C5a inhibitor protects against ischemia/reperfusion injury in rat small intestine.

Acute mesenteric ischemia (AMI) is caused by considerable intestinal injury, which is associated with intestinal ischemia followed by reperfusion. To elucidate the mechanisms of ischemia/reperfusion injuries, a C5a inhibitory peptide termed AcPepA was used to examine the role of C5a anaphylatoxin, induction of inflammatory cells, and cell proliferation of the intestinal epithelial cells in an experimental AMI model. In this rat model, the superior mesenteric artery was occluded and subsequently reperfused (Induce-I/R). Other groups were treated with AcPepA before ischemia or reperfusion. Induce-I/R induced injuries in the intestine and AcPepA significantly decreased the proportion of severely injured villi. Induce-I/R induced secondary receptor for C5a-positive polymorphonuclear leukocytes in the vessels and CD204-positive macrophages near the injured site; this was correlated with hypoxia-induced factor 1-alpha-positive cells. Induction of these inflammatory cells was attenuated by AcPepA. In addition, AcPepA increased proliferation of epithelial cells in the villi, possibly preventing further damage. Therefore, Induce-I/R activates C5a followed by the accumulation of polymorphonuclear leukocyte and hypoxia-induced factor 1-alpha-producing macrophages, leading to villus injury. AcPepA, a C5a inhibitory peptide, blocks the deleterious effects of C5a, indicating it has a therapeutic effect on the inflammatory consequences of experimental AMI.

Anti-C5a complementary peptide ameliorates acute peritoneal injury induced by neutralization of Crry and CD59.

In peritoneal dialysis (PD) therapy, physical stresses such as exposure to peritoneal dialysate, catheter trauma, and peritonitis may induce peritoneal injury that can prevent continued long-term PD therapy. Therefore, protection of the peritoneum is an important target to enable long-term PD therapy in patients with end-stage renal disease. We previously showed that neutralization of the membrane complement regulators (CRegs) Crry and CD59 in rat peritoneum provokes development of acute peritoneal injury due to uncontrolled complement activation. C5a is a key effecter molecule of the complement system released during acute inflammation. Control of C5a has been proposed as a strategy to suppress inflammatory reactions and, because peritoneal injury is accompanied by inflammation, we hypothesized that C5a targeted therapy might be an effective way to suppress peritoneal injury. In the present study we used an established acute peritonitis model induced by neutralization of CRegs to investigate the effects on acute peritoneal injury of inhibiting C5a. Intravenous administration of an anti-C5a complementary peptide (AcPepA) up to 4 h after induction of injury significantly and dose-dependently prevented accumulation of inflammatory cells and reduced tissue damage in the model, accompanied by decreased C3b deposition. We show that C5a contributed to the development of peritoneal injury. Our results suggest that C5a is a target for preventing or treating peritoneal injury in patients undergoing prolonged PD therapy or with infectious complications.

Complement C5A antagonist treatment improves the acute circulatory and inflammatory consequences of experimental cardiac tamponade.

OBJECTIVE: Cardiogenic shock often leads to splanchnic macro- and microcirculatory complications, and these events are linked to local and systemic inflammatory activation. Our aim was to investigate the consequences of complement C5a antagonist treatment on the early circulatory and inflammatory changes in a clinically relevant large animal model of cardiac tamponade. DESIGN AND SETTING: A randomized, controlled in vivo animal study in a university research laboratory. SUBJECTS: Anesthetized, ventilated, and thoracotomized Vietnamese mini pigs (24 ± 3 kg). INTERVENTIONS: Group 1 (n = 6) served as sham-operated control. In group 2 (n = 7), cardiac tamponade was induced for 60 minutes by the administration of intrapericardial fluid, while the mean arterial pressure was kept in the interval 40 to 45 mm Hg. Group 3 (n = 6) was treated with a complement C5a antagonist compound (the peptide acetyl-peptide-A, 4 mg/kg) after 45 minutes of tamponade. MEASUREMENTS AND MAIN RESULTS: The macrohemodynamics, including the superior mesenteric artery flow, was monitored; the average red blood cell velocity in the small intestinal mucosa was determined by an intravital orthogonal polarization imaging technique. The whole blood superoxide production, the plasma level of high-mobility group box protein-1 and big-endothelin and the small intestinal myeloperoxidase activity were measured. One hundred eighty minutes after the relief of tamponade, the mean arterial pressure was decreased, while the plasma levels of superoxide, high-mobility group box protein-1, and big-endothelin, and the intestinal myeloperoxidase activity were increased. The administration of acetyl-peptide-A normalized the mean arterial pressure and preserved the cardiac output, while the superior mesenteric artery flow and mucosal average red blood cell velocity were increased significantly, and the plasma superoxide, high-mobility group box protein-1, big-endothelin, and intestinal myeloperoxidase levels were reduced. CONCLUSIONS: These results provide evidence that blockade of the C5a effects significantly influences the acute splanchnic macro- and microhemodynamic complications and decreases the potentially harmful inflammatory consequences of experimental cardiogenic shock.

Membrane complement regulators protect against fibrin exudation increases in a severe peritoneal inflammation model in rats.

Peritonitis and the rare sequela of encapsulating peritoneal sclerosis (EPS) are serious problems in patients on peritoneal dialysis therapy. Chronic and persistent peritoneal injuries may be a risk factor of EPS. We previously reported that a chronic, proliferative peritonitis developed when zymosan was administered intraperitoneally following scraping injury of rat peritoneum (Mizuno M, Ito Y, Hepburn N, Mizuno T, Noda Y, Yuzawa Y, Harris CL, Morgan BP, Matsuo S. J Immunol 183: 1403-1412, 2009). Peritoneal membrane complement regulators (CRegs), especially Crry and CD59, protected from injury by inhibiting local complement activation, suggesting that CRegs play important roles in maintaining homeostasis in rat peritoneum. Here, we investigated roles of complement in the development of EPS by neutralizing CReg function with monoclonal antibodies (MAbs). Proliferative peritonitis was induced by scraping the peritoneum, followed by daily intraperitoneal administration of zymosan. When either Crry or CD59 alone was neutralized by MAb, the tissue injuries were not significantly changed compared with rats without neutralizing MAb. When both Crry and CD59 were neutralized in this model, severe fibrin exudation was observed on the peritoneal surface on day 5, accompanied by inflammatory cell infiltration, resembling the early stages of development of EPS. Dense peritoneal deposition of C3 fragments and membrane attack complex were observed, along with the fibrin exudates. Intravenous administration of cobra venom factor, which profoundly activates complement, further enhanced these pathological changes. Our results show that complement activation in injured peritoneum drives peritoneal inflammation, and that enhancement of complement activation by inhibiting CReg and/or enhancing systemic activation contributes to the initiation of EPS; therefore, anti-complement agents might be of therapeutic value in humans for the treatment of EPS.

Endothelin receptor antagonist attenuates oxidative stress in a neonatal sepsis piglet model.

BACKGROUND: Oxidative stress (oxidant-antioxidant imbalance) plays an important role in the pathophysiology of neonatal sepsis. This study evaluated whether an antisense peptide endothelin receptor antagonist, ETR-P1/fl, could attenuate oxidative stress in a neonatal sepsis model. METHODS: A total of 18 3-d-old piglets were anesthetized and mechanically ventilated. Six piglets received cecal ligation and perforation (CLP group) for induction of sepsis. Six piglets also received continuous infusion (0.05 mg/kg/h) of ETR-P1/fl 30 min after CLP (ETR-P1/fl group). Six piglets received a sham operation. Serum total hydroperoxide (TH), biological antioxidant potentials (BAPs), oxidative stress index (OSI, calculated as TH/BAP), interleukin (IL)-6, serum glutamic oxaloacetic transaminase (GOT), and creatinine were measured before CLP and at 1, 3, and 6 h after CLP. RESULTS: CLP evoked a state of shock resulting in elevated TH, OSI, and IL-6 levels. ETR-P1/fl administration after CLP resulted in lower serum TH at 1 and 3 h after CLP, OSI at 1 and 3 h after CLP, IL-6 at 1 and 3 h after CLP, and GOT at 3 and 6 h after CLP as compared with the CLP group. CONCLUSION: ETR-P1/fl treatment significantly attenuated the elevation of serum oxidative stress markers (TH and OSI), IL-6, and GOT in a progressive neonatal sepsis CLP model.

Guideline for hereditary angioedema (HAE) 2010 by the Japanese Association for Complement Research - secondary publication.

This guideline was provided by the Japanese Association for Complement Research targeting clinicians for making an accurate diagnosis of hereditary angioedema (HAE), and for prompt treatment of the HAE patient in Japan. This is a 2010 year version and will be updated according to any pertinent medical advancements.

Specific collaboration between rat membrane complement regulators Crry and CD59 protects peritoneum from damage by autologous complement activation.

BACKGROUND: The peritoneal cavity is isolated from the outside and is usually a sterile environment. Patients on peritoneal dialysis (PD) have PD fluid (PDF) infused into the peritoneal cavity. We previously showed that unregulated complement activation could contribute to the development of peritoneal inflammation in yeast peritonitis in PD therapy. In that situation, suppression of local complement activation is essential to protect the host from further injury. The membrane complement regulators (CRegs), Crry, CD55 and CD59, are expressed in the rat peritoneum, especially along the mesothelial cell layer. METHODS: We investigated CRegs' functional roles in the peritoneal cavity using blocking mAb against each CReg and complement activation in different PDFs. RESULTS: Blockade of any single CReg did not cause spontaneous peritoneal injury in rat. Combined blockade of Crry and CD59 induced focal peritoneal tissue injury and heavy accumulation of inflammatory cells with peritoneal edema at 24 h. Deposits of C3 and C5b-9 were found on the peritoneal surface after combined blocking of Crry and CD59. Systemic complement depletion by cobra venom factor abrogated these inflammatory changes. When combined blockade of Crry and CD59 was performed with PDF of different pH and glucose concentration in rats, the peritoneal injuries were enhanced with lower pH and higher glucose concentration. These results were confirmed by in vitro experiments using primary rat mesothelial cell culture. CONCLUSIONS: Rat CRegs, Crry and CD59, specifically collaborate to control complement activation in rat peritoneum. During PD, impairment of CReg might contribute to the development of severe peritoneal inflammation.

Serum concentrations of complement anaphylatoxins and proinflammatory mediators in patients with 2009 H1N1 influenza.

Anaphylatoxins (C5a, C4a, and C3a) are fragments of activated complement and are leading mediators of the inflammatory response for controlling viral infection. However, an excessive response may increase the severity of infectious diseases. Serum concentrations of proinflammatory mediators, including cytokines, high-mobility group box 1 and anaphylatoxins, were measured in pediatric 2009 H1N1 influenza patients in order to investigate the pathology of this new influenza. The concentrations of all three anaphylatoxins were significantly enhanced by 2009 H1N1 influenza infection. However, there were no significant differences in anaphylatoxin concentrations between 2009 H1N1 influenza patients with and without severe complications during the early stages of the disease. C3a concentrations dropped significantly during the recovery phase, whereas there were no significant differences between the acute and recovery phases in C5a and C4a concentrations. There was a correlation between C5a and IL-2. C4a was associated with IL-1ra, eotaxin, MCP-1, PDGFbb, and VEGF. C3a was correlated with IL-2 and IFN-γ. Taken together, these findings indicate that complement activation occurs in patients infected with 2009 H1N1 influenza virus and demonstrate that anaphylatoxins are involved in increased production of proinflammatory mediators in this new influenza.

A complement-dependent cytotoxicity-enhancing anti-CD20 antibody mediating potent antitumor activity in the humanized NOD/Shi-scid, IL-2Rγ(null) mouse lymphoma model.

Engineering the Fc region of monoclonal antibodies (mAb) in order to enhance effector functions such as antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity (CDC) is likely to a be promising approach for next-generation mAb therapy. Here, we report on such an antibody, 113F, a novel CDC-enhancing variant of rituximab, and determine the tumor-associated factors influencing susceptibility to 113F-induced CDC. The latter included the quantity of complement inhibitors present, such as CD55 and CD59. We report that compared to rituximab, 113F mediated highly enhanced CDC against primary CD20-expressing lymphoma cells in vitro. Currently, a major problem in the field of immunotherapy research is the lack of suitable small animal models to evaluate human CDC in vivo. Therefore, we established a novel human tumor-bearing NOD/Shi-scid, IL-2Rγ(null) mouse model, in which human complement functions as the CDC mediator. We demonstrated that rituximab exerted significant antitumor effects via human CDC in this humanized mouse. The finding of specific localization of human C1q on CD20-expressing tumor cell membranes was consistent with the observation that human CDC indeed contributed to the antitumor effect in this model. Moreover, 113F exerted significantly more potent antitumor effects than rituximab in this in vivo model. The detection of more abundant dense signals from C1q using 113F compared to rituximab was consistent with the concept that this reagent represented a CDC-enhancing mAb. In the near future, the efficacy of this type of CDC-enhancing antibody will be determined in clinical trials in humans.

Procarboxypeptidase R deficiency causes increased lethality in concanavalin A-induced hepatitis in female mice.

Carboxypeptidase R (CPR), also known as thrombin-activatable fibrinolysis inhibitor (TAFI), is an enzyme generated by proteolytic cleavage of its zymogen (proCPR). CPR removes the C-terminal arginine from inflammatory peptides such as C3a and C5a, bradykinin, enkephalin, and the thrombin-cleaved N-terminal fragment osteopontin (cleaved N-OPN). In the mouse model of concanavalin A (Con A)-induced immune-mediated fulminating hepatitis, cleaved N-OPN is one of the important peptides that induce the production of chemokines or cytokines. In the current study using proCPR deficient mice, we showed that injection of Con A into the mouse tail vein can induce a significantly higher lethality in proCPR-deficient female but not in male mice. Furthermore, a lack of CPR activity increased serum macrophage inflammatory protein-2 (MIP-2) and high-mobility group box 1 (HMGB1) levels after Con A injection. These in vivo findings suggest that CPR helps to protect against Con A-induced hepatitis.

[Refractory acquired hemophilia A successfully treated with CVP].

A 44-year-old woman was referred to our hospital for massive subcutaneous and intramuscular hemorrhage. Prolonged APTT, low factor VIII activity and factor VIII inhibitor with high titer (30 BU/ml) were observed, confirming the diagnosis of acquired factor VIII inhibitor. Although treated with methylprednisolone, she relapsed after a month. Subsequently, she was treated with three courses of CVP (cyclophosphamide, vincristine, prednisolone) therapy, combined with recombinant activated factor VII. The activity of factor VIII was normalized one week after starting CVP, and the inhibitor disappeared 13 months later. She has maintained complete remission for 26 months without recurrence to date. CVP therapy is very effective against refractory acquired factor VIII inhibitor.

Estrogen enhances expression of the complement C5a receptor and the C5a-agonist evoked calcium influx in hormone secreting neurons of the hypothalamus.

In the present study we examined presence of the complement C5a receptor (C5aR) in hypothalamic neurosecretory neurons of the rodent brain and effect of estrogen on C5aR expression. Whole cell patch clamp measurements revealed that magnocellular neurons in the supraoptic and paraventricular nuclei of hypothalamic slices of the rats responded to the C5aR-agonist PL37-MAP peptide with calcium ion current pulses. Gonadotropin-releasing hormone (GnRH) producing neurons in slices of the preoptic area of the mice also reacted to the peptide treatment with inward calcium current. PL37-MAP was able to evoke the inward ion current of GnRH neurons in slices from ovariectomized animals. The amplitude of the inward pulses became higher in slices obtained from 17beta-estradiol (E2) substituted mice. Calcium imaging experiments demonstrated that PL37-MAP increased the intracellular calcium content in the culture of the GnRH-producing GT1-7 cell line in a concentration-dependent manner. Calcium imaging also showed that E2 pretreatment elevated the PL37-MAP evoked increase of the intracellular calcium content in the GT1-7 cells. The estrogen receptor blocker Faslodex in the medium prevented the E2-evoked increase of the PL37-MAP-triggered elevation of the intracellular calcium content in the GT1-7 cells demonstrating that the effect of E2 might be related to the presence of estrogen receptor. Real-time PCR experiments revealed that E2 increased the expression of C5aR mRNA in GT1-7 neurons, suggesting that an increased C5aR synthesis could be involved in the estrogenic modulation of calcium response. These data indicate that hypothalamic neuroendocrine neurons can integrate immune and neuroendocrine functions. Our results may serve a better understanding of the inflammatory and neurodegeneratory diseases of the hypothalamus and the related neuroendocrine and autonomic compensatory responses.

Low CR1 (C3b receptor) level on erythrocytes is associated with poor prognosis in hemodialysis patients.

BACKGROUND: Erythropoietin in patients under dialysis treatment for renal failure is low which induces anemia. Treatment with recombinant erythropoietin (rEPO) has been used routinely as a supplement treatment for these patients. Immune complexes (IC) react with complement and bind to CR1 on erythrocytes (E-CR1), and are transported to the liver and/or spleen where IC removal and degradation occurs. The erythrocytes then return to circulation where they bind to additional IC. There are some patients whose E-CR1 expression is low with chronic anemia in spite of rEPO treatment. We hypothesized that in hemodialysis (HD) patients altered host defense against infection is associated with low levels of E-CR1. We examined if low E-CR1 in dialysis patients constitutes a risk factor for reduced host defense and poor outcome. METHODS: In 95 HD patients, E-CR1 was quantified using a monoclonal E-CR1 antibody and FACS analysis followed by clinical course studies for 5 years. RESULTS: The patients were divided into three groups by E-CR1 level. Percent survival for the low E-CR1 group (53.3%) was significantly lower than the high E-CR1 group (86.4%) (p < 0.01). There were more hepatitis C virus-positive patients within the low E-CR1 group (27.3%) than in the high E-CR1 group (4.7%) (p < 0.05). Furthermore, 10 patients with the lowest E-CR1 levels had severe complications, notably infection at an arteriovenous fistula. CONCLUSION: A reduced E-CR1 level might be a risk factor for reduced host defense and can be used as a predicting factor for poor prognosis in a HD patient.

A tumor-expressed inhibitor of the early but not late complement lytic pathway enhances tumor growth in a rat model of human breast cancer.

Membrane-bound complement inhibitors protect host cells from inadvertent complement attack, and complement inhibitors are often up-regulated on tumors, possibly representing a selective adaptation by tumors to escape elimination by a host antitumor immune response. Relevant in vivo studies using rodent models of human cancer have been hampered by the fact that human complement inhibitors are not effective against rodent complement. Using nude rats and MCF7 cells expressing different rat complement inhibitors, a model of human breast cancer was established to investigate the role of complement and complement inhibitors in tumor progression. Expression of rat CD59, an inhibitor of the terminal cytolytic membrane attack complex of complement, had no effect on the incidence or growth rate of MCF7 tumors. In contrast, expression of rat Crry, an inhibitor of complement activation, dramatically enhanced the tumorigenicity of MCF7 cells. The expression of rat Crry on MCF7 inhibited the in vivo deposition of complement C3 fragments that serve as opsonins for receptors on phagocytes and natural killer cells. These data provide direct in vivo evidence that an inhibitor of complement activation can facilitate tumor growth by modulating C3 deposition. These data indicate an important role for complement opsonization in promoting cell-mediated antitumor immune function, a conclusion further supported by the demonstration that expression of rat Crry, but not rat CD59, on MCF7 cells inhibits rat cell-mediated cytotoxicity in vitro. Rat complement activation on MCF7 tumors was mediated by tumor-reactive antibodies present in the serum of naïve nude rats, but there was also an IgM response to MCF7 tumors, a situation with similarities to some human cancers. These data support a hypothesis that blocking complement inhibitor function on tumor cells will not only enhance monoclonal antibody-mediated immunotherapy but may also be effective at enhancing a normally ineffective humoral immune response in the absence of administered antitumor antibody.

Tumor-specific inhibition of membrane-bound complement regulatory protein Crry with bispecific monoclonal antibodies prevents tumor outgrowth in a rat colorectal cancer lung metastases model.

Membrane-bound complement regulatory proteins (mCRP) inhibit complement-mediated tumor cell eradication in vitro and in vivo. Immunotherapy of cancer with monoclonal antibodies (mAbs) that activate complement might be hampered by expression of mCRP on tumor cells. An important strategy to improve mAb immunotherapy can be blocking or overwhelming mCRP at the tumor cells surface in a tumor-specific manner. In our study, we investigated the feasibility of this approach in vivo using bispecific mAbs (bi-mAbs). This study, performed in a syngeneic lung metastases model of rat (WAG/Rij) colorectal cancer, showed that modulation of mCRP on tumor cells resulted in significantly decreased tumor outgrowth. Opsonization of tumor cells with a bi-mAb directed against a tumor-associated antigen and rat mCRP Crry (MG4(2a)*5I2) almost completely prevented the outgrowth of lung tumors (0-7 tumors/rat; n = 17). Opsonization with mAb-cobra venom factor conjugates significantly reduced the number of lung tumors (23-59 tumors; n = 12) compared with the unconjugated MG4(2a) (175-246 tumors; n = 17; P = 0.008 and 0.014, respectively). The effect of MG4(2a)*5I2 was shown to be caused by increased complement activation due to inhibition of Crry. Moreover, prophylactic treatment with MG4(2a)*5I2 or MG4(2a) showed comparable results (3-24 and 215-472 tumors, P = 0.02; n = 6) as observed with pre-opsonized tumor cells without noticeable side effects, despite binding of MG4(2a)*5I2 to endothelium and leukocytes. These results demonstrate that Crry inhibits complement-mediated tumor cell eradication by immunotherapeutic mAbs and show that tumor-specific inhibition of complement regulatory proteins using bi-mAbs can significantly improve mAb-mediated immunotherapy.

Complement C5a inhibition improves late hemodynamic and inflammatory changes in a rat model of nonocclusive mesenteric ischemia.

BACKGROUND: Nonocclusive mesenteric ischemia (NOMI) can evolve in a variety of low-flow states. Although the mechanisms leading to NOMI-related intestinal necrosis are largely unknown, circumstantial evidence suggests that excessive vasoconstriction and complement activation both play important roles in this process. Because targeting of the circulatory malfunction of the splanchnic area could be of therapeutic relevance, we set out to investigate the long-term effects of treatment with a complement C5a antagonist in a rat model of partial aortic occlusion (PAO)-induced transient mesenteric hypoperfusion. METHODS: The mean arterial pressure of the splanchnic area was kept between 30 and 40 mm Hg by 60 minutes of PAO in anesthetized male Sprague-Dawley rats. C5a inhibitor acetyl-peptide-A (AcPepA; 4 mg kg(-1) intravenously) or vehicle administration was initiated at the 45th minute of PAO. After 24 hours, the animals were reanesthetized to record the macrohemodynamics and ileal microcirculation, and plasma and tissue samples were taken for determination of high-mobility group box protein-1 (HMGB-1), endothelin-1, tumor necrosis factor (TNF)-α levels, and small intestinal leukocyte infiltration. Epithelial structural changes were visualized by in vivo confocal laser scanning endomicroscopy. RESULTS: At 24 hours after PAO, mean arterial pressure, heart rate, and cardiac output were significantly greater, the intestinal intramural microcirculation was significantly impaired, and plasma HMGB-1, endothelin-1, TNF-α levels, the degree of epithelial damage and leukocyte infiltration was increased. The AcPepA treatment moderated the hemodynamic and microcirculatory changes, and decreased inflammatory activation and histologic signs of mucosal damage. CONCLUSION: C5a inhibition ameliorated the potentially harmful local mesenteric hypoperfusion and global long-term inflammatory consequences of PAO. This approach is of promise for use in NOMI-associated situations.

Combination effects of complement regulatory proteins and anti-complement polymer.

We previously reported the development of a "cytomedicine" that consists of cells trapped in alginate-poly-L-lysine-alginate (APA) microcapsules and agarose microbeads. The functional cells that are entrapped in semipermeable polymer are completely isolated from cellular immune system. However, the ability of cytomedicine to isolate cells from the humoral immune system, which plays an essential role in xenograft rejection, is low. Therefore, the goal of the present study was to develop a novel cytomedicine that could protect the entrapped cells from injury of the complement system. We investigated the applicability of the complement regulatory protein (CRP), Crry, to cytomedicine. Crry-transfected cells entrapped within agarose microbeads resisted injury by complement to a degree, while entrapment of Crry transfected cells within agarose microbeads containing polyvinyl sulfate (PVS), a novel cytomedical device with anti-complement activity, clearly protected against complement attack. These data indicate that the combination of a CRP and a cytomedical device with anti-complement activity is a superior device for cytomedical therapy.

Rational structure-based design of a novel carboxypeptidase R inhibitor.

A novel carboxypeptidase R (CPR) inhibitor, related to potato carboxypeptidase inhibitor (PCI), was designed using rational structure-based strategies, incorporating two principle facts: CPR has a strong affinity for basic amino acids, and the two lysine and arginine residues of PCI are orientated in the same direction and held in close spatial proximity by three disulfide bonds. Initially, a disulfide-bonded fragment of PCI was synthesized showing weak competitive inhibitory activity against CPR. Subsequently, a smaller linear 9-mer peptide, designated CPI-2KR, was designed/synthesized and found to be a more efficient competitive inhibitor of CPR, without affecting the activity of the other plasma carboxypeptidase, carboxypeptidase N. In vitro studies showed that, together with tissue plasminogen activator, CPI-2KR synergistically accelerated fibrinolysis, representing a lead compound for the design of smaller organic molecules for use in thrombolytic therapy.

The CC chemokine receptor 4 as a novel specific molecular target for immunotherapy in adult T-Cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell neoplasm with dismal prognosis, and no optimal therapy has been developed. We tested the defucosylated chimeric anti-CC chemokine receptor 4 (CCR4) monoclonal antibody, KM2760, to develop a novel immunotherapy for this refractory tumor. In the presence of peripheral blood mononuclear cells (PBMCs) from healthy adult donors, KM2760 induced CCR4-specific antibody-dependent cellular cytotoxicity (ADCC) against CCR4-positive ATLL cell lines and primary tumor cells obtained from ATLL patients. We next examined the KM2760-induced ADCC against primary ATLL cells in an autologous setting. Antibody-dependent cellular cytotoxicity mediated by autologous effector cells was generally lower than that mediated by allogeneic control effector cells. However, a robust ADCC activity was induced in some cases, which was comparable with that mediated by allogeneic effector cells. It suggests that the ATLL patients' PBMCs retain substantial ADCC-effector function, although the optimal conditions for maximal effect have not yet been determined. In addition, we also found a high expression of FoxP3 mRNA and protein, a hallmark of regulatory T cells, in ATLL cells, indicating the possibility that ATLL cells originated from regulatory T cells. KM2760 reduced FoxP3 mRNA expression in normal PBMCs along with CCR4 mRNA by lysis of CCR4+ T cells in vitro. Our data suggest not only that the CCR4 molecule could be a suitable target for the novel antibody-based therapy for patients with ATLL but also that KM2760 may induce effective tumor immunity by reducing the number of regulatory T cells.

HIV-1 Nef protein in the nucleus influences adipogenesis as well as viral transcription through the peroxisome proliferator-activated receptors.

BACKGROUND: Although the HIV-1 Nef protein (27 kDa) localizes primarily in cytoplasm, there is considerable evidence suggesting its occasional localization in the nucleus. Nef is known to play an important role in transcriptional events and viral replication, but the actual target of Nef in the nucleus remains to be identified. OBJECTIVE: To examine the functional roles of Nef in the nucleus and its possible interactions with other unknown factors in the nucleus. METHODS: High-density microarray analysis was used to screen directly the unique functions of Nef on host gene transcription. The nuclear localization of Nef and its effects on the expression of peroxisome proliferator-activated receptors (PPAR) was examined using PPAR promoter/reporter assay and immunoblotting. A long terminal repeat/reporter assay was used to investigated the effects of Nef and PPAR on viral transcription. RESULTS: Nef in the nucleus suppressed PPAR gamma expression and reduced fatty acid levels in human T and macrophage cell lines. Expression of Nef or PPAR suppressed viral replication; the effect of PPAR gamma or retinoid X receptor-alpha on viral replication were reduced by coexpression of Nef in MT(-)4 T cells. CONCLUSION: Nef may be involved in both viral replication and the wasting syndrome associated with AIDS.