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The review article titled CD39 Transforming Cancer Therapy by Modulating Tumor Microenvironment published in June 2024 in Cancer Letters provides a comprehensive overview of CD39's multifaceted roles in cancer, particularly its influence on immunoregulation, angiogenesis, and metabolic reprogramming within the tumor microenvironment (TME). This commentary builds on that foundation by incorporating recent advancements in CD39 research, highlighting unresolved issues, and proposing future research directions. We delve into the therapeutic potential of targeting CD39, addressing clinical translation challenges, and exploring the integration of CD39-based strategies into precision oncology.

Intestinal epithelial cells represent the first line of defense from invading enteric pathogens. During the course of infection, pro-inflammatory programmed cell death is an effective way to eliminate invading microbes and to create a localized inflammatory environment. On the other hand, pathogens evolved countless strategies to overcome cell death and to keep the host alive ensuring their spread. It was previously shown that Shigella flexneri apyrase interacts with OmpA to contribute to a proper polar exposition of IcsA, which mediates actin-based motility. However, apyrase is also an ATP-diphosphohydrolase whose catalytic activity function has not been elucidated yet. Herein, we demonstrated that apyrase contributes to the manipulation of host cell fate by S. flexneri since it is released within the host cell cytoplasm during infection to degrade intracellular ATP. Thus, apyrase contributes to prevent caspase-1 activation, thereby downregulating the activation of pyroptosis in infected cells. Overall, apyrase is involved in the modulation of host cell survival and dampens the inflammatory response.

T cell dependent secretory IgA (SIgA) generated in the Peyer’s patches (PPs) of the small intestine shapes a broadly diverse microbiota that is crucial for host physiology. The mutualistic co-evolution of host and microbes led to the relative tolerance of host’s immune system towards commensal microorganisms. The ATP-gated ionotropic P2X7 receptor limits T follicular helper (Tfh) cells expansion and germinal center (GC) reaction in the PPs. Here we show that transient depletion of intestinal ATP can dramatically improve high-affinity IgA response against both live and inactivated oral vaccines. Ectopic expression of Shigella flexneri periplasmic ATP-diphosphohydrolase (apyrase) abolishes ATP release by bacteria and improves the specific IgA response against live oral vaccines. Antibody responses primed in the absence of intestinal extracellular ATP (eATP) also provide superior protection from enteropathogenic infection. Thus, modulation of eATP in the small intestine can affect high-affinity IgA response against gut colonizing bacteria.

Opiates are essential for treating pain, but termination of opiate therapy can cause a debilitating withdrawal syndrome in chronic users. To alleviate or avoid the aversive symptoms of withdrawal, many of these individuals continue to use opiates. Withdrawal is therefore a key determinant of opiate use in dependent individuals, yet its underlying mechanisms are poorly understood and effective therapies are lacking. Here, we identify the pannexin-1 (Panx1) channel as a therapeutic target in opiate withdrawal. We show that withdrawal from morphine induces long-term synaptic facilitation in lamina I and II neurons within the rodent spinal dorsal horn, a principal site of action for opiate analgesia. Genetic ablation of Panx1 in microglia abolished the spinal synaptic facilitation and ameliorated the sequelae of morphine withdrawal. Panx1 is unique in its permeability to molecules up to 1 kDa in size and its release of ATP. We show that Panx1 activation drives ATP release from microglia during morphine withdrawal and that degrading endogenous spinal ATP by administering apyrase produces a reduction in withdrawal behaviors. Conversely, we found that pharmacological inhibition of ATP breakdown exacerbates withdrawal. Treatment with a Panx1-blocking peptide (10panx) or the clinically used broad-spectrum Panx1 blockers, mefloquine or probenecid, suppressed ATP release and reduced withdrawal severity. Our results demonstrate that Panx1-mediated ATP release from microglia is required for morphine withdrawal in rodents and that blocking Panx1 alleviates the severity of withdrawal without affecting opiate analgesia.

Opiates are essential for treating pain, but termination of opiate therapy can cause a debilitating withdrawal syndrome in chronic users. To alleviate or avoid the aversive symptoms of withdrawal, many of these individuals continue to use opiates. Withdrawal is therefore a key determinant of opiate use in dependent individuals, yet its underlying mechanisms are poorly understood and effective therapies are lacking. Here, we identify the pannexin-1 (Panx1) channel as a therapeutic target in opiate withdrawal. We show that withdrawal from morphine induces long-term synaptic facilitation in lamina I and II neurons within the rodent spinal dorsal horn, a principal site of action for opiate analgesia. Genetic ablation of Panx1 in microglia abolished the spinal synaptic facilitation and ameliorated the sequelae of morphine withdrawal. Panx1 is unique in its permeability to molecules up to 1 kDa in size and its release of ATP. We show that Panx1 activation drives ATP release from microglia during morphine withdrawal and that degrading endogenous spinal ATP by administering apyrase produces a reduction in withdrawal behaviors. Conversely, we found that pharmacological inhibition of ATP breakdown exacerbates withdrawal. Treatment with a Panx1-blocking peptide (10panx) or the clinically used broad-spectrum Panx1 blockers, mefloquine or probenecid, suppressed ATP release and reduced withdrawal severity. Our results demonstrate that Panx1-mediated ATP release from microglia is required for morphine withdrawal in rodents and that blocking Panx1 alleviates the severity of withdrawal without affecting opiate analgesia.

Ischemia/reperfusion (I/R) elicits renin release from cardiac mast cells (MC), thus activating a local renin-angiotensin system (RAS), culminating in ventricular fibrillation. We hypothesized that in I/R, neurogenic ATP could degranulate juxtaposed MC and that ecto-nucleoside triphosphate diphosphohydrolase 1/CD39 (CD39) on MC membrane could modulate ATP-induced renin release. We report that pharmacological inhibition of CD39 in a cultured human mastocytoma cell line (HMC-1) and murine bone marrow-derived MC with ARL67156 (100 µM) increased ATP-induced renin release (≥2-fold), whereas purinergic P2X7 receptors (P2X7R) blockade with A740003 (3 µM) prevented it. Likewise, CD39 RNA silencing in HMC-1 increased ATP-induced renin release (≥2-fold), whereas CD39 overexpression prevented it. Acetaldehyde, an I/R product (300 µM), elicited an 80% increase in ATP release from HMC-1, in turn, causing an autocrine 20% increase in renin release. This effect was inhibited or potentiated when CD39 was overexpressed or silenced, respectively. Moreover, P2X7R silencing prevented ATP- and acetaldehyde-induced renin release. I/R-induced RAS activation in ex vivo murine hearts, characterized by renin and norepinephrine overflow and ventricular fibrillation, was potentiated (∼2-fold) by CD39 inhibition, an effect prevented by P2X7R blockade. Our data indicate that by regulating ATP availability at the MC surface, CD39 modulates local renin release and thus, RAS activation, ultimately exerting a cardioprotective effect.

Human Ag-specific CD4+ T cells can be detected by their dual expression of CD134 (OX40) and CD25 after a 44 hours stimulation with cognate Ag. We show that surface expression of CD39 on Ag-specific cells consistently identifies a substantial population of CD4+CD25+CD134+CD39+ T cells that have a Treg-cell-like phenotype and mostly originate from bulk memory CD4+CD45RO+CD127lowCD25highCD39+ Treg cells. Viable, Ag-specific CD25+CD134+CD39+ T cells could be expanded in vitro as cell lines and clones, and retained high Forkhead Box Protein 3, CTLA-4 and CD39 expression, suppressive activity and Ag specificity. We also utilised this combination of cell surface markers to measure HIV-Gag responses in HIV+ patients before and after anti-retroviral therapy (ART). Interestingly, we found that the percentage of CD39- cells within baseline CD4+ T-cell responses to HIV-Gag was negatively correlated with HIV viral load pre-ART and positively correlated with CD4+ T-cell recovery over 96 weeks of ART. Collectively, our data show that Ag-specific CD4+CD25+CD134+CD39+ T cells are highly enriched for Treg cells, form a large component of recall responses and maintain a Treg-cell-like phenotype upon in vitro expansion. Identification and isolation of these cells enables the role of Treg cells in memory responses to be further defined and provides a development pathway for novel therapeutics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Activation of the thrombotic and complement systems is the main recognition and effector mechanisms in the multiple adverse biological responses triggered when biomaterials or therapeutic cells come into blood contact. We have created a surface which is auto-protective to human innate immunity by combining three fundamentally different strategies, all developed by us previously, which have been shown to induce substantial, but incomplete hemocompatibility when used separately. In summary, we have conjugated a factor H-binding peptide; and an ADP-degrading enzyme; using a PEG linker on both material and cellular surfaces. When exposed to human whole blood, factor H was specifically recruited to the modified surfaces and inhibited complement attack. In addition, activation of platelets and coagulation was efficiently attenuated, by degrading ADP. Thus, by inhibiting thromboinflammation using a multicomponent approach, we have created a hybrid surface with the potential to greatly reduce incompatibility reactions involving biomaterials and transplantation., K.N.E., J.D.L., B.N. and Y.T. equally contributed to this paper as a supervisor.

Activation of the thrombotic and complement systems is the main recognition and effector mechanisms in the multiple adverse biological responses triggered when biomaterials or therapeutic cells come into blood contact. We have created a surface which is auto-protective to human innate immunity by combining three fundamentally different strategies, all developed by us previously, which have been shown to induce substantial, but incomplete hemocompatibility when used separately. In summary, we have conjugated a factor H-binding peptide; and an ADP-degrading enzyme; using a PEG linker on both material and cellular surfaces. When exposed to human whole blood, factor H was specifically recruited to the modified surfaces and inhibited complement attack. In addition, activation of platelets and coagulation was efficiently attenuated, by degrading ADP. Thus, by inhibiting thromboinflammation using a multicomponent approach, we have created a hybrid surface with the potential to greatly reduce incompatibility reactions involving biomaterials and transplantation., K.N.E., J.D.L., B.N. and Y.T. equally contributed to this paper as a supervisor.

Activation of the thrombotic and complement systems is the main recognition and effector mechanisms in the multiple adverse biological responses triggered when biomaterials or therapeutic cells come into blood contact. We have created a surface which is auto-protective to human innate immunity by combining three fundamentally different strategies, all developed by us previously, which have been shown to induce substantial, but incomplete hemocompatibility when used separately. In summary, we have conjugated a factor H-binding peptide; and an ADP-degrading enzyme; using a PEG linker on both material and cellular surfaces. When exposed to human whole blood, factor H was specifically recruited to the modified surfaces and inhibited complement attack. In addition, activation of platelets and coagulation was efficiently attenuated, by degrading ADP. Thus, by inhibiting thromboinflammation using a multicomponent approach, we have created a hybrid surface with the potential to greatly reduce incompatibility reactions involving biomaterials and transplantation., K.N.E., J.D.L., B.N. and Y.T. equally contributed to this paper as a supervisor.

Activation of the thrombotic and complement systems is the main recognition and effector mechanisms in the multiple adverse biological responses triggered when biomaterials or therapeutic cells come into blood contact. We have created a surface which is auto-protective to human innate immunity by combining three fundamentally different strategies, all developed by us previously, which have been shown to induce substantial, but incomplete hemocompatibility when used separately. In summary, we have conjugated a factor H-binding peptide; and an ADP-degrading enzyme; using a PEG linker on both material and cellular surfaces. When exposed to human whole blood, factor H was specifically recruited to the modified surfaces and inhibited complement attack. In addition, activation of platelets and coagulation was efficiently attenuated, by degrading ADP. Thus, by inhibiting thromboinflammation using a multicomponent approach, we have created a hybrid surface with the potential to greatly reduce incompatibility reactions involving biomaterials and transplantation., K.N.E., J.D.L., B.N. and Y.T. equally contributed to this paper as a supervisor.

Activation of the thrombotic and complement systems is the main recognition and effector mechanisms in the multiple adverse biological responses triggered when biomaterials or therapeutic cells come into blood contact. We have created a surface which is auto-protective to human innate immunity by combining three fundamentally different strategies, all developed by us previously, which have been shown to induce substantial, but incomplete hemocompatibility when used separately. In summary, we have conjugated a factor H-binding peptide; and an ADP-degrading enzyme; using a PEG linker on both material and cellular surfaces. When exposed to human whole blood, factor H was specifically recruited to the modified surfaces and inhibited complement attack. In addition, activation of platelets and coagulation was efficiently attenuated, by degrading ADP. Thus, by inhibiting thromboinflammation using a multicomponent approach, we have created a hybrid surface with the potential to greatly reduce incompatibility reactions involving biomaterials and transplantation., K.N.E., J.D.L., B.N. and Y.T. equally contributed to this paper as a supervisor.

Disturbances of host integrity have the potential to evoke activation of innate immunologic and hemostatic protection mechanisms in blood. Irrespective of whether the activating stimulus is typically immunogenic or thrombotic, it will generally affect both the complement system and platelets to a certain degree. The theme of this thesis is complement and platelet activity, which is intersected in all five included papers. The initial aim was to study the responses and mechanisms of the complement cascade in relation to platelet activation. The secondary aim was to use an applied approach to regulate platelets and complement on model biomaterial and cell surfaces. Complement activation was found in the fluid phase in response to platelet activation in whole blood. The mechanism was traced to platelet release of stored chondroitin sulfate-A (CS-A) and classical pathway activation via C1q. C3 was detected at the platelet surface, though its binding was independent of complement activation. The inhibitors factor H and C4-binding protein (C4BP) were detected on activated platelets, and their binding was partly dependent on surface-exposed CS-A. Collectively, these results showed that platelet activation induces inflammatory complement activation in the fluid phase. CS-A was shown to be a central molecule in the complement-modulatory functions of platelets by its interaction with C1q, C4BP, and factor H. Platelet activation and surface adherence were successfully attenuated by conjugating an ADP-degrading apyrase on a model biomaterial. Only minor complement regulation was seen, and was therefore targeted specifically on surfaces and cells by co-immobilizing a factor H-binding peptide together with the apyrase. This combined approach led to a synchronized inhibition of both platelet and complement activation at the interface of biomaterials/xenogeneic cells and blood. In conclusion, here presents a novel crosstalk-mechanism for activation of complement when triggering

Disturbances of host integrity have the potential to evoke activation of innate immunologic and hemostatic protection mechanisms in blood. Irrespective of whether the activating stimulus is typically immunogenic or thrombotic, it will generally affect both the complement system and platelets to a certain degree. The theme of this thesis is complement and platelet activity, which is intersected in all five included papers. The initial aim was to study the responses and mechanisms of the complement cascade in relation to platelet activation. The secondary aim was to use an applied approach to regulate platelets and complement on model biomaterial and cell surfaces. Complement activation was found in the fluid phase in response to platelet activation in whole blood. The mechanism was traced to platelet release of stored chondroitin sulfate-A (CS-A) and classical pathway activation via C1q. C3 was detected at the platelet surface, though its binding was independent of complement activation. The inhibitors factor H and C4-binding protein (C4BP) were detected on activated platelets, and their binding was partly dependent on surface-exposed CS-A. Collectively, these results showed that platelet activation induces inflammatory complement activation in the fluid phase. CS-A was shown to be a central molecule in the complement-modulatory functions of platelets by its interaction with C1q, C4BP, and factor H. Platelet activation and surface adherence were successfully attenuated by conjugating an ADP-degrading apyrase on a model biomaterial. Only minor complement regulation was seen, and was therefore targeted specifically on surfaces and cells by co-immobilizing a factor H-binding peptide together with the apyrase. This combined approach led to a synchronized inhibition of both platelet and complement activation at the interface of biomaterials/xenogeneic cells and blood. In conclusion, here presents a novel crosstalk-mechanism for activation of complement when triggering

Disturbances of host integrity have the potential to evoke activation of innate immunologic and hemostatic protection mechanisms in blood. Irrespective of whether the activating stimulus is typically immunogenic or thrombotic, it will generally affect both the complement system and platelets to a certain degree. The theme of this thesis is complement and platelet activity, which is intersected in all five included papers. The initial aim was to study the responses and mechanisms of the complement cascade in relation to platelet activation. The secondary aim was to use an applied approach to regulate platelets and complement on model biomaterial and cell surfaces. Complement activation was found in the fluid phase in response to platelet activation in whole blood. The mechanism was traced to platelet release of stored chondroitin sulfate-A (CS-A) and classical pathway activation via C1q. C3 was detected at the platelet surface, though its binding was independent of complement activation. The inhibitors factor H and C4-binding protein (C4BP) were detected on activated platelets, and their binding was partly dependent on surface-exposed CS-A. Collectively, these results showed that platelet activation induces inflammatory complement activation in the fluid phase. CS-A was shown to be a central molecule in the complement-modulatory functions of platelets by its interaction with C1q, C4BP, and factor H. Platelet activation and surface adherence were successfully attenuated by conjugating an ADP-degrading apyrase on a model biomaterial. Only minor complement regulation was seen, and was therefore targeted specifically on surfaces and cells by co-immobilizing a factor H-binding peptide together with the apyrase. This combined approach led to a synchronized inhibition of both platelet and complement activation at the interface of biomaterials/xenogeneic cells and blood. In conclusion, here presents a novel crosstalk-mechanism for activation of complement when triggering

Disturbances of host integrity have the potential to evoke activation of innate immunologic and hemostatic protection mechanisms in blood. Irrespective of whether the activating stimulus is typically immunogenic or thrombotic, it will generally affect both the complement system and platelets to a certain degree. The theme of this thesis is complement and platelet activity, which is intersected in all five included papers. The initial aim was to study the responses and mechanisms of the complement cascade in relation to platelet activation. The secondary aim was to use an applied approach to regulate platelets and complement on model biomaterial and cell surfaces. Complement activation was found in the fluid phase in response to platelet activation in whole blood. The mechanism was traced to platelet release of stored chondroitin sulfate-A (CS-A) and classical pathway activation via C1q. C3 was detected at the platelet surface, though its binding was independent of complement activation. The inhibitors factor H and C4-binding protein (C4BP) were detected on activated platelets, and their binding was partly dependent on surface-exposed CS-A. Collectively, these results showed that platelet activation induces inflammatory complement activation in the fluid phase. CS-A was shown to be a central molecule in the complement-modulatory functions of platelets by its interaction with C1q, C4BP, and factor H. Platelet activation and surface adherence were successfully attenuated by conjugating an ADP-degrading apyrase on a model biomaterial. Only minor complement regulation was seen, and was therefore targeted specifically on surfaces and cells by co-immobilizing a factor H-binding peptide together with the apyrase. This combined approach led to a synchronized inhibition of both platelet and complement activation at the interface of biomaterials/xenogeneic cells and blood. In conclusion, here presents a novel crosstalk-mechanism for activation of complement when triggering

Extracellular adenosine (ADO), generated from ATP or ADP through the concerted action of the ectoenzymes CD39 and CD73, elicits autocrine and paracrine effects mediated by type 1 purinergic receptors. We have tested whether the expression of CD39 and CD73 by chronic lymphocytic leukemia (CLL) cells activates an adenosinergic axis affecting growth and survival. By immunohistochemistry, CD39 is widely expressed in CLL lymph nodes, whereas CD73 is restricted to proliferation centers. CD73 expression is highest on Ki-67(+) CLL cells, adjacent to T lymphocytes, and is further localized to perivascular areas. CD39(+)/CD73(+) CLL cells generate ADO from ADP in a time- and concentration-dependent manner. In peripheral blood, CD73 expression occurs in 97/299 (32%) CLL patients and pairs with CD38 and ZAP-70 expression. CD73-generated extracellular ADO activates type 1 purinergic A2A receptors that are constitutively expressed by CLL cells and that are further elevated in proliferating neoplastic cells. Activation of the ADO receptors increases cytoplasmic cAMP levels, inhibiting chemotaxis and limiting spontaneous drug-induced apoptosis of CLL cells. These data are consistent with the existence of an autocrine adenosinergic loop, and support engraftment of leukemic cells in growth-favorable niches, while simultaneously protecting from the action of chemotherapeutic agents.

In myocardial ischemia-reperfusion (I/R) injury, complement activation, tissue plasminogen activator (t-PA) and extracellular adenosine triphosphate (ATP) release contribute to myocardial injury. ATP is degraded into adenosine by the enzyme apyrase, and adenosine possesses cardioprotective properties. ADC-1004 is an antagonist of the receptor to the activated complement factor C5a. Hypothermia has been shown to suppress the development of I/R injury. In this thesis, the cardioprotective effects of ADC-1004 (paper I), apyrase (paper II) and hy- pothermia (paper III) were investigated. The effects of hypothermia on coronary t-PA release (paper IV), and on systemic t-PA release in cardiogenic shock (paper V) were also studied. An experimental porcine ischemia/reperfusion model was used. Infarct size (IS), microvascular obstruction and area at risk (AAR) were measured with ex-vivo MRI and SPECT. ADC-1004 treatment (paper I) was found to reduce infarct size (ADC-1004: 58.3±3.4 vs control: 74.1±2.9 %AAR, p=0.007) but not microvascular obstruction (ADC-1004: 2.2±1.2 vs control: 5.3±2.5 %AAR, p=NS). Treatment with apyrase (paper II) did not reduce infarct size (apyrase: 75.7±4.2 vs saline: 69.4±5.0 %AAR, p=NS) nor microvascular obstruction (apyrase: 10.7±4.8 vs saline: 11.4±4.8 %IS, p=NS). Hypothermia (paper III) reduced both infarct size (hypothermia: 60.8±4.9 vs normothermia: 73.8±4.0 %AAR, p<0.05) and microvascular obstruction (hypothermia: 0.5±0.5 vs normothermia: 21.5±5.2 %IS, p<0.001). Hypothermia also inhibited an increase in coronary net t-PA release during reperfusion (paper IV; hypothermia: 0.79±0.45 ng/ml vs normothermia: 9.44±4.34 ng/ml, p<0.05); and an increase in systemic net t-PA release in cardiogenic shock (paper V; hypothermia: 0.60 ± 0.12 ng/ml vs normothermia: 2.16 ± 1.09 ng/ml, p<0.05). In conclusion, complement inhibition by ADC-1004 and therapeutic hypothermia reduces myocardial ischemia-reperfusion injury, and represents clinically applicable treatme

Blood incompatibility reactions caused by surfaces often involve platelet activation and subsequent platelet-initiated activation of the coagulation and complement cascades. The goal of this study was to immobilize apyrase on a biomaterial surface in order to develop an enzymatically active surface that would have the capacity to inhibit platelet activation by degrading ADP. We were able to immobilize apyrase on a polystyrene surface with preservation of the enzymatic activity. We then analyzed the hemocompatibility of the apyrase surface and of control surfaces by incubation with platelet-rich plasma (PRP) or whole blood. Monitoring of markers of platelet, coagulation, and complement activation and staining of the surfaces revealed decreased levels of platelet and coagulation activation parameters on the apyrase surface. The formation of antithrombin-thrombin and antithrombin-factor XIa complexes and the extent of platelet consumption were significantly lower on the apyrase surface than on any of the control surfaces. No significant differences were seen in complement activation (C3a levels). Staining of the apyrase surface revealed low platelet adherence and no formation of granulocyte-platelet complexes. These results demonstrate that it is possible to create an antithrombotic surface targeting the ADP amplification of platelet activation by immobilizing apyrase.

Blood incompatibility reactions caused by surfaces often involve platelet activation and subsequent platelet-initiated activation of the coagulation and complement cascades. The goal of this study was to immobilize apyrase on a biomaterial surface in order to develop an enzymatically active surface that would have the capacity to inhibit platelet activation by degrading ADP. We were able to immobilize apyrase on a polystyrene surface with preservation of the enzymatic activity. We then analyzed the hemocompatibility of the apyrase surface and of control surfaces by incubation with platelet-rich plasma (PRP) or whole blood. Monitoring of markers of platelet, coagulation, and complement activation and staining of the surfaces revealed decreased levels of platelet and coagulation activation parameters on the apyrase surface. The formation of antithrombin-thrombin and antithrombin-factor XIa complexes and the extent of platelet consumption were significantly lower on the apyrase surface than on any of the control surfaces. No significant differences were seen in complement activation (C3a levels). Staining of the apyrase surface revealed low platelet adherence and no formation of granulocyte platelet complexes. These results demonstrate that it is possible to create an antithrombotic surface targeting the ADP amplification of platelet activation by immobilizing apyrase.

Objective: Hypothermia is employed in cardiac surgery to inhibit ischemia-related organ damage. However, hypothermia causes platelet activation and dysfunction, which can result in bleeding as well as thrombotic complications. Method(s): Platelet adhesion and spreading on different physiologically relevant surfaces was investigated at normothermia (37degreeC), hypothermia (18-28degreeC) and after rewarming under ex vivo flow and static conditions. In mice with body temperatures of 37degreeC and 28degreeC tail bleeding times were assessed and platelet aggregation in mesenteric arteries examined using intravital microscopy. Platelet agonist ADP levels and ADPase CD39 activity were determined using bioluminometry and thin layer chromatography. Result(s): Bleeding times as well as platelet-collagen and platelet-vWF adhesion at physiological flow are reversibly prolonged by hypothermia. Furthermore, hypothermia causes a partially reversible platelet spreading defect. In contrast, platelet thrombi formed in vivo at hypothermia are 2.2-fold larger (p < 0.001) and dissagregate 5-fold less (p < 0.001) compared to normothermia. This is paralleled by a 2.2-fold increase of platelet-fibrinogen adhesion (p < 0.001). Hypothermia reduces CD39-activity, subsequently impairing ADP degradation and increasing ADP-mediated platelet activation. Administration of platelet ADP receptor P2Y12 antagonists reverses hypothermia-induced platelet thrombus formation in vivo. Conclusion(s): Most hypothermia induced platelet function-inhibiting effects are reversible on rewarming. Hypothermia-induced platelet activation can be explained by the observed reduction of CD39 ADP-metabolising activity. We present a novel concept of platelet protection against activation during hypothermia, which is based on P2Y12 inhibition. Because short-acting intravenously applicable P2Y12-blockers may soon be clinically available further clinical studies demonstrating the transferability of our concept into clinical

Objective: Hypothermia is employed in cardiac surgery to inhibit ischemia-related organ damage. However, hypothermia causes platelet activation and dysfunction, which can result in bleeding as well as thrombotic complications. Method(s): Platelet adhesion and spreading on different physiologically relevant surfaces was investigated at normothermia (37degreeC), hypothermia (18-28degreeC) and after rewarming under ex vivo flow and static conditions. In mice with body temperatures of 37degreeC and 28degreeC tail bleeding times were assessed and platelet aggregation in mesenteric arteries examined using intravital microscopy. Platelet agonist ADP levels and ADPase CD39 activity were determined using bioluminometry and thin layer chromatography. Result(s): Bleeding times as well as platelet-collagen and platelet-vWF adhesion at physiological flow are reversibly prolonged by hypothermia. Furthermore, hypothermia causes a partially reversible platelet spreading defect. In contrast, platelet thrombi formed in vivo at hypothermia are 2.2-fold larger (p < 0.001) and dissagregate 5-fold less (p < 0.001) compared to normothermia. This is paralleled by a 2.2-fold increase of platelet-fibrinogen adhesion (p < 0.001). Hypothermia reduces CD39-activity, subsequently impairing ADP degradation and increasing ADP-mediated platelet activation. Administration of platelet ADP receptor P2Y12 antagonists reverses hypothermia-induced platelet thrombus formation in vivo. Conclusion(s): Most hypothermia induced platelet function-inhibiting effects are reversible on rewarming. Hypothermia-induced platelet activation can be explained by the observed reduction of CD39 ADP-metabolising activity. We present a novel concept of platelet protection against activation during hypothermia, which is based on P2Y12 inhibition. Because short-acting intravenously applicable P2Y12-blockers may soon be clinically available further clinical studies demonstrating the transferability of our concept into clinical

Blood incompatibility reactions caused by surfaces often involve platelet activation and subsequent platelet-initiated activation of the coagulation and complement cascades. The goal of this study was to immobilize apyrase on a biomaterial surface in order to develop an enzymatically active surface that would have the capacity to inhibit platelet activation by degrading ADP. We were able to immobilize apyrase on a polystyrene surface with preservation of the enzymatic activity. We then analyzed the hemocompatibility of the apyrase surface and of control surfaces by incubation with platelet-rich plasma (PRP) or whole blood. Monitoring of markers of platelet, coagulation, and complement activation and staining of the surfaces revealed decreased levels of platelet and coagulation activation parameters on the apyrase surface. The formation of antithrombin-thrombin and antithrombin-factor XIa complexes and the extent of platelet consumption were significantly lower on the apyrase surface than on any of the control surfaces. No significant differences were seen in complement activation (C3a levels). Staining of the apyrase surface revealed low platelet adherence and no formation of granulocyte platelet complexes. These results demonstrate that it is possible to create an antithrombotic surface targeting the ADP amplification of platelet activation by immobilizing apyrase.

The mechanisms that lead to loss of tolerance in autoimmune disease have remained both elusive and diverse, including both genetic predisposition and generic dysregulation of critical mononuclear cell subsets. In primary biliary cirrhosis (PBC), patients exhibit a multilineage response to the E2 component of pyruvate dehydrogenase involving antibody as well as autoreactive CD4 and CD8 responses. Recent data from murine models of PBC have suggested that a critical mechanism of biliary destruction is mediated by liver-infiltrating CD8 cells. Further, the number of autoreactive liver-infiltrating CD4 and CD8 cells is significantly higher in liver than blood in patients with PBC. Based on this data, we have studied the frequencies and phenotypic characterization of both CD4 and CD8 regulatory T cell components in both patients with PBC and age-sex matched controls. Our data is striking and indicate that CD8 Treg populations from PBC patients, but not controls, have significant phenotypic alterations, including increased expression of CD127 and reduced CD39. Furthermore, in vitro induction of CD8 Tregs by incubation with IL10 is significantly reduced in PBC patients. Importantly, the frequencies of circulating CD4+CD25+ and CD8+ and CD28- T cell subpopulations are not significantly different between patients and controls. In conclusion, these data identify the CD8 Treg subset as a regulatory T cell subpopulation altered in patients with PBC. © 2010 Elsevier Ltd

Blebbistatin is a small-molecule, high-affinity, noncompetitive inhibitor of myosin II. We have used negative staining electron microscopy to study the effects of blebbistatin on the organization of the myosin heads on muscle thick filaments. Loss of ADP and Pi from the heads causes thick filaments to lose their helical ordering. In the presence of 100 microM blebbistatin, disordering was at least 10 times slower. In the M.ADP state, myosin heads are also disordered. When blebbistatin was added to M.ADP thick filaments, helical ordering was restored. However, blebbistatin did not improve the order of thick filaments lacking bound nucleotide. Addition of calcium to relaxed muscle homogenates induced thick-thin filament interaction and filament sliding. In the presence of blebbistatin, filament interaction was inhibited. These structural observations support the conclusion, based on biochemical studies, that blebbistatin inhibits myosin ATPase and actin interaction by stabilizing the closed switch 2 structure of the myosin head. These properties make blebbistatin a useful tool in structural and functional studies of cell motility and muscle contraction.

QC 20101222

In this thesis techniques are presented that aim to determine individual DNA signatures by controlled synthesis of nucleic acid multimers. Allele-specific extension reactions with an improved specificity were applied for several genomic purposes. Since DNA polymerases extend some mismatched 3’-end primers, an improved specificity is a concern. This has been possible by exploiting the faster extension of matched primers and applying the enzymes apyrase or Proteinase K. The findings were applied to methods for resequencing and viral and single nucleotide polymorphism (SNP) genotyping. P53 mutation is the most frequent event in human cancers. Here, a model system for resequencing of 15 bps in p53 based on apyrase-mediated allele-specific extension (AMASE) is described, investigated and evaluated (Paper I). A microarray format with fluorescence detection was used. On each array, four oligonucleotides were printed for each base to resequence. Target PCR products were hybridized and an AMASE-reaction performed in situ to distinguish which of the printed oligonucleotides matched the target. The results showed that without the inclusion of apyrase, the resulting sequence was unreadable. The results open the possibilities for developing large-scale resequencing tools. The presence of certain types of human papillomaviruses (HPV) transforms normal cells into cervical cancer cells. Thus, HPV type determination is clinically important. Also, multiple HPV infections are common but difficult to distinguish. Therefore, a genotyping platform based on competitive hybridization and AMASE is described, used on clinical sample material and evaluated by comparison to Sanger DNA sequencing (Papers II and III). A flexible tag-microarray was used for detection and the two levels of discrimination gave a high level of specificity. Easy identification of multiple infections was possible which provides new opportunities to investigate the importance of multiply infected samples. To achieve hi, QC 20101028

In this thesis techniques are presented that aim to determine individual DNA signatures by controlled synthesis of nucleic acid multimers. Allele-specific extension reactions with an improved specificity were applied for several genomic purposes. Since DNA polymerases extend some mismatched 3’-end primers, an improved specificity is a concern. This has been possible by exploiting the faster extension of matched primers and applying the enzymes apyrase or Proteinase K. The findings were applied to methods for resequencing and viral and single nucleotide polymorphism (SNP) genotyping. P53 mutation is the most frequent event in human cancers. Here, a model system for resequencing of 15 bps in p53 based on apyrase-mediated allele-specific extension (AMASE) is described, investigated and evaluated (Paper I). A microarray format with fluorescence detection was used. On each array, four oligonucleotides were printed for each base to resequence. Target PCR products were hybridized and an AMASE-reaction performed in situ to distinguish which of the printed oligonucleotides matched the target. The results showed that without the inclusion of apyrase, the resulting sequence was unreadable. The results open the possibilities for developing large-scale resequencing tools. The presence of certain types of human papillomaviruses (HPV) transforms normal cells into cervical cancer cells. Thus, HPV type determination is clinically important. Also, multiple HPV infections are common but difficult to distinguish. Therefore, a genotyping platform based on competitive hybridization and AMASE is described, used on clinical sample material and evaluated by comparison to Sanger DNA sequencing (Papers II and III). A flexible tag-microarray was used for detection and the two levels of discrimination gave a high level of specificity. Easy identification of multiple infections was possible which provides new opportunities to investigate the importance of multiply infected samples. To achieve hi, QC 20101028

In this thesis techniques are presented that aim to determine individual DNA signatures by controlled synthesis of nucleic acid multimers. Allele-specific extension reactions with an improved specificity were applied for several genomic purposes. Since DNA polymerases extend some mismatched 3’-end primers, an improved specificity is a concern. This has been possible by exploiting the faster extension of matched primers and applying the enzymes apyrase or Proteinase K. The findings were applied to methods for resequencing and viral and single nucleotide polymorphism (SNP) genotyping. P53 mutation is the most frequent event in human cancers. Here, a model system for resequencing of 15 bps in p53 based on apyrase-mediated allele-specific extension (AMASE) is described, investigated and evaluated (Paper I). A microarray format with fluorescence detection was used. On each array, four oligonucleotides were printed for each base to resequence. Target PCR products were hybridized and an AMASE-reaction performed in situ to distinguish which of the printed oligonucleotides matched the target. The results showed that without the inclusion of apyrase, the resulting sequence was unreadable. The results open the possibilities for developing large-scale resequencing tools. The presence of certain types of human papillomaviruses (HPV) transforms normal cells into cervical cancer cells. Thus, HPV type determination is clinically important. Also, multiple HPV infections are common but difficult to distinguish. Therefore, a genotyping platform based on competitive hybridization and AMASE is described, used on clinical sample material and evaluated by comparison to Sanger DNA sequencing (Papers II and III). A flexible tag-microarray was used for detection and the two levels of discrimination gave a high level of specificity. Easy identification of multiple infections was possible which provides new opportunities to investigate the importance of multiply infected samples. To achieve hi, QC 20101028

In this thesis techniques are presented that aim to determine individual DNA signatures by controlled synthesis of nucleic acid multimers. Allele-specific extension reactions with an improved specificity were applied for several genomic purposes. Since DNA polymerases extend some mismatched 3’-end primers, an improved specificity is a concern. This has been possible by exploiting the faster extension of matched primers and applying the enzymes apyrase or Proteinase K. The findings were applied to methods for resequencing and viral and single nucleotide polymorphism (SNP) genotyping. P53 mutation is the most frequent event in human cancers. Here, a model system for resequencing of 15 bps in p53 based on apyrase-mediated allele-specific extension (AMASE) is described, investigated and evaluated (Paper I). A microarray format with fluorescence detection was used. On each array, four oligonucleotides were printed for each base to resequence. Target PCR products were hybridized and an AMASE-reaction performed in situ to distinguish which of the printed oligonucleotides matched the target. The results showed that without the inclusion of apyrase, the resulting sequence was unreadable. The results open the possibilities for developing large-scale resequencing tools. The presence of certain types of human papillomaviruses (HPV) transforms normal cells into cervical cancer cells. Thus, HPV type determination is clinically important. Also, multiple HPV infections are common but difficult to distinguish. Therefore, a genotyping platform based on competitive hybridization and AMASE is described, used on clinical sample material and evaluated by comparison to Sanger DNA sequencing (Papers II and III). A flexible tag-microarray was used for detection and the two levels of discrimination gave a high level of specificity. Easy identification of multiple infections was possible which provides new opportunities to investigate the importance of multiply infected samples. To achieve hi, QC 20101028

Alterations in the p53 tumor suppressor gene are important events in many cases of human cancers. We have developed a novel microarray based approach for re-sequencing and mutation detection of the p53 gene. The method facilitates rapid and simple scanning of the target gene sequence and could be expanded to include other candidate cancer genes. The methodology employs the previously described apyrase-mediated allele-specific extension reaction (AMASE). In order to re-sequence the selected region, four extension oligonucleotides with different 3'-termini were used for each base position and they were covalently attached to the glass slide's surface. The amplified single-stranded DNA templates were then hybridized to the array followed by in situ extension with fluorescently labeled dNTPs in the presence of apyrase. The model system used was based on analysis of a 15 bp stretch in exon 5 of the p53 gene. Mutations were scored as allelic fractions calculated as (wt)/(wt + mut) signals. When apyrase was included in the extension reactions of wild type templates, the mean allelic fraction was 0.96. When apyrase was excluded with the same wild type templates, significantly lower allelic fractions were obtained. Two 60-mer synthetic oligonucleotides were used to establish the detectable amount of mutations with AMASE and a clear distinction between all the points could be made. Several samples from different stages of skin malignancies were also analyzed. The results from this study imply the possibility to efficiently and accurately re-sequence the entire p53 gene with AMASE technology., QC 20100922 QC 20110923

The Pyrosequencing(TM) technology is a newly developed DNA sequencing method that monitors DNA nucleotide incorporation in real-time. A set of coupled enzymatic reactions, together with bioluminescence, detects incorporated nucleotides in the form of light pulses, yielding a characteristic light profile. In this study, a biochemical model of the Pyrosequencing reaction system is suggested and implemented. The model is constructed utilizing an assumption of irreversible Michaelis-Menten rate equations and a constant incorporation efficiency. The kinetic parameters are studied and values are chosen to obtain as reliable simulation results as possible. The results presented here show strong resemblance with real experiments. The model is able to capture the dynamics of a single light pulse with great accuracy, as well as the overall characteristics of a whole pyrogram(TM). The plus- and minus-shift effects observed in experiments are successfully reconstructed by two constant efficiency factors. Furthermore, pulse broadening can partly be explained by apyrase inhibition and successive dilution., QC 20100525 QC 20111101

Pyrosequencing is a DNA sequencing method based on thedetection of released pyrophosphate (PPi) during DNA synthesis.In a cascade of enzymatic reactions, visible light isgenerated, which is proportional to the number of nucleotidesincorporated into the DNA template. When dNTP(s) areincorporated into the DNA template, inorganic PPi is released.The released PPi is converted to ATP by ATP sulfurylase, whichprovides the energy to luciferase to oxidize luciferin andgenerate light. The excess of dNTP(s) and the ATP produced areremoved by the nucleotide degrading enzyme apyrase. The commercially available enzymes, isolated from nativesources, show batch-tobatch variations in activity and quality,which decrease the efficiency of the Pyrosequencing reaction.Therefore, the aim of the research presented in this thesis wasto develop methods to recombinantly produce the enzymes used inthe Pyrosequencing method. Production of the nucleotidedegrading enzyme apyrase by Pichia pastoris expression system,both in small-scale and in an optimized large-scale bioreactor,is described. ATP sulfurylase, the second enzyme in thePyrosequencing reaction, was produced inEscherichia coli. The protein was purified and utilizedin the Pyrosequencing method. Problems associated with enzymecontamination (NDP kinase) and batch-to-batch variations wereeliminated by the use of the recombinant ATP sulfurylase. As a first step towards sequencing on chip-format,SSB-(single-strand DNA binding protein)-luciferase and KlenowDNA polymerase-luciferase fusion proteins were generated inorder to immobilize the luciferase onto the DNA template. The application field for the Pyrosequencing technology wasexpanded by introduction of a new method for clone checking anda new method for template preparation prior the Pyrosequencingreaction. Keywords:apyrase, Pyrosequencing technology, Zbasictag fusion, luciferase, ATP sulfurylase, dsDNAsequencing, clone checking, Klenow-luciferase, SSB-luciferase,Pichia pastoris, Echeric

Pyrosequencing is a DNA sequencing method based on thedetection of released pyrophosphate (PPi) during DNA synthesis.In a cascade of enzymatic reactions, visible light isgenerated, which is proportional to the number of nucleotidesincorporated into the DNA template. When dNTP(s) areincorporated into the DNA template, inorganic PPi is released.The released PPi is converted to ATP by ATP sulfurylase, whichprovides the energy to luciferase to oxidize luciferin andgenerate light. The excess of dNTP(s) and the ATP produced areremoved by the nucleotide degrading enzyme apyrase. The commercially available enzymes, isolated from nativesources, show batch-tobatch variations in activity and quality,which decrease the efficiency of the Pyrosequencing reaction.Therefore, the aim of the research presented in this thesis wasto develop methods to recombinantly produce the enzymes used inthe Pyrosequencing method. Production of the nucleotidedegrading enzyme apyrase by Pichia pastoris expression system,both in small-scale and in an optimized large-scale bioreactor,is described. ATP sulfurylase, the second enzyme in thePyrosequencing reaction, was produced inEscherichia coli. The protein was purified and utilizedin the Pyrosequencing method. Problems associated with enzymecontamination (NDP kinase) and batch-to-batch variations wereeliminated by the use of the recombinant ATP sulfurylase. As a first step towards sequencing on chip-format,SSB-(single-strand DNA binding protein)-luciferase and KlenowDNA polymerase-luciferase fusion proteins were generated inorder to immobilize the luciferase onto the DNA template. The application field for the Pyrosequencing technology wasexpanded by introduction of a new method for clone checking anda new method for template preparation prior the Pyrosequencingreaction. Keywords:apyrase, Pyrosequencing technology, Zbasictag fusion, luciferase, ATP sulfurylase, dsDNAsequencing, clone checking, Klenow-luciferase, SSB-luciferase,Pichia pastoris, Echeric

Pyrosequencing is a DNA sequencing method based on thedetection of released pyrophosphate (PPi) during DNA synthesis.In a cascade of enzymatic reactions, visible light isgenerated, which is proportional to the number of nucleotidesincorporated into the DNA template. When dNTP(s) areincorporated into the DNA template, inorganic PPi is released.The released PPi is converted to ATP by ATP sulfurylase, whichprovides the energy to luciferase to oxidize luciferin andgenerate light. The excess of dNTP(s) and the ATP produced areremoved by the nucleotide degrading enzyme apyrase. The commercially available enzymes, isolated from nativesources, show batch-tobatch variations in activity and quality,which decrease the efficiency of the Pyrosequencing reaction.Therefore, the aim of the research presented in this thesis wasto develop methods to recombinantly produce the enzymes used inthe Pyrosequencing method. Production of the nucleotidedegrading enzyme apyrase by Pichia pastoris expression system,both in small-scale and in an optimized large-scale bioreactor,is described. ATP sulfurylase, the second enzyme in thePyrosequencing reaction, was produced inEscherichia coli. The protein was purified and utilizedin the Pyrosequencing method. Problems associated with enzymecontamination (NDP kinase) and batch-to-batch variations wereeliminated by the use of the recombinant ATP sulfurylase. As a first step towards sequencing on chip-format,SSB-(single-strand DNA binding protein)-luciferase and KlenowDNA polymerase-luciferase fusion proteins were generated inorder to immobilize the luciferase onto the DNA template. The application field for the Pyrosequencing technology wasexpanded by introduction of a new method for clone checking anda new method for template preparation prior the Pyrosequencingreaction. Keywords:apyrase, Pyrosequencing technology, Zbasictag fusion, luciferase, ATP sulfurylase, dsDNAsequencing, clone checking, Klenow-luciferase, SSB-luciferase,Pichia pastoris, Echeric

Pyrosequencing is a DNA sequencing method based on thedetection of released pyrophosphate (PPi) during DNA synthesis.In a cascade of enzymatic reactions, visible light isgenerated, which is proportional to the number of nucleotidesincorporated into the DNA template. When dNTP(s) areincorporated into the DNA template, inorganic PPi is released.The released PPi is converted to ATP by ATP sulfurylase, whichprovides the energy to luciferase to oxidize luciferin andgenerate light. The excess of dNTP(s) and the ATP produced areremoved by the nucleotide degrading enzyme apyrase. The commercially available enzymes, isolated from nativesources, show batch-tobatch variations in activity and quality,which decrease the efficiency of the Pyrosequencing reaction.Therefore, the aim of the research presented in this thesis wasto develop methods to recombinantly produce the enzymes used inthe Pyrosequencing method. Production of the nucleotidedegrading enzyme apyrase by Pichia pastoris expression system,both in small-scale and in an optimized large-scale bioreactor,is described. ATP sulfurylase, the second enzyme in thePyrosequencing reaction, was produced inEscherichia coli. The protein was purified and utilizedin the Pyrosequencing method. Problems associated with enzymecontamination (NDP kinase) and batch-to-batch variations wereeliminated by the use of the recombinant ATP sulfurylase. As a first step towards sequencing on chip-format,SSB-(single-strand DNA binding protein)-luciferase and KlenowDNA polymerase-luciferase fusion proteins were generated inorder to immobilize the luciferase onto the DNA template. The application field for the Pyrosequencing technology wasexpanded by introduction of a new method for clone checking anda new method for template preparation prior the Pyrosequencingreaction. Keywords:apyrase, Pyrosequencing technology, Zbasictag fusion, luciferase, ATP sulfurylase, dsDNAsequencing, clone checking, Klenow-luciferase, SSB-luciferase,Pichia pastoris, Echeric

We have developed an array-based resequencing method to determine genetic alterations in putative cancer genes. The method relies on that the specificity of DNA polymerase in allele-specific extensions can be enhanced by terminating the extension reactions with apyrase and that a tiling set of primers are synthesized covering the investigated gene sequence. We report on such apyrase-mediated allele-specific primer extension (AMASE) assay as a method suitable for high-throughout resequencing and mutation detection in tumor suppressor genes and oncogenes. In the experimental setup, primers complementary to codons 12, 13 and codon 61 of the N-ras proto-oncogene were spotted onto glass slides. Overlapping sense and anti-sense primers were designed so that complementary primers for all possible mutations in each base position were investigated. The extension reactions were performed in a single step following hybridization of target DNA to the immobilized primers on the array surface. Mutation detection limits and the possibility of quantifying the mutations were investigated using synthetic oligonucleotides. In addition, 64 clinical samples were sequenced and 16 of these showed mutations in the N-ras gene., QC 20100525

A new method for simple and fast clone checking is described. We combined the Pyrosequencing(TM) technology with a preprogrammed nucleoticle dispensation strategy for fast analysis of DNA constructs. To test this method, the N-terminus region of plasmids constructed for the production of recombinant apyrase was analyzed. Of the ten plasmids tested, seven constructs were correct, two constructs showed one base deletion, and one construct showed deletion of a 195 bp fragment. The preprogrammed nucleoticle dispensation strategy allowed the identification of the sequence downstream of the deletions. Thus, this method determines both the location and nature of possible artifacts., QC 20100525