Antiflammins: endogenous nonapeptides with regulatory effect on inflammation

JTP-117968, a novel selective glucocorticoid receptor modulator, exhibits significant anti-inflammatory effect while maintaining bone mineral density in mice

Classic glucocorticoids have been prescribed for various inflammatory diseases, such as rheumatoid arthritis, due to their outstanding anti-inflammatory effects. However, glucocorticoids cause numerous unwanted side effects, including osteoporosis and diabetes. Hence, selective glucocorticoid receptor modulators (SGRMs), which retain anti-inflammatory effects with minimized side effects, are among the most anticipated drugs in the clinical field. The assumption is that there are two major mechanisms of action via glucocorticoid receptors, transrepression (TR) and transactivation (TA). In general, anti-inflammatory effects of glucocorticoids are largely due to TR, while the side effects associated with glucocorticoids are mostly mediated through TA. We previously reported that JTP-117968, a novel SGRM, maintained partial TR activity while remarkably reducing the TA activity. In this study, we investigated the anti-inflammatory effect of JTP-117968 on a lipopolysaccharide (LPS) challenge model and collagen-induced arthritis (CIA) model in mice. Meanwhile, we tested the effect of JTP-117968 on the bone mineral density (BMD) in mouse femur to evaluate the side effect. Based on the evaluation, JTP-117968 reduced the plasma levels of tumor necrosis factor α induced by LPS challenge in mice significantly. Remarkably, CIA development was suppressed by JTP-117968 comparably with prednisolone and PF-802, an active form of fosdagrocorat that has been developed clinically as an orally available SGRM. Strikingly, the side effect of JTP-117968 on mouse femoral BMD was much lower than those of PF-802 and prednisolone. Therefore, JTP-117968 has attractive potential as a new therapeutic option against inflammatory diseases with minimized side effects compared to classic glucocorticoids.

JTP-117968, a novel selective glucocorticoid receptor modulator, exhibits improved transrepression/transactivation dissociation

Classic glucocorticoids that have outstanding anti-inflammatory effects are still widely prescribed for the treatment of various inflammatory and autoimmune diseases. Conversely, glucocorticoids cause numerous unwanted side effects, particularly systemically dosed glucocorticoids. Therefore, selective glucocorticoid receptor modulator (SGRM), which maintains beneficial anti-inflammatory effects while reducing the occurrence of side effects, is one of the most anticipated drugs. However, there have been no SGRMs marketed to date. The assumption is that there are two major mechanisms of action of glucocorticoids via glucocorticoid receptors, transrepression (TR) and transactivation (TA). In general, the anti-inflammatory effects of glucocorticoids are mostly mediated through TR, while the side effects associated with glucocorticoids are largely caused by TA. We started to evaluate novel orally available SGRMs that maintain anti-inflammatory effects while minimizing adverse effects by favoring TR over TA. Based on this evaluation, we discovered JTP-117968, (4b'S,7'R,8a'S)-4b'-benzyl-7'-hydroxy-N-(2-methylpyridin-3-yl)-7'-(trifluoromethyl)-4b',6',7',8',8a',10'-hexahydro-5'H-spiro[cyclopropane-1,9'-phenanthrene]-2'-carboxamide, a non-steroidal SGRM. JTP-117968 has partial TR activity, but exhibits extremely low TA activity. The maximum TR efficacy of JTP-117968 was comparable to its structural analogue, PF-802, (4bS,7R,8aR)-4b-Benzyl-7-hydroxy-N-(2-methylpyridin-3-yl)-7-(trifluoromethyl)-4b,5,6,7,8,8a,9,10-octahydrophenanthrene-2-carboxamide, which is the active form of Fosdagrocorat that has been developed clinically as a first-in-class orally available SGRM. Remarkably, the TA activity of JTP-117968 was much weaker than PF-802 not only in in vitro assays, but also in in vivo mice experiments. These findings indicate that JTP-117968 exhibits improved TR/TA dissociation because the compound has significantly lower TA activity compared with an already reported SGRM. Therefore, JTP-117968 is expected to be a useful compound for evaluating ideal SGRMs in the future.

Secretoglobin 1A1 and 1A1A differentially regulate neutrophil reactive oxygen species production, phagocytosis and extracellular trap formation

Secretoglobin family 1A member 1 (SCGB 1A1) is a small protein mainly secreted by mucosal epithelial cells of the lungs and uterus. SCGB 1A1, also known as club (Clara) cell secretory protein, represents a major constituent of airway surface fluid. The protein has anti-inflammatory properties, and its concentration is reduced in equine recurrent airway obstruction (RAO) and human asthma. RAO is characterized by reversible airway obstruction, bronchoconstriction and neutrophilic inflammation. Direct effects of SCGB 1A1 on neutrophil functions are unknown. We have recently identified that the SCGB1A1 gene is triplicated in equids and gives rise to two distinct proteins. In this study we produced the endogenously expressed forms of SCGBs (SCGB 1A1 and 1A1A) as recombinant proteins, and analyzed their effects on reactive oxygen species production, phagocytosis, chemotaxis and neutrophil extracellular trap (NET) formation ex vivo. We further evaluated whether NETs are present in vivo in control and inflamed lungs. Our data show that SCGB 1A1A but not SCGB 1A1 increase neutrophil oxidative burst and phagocytosis; and that both proteins markedly reduce neutrophil chemotaxis. SCGB 1A1A reduced chemotaxis significantly more than SCGB 1A1. NET formation was significantly reduced in a time- and concentration-dependent manner by SCGB 1A1 and 1A1A. SCGB mRNA in bronchial biopsies, and protein concentration in bronchoalveolar lavage fluid, was lower in horses with RAO. NETs were present in bronchoalveolar lavage fluid from horses with exacerbated RAO, but not in fluid from horses with RAO in remission or in challenged healthy horses. These findings indicate that SCGB 1A1 and 1A1A have overlapping and diverging functions. Considering disparities in the relative abundance of SCGB 1A1 and 1A1A in airway secretions of animals with RAO suggests that these functional differences may contribute to the pathogenesis of RAO and other neutrophilic inflammatory lung diseases.

Uteroglobin, a possible ligand of the lipoxin receptor inhibits serum amyloid A-driven inflammation

Serum amyloid A (SAA) production is increased by inflamed arthritic synovial tissue, where it acts as a cytokine/chemoattractant for inflammatory and immune cells and as an inducer of matrix degrading enzymes. SAA has been shown to bind lipoxin A4 receptor, a member of the formyl-peptide related 2 G-protein coupled receptor family (ALX) and elicit proinflammatory activities in human primary fibroblast-like synoviocytes (FLS). We report on the identification of uteroglobin, a small globular protein with potent anti-inflammatory activities, as a possible ligand of ALX. Uteroglobin-specific association with ALX was demonstrated by an enzyme immunoassay experiment employing a cell line engineered to express the human ALX receptor. Uteroglobin's interaction with ALX resulted in the inhibition of SAA responses, such as attenuation of phospholipase A2 activation and cellular chemotaxis. In FLS, uteroglobin showed an antagonism against SAA-induced interleukin-8 release and decreased cell migration. These novel roles described for uteroglobin via ALX may help elucidate genetic and clinical observations indicating that a polymorphism in the uteroglobin promoter is linked to disease outcome, specifically prediction of bone erosion in patients with rheumatoid arthritis or severity of IgA glomerulonephritis and sarcoidosis.

Antiflammin-2 activates the human formyl-peptide receptor like 1

The anti-inflammatory actions of the nonapeptide antiflammin-2, identified by homology with uteroglobin and annexin-A1 sequences, have been described in some detail, yet its mechanisms of action remain elusive. Since recent data indicate an involvement of the formyl peptide receptor (FPR)-like 1 (or FPRL-1) in the effects of annexin-A1, we have tested here the effect of antiflammin-2 with respect to this receptor family. Using HEK-293 cells expressing either human FPR and FPRL-1, and an annexin-A1 peptide as tracer ([¹²⁵I-Tyr]-Ac2-26), we found that antiflammin-2 competed for binding only at FPRL-1, and not FPR, with an approximate EC₅₀ of 1 μM. In line with data produced for the full-length protein, genuine receptor activation by antiflammin-2 was confirmed by rapid phosphorylation of extracellular-regulated kinase 1 and 2. Finally, study of the neutrophil interaction with activated endothelium under flow demonstrated an inhibitory effect of antiflammin-2, thus providing functional support to a role for the antiflammin-2/FPRL-1 anti-inflammatory axis.

Effects of antiflammins on transglutaminase and phospholipase A2 activation by transglutaminase

Two anti-inflammatory peptides, named antiflammins (AFs), corresponding to a region with high amino acid similarity between lipocortin-1 and uteroglobin were tested for their ability to inhibit transglutaminase (TG) and low-molecular-mass phospholipase A2 (PLA2). Porcine pancreatic PLA2 activity and guinea pig hepatic TG activity were determined by arachidonyl release from arachidonyl-phosphatidylcholine and by the incorporation of putrescine into succinylated casein, respectively. AFs inhibited TG activity but did not affect PLA2 activity. Moreover, porcine pancreatic PLA2 was activated by TG and AFs decreased porcine pancreatic PLA2 activation induced by TG. Taken together, our results support the hypothesis that the anti-inflammatory effects of AFs are, at least in part, due to the action of AFs on TG activity.

Expression of annexin-1 in multiple sclerosis plaques

This study describes the distribution and identity of annexin-1 positive cells in the central nervous system in patients with multiple sclerosis (MS). Glucocorticoid-inducible, anti-inflammatory properties have been ascribed to annexin-1, a member of a family of calcium-binding proteins that are referred to collectively as annexins. We have found annexin-1 to be spatially associated with active MS lesions and demonstrated a stage-dependent expression of annexin-1 in MS plaques. All of the most important pathogenetically involved cells of MS lesions showed a strong annexin-1 reactivity. Both correlation analysis and double staining procedures suggested annexin-1 expression in macrophages and perivascular lymphocytes, where a cytoplasmic reactivity was displayed, whereas in activated, gemistocytic astrocytes it was also concentrated close to the plasma membrane. Although the exact roles of annexin-1 in this setting are still to be determined, a possible contribution to anti-inflammatory processes might be suggested.

Purification and characterization of the mammaglobin/lipophilin B complex, a promising diagnostic marker for breast cancer

Mammaglobin, a promising diagnostic marker for breast cancer, forms a covalent complex with lipophilin B. mRNA levels for each component of the complex were determined for a number of breast tumors and normal tissues, and correlation of message expression was highly significant between mammaglobin and lipophilin B (p < 0.0001). The complex was purified by both standard biochemical techniques and immunoaffinity chromatography. N-Terminal sequencing revealed that mammaglobin and lipophilin B are processed as predicted by cleavage of their signal sequence after amino acids 19 and 21, respectively. Three molecular masses-representing the fully glycosylated form, the complex without one of the carbohydrate chains, and the deglycosylated proteins-are detected by ProteinChip array SELDI-TOF mass spectrometry after partial enzymatic deglycosylation. This is consistent with the two predicted N-linked glycosylation sites in the primary sequence of mammaglobin and each site having an attached sugar of approximately 3500 Da. Reducing agents release lipophilin B from mammaglobin, and the free peptides are seen at their predicted molecular masses in the deglycosylated complex. Molecular modeling, secondary structure prediction, and circular dichroism indicate that the complex is a small alpha-helical globule that has three disulfide bridges and a carbohydrate chain at each pole. LC-ESI-MS shows that mammaglobin and lipophilin B are bonded in a head to tail orientation. This work describes the biochemistry of the mammaglobin/lipophilin B complex and lays the framework for use of this complex as a novel protein-based serological marker for breast cancer.

Altered lung gene expression in CCSP-null mice suggests immunoregulatory roles for Clara cells

Clara cell secretory protein (CCSP) is one of the most abundant proteins present in airway lining fluid of mammals. In an effort to elucidate the function of CCSP, we established CCSP-null [CCSP(-/-)] mice and demonstrated altered sensitivity to various environmental agents including oxidant pollutants and microorganisms. Although CCSP deficiency itself may be central to the observed changes in environmental susceptibility, altered lung gene expression associated with CCSP deficiency may contribute to the observed phenotype. To determine whether CCSP deficiency results in altered lung gene expression, high-density cDNA microarrays were used to profile gene expression in the total lung RNA of wild-type and CCSP(-/-) mice. Genes that were differentially expressed between wild-type and CCSP(-/-) mice included a previously non-annotated expressed sequence tag (EST W82219) and immunoglobulin A (IgA), both of which were elevated with CCSP deficiency. mRNA expression of EST W82219 and IgA was localized in the lungs of wild-type and CCSP(-/-) mice to airway Clara cells and peribronchial lymphoid tissues, respectively. We conclude that CCSP deficiency is associated with 1) altered gene expression in Clara cells of the conducting airway epithelium and 2) alterations to peribronchial B lymphocytes. These findings identify new roles for Clara cells and their secretions in airway homeostasis.

Annexin I is a local mediator in neural-endocrine feedback control of inflammation

Annexin I is a local mediator in neural-endocrine feedback control of inflammation. J. Neurophysiol. 80: 3120-3126, 1998. Activation of primary afferent nociceptors induces a neural endocrine-mediated inhibition of the inflammatory response via a circuit that includes ascending spinal pathways and activation of the hypothalamic-pituitary adrenal (HPA) axis. This circuit inhibits sympathetic neuron-dependent plasma extravasation (PE) in the rat knee joint produced by bradykinin (BK), but not sympathetic neuron-independent PE produced by platelet activating factor (PAF). Noxious (25 mA) but not non-noxious (2.5 mA) electrical stimulation significantly increased plasma corticosterone concentrations, and intravenous infusion of corticosterone (5 micrograms/min) mimicked inhibition of BK-induced PE produced by noxious stimulation. However, perfusion of corticosterone locally through the knee joint, at doses that do not have a systemic action (i.e., </=1 microM), did not inhibit BK-induced PE. Annexin I (lipocortin-1), a 37-kDa member of a family of phospholipid and calcium binding proteins, can mediate local anti-inflammatory effects of glucocorticoids via a mechanism that is partially dependent on inhibition of phospholipase A2 activity and adhesion and transmigration of polymorphonuclear leukocytes. Because BK-induced PE is dependent on both polymorphonuclear leukocytes and phospholipase A2 activity, we tested the hypothesis that the action of corticosterone to inhibit BK-induced PE is mediated by stimulating the production and release of annexin I. Perfusion of BK (150 nM) through the rat knee joint induces a rapid and sustained increase in PE. Co-perfusion of BK with annexin I (100 ng/ml) through the knee joint mimics the inhibition of BK-induced PE produced by noxious electrical stimulation or by intravenous corticosterone. Co-perfusion of BK with annexin I antibody (LCPS1, 1:60 dilution) prevented the inhibition of BK-induced PE produced by noxious electrical stimulation or intravenous corticosterone adminstration. PAF-induced PE, which is not dependent on polymorphonuclear leukocytes, was not inhibited by local perfusion of annexin I. These data suggest that the inhibitory effect of C-fiber activity on BK-induced PE, acting via an HPA circuit, is mediated by annexin I in the knee joint.