31, MHC) of 11 AR patients and 11 controls were analyzed within the first week after transplantation.

RESULTS

CD4, CD8 and CD31 positive MP were higher in the AR, whereas overall MP count, CD25 and MHCI positive MP proportions did not differ between both groups.

DISCUSSION AND CONCLUSION

MP dynamics within the first period of transplantation could help to clarify on-going mechanisms of immunomodulation.

Detection of Donor-Derived Microparticles in the Peripheral Blood of a Hand Transplant Recipient During Rejection

BACKGROUND

Microparticles (MPs) are released from the plasma membrane of activated or dying cells and bear surface molecules from those cells. We examined whether donor-derived MPs in the peripheral blood of the recipient could serve as a marker of tissue damage due to rejection of a transplanted hand.

METHODS

Platelet-free plasma from the recipient of the transplanted hand was analyzed for MPs bearing the donor-specific HLA molecule A*02 using flow cytometry. Rejection status of the transplanted hand was monitored by histopathology of skin punch biopsies.

RESULTS

Donor-specific MPs expressing HLA A*02 were quantifiable in the peripheral blood of the recipient. Levels of these MPs increased with worsening rejection of the transplanted hand.

CONCLUSIONS

These findings demonstrate the ability to detect donor specific MPs through staining of graft cell-specific HLA and promote further investigation into the potential utility of flow cytometry for donor-derived MPs as a noninvasive tool to assess rejection in solid organ transplantation patients.

Microparticles: A new insight into lung primary graft dysfunction?

Lung transplantation is the only life-saving treatment for end stage respiratory disease. The immediate outcome is still hampered by primary graft dysfunction. The latter is a form of acute lung injury occurring within the 30min following the unclamping of the pulmonary artery that prompts ischemia reperfusion injury. Severe forms may need prolonged mechanical ventilation and extra-corporeal membrane oxygenation. Overall, primary graft dysfunction accounts for at least one third of the deaths during the first post-operative month. Despite increasing experience and knowledge on the underlying cellular events, there is still a lack of an early marker of ischemia reperfusion graft injuries. Microparticles are plasma membrane vesicles that are released from damaged or stressed cells in biological fluids and remodeling tissues, among which the lung parenchyma during acute or chronic injury. We recently evidenced alveolar microparticles as surrogate markers of strong ischemia injury in ex-vivo reperfusion experimental models. We propose herein new insights on how microparticles may be helpful to evaluate the extent of lung ischemia reperfusion injuries and predict the occurrence of primary graft dysfunction.