In vitro and in vivo effects of the anti-inflammatory peptides, antiflammins

Antiinflammatory peptides: current knowledge and promising prospects

BACKGROUND

Inflammation is part of the regular host reaction to injury or infection caused by toxic factors, pathogens, damaged cells, irritants, and allergens. Antiinflammatory peptides (AIPs) are present in all living organisms, and many peptides from herbal, mammalian, bacterial, and marine origins have been shown to have antimicrobial and/or antiinflammatory properties.

METHODS

In this study, we investigated the effects of antiinflammatory peptides on inflammation, and highlighted the underlying mechanisms responsible for these effects.

RESULTS

In multicellular organisms, including humans, AIPs constitute an essential part of their immune system. In addition, numerous natural and synthetic AIPs are effective immunomodulators and can interfere with signal transduction pathways involved in inflammatory cytokine expression. Among them, some peptides such as antiflammin, N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), and those derived from velvet antler proteins, bee venom, horse fly salivary gland, and bovine β-casein have received considerable attention over the past few years.

CONCLUSION

This article presents an overview on the major properties and mechanisms of action associated with AIPs as immunomodulatory, chemotactic, antioxidant, and antimicrobial agents. In addition, the results of various studies dealing with effects of AIPs on numerous classical models of inflammation are reviewed and discussed.

Antiflammin-1 attenuates bleomycin-induced pulmonary fibrosis in mice

BACKGROUND

Antiflammin-1 (AF-1), a derivative of uteroglobin (UG), is a synthetic nonapeptide with diverse biological functions. In the present study, we investigated whether AF-1 has a protective effect against bleomycin-induced pulmonary fibrosis.

METHODS

C57BL/6 mice were injected with bleomycin intratracheally to create an animal model of bleomycin-induced pulmonary fibrosis. On Day 7 and Day 28, we examined the anti-inflammatory effect and antifibrotic effect, respectively, of AF-1 on the bleomycin-treated mice. The effects of AF-1 on the transforming growth factor-beta 1 (TGF-β1)-induced proliferation of murine lung fibroblasts (NIH3T3) were examined by a bromodeoxycytidine (BrdU) incorporation assay and cell cycle analysis.

RESULTS

Severe lung inflammation and fibrosis were observed in the bleomycin-treated mice on Day 7 and Day 28, respectively. Administration of AF-1 significantly reduced the number of neutrophils in the bronchoalveolar lavage fluid (BALF) and the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in the lung homogenates on Day 7. Histological examination revealed that AF-1 markedly reduced the number of infiltrating cells on Day 7 and attenuated the collagen deposition and destruction of lung architecture on Day 28. The hydroxyproline (HYP) content was significantly decreased in the AF-1-treated mice. In vitro, AF-1 inhibited the TGF-β1-induced proliferation of NIH3T3 cells, which was mediated by the UG receptor.

CONCLUSIONS

AF-1 has anti-inflammatory and antifibrotic actions in bleomycin-induced lung injury. We propose that the antifibrotic effect of AF-1 might be related to its suppression of fibroblast growth in bleomycin-treated lungs and that AF-1 has potential as a new therapeutic tool for pulmonary fibrosis.

Inhibition of smooth muscle contraction and platelet aggregation by peptide 204-212 of lipocortin 5: an attempt to define some structure requirements

Peptide 204-212 of lipocortin (LC) 5 inhibited porcine pancreatic phospholipase A(2) (PLA(2)) induced rat stomach strip contractions and ADP induced rabbit platelet aggregation in a concentration dependent manner (IC(30) of 10 muM and 400 muM, respectively). The first two amino acids are not necessary since the eptapeptide 206-212 was equipotent in both assays (IC(30) of 12.5 muM and 420 muM). Of the two pentapeptides 204-208 and 208-212 only the latter showed inhibitory activity in both models although the potency was much reduced (IC(30) of 170 muM and 630 muM) compared with that of the parent nonapeptide. Comparison of peptide 204-212 effects with those of its analogues on LC1 and LC2 indicate that lysine 208 and aspartic acid 211 are essential in order to maintain a fully active nonapeptide.

Evidence for an anti-inflammatory loop centered on polymorphonuclear leukocyte formyl peptide receptor 2/lipoxin A4 receptor and operative in the inflamed microvasculature

The importance of proresolving mediators in the overall context of the resolution of acute inflammation is well recognized, although little is known about whether these anti-inflammatory and proresolving molecules act in concert. In this article, we focused on lipoxin A(4) (LXA(4)) and annexin A1 (AnxA1) because these two very different mediators converge on a single receptor, formyl peptide receptor type 2 (FPR2/ALX). Addition of LXA(4) to human polymorphonuclear leukocytes (PMNs) provoked a concentration- and time-dependent mobilization of AnxA1 onto the plasma membrane, as determined by Western blotting and flow cytometry analyses. This property was shared by another FPR2/ALX agonist, antiflammin-2, and partly by fMLF or peptide Ac2-26 (an AnxA1 derivative that can activate all three members of the human FPR family). An FPR2/ALX antagonist blocked AnxA1 mobilization activated by LXA(4) and antiflammin-2. Analysis of PMN degranulation patterns and phospho-AnxA1 status suggested a model in which the two FPR2/ALX agonists mobilize the cytosolic (and not the granular) pool of AnxA1 through an intermediate phosphorylation step. Intravital microscopy investigations of the inflamed mesenteric microvasculature of wild-type and AnxA1(-/-) mice revealed that LXA(4) provoked leukocyte detachment from the postcapillary venule endothelium in the former (>50% within 10 min; p < 0.05), but not the latter genotype (∼15%; NS). Furthermore, recruitment of Gr1(+) cells into dorsal air-pouches, inflamed with IL-1β, was significantly attenuated by LXA(4) in wild-type, but not AnxA1(-/-), mice. Collectively, these data prompt us to propose the existence of an endogenous network in anti-inflammation centered on PMN AnxA1 and activated by selective FPR2/ALX agonists.

Interaction of antiflammin-1 with uteroglobin-binding protein induces phosphorylation of ERK1/2 in NIH 3T3 cells

Previously, it has been suggested that uteroglobin (UG)-binding protein functions as a putative receptor of UG; however, the specific epitope of UG that interacts with this receptor has not yet been identified. The downstream events of UG-binding protein signaling remain unclear. Here we report that antiflammin-1 (AF-1, a bioactive C-terminal peptide of UG) specifically binds to UG-binding protein and has a cellular signaling consequence. We reduced the level of endogenous UG-binding protein expression in murine fibroblast cell line NIH 3T3 by RNA interference and found that knockdown of UG-binding protein inhibited AF-1-induced extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation. Meanwhile, the interaction between AF-1 and UG-binding protein was confirmed by flow cytometry-based binding assays and co-localization of AF-1 and enhanced green fluorescent protein (EGFP)-tagged UG-binding protein. The present study provides evidence for the first time for AF-1 binding with UG-binding protein, and preliminarily characterized UG-binding protein as a point downstream of AF-1 in mediating ERK phosphorylation.

The Antiplatelet Activity of Danggijakyaksan by Inhibition of Phospholipase C

We investigated the effects of the traditional Korean prescription, Danggijakyaksan (DJS) on antiplatelet activity in human platelet suspensions. The effect of oriental medicinal prescriptions, Danggijakyaksan consisting of 6 herbes of Paeoniae Radix (2 g), Poria Cocos (1.33 g), Angelicae Sinensis Radix (1 g), Cnidii Rhizoma (1 g), Atractylodis Macrocephalae Rhizoma (1.33 g) and Alismatis Rhizoma (1.66 g), was studied. In this study, the mechanism involved in the antiplatelet activity of DJS in human platelet suspensions was investigated. Danggijakyaksan did not significantly affect the thromboxane synthetase activity of aspirin-treated platelet microsomes and DJS (20 and 40 microg/mL) significantly inhibited [3H]arachidonic acid (AA) released in collagen-activated platelets but not in unactivated-platelets. Nitric oxide (NO) production in human platelets was measured by a chemiluminesence detection method in this study. Danggijakyaksan did not significantly affect nitrate production in collagen (10 microg/mL)-induced human platelet aggregation. On the other hand, various concentrations of DJS (10, 20, and 40 microg/mL) dose-dependently inhibited [3H]inositol monophosphate (IP) formation stimulated by collagen (10 microg/mL) in [3H]myoinositolloaded platelets at different incubation times (1, 2, 3, and 5 min). It is concluded that the antiplatelet activity of DJS may possibly be due to the inhibition of phospholipase C activity, leading to reduced phosphoinositide breakdown, followed by the inhibition of thromboxane A2 formation, and then inhibition of [Ca2+]i mobilization of platelet aggregation stimulated by agonists.

The antiplatelet activity of Geiji-Bokryung-Hwan, Korean traditional formulation, is mediated through inhibition of phospholipase C and inhibition of TxB(2) synthetase activity

Geiji-Bokryung-Hwan (GBH), consisting of herbes of Cinnamomi ramulus (Geiji), Poria cocos (Bokryun), Mountan cortex radicis (Mokdanpi), Paeoniae radix (Jakyak), and Persicae semen (Doin), on antiplatelet activity in human platelet suspensions was studied. The mechanism involved in the antiplatelet activity of GBH in human platelet suspensions was investigated. GBH did not significantly affect the thromboxane synthetase activity of aspirin-treated platelet microsomes and GBH (15 and 30 microg/ml) significantly inhibited [3H]arachidonic acid released in collagen-activated platelets but not in unactivated-platelets. Nitric oxide (NO) production in human platelets was measured by a chemiluminesence detection method in this study. GBH did not significantly affect nitrate production in collagen (10 microg/ml)-induced human platelet aggregation. Various concentrations of GBH (0, 5, 10, 15, and 30 microg/ml) dose-dependently inhibited [3H]inositol monophosphate formation stimulated by collagen (10 microg/ml) in [3H]myoinositol-loaded platelets at different incubation times (1, 2, 3, and 5 min). These results indicated that the antiplatelet activity of GBH may possibly be due to the inhibition of phospholipase C (PLC) activity, leading to reduce phosphoinositide breakdown, followed by the inhibition of thromboxane A(2) formation, and then inhibition of [Ca(2+)](i) mobilization of platelet aggregation stimulated by agonists. In conclusion, GBH suppressed PLC in a dose-dependent manner, and may have pharmaceutical applications. These data suggest that GBH extracts merit investigation as a potential anti-atherosclerogenic agent in humans.

Venom from the ectoparasitic wasp Nasonia vitripennis increases Na+ influx and activates phospholipase C and phospholipase A2 dependent signal transduction pathways in cultured insect cells

The mode of action of venom from the ectoparasitic wasp Nasonia vitripennis in eliciting cell death was examined using an in vitro approach with BTI-TN-5B1-4 cells, and the cell responses were compared to those evoked by the extensively studied wasp toxin mastoparan. Wasp venom increased plasma membrane permeability to Na+, resulting in cellular swelling and death due to oncosis. When ouabain was used to disable Na+, K+-ATPases, the effects of venom were enhanced. Measurements of intracellular calcium using fluo-4 AM revealed a rearrangement and an increase in cytosolic [Ca+2]i within 30 min after exposure of BTI-TN-5B1-4 cells to venom. This venom-mediated increase in Ca+2 was apparently due to mobilization of intracellular stores since the changes occurred in the absence of extracellular Ca+2. Phospholipase C (PLC) inhibitors, neomycin and U-73122, blocked the venom-induced death temporarily (<3h), but by 24h, all venom-treated cells swelled and lysed. Pre-treatment of cells with caffeine or theophylline but not ryanodine attenuated the induction of oncosis by wasp venom. Anti-inflammatory peptide 1 (antiflammin 1) but not bromophenacyl bromide, agents that block phospholipase A2 (PLA2) activity, abolished the responsiveness of BTI-TN-5B1-4 cells to venom. These results suggest that venom initiates cell death by inducing Ca+2 release from intracellular stores probably via phospholipase C and IP3. A possible mode of action for venom from N. vitripennis requiring dual activation of PLC and PLA2 is discussed and compared to the pathways known to be activated by mastoparan.

An annexin 1 (ANXA1)-derived peptide inhibits prototype antigen-driven human T cell Th1 and Th2 responses in vitro

BACKGROUND

Annexin-1 (ANXA1, lipocortin 1) is a pleiotrophic protein produced by many cell types including peripheral blood leucocytes. Although it has been shown to inhibit "macroscopic" inflammatory processes in animal models, its direct effects on antigen-activated human T cells have not been studied.

OBJECTIVE

To test the hypothesis that ANXA1-derived peptides inhibit antigen-driven prototype Th1 and Th2-type human T cell responses of clinical relevance and lectin-driven responses in vitro.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from 14 atopic subjects sensitized to house dust mite allergen (Dermatophagoides pteronyssinus, Der p) and purified protein derivative (PPD) of Mycobacterium tuberculosis. PBMC (1 x 106/mL) were cultured with phytohaemagglutinin (PHA; 5 microg/mL; 4 days), Der p (25 microg/mL; 6 days), PPD (10 microg/mL, 6 days) or medium control. Two ANXA1-derived peptides, Ac2-26 and AF-2 (5-500 microM), were assessed for possible inhibition of PHA-and antigen-induced T cell proliferation (measured by 3H-thymidine uptake), while Ac2-26 was assessed for inhibition of Der p-induced interleukin (IL)-5 release and PPD-induced interferon-gamma (IFN-gamma) release (measured by ELISA). Comparison was made with dexamethasone as an established inhibitory control. Endogenous production by PBMC of cell surface-associated and intracellular ANXA1 in response to PHA, Der p and PPD in the presence and absence of dexamethasone was measured by specific ELISA.

RESULTS

Both PHA- and antigen-induced T cellular proliferation were inhibited by dexamethasone. Although neither ANXA1-derived peptide significantly altered PHA-induced proliferation, both effected concentration-dependent reductions in antigen-induced proliferation, Ac2-26 being the more potent. Peptides of identical amino acid composition to Ac2-26 and AF-2, but of random sequence, were ineffective at equivalent concentrations. In addition, Ac2-26 and dexamethasone inhibited Der p-induced IL-5 release and PPD-induced IFN-gamma release in a concentration-dependent fashion. Endogenous ANXA1 was detectable in PBMC, but at concentrations approximately 104-fold lower, in molar terms, than the effective concentrations of the exogenously added, ANXA1-derived inhibitory peptides. Endogenous production was not significantly altered by any of the T cell stimuli employed in this study, in the presence or absence of dexamethasone.

CONCLUSION

In prototype Th1 and Th2-type human T cell responses, ANXA1-derived peptides can inhibit antigen-driven cellular proliferation and cytokine production.

Therapeutic applications of antiflammin peptides in experimental ocular inflammation

Antiflammins are synthetic peptides derived from the region of highest local similarity between uteroglobulin and lipocortin. These peptides have shown anti-inflammatory activity on carrageenan-induced rat footpad edema. They are potent inhibitors for phospholipase A2 activation both in vitro and in vivo. Previously, we have demonstrated the effectiveness of topical antiflammins in suppressing acute ocular inflammation and allergic response in rodent endotoxin-induced uveitis and murine allergic conjunctivitis. The mechanisms by which antiflammins protect against inflammation and allergy in these ocular models may involve inhibition of phospholipase A2 and inducible nitric oxide synthase (iNOS) as well as the production of proinflammatory cytokine, interleukin-6.

Antiflammin peptides in the regulation of inflammatory response

This review focuses on the role of antiflammins in the regulation of the inflammatory response, in particular acute inflammation. The results show that antiflammins were effective on several classical models of inflammation. Preliminary data suggest that antiflammin action may be due to their ability to suppress leukocyte trafficking to the lesion.

Antiflammins. Bioactive peptides derived from uteroglobin

Uteroglobin/Clara cell 10-kDa protein (UG/CC10) is a hormonally regulated small secretory protein that has a variety of in vitro and in vivo pharmacological effects. These include a potent anti-inflammatory activity and inhibitory effects on neutrophil migration, thrombin-induced platelet aggregation, in vitro chemoinvasion, as well as "tumor suppressor"-like effects and other properties. Several mechanisms of action have been proposed for these effects. Pharmacological properties suggest that UG itself or substances derived from it may be used as experimental drugs for several indications. The group of oligopeptides collectively known as "antiflammins" (AFs) were originally described in 1988. Their design was derived from the region of highest sequence similarity between UG and another group of proteins with anti-inflammatory properties, the lipocortins or annexins. Nanomolar concentrations of these peptides can reproduce several of the pharmacological activities of UG, including its in vivo anti-inflammatory effects and inhibition of platelet aggregation. The AFs have been safely and effectively used to suppress inflammation and fibrosis in several animal models. Progress in clarifying the mechanism of action of the AFs may facilitate the structure-based design of a novel class of potent anti-inflammatory, antichemotactic drugs.

Evidence that the ATP-induced increase in vasomotion of guinea-pig mesenteric lymphatics involves an endothelium-dependent release of thromboxane A2

1. Experiments were made to investigate mechanisms by which adenosine 5'-trisphosphate (ATP) enhanced vasomotion in mesenteric lymphatic vessels isolated from young guinea-pigs. 2. ATP (10-8 - 10-3 M) caused a concentration-dependent increase of perfusion-induced vasomotion with the endothelium mediating a fundamental role at low ATP concentrations (10-8 - 10-6 M). 3. The response to 10-6 M ATP showed tachyphylaxis when applied at intervals of 10 min but not at intervals of 20 or 30 min. 4. Suramin (10-4 M) or reactive blue 2 (3x10-5 M) but not PPADS (3x10-5 M) abolished the excitatory response to 10-6 M ATP confirming an involvement of P2 purinoceptors. 5. The excitatory response to 10-6 M ATP was abolished by treatment with either pertussis toxin (100 ng ml-1), antiflammin-1 (10-9 M), indomethacin (3x10-6 M) or SQ29548 (3x10-7 M), inhibitors of specific G proteins, phospholipase A2, cyclo-oxygenase and thromboxane A2 receptors respectively. 6. ATP simultaneously induced a suramin-sensitive inhibitory response, which was normally masked by the excitatory response. ATP-induced inhibition was mediated by endothelium-derived nitric oxide (EDNO) as the response was abolished by NG-nitro-L-arginine (L-NOARG; 10-4 M), an inhibitor of nitric oxide synthase. 7. We conclude that ATP modulates lymphatic vasomotion by endothelium-dependent and endothelium-independent mechanisms. One of these is a dominant excitation caused through endothelial P2 purinoceptors which because of an involvement of a pertussis toxin sensitive G-protein may be of the P2Y receptor subtype. Their stimulation increases synthesis of phospholipase A2 and production of thromboxane A2, an arachidonic acid metabolite which acts as an endothelium-derived excitatory factor.

Early metabolic inhibition-induced intracellular sodium and calcium increase in rat cerebellar granule cells

1. Possible mechanisms responsible for the increases in intracellular calcium ([Ca2+]i) and sodium ([Na+]i) levels seen during metabolic inhibition were investigated by continuous [Ca2+]i and [Na+]i measurement in cultured rat cerebellar granule cells. An initial small mitochondrial Ca2+ release was seen, followed by a large influx of extracellular Ca2+. A large influx of extracellular Na+ was also seen. 2. The large [Ca2+]i increase was not due to opening of voltage-dependent or voltage-independent calcium channels, activation of NMDA/non-NMDA channels, activation of the Na+i-Ca2+o exchanger, or inability of plasmalemmal Ca2+-ATPase to extrude, or mitochondria to take up, calcium. 3. The large [Na+]i increase was not due to activation of the TTX-sensitive Na+ channel, the Na+i-Ca2+o exchanger, the Na+-H+ exchanger, or the Na+-K+-2Cl- cotransporter, or an inability of Na+-K+-ATPase to extrude the intracellular sodium. 4. Phospholipase A2 (PLA2) activation may be involved in the large influx, since both were completely inhibited by PLA2 inhibitors. Moreover, melittin (a PLA2 activator) or lysophosphatidylcholine or arachidonic acid (both PLA2 activation products) caused similar responses. Inhibition of PLA2 activity may help prevent the influx of these ions that may result in serious brain injury and oedema during hypoxia/ischaemia.

The antiplatelet activity of rutaecarpine, an alkaloid isolated from Evodia rutaecarpa, is mediated through inhibition of phospholipase C

In this study, the mechanism involved in the antiplatelet activity of rutaecarpine in human platelet suspensions was investigated. In platelet suspensions (4.5 x 10(8)/ml), rutaecarpine (100 and 200 microM) did not influence the binding of FITC-triflavin to platelet glycoprotein IIb/IIIa complex. Additionally, rutaecarpine (200 microM) did not significantly change the fluorescence of platelet membrane labeled with diphenylhexatriene (DPH). On the other hand, rutaecarpine (50 and 100 microM) dose-dependently inhibited the increase in intracellular free Ca2+ of Fura 2-AM loaded platelets stimulated by collagen. Moreover, rutaecarpine (100 and 200 microM) did not significantly affect the thromboxane synthetase activity of aspirin-treated platelet microsomes. Furthermore, retaecarpine (100 and 200 microM) significantly inhibited [3H]arachidonic acid released in collagen-activated platelets but not in unactivated-platelets. Nitric oxide (NO) production in human platelets was measured by a chemiluminesence detection method in this study. Rutaecarpine (100 and 200 microM) did not significantly affect nitrate production in collagen (10 microg/ml)-induced human platelet aggregation. On the other hand, various concentrations of rutaecarpine (50, 100, and 200 microM) dose-dependently inhibited [3H]inositol monophosphate formation stimulated by collagen (10 microg/ml) in [3H]myoinositol-loaded platelets at different incubation times (1, 2, 3, and 5 minutes). It is concluded that the antiplatelet activity of rutaecarpine may possibly be due to the inhibition of phospholipase C activity, leading to reduce phosphoinositide breakdown, followed by the inhibition of thromboxane A2 formation, and then inhibition of [Ca2+]i mobilization of platelet aggregation stimulated by agonists.

Evidence that the substance P-induced enhancement of pacemaking in lymphatics of the guinea-pig mesentery occurs through endothelial release of thromboxane A2

1. In vitro studies were performed to examine the mechanisms underlying substance P-induced enhancement of constriction rate in guinea-pig mesenteric lymphatic vessels. 2. Substance P caused an endothelium-dependent increase in lymphatic constriction frequency which was first significant at a concentration of 1 nM (115 +/- 3% of control, n = 11) with 1 microM, the highest concentration tested, increasing the rate to 153 +/- 4% of control (n = 9). 3. Repetitive 5 min applications of substance P (1 microM) caused tachyphylaxis with tissue responsiveness tending to decrease (by an average of 23%) and significantly decreasing (by 72%) for application at intervals of 30 and 10 min, respectively. 4. The competitive antagonist of tachykinin receptors, spantide (5 microM) and the specific NK1 receptor antagonist, WIN51708 (10 microM) both prevented the enhancement of constriction rate induced by 1 microM substance P. 5. Endothelial cells loaded with the Ca2+ sensing fluophore, fluo 3/AM did not display a detectable change in [Ca2+]i upon application of 1 microM substance P. 6. Inhibition of nitric oxide synthase by NG nitro-L-arginine (L-NOARG; 100 microM) had no significant effect on the response induced by 1 microM substance P. 7. The enhancement of constriction rate induced by 1 microM substance P was prevented by the cyclooxygenase inhibitor, indomethacin (3 microM), the thromboxane A2 synthase inhibitor, imidazole (50 microM), and the thromboxane A2 receptor antagonist, SQ29548 (0.3 microM). 8. The stable analogue of thromboxane A2, U46619 (0.1 microM) significantly increased the constriction rate of lymphangions with or without endothelium, an effect which was prevented by SQ29548 (0.3 microM). 9. Treatment with pertussis toxin (PTx; 100 ng ml-1) completely abolished the response to 1 microM substance P without inhibiting either the perfusion-induced constriction or the U46619-induced enhancement of constriction rate. 10. Application of the phospholipase A2 inhibitor, antiflammin-1 (1 nM) prevented the enhancement of lymphatic pumping induced by substance P (1 microM), without inhibiting the response to either U46619 (0.1 microM) or acetylcholine (10 microM). 11. The data support the hypothesis that the substance P-induced increase in pumping rate is mediated via the endothelium through NK1 receptors coupled by a PTx sensitive G-protein to phospholipase A2 and resulting in generation of the arachidonic acid metabolite, thromboxane A2 this serving as the diffusible activator.

Antiflammin 1 peptide delivered non-invasively by iontophoresis reduces irritant-induced inflammation in vivo

The potential of an anti-inflammatory peptide (antiflammin 1) to reduce irritation when delivered transdermally by iontophoresis was examined. A model drug irritant, chlorpromazine, was co-delivered with and without antiflammin 1 by iontophoresis to hairless guinea pigs transdermally. Quantitative skin irritation measurements were obtained by monitoring erythema by skin color reflectance with the Minolta Chromameter. Antiflammin 1 delivered by iontophoresis significantly decreased, but did not eliminate, the erythema associated with co-delivery of an irritating drug compound. Lesion formation was also reduced in the presence of antiflammin 1. In vitro flux across hairless guinea pig skin demonstrated no significant differences in flux of the irritant compound in the presence or absence of antiflammin 1. In vivo generation and efflux of the inflammation mediator Prostaglandin E2 increased during 24-h application of irritant and was unchanged in the presence of antiflammin 1. This result is discussed with respect to recent evidence that antiflammins may act on the lipo-oxygenase pathway. In summary, antiflammin 1, an anti-inflammatory peptide, can be delivered transdermally by iontophoresis with retention of its biological activity in vivo.

Antiflammins: endogenous nonapeptides with regulatory effect on inflammation

1. Antiflammins are a new family of peptides that share a common sequence with uteroglobin and lipocortin-1, which retain the anti-inflammatory action of these proteins. 2. However, it is controversial whether or not the antiflammins have any effect on enzymes involved in arachidonic acid mobilization and/or arachidonic acid metabolism. 3. This review summarizes our current knowledge of the properties and activity of antiflammins.

Antiflammin-2, a nonapeptide of lipocortin-1, inhibits leukocyte chemotaxis but not arachidonic acid mobilization

We have studied the effects of antiflammin-2, a fragment corresponding to amino acids 246-254 of lipocortin-1 (HDMNKVLDL), on arachidonate mobilization and metabolism and we also determined the effect of antiflammin-2 on the chemotaxis of phagocytes. Our results demonstrated that the antiflammin-2 was not able to diminish significantly [3H]arachidonic acid mobilization stimulated by 4 beta-phorbol-12-myristate 13-acetate or calcium ionophore A23187 in murine 3T6 fibroblasts or resident peritoneal macrophages. Further, antiflammin-2 had no effect on arachidonate metabolism. In contrast, a glucocorticoid such as dexamethasone reduced significantly [3H]arachidonic acid release and arachidonate metabolism induced in both cells. This study confirms the inhibitory effect of antiflammin on leukocyte migration and suggests that it acts partly through the inhibition of leukocyte binding to endothelial cells.

Ketoprofen produces profound inhibition of spinal c-Fos protein expression resulting from an inflammatory stimulus but not from noxious heat

This study assesses the anti-inflammatory/analgesic effects of ketoprofen a non-steroidal anti-inflammatory drug, using the method of c-Fos immunoreactivity at the spinal cord level in two models of noxious stimulation: carrageenan-induced inflammatory pain or acute noxious heat. Ketoprofen was pre-administered intravenously or orally 25 min before an intraplantar injection of carrageenan (6 mg in 150 microliters of saline) in hindpaw of the non-anaesthetised rat or before a single noxious heat (52 degrees C, 15 sec) stimulation of hindpaw of the anaesthetised rat. Three hours after carrageenan or 2 h after noxious heat, the number of spinal c-Fos protein-like immunoreactive (c-Fos-LI) neurons in L4-L5 segments and both the ankle and paw diameter, the indicator of peripheral oedema, were assessed. Pre-administered ketoprofen (1, 3 and 10 mg/kg i.v.) dose-dependently blocks the development of the carrageenan-induced spinal c-Fos protein expression and peripheral oedema, with the highest dose influencing in parallel both parameters (75 +/- 2% diminution of total number of c-Fos-LI neurons per L4-L5 section; 64 +/- 4% and 82 +/- 6% diminution of paw and ankle oedema, respectively). The effect of ketoprofen was significantly greater on the number of c-Fos-LI neurons in deep, as compared to superficial, laminae. Furthermore, the dose-dependent effects of ketoprofen on the carrageenan-induced spinal c-Fos protein expression and both the paw and ankle oedema were correlated. Oral pre-administration of ketoprofen (20 mg/kg) produced the blockage of development of the carrageenan-induced spinal c-Fos protein expression (65 +/- 3% diminution of total number of c-Fos-LI neurons per L4-L5 section) and peripheral oedema (20 +/- 3% and 59 +/- 10% diminution of paw and ankle oedema, respectively). In contrast, the same doses of both the intravenous and oral pre-administration of ketoprofen did not influence either the spinal c-Fos protein expression nor slightly enhanced paw diameter induced by a single noxious heat stimulation. This study suggests a predominant peripheral site, without excluding a central site of action of ketoprofen in the carrageenan-induced inflammation. The method of c-Fos protein-like immunoreactivity revealed ketoprofen to be more potent in comparison to members of other families of non-steroidal anti-inflammatory drugs, previously studied in the same experimental conditions of carrageenan-induced inflammatory pain.

Degradation of antiflammin 2 under acidic conditions

Antiflammin 2 (HDMNKVLDL, AF2) is a synthetic peptide derived from the region of highest sequence similarity of lipocortin I and uteroglobin, and is a potent antiinflammatory agent without any known side effects of corticosteroids. The antiinflammatory activity of AF2 has been demonstrated, but is not reproducible between laboratories. It has been suggested that the chemical instability of this peptide is responsible for the loss of activity. The degradation of AF2 in aqueous solutions at a pH range of 3 to 10 has been reported. In this study, the degradation of AF2 at acidic pHs was monitored by reversed-phase HPLC. The reactions were studied as functions of buffer concentration and temperature. The rates of loss of AF2 followed apparent pseudo-first-order kinetics. Several products were isolated and identified by fast atom bombardment mass spectroscopy and tandem mass spectroscopy, and were the result of C- and N-terminus hydrolyses of aspartyl peptide bonds in AF2. The peptide bonds at C-termini of the aspartyl residues were most susceptible to hydrolysis, resulting in the formation of major degradation products, HDMNKVLD, MNKVLDL, and MNKVLD. The minor products from the N-terminus hydrolysis were HDMNKVL and MNKVL and formed at much slower rates.

Effects of an anti-inflammatory peptide (antiflammin 2) on cell influx, eicosanoid biosynthesis and oedema formation by arachidonic acid and tetradecanoyl phorbol dermal application

Antiflammins are synthetic peptides with sequence homology to proteins inhibitory for phospholipase A2 (EC 3.1.1.4). The effect of antiflammin 2 on murine arachidonate or 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced ear oedema has been studied. Topical application of arachidonic acid (AA) produced a short-lived oedema response with rapid onset associated with marked increases in prostaglandin E2 levels. TPA produced a longer-lasting oedema associated with marked influx of neutrophils and mononuclear cells as well as predominant formation of leukotriene B4 (LTB4). Topical pretreatment with indomethacin or dexamethasone reduced plasma leakage, oedema and prostaglandin E2 biosynthesis in AA-induced oedema, whereas antiflammin 2 had no effect. However, topical pretreatment with antiflammin 2 dose-dependently reduced plasma leakage, cell influx, oedema and LTB4 levels in response to TPA. These results indicate that the anti-inflammatory effect of antiflammins can be attributed to AA mobilization and/or 5 lipoxygenase inhibition but can be dissociated from an effect on arachidonic acid metabolism by the cyclooxygenase pathway.

Regulation of phospholipase A2 enzymes: selective inhibitors and their pharmacological potential

The area of PLA2 research has grown immensely over the past 20 years. There is a better understanding of the kinetics, or factors that affect the kinetics, of the different forms of PLA2. New forms of PLA2 are being discovered, such as the cPLA2, which fit the role of an intracellularly regulated enzyme. Multiple forms of PLA2 tend to complicate the elucidation of the cellular mechanisms that regulate AA release and the subsequent eicosanoid production. Because of the factors that affect PLA2 kinetics and the unknown nature of the PLA2 that regulates AA release (there may be more than one), it has been difficult to design or isolate specific inhibitors. This review discussed selected classes of inhibitors because these have generated the most intense research in the field. There is a multitude of structurally diverse compounds reported in the literature that have been reported to be inhibitors of PLA2 in vitro and some have been reported to have anti-inflammatory activity (Wilkerson, 1990; Connolly and Robinson, 1993a). It is clear from a brief survey of the literature that the bulk of PLA2 inhibitors have topical anti-inflammatory activity. This may be due to the nature of these inhibitors: because they are hydrophobic they may be more readily absorbed in the skin whereas when given orally they may not be absorbed. To data, manoalide has been clinically evaluated in man and a new Bristol-Myers Squibb retenoid derivative may enter clinical trials for psoriasis (BMS-181162 (XVI)); however, there are no PLA2 inhibitors on the market or significantly advanced in clinical development (Table III). This indicates the lack of understanding of this enzyme for the development of relevant inhibitors, which is related to the lack of understanding of the relevant PLA2 that regulates AA release and eicosanoid biosynthesis. The concept of regulation of eicosanoid biosynthesis by PLA2 inhibition and decreased AA availability still remains a viable therapeutic approach for the treatment of inflammatory diseases. The proof of this concept has not been obtained because of the complex nature of PLA2 and the multiple forms of PLA2 in the cell. Clinical results with cyclooxygenase inhibitors and recent clinical results with inhibitor of 5-lipoxygenase demonstrate that if inhibition of PLA2 results in reduction in both lipid mediators, a good anti-inflammatory compound should result. The added advantage of PLA2 inhibitors would be the reduction of PAF levels; however, the clinical results with potent and specific PAF antagonists has been less encouraging about the potential benefits of reduction in PAF levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of nonapeptide fragments of uteroglobin and lipocortin I on oedema and mast cell degranulation

The anti-inflammatory action of nonapeptide fragments of uteroglobin or lipocortin I known as antiflammins, was tested in the carrageenan or phospholipase A2 rat paw oedema model. The development of carrageenan-induced oedema in rats was significantly inhibited during the early and late phases of the oedema by the local administration of antiflammins 1 and 2. However, the peptides were not able to inhibit phospholipase A2-induced oedema. The time course of the anti-oedematous activity of nonapeptides after intradermal carrageenan injection may be attributed to their effect on mast cell degranulation and accumulation and activation of leukocytes. Naja naja phospholipase A2 exhibited strong histamine release-inducing activity, which may have contributed to the rat paw oedema induction. Surprisingly, antiflammins had a limited but significant inhibitory effect on histamine secretion.

Crystallization and characterization of the recombinant human Clara cell 10-kDa protein

Crystals of recombinant human Clara cell 10-kDa protein were grown both from ammonium sulfate and polyethylene glycol (PEG) solutions. Crystals grown from ammonium sulfate solution have been characterized by X-ray diffraction studies as monoclinic with the space group C2 and lattice constants a = 69.2 A, b = 83.0 A, c = 58.3 A, and beta = 99.7 degrees. The monoclinic crystals diffract to beyond 2.5 A. Some of the crystals grown from PEG were of a similar habit to those grown from ammonium sulfate, but others were triclinic with the space group P1 and cell constants a = 40.3 A, b = 46.3 A, c = 51.3 A, alpha = 117.7 degrees, beta = 102.3 degrees, and gamma = 71.4 degrees. These crystals diffract to beyond 3.2 A.

Tissue-specific expression of the gene coding for human Clara cell 10-kD protein, a phospholipase A2-inhibitory protein

Clara cell 10-kD protein (cc10kD), a secretory phospholipase A2 inhibitor, is suggested to be the human counterpart of rabbit uteroglobin (UG). Because cc10kD is expressed constitutively at a very high level in the human respiratory epithelium, the 5' region of its gene may be useful in achieving organ-specific expression of recombinant DNA in gene therapy of diseases such as cystic fibrosis. However, it is important to establish the tissue-specific expression of this gene before designing gene transfer experiments. Since the UG gene in the rabbit is expressed in many other organs besides the lung and the endometrium, we investigated the organ and tissue specificity of human cc10kD gene expression using polymerase chain reaction, nucleotide sequence analysis, immunofluorescence, and Northern blotting. Our results indicate that, in addition to the lung, cc10kD is expressed in several nonrespiratory organs, with a distribution pattern very similar, if not identical, to that of UG in the rabbit. These results underscore the necessity for more detailed analyses of the 5' region of the human cc10kD gene before its usefulness in gene therapy could be fully assessed. These data also suggest that cc10kD and UG may have similar physiological function(s).

Phospholipase A2 enzymes: regulation and inhibition

The phospholipase A2 enzymes are important components of the cellular machinery that responds to inflammatory stimuli and maintains cell homeostasis by membrane remodelling. Their role as the rate-limiting step in the production of pro-inflammatory lipid mediators makes these enzymes an important therapeutic target for the treatment of inflammatory disorders. Keith Glaser and colleagues explain how the two major groups of phospholipase A2, the secretory and cytosolic forms, are very different both structurally and enzymatically. Understanding the relative contributions of these different forms of phospholipase A2 to physiological and pathological conditions requires greater insight into their cellular regulation and the development of selective inhibitors.