T cell epitopes of type II collagen that regulate murine collagen-induced arthritis

Chick type II collagen (CII), a protein commonly found in joint cartilage, induces an autoimmune arthritis when administered to susceptible strains of mice. A cyanogen bromide fragment of CII, CB11, contains the requisite epitopes critical for inducing collagen-induced arthritis. If administered as a tolerogen, however, before immunization, CB11 prevents the onset of disease. Therefore, delineation of structural elements of CB11 that can regulate autoreactive T cells became the goal of this study. To delineate the structural elements of CB11 antigenic to T cells, 14 peptides containing overlapping sequences of CB11 were generated. Mononuclear cells from CII-immunized DBA/1 mice were cultured with these peptides and the resulting supernatants examined for the production of IFN-gamma. Two peptides, CII 181-209 and CII 245-270, generated the greatest responses. The ability of these two peptides to regulate arthritis was tested by administering them to neonatal DBA/1 mice as tolerogens before immunization with CII. Both peptides suppressed the incidence of arthritis whereas no other peptide used as a tolerogen significantly altered the course of the disease. T cells from four arthritis-resistant murine strains did not recognize either peptide when immunized with CII, whereas cells from the disease-susceptible B10.Q mice responded well to both. Thus, the coincidence of T cell responses to CII 181-209 and CII 245-270 in CIA-susceptible mice and the lack of response in disease-resistant strains or CII-tolerized mice identify these two peptides as containing important T cell epitopes that regulate CIA.

T cell epitopes of type II collagen that regulate murine collagen-induced arthritis

Chick type II collagen (CII), a protein commonly found in joint cartilage, induces an autoimmune arthritis when administered to susceptible strains of mice. A cyanogen bromide fragment of CII, CB11, contains the requisite epitopes critical for inducing collagen-induced arthritis. If administered as a tolerogen, however, before immunization, CB11 prevents the onset of disease. Therefore, delineation of structural elements of CB11 that can regulate autoreactive T cells became the goal of this study. To delineate the structural elements of CB11 antigenic to T cells, 14 peptides containing overlapping sequences of CB11 were generated. Mononuclear cells from CII-immunized DBA/1 mice were cultured with these peptides and the resulting supernatants examined for the production of IFN-gamma. Two peptides, CII 181-209 and CII 245-270, generated the greatest responses. The ability of these two peptides to regulate arthritis was tested by administering them to neonatal DBA/1 mice as tolerogens before immunization with CII. Both peptides suppressed the incidence of arthritis whereas no other peptide used as a tolerogen significantly altered the course of the disease. T cells from four arthritis-resistant murine strains did not recognize either peptide when immunized with CII, whereas cells from the disease-susceptible B10.Q mice responded well to both. Thus, the coincidence of T cell responses to CII 181-209 and CII 245-270 in CIA-susceptible mice and the lack of response in disease-resistant strains or CII-tolerized mice identify these two peptides as containing important T cell epitopes that regulate CIA.

A synthetic peptide analogue of a determinant of type II collagen prevents the onset of collagen-induced arthritis

The immunization of genetically susceptible strains of mice with type II collagen (CII) elicits a collagen-induced arthritis that resembles rheumatoid arthritis. Our laboratory previously identified a region of CII, CII-245-270, that contains a T cell epitope that is prominent in the immune response to CII. Residues critical to the I-Aq-restricted presentation of this determinant have been characterized. To produce synthetic peptides with the potential of disrupting I-Aq-restricted Ag presentation, synthetic analogue peptides were developed that contain site-directed substitutions in critical positions. One analogue peptide was found to be an efficient competitor for binding to I-Aq and to be capable of inhibiting T cell responses in vitro. When DBA/1 mice were coimmunized with CII and the analogue peptide, the incidence and severity of arthritis were greatly reduced, concordant with the humoral immune responses to CII.

A synthetic peptide analogue of a determinant of type II collagen prevents the onset of collagen-induced arthritis

The immunization of genetically susceptible strains of mice with type II collagen (CII) elicits a collagen-induced arthritis that resembles rheumatoid arthritis. Our laboratory previously identified a region of CII, CII-245-270, that contains a T cell epitope that is prominent in the immune response to CII. Residues critical to the I-Aq-restricted presentation of this determinant have been characterized. To produce synthetic peptides with the potential of disrupting I-Aq-restricted Ag presentation, synthetic analogue peptides were developed that contain site-directed substitutions in critical positions. One analogue peptide was found to be an efficient competitor for binding to I-Aq and to be capable of inhibiting T cell responses in vitro. When DBA/1 mice were coimmunized with CII and the analogue peptide, the incidence and severity of arthritis were greatly reduced, concordant with the humoral immune responses to CII.

A pentapeptide from type I procollagen promotes extracellular matrix production

The NH2 and COOH propieces of fibril-forming collagens are cleaved off extracellularly and have been implicated in feedback regulation of their own synthesis. Recently, we showed that a subfragment of the carboxyl-terminal propeptide of type I collagen (residues 197-241) dramatically augments extracellular matrix production in subconfluent fibroblasts. This stimulation of type I collagen, type III collagen, and fibronectin production occurred in a dose- and time-dependent manner with no effect on total protein synthesis or on the ratio of secreted proteins to cell-associated proteins (Katayama, K., Seyer, J.M., Raghow, R., and Kang, A.H. (1991) Biochemistry 30, 7097-7104). In the present report, we have extensively dissected this subfragment of the propeptide and found that the pentapeptide Lys-Thr-Thr-Lys-Ser (residues 212-216) is the minimum sequence necessary for potent stimulation of collagen and fibronectin production in a variety of mesenchymal cells. We postulate that the extracellular matrix production in fibroblasts may be subject to either positive or negative feedback regulation depending on the repertoire of specific proteases during postinflammatory tissue regeneration and fibrosis.

Intercellular adhesion molecule-1 expression induced by interleukin (IL)-1 beta or an IL-1 beta fragment is blocked by an IL-1 receptor antagonist and a soluble IL-1 receptor

The effects of a recombinant human interleukin-1 (IL-1) receptor antagonist (IL-1ra) and a recombinant human soluble IL-1 receptor (sIL-1R) on cytokine-induced intercellular adhesion molecule-1 (ICAM-1) expression in a human glioblastoma cell line and a neuroblastoma cell line were determined. Cells were incubated with IL-1 beta, tumor necrosis factor (TNF) alpha and interferon (IFN) gamma. Cells were also tested under identical conditions with an IL-1 beta synthetic peptide fragment (IL-1 beta 208-240) previously shown to possess biological activity. IL-1 beta, TNF alpha and IFN gamma potentiated ICAM-1 expression in both cell lines in a dose-related manner. The IL-1 beta 208-240 fragments, corresponding to the rabbit, rat and human sequences, enhanced ICAM-1 expression in glioblastoma cells at high doses. ICAM-1 expression induced by IL-1 beta, rabbit IL-1 beta 208-240 and human IL-1 beta 208-240 was blocked by the IL-1ra, while TNF alpha- and IFN gamma-induced ICAM-1 expression were not. ICAM-1 expression induced by IL-1 beta and human IL-1 beta 208-240 was also blocked by the sIL-1R. Our findings suggest that IL1 beta 208-240 acts as an IL-1 beta agonist in enhancing ICAM-1 expression in vitro and that this effect is receptor-mediated.

Susceptibility of type I collagen containing mutated alpha 1(1) chains to cleavage by human neutrophil collagenase

Two members of the matrix metalloproteinase family which can cleave native types I, II and III triple helical collagens are collagenases from fibroblasts and neutrophils. These enzymes are the products of different genes which share structural motifs but are only 57% identical. In this study, we determined the site of cleavage in the alpha 1(I) chains and showed that the neutrophil collagenase acted at the same site as the fibroblast collagenase. We also used collagens as substrates which were generated by site-directed mutagenesis of the murine Col1a1 gene and found that the pattern of susceptibility to cleavage by purified neutrophil collagenase was indistinguishable from that previously described for the fibroblast collagenase. Collagens containing substitutions of Pro for Ile-776 (P1) were not cleaved; whereas those containing substitutions of Met for Ile-776 were cleaved. Type I collagen which contained alpha 1(I) chains in which there were double substitutions of Pro for Gln-774 (P2) and Ala-777 (P2') were also not cleaved. These type I collagens contained wild type alpha 2(I) chains as well as mutant alpha 1(I) chains in the mixed helical trimers; the alpha 2(I) chain in the trimers containing the resistant alpha 1(I) chains were also not cleaved by the neutrophil collagenase.

Identification of vicinal thiols of phosphoenolpyruvate carboxykinase (GTP)

Phosphoenolpyruvate carboxykinase (PEPCK) from the cytosol of rat liver has 13 cysteines, at least one of which (Cys288) is known to be very reactive and critical for catalytic activity (Lewis, C. T., Seyer, J. M., and Carlson, G. M. (1989) J. Biol. Chem. 264, 27-33). Previous results provided evidence for the existence of at least 1 pair of vicinal cysteines within or near the active site of PEPCK (Lewis, C. T., Haley, B. E., and Carlson, G. M. (1989) Biochemistry 28, 9248-9255). An intramolecular cystine disulfide is induced to form upon treatment of PEPCK with equimolar 5,5'-dithiobis(2-nitrobenzoate) (Nbs2) or upon irradiation of the enzyme in the presence of the photoaffinity probe 8-azidoGTP. In each case, modification is accompanied by a substantial loss in catalytic activity, and substrates protect against inactivation and modification. We now report the identification of these modified thiols by differential alkylation of cysteines and half-cystines with radioactive iodoacetate, followed by isolation and sequencing of the modified tryptic peptides. The results indicate that the disulfide formed by equimolar Nbs2 lies within a 15-residue region of the PEPCK sequence that includes Cys399, Cys407, and Cys413. In addition, Cys407 and/or Cys413 also appear to participate in formation of the disulfide induced by 8-azidoGTP. These thiols lie very near a consensus sequence that has been suggested to represent the binding site for the guanine ring of GTP.

Isolation, characterization and immunolocalization of a 53-kDal dentin sialoprotein (DSP)

We isolated a sialic-rich protein from rat dentin extracts and have named it dentin sialoprotein, DSP (formerly called 95K glycoprotein). DSP is rich in aspartic acid, glutamic acid, glycine and serine, but contains no cysteine or phosphate. The 30% carbohydrate content includes about 9% sialic acid and indicates that several N-glycosides and O-glycosides are present. Sedimentation equilibrium analysis gave a M(r) of 52,570. Based on this molecular weight we calculated that DSP contains about 350-amino acids and 75 monosaccharides. With automated Edman degradation the sequence of the first 8-amino acids was shown to be: Ile-Pro-Val-Pro-Gln-Leu-Val-Pro. The initial 3 residues of this sequence are identical to the first 3 in human osteopontin (OPN) and are closely similar to the Leu-Pro-Val sequences of OPN from other species, as well as at the beginning of bone acidic glycoprotein-75 (BAG-75). On Western immunoblots, purified polyclonal antibodies reacted only with DSP in dentin extracts and with none of the proteins from bone. Similarly, immunolocalization experiments showed the presence of DSP in dentin but not in enamel or alveolar bone. Along with immunohistochemical localization data reported elsewhere, these observations suggest that DSP may be an important marker for cells in the odontoblast lineage.

Somnogenic, pyrogenic, and anorectic activities of tumor necrosis factor-alpha and TNF-alpha fragments

Exogenously administered tumor necrosis factor-alpha (TNF-alpha) elicits several symptoms of generalized infections such as fever, increased sleep, and anorexia. The aim of the present work was to localize these effects of TNF-alpha to specific amino acid sequences of the parent molecule by characterizing the in vivo and in vitro activities of several synthetic TNF-alpha fragments. Intracerebroventricular injection of TNF-alpha elicited dose-dependent fevers and increases in non-rapid-eye-movement sleep (NREMS) in rabbits. Four fragments also promoted NREMS and five elicited monophasic fevers. All of the somnogenic fragments share the amino acid sequence 31-36. In rats, TNF-alpha and one of the fragments [TNF-alpha-(69-100)] suppressed 12-h food intake. Furthermore, TNF-alpha increased the expression of the intercellular adhesion molecule-1 and enhanced interferon-gamma-induced HLA-DR expression in human glioblastoma cell line. In contrast, none of the fragments possessed these in vitro activities. Our in vivo results support the concept that there are biologically active regions in the TNF-alpha molecule.

Characterization of a tolerogenic T cell epitope of type II collagen and its relevance to collagen-induced arthritis

A synthetic peptide representing sequences of type II collagen, (CII 245-270), has previously been used to induce tolerance and suppress arthritis in DBA/1 mice. To determine important residues, a series of peptides, each containing one or two site-directed substitutions, was generated. Mononuclear cells from DBA/1 mice immunized with CII were cultured in the presence of each peptide and the T cell response determined by measuring IFN-gamma in culture supernatant fluids. Substitutions within the region CII 260-270 led to significant decreases in IFN-gamma responses, identifying this sequence as a T cell epitope. To determine the effects of substitutions within this epitope on arthritis, substituted peptides were administered to neonatal mice as tolerogens. Five site-directed substitutions, four of which included the insertion of a residue found in type I collagen to replace its type II counterpart, abrogated the ability of the peptides to induce tolerance and suppress arthritis. These substitutions were located at residues 260, 261, 263, 264, and 266. Two patterns of T cell reactivity were observed. Peptides containing individual substitutions at positions 261, 264, or 266 were capable of generating a significant T lymphokine response, although those containing substitutions at residues 260 or 263 were ineffective Ag. Systematic analysis of the fine structures of T cell determinants important for autoimmune arthritis can lead to strategies for therapeutic intervention.

Characterization of a tolerogenic T cell epitope of type II collagen and its relevance to collagen-induced arthritis

A synthetic peptide representing sequences of type II collagen, (CII 245-270), has previously been used to induce tolerance and suppress arthritis in DBA/1 mice. To determine important residues, a series of peptides, each containing one or two site-directed substitutions, was generated. Mononuclear cells from DBA/1 mice immunized with CII were cultured in the presence of each peptide and the T cell response determined by measuring IFN-gamma in culture supernatant fluids. Substitutions within the region CII 260-270 led to significant decreases in IFN-gamma responses, identifying this sequence as a T cell epitope. To determine the effects of substitutions within this epitope on arthritis, substituted peptides were administered to neonatal mice as tolerogens. Five site-directed substitutions, four of which included the insertion of a residue found in type I collagen to replace its type II counterpart, abrogated the ability of the peptides to induce tolerance and suppress arthritis. These substitutions were located at residues 260, 261, 263, 264, and 266. Two patterns of T cell reactivity were observed. Peptides containing individual substitutions at positions 261, 264, or 266 were capable of generating a significant T lymphokine response, although those containing substitutions at residues 260 or 263 were ineffective Ag. Systematic analysis of the fine structures of T cell determinants important for autoimmune arthritis can lead to strategies for therapeutic intervention.

Transcriptional mechanisms of type I collagen gene expression are differentially regulated by interleukin-1 beta, tumor necrosis factor alpha, and transforming growth factor beta in Ito cells

Regulation of the procollagen type I (Pro alpha 1) gene in cultured Ito cells by diverse cytokines was studied. Specifically, we have examined the effect of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha), and transforming growth factor beta (TGF beta) on collagen biosynthesis, levels of Pro alpha 1 (I) mRNA, and rate of transcription of Pro alpha 1 (I) gene. TGF beta stimulated procollagen synthesis at least 2-fold at every concentration tested (5-20 ng/ml), whereas TNF alpha inhibited it at the same concentrations. In contrast to what occurs in dermal fibroblasts, IL-1 beta (5-20 units/ml) preferentially inhibited procollagen production as measured by [3H]proline incorporation. A similar pattern was obtained when total protein synthesis was analyzed by [25S]methionine radiolabeling. Interestingly, while TGF beta-treated cells exhibited greater than 3-fold increase in steady-state levels of Pro alpha 1 (I) mRNA, the treatment with IL-1 had no effect on procollagen mRNA levels. TNF alpha treatment resulted in a 2-fold decrease in the amount of collagen mRNA. The treatment with combinations of cytokines indicated that collagen gene expression in Ito cells is differentially regulated by these cytokines. Furthermore, nuclear run-off transcription experiments were performed. The results obtained suggest that TGF beta regulates increasing collagen type I gene expression at transcriptional levels, and TNF alpha inhibits the transcriptional rate of Pro alpha 1 (I) gene. It is noteworthy that IL-1 beta acts on collagen type I gene regulation by a separate mechanism at a posttranscriptional level.

Interleukin 1 receptor antagonist blocks somnogenic and pyrogenic responses to an interleukin 1 fragment

Previously it was shown that human interleukin 1 (huIL-1) and a huIL-1 fragment, huIL-1 beta 208-240, are somnogenic and pyrogenic in rabbits. However, the amino acid sequences for IL-1 are species-specific and it was unknown whether rabbit (rb) IL-1 beta 208-240 and rat (rt) IL-1 beta 208-240 were active in their respective species. Furthermore, it was unknown whether these fragments elicited their effects via the IL-1 receptors. Two doses of rbIL-1 beta 208-240 (6.0 and 12.0 nmol) were intracerebroventricularly administered to rabbits. The 6.0-nmol dose had little effect, whereas the 12.0-nmol dose greatly increased non-rapid-eye-movement sleep across a 6-hr recording period and induced a febrile response. Rats injected intracerebroventricularly with rtIL-1 beta 208-240 at dark onset responded to three doses of the peptide (1.2, 2.4, and 4.8 nmol). The 1.2-nmol dose did not greatly affect sleep but did induce a moderate febrile response. The 2.4- and 4.8-nmol doses increased non-rapid-eye-movement sleep across the 12-hr recording period. Maximal brain temperature elevations relative to controls after the 2.4- and 4.8-nmol doses of the peptide were 0.9 +/- 0.2 degrees C and 0.7 +/- 0.2 degrees C, respectively. These responses in both rabbits and rats were completely blocked or significantly attenuated when the animals were pretreated with an IL-1 receptor antagonist. These results suggest that the biological activities of IL-1 beta 208-240 are mediated via the IL-1 beta receptors.

Photochemical cross-linking of guanosine 5'-triphosphate to phosphoenolpyruvate carboxykinase (GTP)

Mammalian phosphoenolpyruvate carboxykinase (PEPCK) specifically requires a guanosine or inosine nucleotide as a substrate; however, the structural basis for this nucleotide specificity is not yet known. Because affinity labels derived from guanosine have not yielded a stable, modified peptide in quantities sufficient for sequence analysis, we have investigated the utility of direct photochemical cross-linking of GTP to PEPCK in order to identify the nucleotide binding site. UV irradiation at a distance of 2 cm by a Mineralight lamp (330 microW/cm2) results in the attachment of [alpha-32P]GTP to PEPCK via a stable, covalent linkage in a reaction that is dependent upon GTP concentration and duration of irradiation. After 10 min of irradiation, more than 0.2 mol of [alpha-32P] GTP is incorporated per mole of PEPCK; under these conditions the GTP concentration required for half-maximal labeling is 69 microM. The substrates phosphoenolpyruvate, ITP, and GDP provide protection against photolabeling, as do Mn2+ and Mg2+. One major and one minor radioactive peptide derived from proteolytic digests of photolabeled PEPCK have been isolated and identified. The major modified peptide has been provisionally assigned to an acidic region near the C-terminus, and the minor peptide has been identified as Ser462-Lys471.

Further characterization of the loop structure of platelet glycoprotein IIIa: partial mapping of functionally significant glycoprotein IIIa epitopes

Glycoprotein (GP) IIb-IIIa serves as the platelet fibrinogen receptor. Studies of the tertiary structure of GPIIIa have shown that the protein has a large loop structure of at least 325 amino acids in length. To further characterize this loop structure, intact platelets were digested with alpha-chymotrypsin. Digestion products were examined using the anti-GPIIIa monoclonal antibodies (MoAbs) AP3, D3GP3, and C5GP3, as well as the human alloantibody, anti-PLA1. AP3 recognized GPIIIa digestion products of 109, 95, and 68 Kd. D3GP3 and C5GP3 recognized an additional band of 51 Kd. Time course digestions demonstrated that the 51-Kd fragment was generated by proteolysis of the 68-Kd peptide. Sequence analysis of the reduced 51-Kd peptide showed that this fragment began at amino acid 422. The nonreduced 51-Kd peptide was reactive with antibodies directed against the first 13 amino acids of GPIIIa, demonstrating the presence of a covalently attached N-terminal peptide. These data suggest that: (1) the minimum length of the loop structure is at least 384 amino acids; (2) the AP3 epitope is formed at least in part by a determinant contained within residues 348 to 421; and (3) the D3GP3 and C5GP3 epitopes are contained within amino acids 422 to 692 of GPIIIa, a region that may be flexible and involved in conformational changes that occur after ligand binding.

Kupffer cells from carbon tetrachloride-injured rat livers produce chemotactic factors for fibroblasts and monocytes: the role of tumor necrosis factor-alpha

Conditioned media from cultured Kupffer and mononuclear macrophagic cells obtained 48 hr after CCl4 administration to rats contains chemotactic factors for human skin fibroblasts and human monocytes. The chemotactic mediator for fibroblasts was approximately 17 kD and was more prominent at early stages of culture. It induced a dose-dependent chemotactic response in fibroblasts. Although the conditioned medium from cultured Kupffer cells of normal rats also contained detectable biological activity, it was significantly less than that in conditioned medium from cultured Kupffer cells from CCl4-treated rats. The activity obtained after purification by high-performance liquid chromatography was completely ablated by incubation with tumor necrosis factor-alpha antibody. Transforming growth factor-beta antibody diminished biological activity by 20%. Human recombinant tumor necrosis factor-alpha and transforming growth factor-beta used in the assay as control showed significant chemotactic activity. The chemotactic activity present in whole normal conditioned medium was only present after 24 and 48 hr of culture. Furthermore, this activity was not neutralized by human recombinant tumor necrosis factor-alpha or transforming growth factor-beta antibodies. Incubation of whole 6-hr conditioned medium with human recombinant tumor necrosis factor-alpha and transforming growth factor-beta antibodies demonstrated and confirmed that tumor necrosis factor-alpha plays a major role in inducing the chemotactic response. On acidification of this supernatant, we found a notable increase in the biological response that could be neutralized by transforming growth factor-beta antibody. Thus tumor necrosis factor-alpha and transforming growth factor-beta may sequentially provide important signals for fibroblast and monocyte recruitment in vivo at initial stages of liver injury.

Processing of TCP pilin by TcpJ typifies a common step intrinsic to a newly recognized pathway of extracellular protein secretion by gram-negative bacteria

Biogenesis of the Vibrio cholerae toxin-coregulated pilus (TCP) requires the activities of at least seven accessory proteins. We demonstrate that a portion of this pathway involves a novel processing step in which a hydrophilic leader peptide is proteolytically removed from TcpA by the gene product characterized in this report, TcpJ, to yield the mature, export-competent form of the pilin. Cleavage of the pilin leader peptide is independent of known signal peptidases as demonstrated by pilin-processing profiles in Escherichia coli strains conditionally defective for production of leader peptidase or grown in the presence of the antibiotic globomycin. Additionally, pilin cleavage did not rely on the SecA protein, as evidenced by TcpA processing in azide-treated cells. These results suggest that TcpJ is representative of a new class of proteins involved in SecA-independent proteolytic cleavage of a set of atypical leader peptides during extracellular export.

Regulation of extracellular matrix production by chemically synthesized subfragments of type I collagen carboxy propeptide

The complete COOH-propeptide of human alpha 1(I) procollagen was chemically synthesized as a series of overlapping subfragments which were then tested for their effect on extracellular matrix protein production by subconfluent human lung fibroblasts (HFL-1). One peptide (R11; residues 197-241) stimulated production of both collagen and fibronectin by 6-8-fold while a second peptide with a partial overlap with R11 (R9; residues 182-216) enhanced collagen accumulation. The peptide R12 (residues 197-216), which has a sequence common to both R9 and R11, also stimulated collagen production, suggesting that this 20-residues peptide alone contains the required structure for activity. The other synthetic peptides, R1-R13, were inactive in their ability to alter collagen or fibronectin production. Consistent with previously published data, the COOH-terminal peptide, R14, inhibited extracellular matrix production [Aycock, R.A., Raghow, R., Stricklin, G.P., Seyer, J.M., & Kang, A.H. (1986) J. Biol. Chem. 261, 14355-14360]. Both R9 and R11 preferentially stimulated production of collagen types I and III and fibronectin in dose-dependent manner. Elevated collagen and fibronectin production was evident at 4-h posttreatment, and maximal enhancement was seen at 8 h after exposure to peptides. Interestingly, subconfluent cultures of HFL-1 fibroblasts responded vigorously to the stimulatory action of R9 and R11 while confluent cells failed to show any response. Steady-state levels of messenger RNAs encoding type I procollagen and fibronectin were not measurably altered by treatment with R9 or R11, suggesting that the regulation of procollagens and fibronectin by these peptides involves posttranscriptional mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunity to type XI collagen in mice. Evidence that the alpha 3(XI) chain of type XI collagen and the alpha 1(II) chain of type II collagen share arthritogenic determinants and induce arthritis in DBA/1 mice

To determine whether native bovine type XI collagen (BXI) is arthritogenic, five strains of inbred mice were immunized with BXI/CFA. Arthritis was not observed in any of these strains, though it was prevalent in DBA/1 and B10.RIII controls immunized with bovine type II collagen (BII). Antisera from BXI-immunized mice reacted with mouse type XI collagen (MsXI), weakly with the alpha-chains of BXI, and minimally with mouse type II collagen (MsII). However, antisera to BII reacted with MsII and MsXI, indicating antibodies to conformation-independent epitopes shared by alpha 1(II) and alpha 3(XI). Mice immunized with BXI containing a small amount of BII developed arthritis much like those immunized with BII; sera from these mice reacted with MsXI and MsII. Delayed-type hypersensitivity responses differed from IgG responses, i.e., BXI elicited responses to alpha 1(XI), alpha 2(XI), alpha 3(XI), and alpha 1(II); BII, to alpha 3(XI) and alpha 1(II) exclusively. To determine whether alpha 1(XI), alpha 2(XI), alpha 3(XI), and alpha 1(II) are arthritogenic, DBA/1J mice were immunized with each alpha-chain. Arthritis was seen in mice injected with alpha 3(XI) or alpha 1(II). Sera to both alpha-chains reacted similarly with MsII and peptide fragment alpha 1(II)-CB11. Epitope mapping using polyclonal and mAb to type II collagen revealed that all polyclonal and 11 of 14 mAb reacted with alpha 3(XI) and alpha 1(II), whereas three mAb reacted only with alpha 1(II). In conclusion, BXI is immunogenic but not arthritogenic in five strains of mice, whereas alpha 3(XI) and alpha 1(II) are arthritogenic and immunogenic in DBA/1 mice and share greater than or equal to 11 epitopes recognized by autoantibody.

Immunity to type XI collagen in mice. Evidence that the alpha 3(XI) chain of type XI collagen and the alpha 1(II) chain of type II collagen share arthritogenic determinants and induce arthritis in DBA/1 mice

To determine whether native bovine type XI collagen (BXI) is arthritogenic, five strains of inbred mice were immunized with BXI/CFA. Arthritis was not observed in any of these strains, though it was prevalent in DBA/1 and B10.RIII controls immunized with bovine type II collagen (BII). Antisera from BXI-immunized mice reacted with mouse type XI collagen (MsXI), weakly with the alpha-chains of BXI, and minimally with mouse type II collagen (MsII). However, antisera to BII reacted with MsII and MsXI, indicating antibodies to conformation-independent epitopes shared by alpha 1(II) and alpha 3(XI). Mice immunized with BXI containing a small amount of BII developed arthritis much like those immunized with BII; sera from these mice reacted with MsXI and MsII. Delayed-type hypersensitivity responses differed from IgG responses, i.e., BXI elicited responses to alpha 1(XI), alpha 2(XI), alpha 3(XI), and alpha 1(II); BII, to alpha 3(XI) and alpha 1(II) exclusively. To determine whether alpha 1(XI), alpha 2(XI), alpha 3(XI), and alpha 1(II) are arthritogenic, DBA/1J mice were immunized with each alpha-chain. Arthritis was seen in mice injected with alpha 3(XI) or alpha 1(II). Sera to both alpha-chains reacted similarly with MsII and peptide fragment alpha 1(II)-CB11. Epitope mapping using polyclonal and mAb to type II collagen revealed that all polyclonal and 11 of 14 mAb reacted with alpha 3(XI) and alpha 1(II), whereas three mAb reacted only with alpha 1(II). In conclusion, BXI is immunogenic but not arthritogenic in five strains of mice, whereas alpha 3(XI) and alpha 1(II) are arthritogenic and immunogenic in DBA/1 mice and share greater than or equal to 11 epitopes recognized by autoantibody.

cDNA cloning and expression of platelet p24/CD9. Evidence for a new family of multiple membrane-spanning proteins

This study was designed to clone, sequence, and express the full-length cDNA for the human platelet p24/CD9 antigen. A 1.3-kilobase cDNA clone was identified that has an open reading frame encoding a mature protein of 228 amino acids (approximately 25,400 Da) containing 10 cysteine residues and four putative transmembrane domains. The identity of the clone was confirmed by: (i) its predicted size, (ii) identity to four peptide sequences from the isolated protein including the NH2 terminus, and (iii) expression of the isolated clone in Xenopus oocytes and Chinese hamster ovary cells. p24/CD9 has sequence identity (24-34%) to four other cell-surface proteins: ME491, a melanoma antigen; CO-029, a carcinoma antigen; CD37, a leukocyte antigen; and SM23, an antigen of the parasitic helminth Schistosoma mansoni. The five proteins have a similar number of amino acids and are characterized by the presence of four putative transmembrane domains. These data indicate the presence of a new family of surface antigens that may function in cellular activation and differentiation.

Fibroblast chemotaxis induction by human recombinant interleukin-4. Identification by synthetic peptide analysis of two chemotactic domains residing in amino acid sequences 70-88 and 89-122

Interleukin-4 is a T lymphocyte- and mast cell-derived cytokine with pleiotropic properties with biological effects on a variety of target cells including B and T lymphocytes, macrophages, hematopoietic cells, mast cells, and fibroblasts. In addition to the proliferation effect of IL-4 on fibroblasts, which has been previously described, in this report the chemotactic properties of IL-4 for fibroblasts is described. Human recombinant IL-4 induced the chemotactic migration of dermal fibroblasts in vitro in modified Boyden-type chambers at concentrations between 10(-12) and 10(-11) M. The chemotactic activity of IL-4 was neutralized by anti-human recombinant IL-4 IgG antibodies. Oligopeptides representing the complete deduced amino acid sequence of human IL-4 were synthesized by the Merrifield technique and tested for their ability to induce fibroblast chemotaxis. Two peptides representing residues 70-88 and 89-122 induced fibroblast migration. Peptide 70-88 was the more potent of the two causing chemotaxis of fibroblasts at 10(-8)-10(-6) M while peptide 89-129 induced migration at 10(-7)-10(-5) M. Although the mechanism by which IL-4 and these two peptides induce fibroblast chemotaxis is unknown, each of these three compounds were able to chemotactically desensitize fibroblasts to the chemotactic effects of the other two but not to a structurally unrelated chemotactic cytokine, transforming growth factor beta-1. These studies suggest that IL-4 might function in vivo to induce the accumulation of fibroblasts at sites of tissue injury, inflammatory and immune reactions in which T lymphocytes and mast cells participate.

Identification of the rat bone 60K acidic glycoprotein as alpha 2HS-glycoprotein

Previous reports have described an Mr 60,000-64,000 glycoprotein present in guanidium chloride (GdmCl)/EDTA extracts of bovine and rat bone. We have purified this protein from the long bones of rats and have raised polyclonal antibodies to the purified protein. The 60K glycoprotein has amino acid and carbohydrate compositions that are similar to those reported for the 60-64K protein(s). Several lines of evidence indicate that the 60K bone glycoprotein is the rat homologue of human alpha 2HS-glycoprotein. First, immunochemical data demonstrated that the 60K bone glycoprotein was present in serum as well as in EDTA/GdmCl extracts of bone. Second, immunolocalization and metabolic labelling experiments showed that the 60K protein is synthesized in liver and not in bone cells, although it is sequestered in vascularized regions of bone matrix. Finally, the NH2-terminal sequence for the rat 60K bone glycoprotein was highly similar to that of the human alpha 2HS-glycoprotein A chain. A surprising finding was that small amounts of contaminating 60K/alpha 2HS-glycoprotein were found in several protein fractions purified by ion-exchange chromatography of bone EDTA/GdmCl extracts. Because this protein was found to be highly immunogenic, the presence of anti-60K antibodies in anti-sera prepared against purified bone proteins should be considered as a potential problem.

Genomic organization of the human procollagen alpha 1(II) collagen gene

The nucleotide sequence of the human procollagen alpha 1(II) collagen gene extending from within the first intron through exon 15, and part of the 15th intron has been determined. This sequence analysis (7056 bases) identifies the intron/exon organization of the region of this gene encoding the N-propeptide and part of the triple-helical domain. Structural comparison of this with the genes of other human fibrillar collagens shows considerable diversity in terms of size and number of introns and exons that encodes the N-propeptide domain. Although the genomic structure of the human procollagen alpha 1(II) gene is quite different from the rat procollagen alpha 1(II) gene, the nucleotide coding sequences are 89% identical.