Absence of prostacyclin greatly relieves cyclophosphamide-induced cystitis and bladder pain in mice.

Cyclophosphamide (CP) has been widely used in the treatment of various malignancies and autoimmune diseases, but acrolein, a byproduct of CP, causes severe hemorrhagic cystitis as the major side effect of CP. On the other hand, a large amount of prostacyclin (PGI2 ) is produced in bladder tissues, and PGI2 has been shown to play a critical role in bladder homeostasis. PGI2 is biosynthesized from prostaglandin (PG) H2 , the common precursor of PGs, by PGI2 synthase (PTGIS) and is known to also be involved in inflammatory responses. However, little is known about the roles of PTGIS-derived PGI2 in bladder inflammation including CP-induced hemorrhagic cystitis. Using both genetic and pharmacological approaches, we here revealed that PTGIS-derived PGI2 -IP (PGI2 receptor) signaling exacerbated CP-induced bladder inflammatory reactions. Ptgis deficiency attenuated CP-induced vascular permeability and chemokine-mediated neutrophil migration into bladder tissues and then suppressed hemorrhagic cystitis. Treatment with RO1138452, an IP selective antagonist, also suppressed CP-induced cystitis. We further found that cystitis-related nociceptive behavior was also relieved in both Ptgis-/- mice and RO1138452-treated mice. Our findings may provide new drug targets for bladder inflammation and inflammatory pain in CP-induced hemorrhagic cystitis.

Prostacyclin-deficient mice develop ischemic renal disorders, including nephrosclerosis and renal infarction.

BACKGROUND: Prostacyclin (PGI2) is a short-lived endogenous inhibitor of platelet aggregation and a potent vasodilator and regulator of the growth of vascular smooth muscle cells. To study the role of PGI2 in the vascular system in vivo, PGI2-deficient (PGID) mice were established by genetic disruption of the PGI2 synthase gene. METHODS AND RESULTS: PGI2 synthase-null mice were generated by replacing the exons of PGI2 synthase gene that encodes for the catalytic site of the enzyme with a neomycin resistance gene. In these mice, PGI2 levels in the plasma, kidneys, and lungs were reduced, whereas thromboxane and prostaglandin E2 levels became elevated. Blood pressure and the amounts of urea nitrogen and creatinine in plasma of the PGID mice were significantly higher than those of wild-type mice (P<0.05). They developed progressive morphological abnormalities in the kidneys, accompanied by atrophy, surface irregularity, fibrosis, cyst, arterial sclerosis, and hypertrophy of vessel walls. Thickening of the thoracic aortic media and adventitia were observed in aged PGID mice. Importantly, these phenotypes have not been reported in PGI2 receptor-deficient mice. CONCLUSIONS: PGI2 deficiency resulted in the development of vascular disorders with the thickening of vascular walls and interstitial fibrosis, especially in mouse kidneys. The findings demonstrated in vivo that PGI2 is important in the homeostasis of blood vessels. Our established PGID mice are useful for studies on the initiation and development of vascular diseases, such as ischemic renal disorders with arterial sclerosis and infarction, and also for studies on the novel signaling pathway of PGI2.

Alterations in blood pressure by derangement of the mechanisms that regulate sodium excretion.

Understanding the sequence of events responsible for pressure-related natriuresis and their pathophysiologic alterations may be useful in distinguishing various types of essential hypertension of renal origin. The perturbation of a distal step in the sequence is likely to be reflected in a simple physiologic defect. For instance, pathophysiologic alterations in the medullary production of prostaglandin E2 might directly influence natriuresis and diuresis because of its modulatory effect on tubular reabsorption of sodium and water. Perturbation of more proximal steps in the sequence could influence all the distal events as well. For instance, prostaglandin I2 and endothelium-derived relaxing factor may be produced by the preglomerular vasculature in response to alterations in renal perfusion pressure and may modulate the release of renin from the juxtaglomerular cells. Thus, variations in the production of prostaglandin I2 or endothelium-derived relaxing factor may be reflected by various renal vascular, tubular, and systemic homeostatic events related to the renin-angiotensin system.

Thrombotic thrombocytopenic purpura and related disorders.

This article provides us with background information on the disease. Clinical features, variants and classification, laboratory findings, and pathology are discussed. Knowledge of the disease's pathogenesis has increased recently and specific causes discussed are predisposing factors, triggering agents, endothelial damage, defective PGI2 bioavailability, FVIII/vWF multimeric structure abnormalities, platelet activation, and hemolytic anemia. Proposed specific therapies discussed are steroids, heparin, antiplatelet agents, prostacyclin, splenectomy, immunosuppressive agents, plasma infusion, and plasma exchange.

PIP: Thrombotic thrombocytopenic purpura (TTP) is a syndrome that occurs mainly in adults with multiorgan microvascular thrombosis consisting of thrombocytopenia, microangiopathic hemolytic anemia, neurologic symptoms, renal involvement, and fever. The female to male ratio is 3:2, and peak incidence occurs in the 3rd decade of life. Clinical signs are the consequence of hyaline thrombosis and occlusion of capillaries and arterioles. Renal ailment manifests itself in hematuria and proteinuria with azotemia and even overt renal failure. In severe disease, azotemia is typical of hemolytic uremic syndrome (HUS). TTP was first described in 1925 by Moschcowitz. The clinical picture of TTP consists of a prodromal phase, a viruslike disease occurring in up to 40% of patients. 60% have neurologic disturbances, 90% have purpura initially, and fever occurs in all. Anemia is often severe with hemoglobin values of 7-9 gm/dl, renal involvement in 90%, and renal failure in 40-80% of patients. Clinical variants include the acute and fulminant variety mortality, the chronic form, and the relapsing form. Predisposing factors and triggering agents are autosomal recessive inherited traits in acute idiopathic TTP, systemic diseases, tumor antigens, pregnancy and puerperium, viruses (endotoxins for HUS), and possibly oral contraceptives and hypertension. Therapy includes corticosteroids (prednisone 100-400 mg/day); heparin for postpartum HUS; and antiplatelet agents (Dextran 70, aspirin, and dipyridamole in high doses). The infusion of PGI2 is controversial; splenectomy is also questionable; and vincristine, azathioprine, and cyclophosphamide have unproven efficacy. Fresh-frozen plasma exchange is the method of choice as it produces survival in 90%. Others are iv immunoglobulins, vitamin E, and dialysis and renal transplant. Platelet transfusions are contraindicated because of sudden death and decreased survival.

Successful treatment by defibrination with ancrod in a patient with hyperacute renal allograft failure and a deficiency of plasma prostacyclin stimulating factor.

Hyperacute and renal allograft failure, whether due to rejection or other mechanisms, such as perfusion injury, is usually associated with extensive intraglomerular fibrin deposition and allograft loss. Defibrination with ancrod was used to treat a patient with hyperacute renal allograft failure and extensive glomerular fibrin deposition and necrosis. The patient's plasma had normal fibrinolytic activity but a complete absence of the ability to generate prostacyclin-like activity from rat aortic endothelium "in vitro". Treatment was associated with complete recovery of renal function, disappearance of glomerular fibrin, and restoration toward normal of glomerular structure.

[Hellp syndrome. Presentation of a case and review of the literature]. / Síndrome Hellp. Presentación de un caso y revisión de la literatura.

A severe case of preeclampsia with Hellp Syndrome is reported. Clinical findings, laboratory abnormalities and pathogenesis, were discussed. We concluded that severe preeclampsia and Hellp Syndrome are not different diseases, but the natural course of preeclampsia per se.

[Problems of intravascular blood coagulation and thrombus formation in ischemic heart disease]. / Problemy vnutrisosudistogo svertyvaniia krovi i tromboobrazovaniia pri ishemicheskoi bolezni serdtsa.

On the basis of the recent literature data and the results of his own studies, the author analyzes the interrelationship and implication of intravascular blood coagulation and thrombosis in coronary heart disease as well as the role which hemocoagulation homeostasis disorders play in their development. The author considers possible variants of the involvement of intravascular blood coagulation and thrombosis in the pathogenesis of myocardial infarction, the periinfarction zone formation and in the growth of damage. The significance of the syndrome of disseminated blood coagulation in myocardial infarction is discussed and the objectives of further research are outlined.

[Prostacyclin-thromboxane balance and risk factors of ischemic heart disease]. / Prostatsiklin-tromboksanovyi balans i faktory riska ishemicheskoi bolezni serdtsa.

The paper considers the significance of prostacyclin-thromboxane (PGI2/TxA2) balance for cardiovascular performance in health and in angina pectoris and myocardial infarction. The functional interaction between prostacyclin and thromboxane was examined in terms of a number of risk factors for coronary heart disease (CHD), such as ageing, atherosclerosis, arterial hypertension, diabetes mellitus, obesity, hypokinesia, smoking, alcoholism, sex differences, and predisposition to the disease. A unidirectional pattern of changes in the PGI2/TxA2 balance towards TxA2 was found in CHD and in the presence of all the aforementioned risk factors. The paper discusses possible mechanisms responsible for these changes, as well as their contribution to the pathogenesis and prevention of CHD.

[Role of intravascular coagulation in the pathophysiology of the hemolytic-uremic syndrome]. / De rol van de intravasale stolling in de pathofysiologie van het hemolytisch-uremisch syndroom.

Endothelial cell injury of capillaries and arterioles is considered to be the primary event in the hemolytic uremic syndrome. Intravascular coagulation increases the damaging processes. This intravascular coagulation can still be active after admission to the clinic. Several new data are available: prostacyclin deficiency can be present possibly due to the absence of a stimulating factor in plasma; the platelets are exhausted; an inhibitor of glomerular fibrinolysis has been demonstrated. A generally accepted therapy for HUS is still lacking.

Prostaglandin I2 analogs inhibit proinflammatory cytokine production and T cell stimulatory function of dendritic cells.

Signaling through the PGI(2) receptor (IP) has been shown to inhibit inflammatory responses in mouse models of respiratory syncytial viral infection and OVA-induced allergic responses. However, little is known about the cell types that mediate the anti-inflammatory function of PGI(2.) In this study, we determined that PGI(2) analogs modulate dendritic cell (DC) cytokine production, maturation, and function. We report that PGI(2) analogs (iloprost, cicaprost, treprostinil) differentially modulate the response of murine bone marrow-derived DC (BMDC) to LPS in an IP-dependent manner. The PGI(2) analogs decreased BMDC production of proinflammatory cytokines (IL-12, TNF-alpha, IL-1alpha, IL-6) and chemokines (MIP-1alpha, MCP-1) and increased the production of the anti-inflammatory cytokine IL-10 by BMDCs. The modulatory effect was associated with IP-dependent up-regulation of intracellular cAMP and down-regulation of NF-kappaB activity. Iloprost and cicaprost also suppressed LPS-induced expression of CD86, CD40, and MHC class II molecules by BMDCs and inhibited the ability of BMDCs to stimulate Ag-specific CD4 T cell proliferation and production of IL-5 and IL-13. These findings suggest that PGI(2) signaling through the IP may exert anti-inflammatory effects by acting on DC.