n-Nonanoyl-CCL14 (NNY-CCL14), a novel inhibitor of allergic airway inflammation is a partial agonist of human CCR2

BACKGROUND

Modulation of leukocyte recruitment through blocking of chemokine receptors has been proposed as an attractive therapeutic strategy. We have previously demonstrated that n-Nonanoyl-CC chemokine ligand 14 (NNY-CCL14), a modified analog of the naturally occurring chemokine CCL14(9-74) internalizes and desensitizes human CCR3 resulting in the inactivation of eosinophils. However, inhibitory effects of NNY-CCL14 in murine models of allergic airway inflammation are assigned to its interaction with CCR1 and CCR5.

AIM OF THE STUDY

As CCL2 and its receptor CCR2 have been shown to play important roles in the development of Th2 inflammation, we further evaluated the effects of NNY-CCL14 treatment on CCL2-mediated activation of CCR2.

METHODS

Effects of NNY-CCL14 treatment were studied on cell lines transfected with human CCR2 and primary leukocytes. Functional effects were assessed by calcium efflux assays, flow cytometry and chemotaxis.

RESULTS

Prestimulation with NNY-CCL14 desensitized CCR2-mediated responses to further stimulation with its selective ligand CCL2. No significant internalization of CCR2 was observed when the cells were stimulated with NNY-CCL14, even at concentrations eliciting maximal [Ca(2+)]i mobilization. Above all, NNY-CCL14 pretreatment blocked CCL2-induced chemotaxis of monocytes.

CONCLUSIONS

This study demonstrates that NNY-CCL14 is a partial agonist of CCR2, inhibiting responses of monocytes to the CCR2-selective ligand CCL2. NNY-CCL14 attenuates CCR2-mediated responses by rapidly desensitizing the receptor and preventing chemotaxis, although it is able to induce calcium mobilization but does not lead to CCR2 internalization. Hence this study provides further insights into the possible mechanisms of action of NNY-CCL14, which interacts with multiple chemokine receptors inhibiting the migration and activation of different cell populations involved, thus acting as a potential therapeutic compound to alleviate allergic inflammation.

The allergy-associated chemokine receptors CCR3 and CCR5 can be inactivated by the modified chemokine NNY-CCL11

BACKGROUND

CC chemokine ligand 11 (CCL11) is the outstanding member of all described CC chemokine receptor 3 (CCR3) ligands and is shown to be selective for this receptor. However, it also activates CCR5 but only in the micromolar range. The in vivo activity of CCL11 is expected to be temporally restricted, as it is degraded by specific proteases such as the dipeptidyl-peptidase IV (DP4), also termed CD26. Based on the approach to inactivate chemokine receptors in allergic disease models as has been demonstrated for DP4-resistant n-nonanoyl (NNY)-CCL14 and for amino-oxypentane (AOP)-CCL5, it is tempting to study similar compounds derived from CCL11.

METHODS

Synthesis of NNY-CCL11 was performed and it was characterized for biological functions in human and mouse eosinophils as well as in cell lines stably transfected either with human CCR3 or CCR5. Resistance to DP4 treatment was also investigated.

RESULTS

The functional activities of NNY-CCL11 mediated via CCR3 show an almost identical pattern to CCL11 with respect to intracellular calcium mobilization and CCR3 internalization. N-terminal cleavage of CCL11 by preincubation with DP4 results in a reduced capacity to internalize CCR3, while preincubation of NNY-CCL11 shows no influence. In contrast to CCL11, NNY-CCL11 also activates CCR5+ cell lines and human monocytes in the nanomolar range, being about 100 times more potent than CCL11.

CONCLUSIONS

n-Nonanoyl-CCL11 represents a compound with dual activity restricted to CCR3 and CCR5. Because of its receptor-inactivating capacity and stability against DP4 degradation, NNY-CCL11 is a suitable tool for the decoding of the pathophysiological mechanisms of allergic diseases.

Differential pattern of CCR1 internalization in human eosinophils: prolonged internalization by CCL5 in contrast to CCL3

BACKGROUND

Whereas recent studies underlie the fundamental importance of the CC chemokine receptor 3 (CCR3) for the recruitment of eosinophils in allergic diseases, controversial data exist about the relevance of CCR1 on eosinophils. Therefore, the purpose of this study was to investigate the expression and regulation of CCR1 on eosinophils.

METHODS

Flow cytometric analysis of whole blood eosinophils and CD16-negative selected eosinophils from healthy nonatopic donors and from patients with atopic disorders was performed and CCR1 receptor internalization and re-expression were studied.

RESULTS

Flow cytometric analysis of whole blood eosinophils revealed that 17.8% of the donors expressed high levels of CCR1 (CCR1high) and 82.2% low levels of CCR1 (CCR1low). A significant down-regulation of CCR1 was induced by 24 h preincubation of isolated eosinophils from CCR1high donors either with IL-3, CC chemokine ligand 3 (CCL3), CCL5, CCL7, or CCL13. Internalization experiments using eosinophils from CCR1high donors revealed that CCL5 is more effective to induce CCR1 internalization than CCL3. Whereas CCR1 re-expression after stimulation with CCL3 reached prestimulation levels (120 min: 81.3% relative CCR1 surface expression) CCL5 induced a prolonged CCR1 internalization (120 min: 15.7%).

CONCLUSIONS

This study demonstrates a distinct pattern of CCR1 internalization and re-expression in human eosinophils between CCL3 and CCL5, as CCL5 induces a prolonged CCR1 internalization and the basic value is not reached after 24 h. Since prolonged receptor internalization plays a central role in chemokine-mediated inhibition of receptor function, CCR1 seems to be an attractive target on human eosinophils for chemokine receptor blockade besides CCR3.

Chemokine receptor antagonists: a novel therapeutic approach in allergic diseases

The aim of this review is to give an overview of the role of chemokines, particularly ligands of the CC chemokine receptor CCR3, in allergic diseases and to show the new concept in the treatment of allergies using chemokine receptor antagonists. Allergic diseases such as allergic asthma, allergic rhinitis and atopic dermatitis are characterized by a complex interaction of different cell types and mediators. Among this, Th2 cells, mast cells, basophils and eosinophils are found in the inflamed tissue due to the attraction of chemokines. Of all the known chemokine receptors, the chemokine receptor CCR3 seems to play the major role in allergic diseases which is supported by the detection of this receptor on the cell types mentioned above. Therefore, academic and industrial research focus on compounds to block this receptor. To date, certain chemokine receptor antagonists derived from peptides and small molecules exist to block the chemokine receptor CCR3. However, the in vivo data about these compounds and the mechanisms of receptor interaction are poorly understood, as yet. For the development of additional chemokine receptor antagonists, more details about the interaction between the ligands and their receptors are required. Therefore, additional studies will lead to the identification of novel CCR3 chemokine receptor antagonists, which can be therapeutically used in allergic asthma, allergic rhinitis, and atopic dermatitis.

Functional analysis of chemically synthesized derivatives of the human CC chemokine CCL15/HCC-2, a high affinity CCR1 ligand

The CCL15 is a human CC chemokine that activates the receptors, CCR1 and CCR3. Unlike other chemokines, it contains an unusually long N-terminal domain of 31 amino acids preceding the first cysteine residue and a third disulfide bond. To elucidate the functional role of distinct structural determinants, a series of sequential amino-terminal truncated and point-mutated CCL15 derivatives as well as mutants lacking the third disulfide bond and the carboxy-terminal alpha-helix were synthesized using 9-fluorenylmethoxycarbonyl (Fmoc) chemistry. We demonstrate that a truncation of 24 amino acid residues (delta24-CCL15) converts the slightly active 92-residue delta0-CCL15 into a potent agonist of CC chemokine receptor 1 (CCR1) and a weak agonist of CCR3 in cell-based assays. The biological activity decreases from delta24-CCL15 to delta29-CCL15, and re-increases from delta29-CCL15 to delta30-CCL15. Thus, an exocyclic N-terminal region of only one amino acid residue is sufficient for efficient CCR1 activation. As none of the peptides investigated except for delta24-CCL15 activates CCR3, we suggest that CCR1 is the major receptor for CCL15 in vivo. Further we demonstrate that the third disulfide bond of CCL15 and an exchange of tyrosine in position 70 by a leucine residue, which is conserved in CXC chemokines, do not alter the interaction with CCR1. In contrast, a CCL15 derivative lacking the carboxy-terminal alpha-helix exhibits a complete loss of tertiary structure and hence loss of CCR1 agonistic and binding activity. This study demonstrates that specific protein residues in chemokines, which contribute to receptor-ligand interaction, vary significantly between chemokines and cannot be extrapolated using data from functionally related chemokines.

Identification of a novel, multifunctional beta-defensin (human beta-defensin 3) with specific antimicrobial activity. Its interaction with plasma membranes of Xenopus oocytes and the induction of macrophage chemoattraction

Previous studies have shown the implication of beta-defensins in host defense of the human body. The human beta-defensins 1 and 2 (hBD-1, hBD-2) have been isolated by biochemical methods. Here we report the identification of a third human beta-defensin, called human beta-defensin 3 (hBD-3; cDNA sequence, Genbank accession no. AF295370), based on bioinformatics and functional genomic analysis. Expression of hBD-3 is detected throughout epithelia of many organs and in non-epithelial tissues. In contrast to hBD-2, which is upregulated by microorganisms or tumor necrosis factor-alpha (TNF-alpha), hBD-3 expression is increased particularly after stimulation by interferon-gamma. Synthetic hBD-3 exhibits a strong antimicrobial activity against gram-negative and gram-positive bacteria and fungi, including Burkholderia cepacia. In addition, hBD-3 activates monocytes and elicits ion channel activity in biomembranes, specifically in oocytes of Xenopus laevis. This paper also shows that screening of genomic sequences is a valuable tool with which to identify novel regulatory peptides. Human beta-defensins represent a family of antimicrobial peptides differentially expressed in most tissues, regulated by specific mechanisms, and exerting physiological functions not only related to direct host defense.

Hemofiltrate CC chemokines with unique biochemical properties: HCC-1/CCL14a and HCC-2/CCL15

The hemofiltrate CC chemokines CCL14a (formerly HCC-1), CCL14b (formerly HCC-3), and CCL15 (formerly HCC-2) are encoded by mono- as well as bicistronic transcripts from a tandem gene arrangement on human chromosome 17q11.2. The transcription and splicing into several mono- and bicistronic transcripts of this gene complex are unique for human genes. No corresponding mechanism is known in nonprimate mammalian species such as mice and rats. The extremely high concentration of CCL14a in human plasma is exceptional for chemokines and led to the identification of this chemokine. Several molecular forms of CCL14a have been isolated and investigated. The mature propeptide CCL14a(1-74) is a low-affinity agonist of CCR1 which is converted to a high-affinity agonist of CCR1 and CCR5 on proteolytic processing by serine proteases. In contrast, CCL15 is characterized using molecular forms deduced from the mRNA/cDNA and shown to activate cells via CCR1 and CCR3, also dependent on the amino-terminal length. Hemofiltrate CC chemokines are chemoattractants for different types of leukocytes including monocytes, eosinophils, T cells, dendritic cells, and neutrophils. In this review, we emphasize the genomic organization, expression patterns, and biochemical properties of CCL14a, CCL14b, and CCL15. We report results of significance for the development of therapeutic strategies, especially concerning HIV infection and inflammatory diseases.

A method for HLA-DQA typing by the PCR-SSP technique

There is preliminary evidence that matching for HLA-DQ is important for kidney graft survival. We developed a method for HLA-DQA typing based on the PCR-SSP principle. The procedure consisted of three steps: DNA isolation, PCR amplification and visualization of the PCR product under UV light. For the identification of all currently known DQA1 alleles, we designed 18 different primers that allowed typing for the specificities DQA1*0101, *1012, *0103, *0104, *0201, *03, *0401, *0501 and DQA1*0601. For the typing of a single individual, 12 PCR mixes were needed, each containing a primer pair specific for a certain allele group, and a pair of control primers that amplified a non-polymorphic region. The time required for this procedure was approximately 3 h from the time of blood collection. Comparison of this method with DQA typing by the RFLP method in 151 individuals revealed only a single discrepancy. The method can be easily applied for prospective cadaver donor typing.

Natural proteolytic processing of hemofiltrate CC chemokine 1 generates a potent CC chemokine receptor (CCR)1 and CCR5 agonist with anti-HIV properties

Hemofiltrate CC chemokine (HCC)-1 is a recently described human chemokine that is constitutively expressed in numerous tissues and is present at high concentrations in normal plasma. Using a cell line expressing CC chemokine receptor (CCR)5 as a bioassay, we isolated from human hemofiltrate an HCC-1 variant lacking the first eight amino acids. HCC-1[9-74] was a potent agonist of CCR1, CCR3, and CCR5 and promoted calcium flux and chemotaxis of T lymphoblasts, monocytes, and eosinophils. It also blocked entry of HIV-1 strains using CCR5 as coreceptor. Limited tryptic digestion of HCC-1 generated the active variant. Conditioned media from several tumor cell lines activated HCC-1 with a high efficiency, and this activity could be inhibited by serine protease inhibitors. Our results indicate that HCC-1 represents a nonfunctional precursor that can be rapidly converted to the active chemokine by proteolytic processing. This process represents an additional mechanism by which tumor cells might generate chemoattractant molecules and recruit inflammatory cells. It might also affect HIV-1 replication in infected individuals and play an important role in AIDS pathogenesis.

Macrophages infiltrating the tissue in chronic pancreatitis express the chemokine receptor CCR5

BACKGROUND

The immunologic mechanisms involved in the development of chronic pancreatitis (CP) are poorly understood. Chronically inflamed tissues contain increased numbers of mononuclear cells expressing the CC chemokine receptor 5 (CCR5), which is also a coreceptor for HIV entry of macrophagetropic strains. However, whether this receptor is involved in the inflammatory process in CP is not known. In the current study, we analyzed the expression of CCR5 in CP. The detection of chemokine receptors on inflammatory cells would strongly suggest their involvement in the pathogenesis of CP (i.e., attraction and activation of these cells). To further evaluate this, we consecutively analyzed the expression of 2 ligands of CCR5: RANTES and MIP-alpha.

METHODS

Pancreatic tissue samples of 22 patients with CP and of 7 healthy pancreas were evaluated. CCR5, RANTES, and MIP-1alpha were analyzed by Northern blot analysis. Consecutive tissue sections were stained for CCR5, CD3, and CD68 to define the leukocyte subtype expressing CCR5 in CP.

RESULTS

By Northern blot analysis, CCR5, RANTES, and MIP-1alpha messenger RNA (mRNA) levels were 12.9-fold, 13.3-fold and 9.2-fold higher in CP specimens compared with healthy controls, respectively (P<.01). Immunostaining for CCR5 revealed a 30-fold increase of CCR5-positive cells in CP tissue compared with the healthy pancreas. Staining of consecutive tissue sections revealed that the majority of CCR5-positive cells were also CD68-positive (macrophages).

CONCLUSIONS

Our data indicate that a remarkable portion of CCR5-positive cells in CP are macrophages. CCR5 is most likely involved in the attraction and activation of these macrophages, since the CCR5 ligands RANTES and MIP-1alpha are concomitantly upregulated.

Conservative surgical treatment of diffuse peritonitis

BACKGROUND

Peritonitis is, even today, a significant source of death and complications. The objective of this study was to determine the morbidity and mortality rates, the incidence of reoperations, and the need for additional treatment strategies (on demand) in patients with diffuse peritonitis.

METHODS

Prospective analysis including all patients (n = 258) with diffuse peritonitis admitted to our surgical service between November 1993 and April 1998 who underwent a uniform surgical treatment concept of peritonitis including early intervention, source control, and extensive intraoperative lavage.

RESULTS

The 258 patients with diffuse peritonitis averaged a mean Mannheim Peritonitis Index of 27.1 points (range, 11-43 points). Source control at the initial operation was possible in 230 of the patients (89%), of those, 21 patients (9%) needed reintervention. In 28 patients (11%), source control was not possible at the initial operation. Twenty of these patients (71%) had to undergo additional treatment strategies (on demand) such as continuous lavage and/or laparostomy. Overall 228 of the 258 patients (88%) needed just 1 initial surgical intervention. The overall morbidity rate was 41%; the rate of reoperation was 12%, and the hospital mortality rate was 14%.

CONCLUSIONS

A conservative surgical treatment concept supplemented with "extensive" intraoperative lavage reduces the reoperation rate compared with other treatment standards of peritonitis and achieves a low mortality rate in patients with diffuse peritonitis.

HCC-2, a human chemokine: gene structure, expression pattern, and biological activity

Cloning and sequencing of the upstream region of the gene of the CC chemokine HCC-1 led to the discovery of an adjacent gene coding for a CC chemokine that was named "HCC-2." The two genes are separated by 12-kbp and reside in a head-to-tail orientation on chromosome 17. At variance with the genes for HCC-1 and other human CC chemokines, which have a three-exon-two-intron structure, the HCC-2 gene consists of four exons and three introns. Expression of HCC-2 and HCC-1 as studied by Northern analysis revealed, in addition to the regular, monocistronic mRNAs, a common, bicistronic transcript. In contrast to HCC-1, which is expressed constitutively in numerous human tissues, HCC-2 is expressed only in the gut and the liver. HCC-2 shares significant sequence homology with CKbeta8 and the murine chemokines C10, CCF18/MRP-2, and macrophage inflammatory protein 1gamma, which all contain six instead of four conserved cysteines. The two additional cysteines of HCC-2 form a third disulfide bond, which anchors the COOH-terminal domain to the core of the molecule. Highly purified recombinant HCC-2 was tested on neutrophils, eosinophils, monocytes, and lymphocytes and was found to exhibit marked functional similarities to macrophage inflammatory protein 1alpha. It is a potent chemoattractant and inducer of enzyme release in monocytes and a moderately active attractant for eosinophils. Desensitization studies indicate that HCC-2 acts mainly via CC chemokine receptor CCR1.

Eotaxin-2, a novel CC chemokine that is selective for the chemokine receptor CCR3, and acts like eotaxin on human eosinophil and basophil leukocytes

A novel human CC chemokine consisting of 78 amino acids and having a molecular mass of 8,778.3 daltons (VVIPSPCCMF FVSKRIPENR VVSYQLSSRS TCLKAGVIFT TKKGQQ SCGD PKQEWVQRYM KNLDAKQKKA SPRARAVA) was isolated together with three minor COOH-terminally truncated variants with 73, 75, and 76 residues. The new chemokine was termed eotaxin-2 because it is functionally very similar to eotaxin. In terms of structure, however, eotaxin and eotaxin-2 are rather distant, they share only 39% identical amino acids and differ almost completely in the NH2-terminal region. Eotaxin-2 induced chemotaxis of eosinophils as well as basophils, with a typically bimodal concentration dependence, and the release of histamine and leukotriene C4 from basophils that had been primed with IL-3. In all assays, eotaxin-2 had the same efficacy as eotaxin, but was somewhat less potent. The migration and the release responses were abrogated in the presence of a monoclonal antibody that selectively blocks the eotaxin receptor, CCR3, indicating that eotaxin-2, like eotaxin, acts exclusively via CCR3. Receptor usage was also studied in desensitization experiments by measuring [Ca2+]i changes in eosinophils. Complete cross-desensitization was observed between eotaxin-2, eotaxin and MCP-4 confirming activation via CCR3. No Ca2+ mobilization was obtained in neutrophils, monocytes and lymphocytes, in agreement with the lack of chemotactic responsiveness. Intradermal injection of eotaxin-2 in a rhesus monkey (100 or 1,000 pmol per site) induced a marked local infiltration of eosinophils, which was most pronounced in the vicinity of postcapillary venules and was comparable to the effect of eotaxin.

CKbeta8, a novel CC chemokine that predominantly acts on monocytes

We have studied the biological properties of a new human CC chemokine, CKbeta8, consisting of 99 amino acids including six cysteines. CKbeta8 mRNA transcripts were induced in monocytes by IL-1beta and, to a lesser extent, by IFNgamma, and were detected in RNA extracted from normal human liver and gastrointestinal tract. CKbeta8 is chemotactic for monocytes, but is inactive on IL-2 conditioned T lymphocytes, eosinophils and neutrophils. Desensitization experiments indicate that CKbeta8 and MIP-1beta completely share receptors on monocytes and that the CKbeta8 receptor, which appears to differ from the known ones, is also recognized by MCP-1, MCP-2, MCP-3, MCP-4, MIP-1alpha and RANTES.

Monocyte chemotactic protein 4 (MCP-4), a novel structural and functional analogue of MCP-3 and eotaxin

A novel human CC chemokine complementary DNA was identified in a library constructed from human fetal RNA, cloned into a baculovirus vector, and expressed in Sf9 insect cells. The mature recombinant protein that was released had the NH2-terminal sequence pyro-QPDALNVPSTC...and consisted of 75 amino acids. Minor amounts of two variants of 77 and 82 residues (NH2 termini: LAQPDA...and FNPQGLAQPDA...) were released as well. The novel chemokine was designated monocyte chemotactic protein 4 (MCP-4) and the variants were designated (LA)MCP-4 and (FNPQGLA)MCP-4. MCP-4 shares the pyroglutamic acidproline NH2-terminal motif and 56-61% sequence identity with the three known monocyte chemotactic proteins and is 60% identical to eotaxin. It has marked functional similarities to MCP-3 and eotaxin. Like MCP-3, MCP-4 is a chemoattractant of high efficacy for monocytes and T lymphocytes. On these cells, it binds to receptors that recognize MCP-1, MCP-3, and RANTES. On eosinophils, MCP-4 has similar efficacy and potency as MCP-3, RANTES, and cotaxin. It shares receptors with eotaxin and shows full cross-desensitization with this cosinophil-selective chemokine. Of the two variants, only (LA)MCP-4 could be purified in sufficient quantities for testing and was found to be at least 30-fold less potent than MCP-4 itself. This suggests that the 75-residue form with the characteristic NH2 terminus of an MCP is the biologically relevant species.