Inhibitory effect of foetal alpha 2 globulin, an acute phase protein, on carrageenin oedema in the rat

Participation of the adrenal gland in the anti-inflammatory effect of polyunsaturated diets

The effect of an n-3 (fish) and n-6 (soybean) fatty acid-rich diet on carrageenin paw oedema in rats, and the participation of adrenal gland, corticosterone and α₂-macroglobulin (α₂-M) in this process were studied. A significant inhibition of carrageenin oedema was observed not only in rats fed a diet rich in fish oil but also in the soybean group. α₂-M was not detectable before carrageenin injection, suggesting that this putative antiinflammatory factor does not participate in the observed anti-inflammatory effect. Corticosterone levels were higher in fat-fed than in control rats, before carrageenin stimulus and adrenalectomy abolished the anti-inflammatory response in fat-fed animals, showing the important role of the adrenocortical hormones in this process.

Relation between acute-phase proteins and enhanced bleomycin-induced pulmonary fibrosis in the rat

Intratracheal application of Bleomycin (Bleo) in rats induces interstitial pneumonitis followed by progressive fibrosis. As the presence of high levels of acute-phase proteins (= reactants = APR), especially alpha 2-macroglobulin of the rat (alpha 2M), enhances liver fibrosis, we investigated whether this phenomenon also occurs in rats with Bleo-induced lung fibrosis. The experiments showed that this is the case; lung fibrosis assessed by measuring hydroxyproline, hexosamine, and prolyl-4-hydroxylase was enhanced when just before Bleo application an acute-phase reaction was induced. This effect can be explained by the inhibitory effect of alpha 2M on collagenase. The experiments showed a significant positive correlation between alpha 2M and parameters of fibrosis. This is especially the case in the third week after Bleo application. Bleo itself does not induce a strong acute-phase reaction, notwithstanding the pneumonitis during the first weeks. The increased fibrosis is accompanied by progressive ventilatory disturbances demonstrated by high arterial pCO2 and low pO2. In patients undergoing Bleo treatment, varying levels of APR can be expected, and this could explain the rapid development of fibrosis in individual cases.

Mechanisms by which acute phase proteins enhance development of liver fibrosis: effects on collagenase and prolyl-4-hydroxylase activity in the rat liver

Previous experiments showed that the presence of high levels of acute phase reactants (APR) enhance CCl4-induced liver fibrosis in the rat. A high correlation was found between the degree of fibrosis and alpha 2-macroglobulin of the rat (alpha 2-macrofetoprotein, alpha M-FP) used for monitoring the acute phase response. This acute phase reaction was provoked by epinephrine just before CCl4 treatment was started. In the present study we analyzed the effect of APR by repeating these experiments and estimating liver neutral collagenase with a synthetic substrate and endogenous collagen as a substrate, and liver prolyl-4-hydroxylase. A strong depression of liver collagenase activity was found in rats with a preceding acute phase reaction contrary to the rats that underwent CCl4 treatment only. A high level of alpha M-FP correlated negatively with collagenase activity. Also in vitro alpha M-FP proved to inhibit collagenase activity. Prolyl-4-hydroxylase was increased in the rats during acute phase reaction and correlated highly and positively with alpha M-FP, haptoglobin, and ceruloplasmin. Thus high levels of APR promote development of CCl4-induced fibrosis, partly by anticollagenase activity and partly because of enhancement of prolyl-4-hydroxylase activity. The latter phenomenon can also be explained by the presence of APR, but this has to be proved.

Acute phase reactants enhance CCl4 induced liver cirrhosis in the rat

High levels of acute phase proteins (acute phase reactants, APR) suppress acute inflammatory reactions in the rat. As many APR have antiprotease properties, including an anticollagenase activity, the effect of APR on the development of CCl4-induced liver fibrosis was investigated in rats. APR were provoked by repeated injections of epinephrine, inducing a broad spectrum of APR. This reaction can be monitored measuring alpha 2-macroglobulin levels in the rat (alpha 2-macrofetoprotein, alpha M FP). This protein was found to inhibit both acute galactosamine hepatitis and acute CCl4-induced liver toxicity. The animals with high levels of APR at the start of CCl4 treatment developed a more severe degree of fibrosis and cirrhosis than the control group in which no acute phase reaction was induced. Epinephrine alone had no such effects. Additionally, the APR positive group showed an initially lower degree of hepatocellular damage when compared to control animals. This uncoupling of liver cell damage and subsequent fibrosis may demonstrate that higher levels of APR might be important as to the development of cirrhosis, possibly based on the anticollagenase activity of these proteins.

Changes in serum and exudate levels of functional macroglobulins and anti-inflammatory effect of alpha 2-acute-phase macroglobulin on carrageenin-induced inflammation in rats

Serum and exudate levels of functional macroglobulins that have the ability to inhibit proteinases were determined at various times after carrageenin injection into a preformed air-pouch on the back of rats. The trypsin-inhibiting activity of serum macroglobulins increased after a lag period of 3 hr, reached a maximum at 24 hr, and decreased steadily until day 16 after carrageenin injection. This change was in good agreement with the change in the serum level of alpha 2-acute-phase macroglobulin. In contrast with the serum level, the exudate level of functional macroglobulins was negligible on day 1, detectable on day 3, and remained at almost the same level from day 5 to day 16 after carregeenin injection. Macroglobulins were partially purified from rat serum obtained at 20 hr after carregeenin injection, and their anti-inflammatory activity was studied. The partially purified alpha 2-acute-phase macroglobulin and the alpha 1 macroglobulin were injected into the air-pouch immediately after carrageenin injection, with the result that a single injection of the functionally active alpha 2-acute-phase macroglobulin significantly inhibited the formation of granulation tissue on day 4 after the carrageenin injection, whereas functionally inactive alpha 1 macroglobulin was without effect. These results suggest that the inhibitory activity of macroglobulins on the development of granulation tissue is due to the proteinase-inhibiting capacity of macroglobulins.

Galactosamine hepatitis, endotoxemia, and lactulose

Studies by Liehr et al. suggest that endotoxins are important in the pathogenesis of galactosamine hepatitis (Gal-N hepatitis) in rats. Lactulose (9.1 gm per kg per day) prevents hepatic lesions induced by Gal-N; an antiendotoxin effect of lactulose is postulated. However, commercial preparations of lactulose are contaminated with galactose, which shows a competitive action to Gal-N. To analyze the effect of galactose, male Wistar rats were pretreated with lactulose (Duphalac, 9.1 gm per kg per day) and given Gal-N (375 mg per kg i.p.). After 24 hr, serum was analyzed for glutamic pyruvate transaminase, glutamate dehydrogenase, and sorbitol dehydrogenase activities. Pretreatment with Duphalac, even 1 hr before Gal-N, abolished toxicity. Duphalac contains 10 gm galactose per 100 ml. Galactose was given in a similar concentration and similar inhibition occurred. Pretreatment with purified lactulose (9.1 gm per kg for 5 days) diminished the effects of Gal-N but did not normalize enzyme concentrations. Because small doses of galactose (80 and 300 mg per kg) showed similar inhibitory effects, we conclude that the protective effect of commercial lactulose preparations is mainly due to galactose contamination and not to an antiendotoxin effect.

Inflammation, counter irritation and rat serum acute phase alpha 2-macroglobulin levels

Following the injection of turpentine and carrageenan into rats, laboratory models for counter irritation were assessed by measuring changes in paw thicknesses and serum acute phase alpha 2-macroglobulin concentrations. Both indices of inflammation were also examined in groups of rats dosed with 6-mercaptopurine, the best inhibitor found so far of elevated levels of alpha 2-macroglobulin in rat serum. Results showed that there is no relationship between the degree of irritant-induced inhibition of inflammation and the serum concentration of the acute phase protein. Hence, at least in the models for counter irritation used in this study, alpha 2-macroglobulin cannot be viewed as an endogenous anti-inflammatory protein.

Inhibition of polymorphonuclear leukocyte chemotaxis by alpha-macrofetoprotein, an acute-phase reactant of the rat

alpha-Macrofetoprotein (alpha M FP) is a normal fetal plasma constituent in the rat, with very low plasma levels in the adult phase but rising sharply after injury. This fetal acute-phase protein is a strong inhibitor of inflammatory edema. Fetal inflammatory reactions show diminished exudation, but also impaired emigration of polymorph nuclear cells (PMNs). Therefore we studied the effect of alpha M FP on chemotaxis of PMN in vitro and in vivo. In vitro experiments showed a strong inhibitory effect on casein-induced leukotaxis (Boyden technique) with a clear dose-effect relationship. In vivo with glycogen-induced pleurisy and peritonitis, high alpha M FP levels are accompanied by diminished PMN emigration and vice versa. The significance of these findings is discussed in relation to fetal pathology and also as a model showing the modulating effects of acute-phase proteins on the inflammatory reaction induced by tissue injury.

Modifications in the regression of the acute inflammation caused by a beta-adrenergic effect unbalanced by the alpha-component ("biased beta-effect")

A biased beta-adrenergic effect was produced either by blocking the alpha-adrenergic component of endogenous catecholamines using phentolamine or by application of isoproterenol. Both experimental conditions led to a prolongation of the lymphocyte phase of the inflammatory process. A beta-bias also curbed the activity of a substance (or substances) inhibiting the ingress of lymphocytes into the site of inflammation (subcutaneously injected Sephadex) around the fourth and fifth day after the onset of inflammation. This lack in activity is evidently connected with the prolonged lymphocyte phase.

A new screen for anti-inflammatory agents. Estimation of rat serum acute phase alpha2-macroglobulin levels using an electroimmunoassay

Induction of alpha2-macroglobulin acute phase protein in rats by the injection of turpentine revealed strain and sex differences in the amounts of this protein detected in sera by rocket immunoelectrophoresis. Studies in vivo with a wide variety of drugs showed that non-steroidal anti-inflammatory drugs (NSAID) such as aspirin, indomethacin and BW 755C as well as colchicine, clofibrate and clozic, inhibited serum concentrations of the acute phase protein 48 h after turpentine injection. The procedure used offers a new and convenient screen for assessing NSAIDs and the method may be of value as a screen for new clozic-like compounds with anti-rheumatic activity. The possibility that the NSAIDs are inhibiting a humoral factor initiated by the inflammatory stimulus and that the humoral factor is a metabolite of arachidonic acid is discussed.

6-sulphanilamidoindazole arthritis of rats: relation between acute-phase proteins, degree of arthritis and treatment with soybean trypsin inhibitor

During 6-sulphanilamidoindazole (6-SAI) arthritis a significant increase of serum levels of the protease inhibitor alpha 2 macroglobulin (= alpha 2 acute phase globulin) and of Darcy's glycoprotein was found, whereas the content of female specific protein and of sulfhydryl groups was proved to be significantly decreased. Intravenous administration of 5 mg/kg soybean trypsin inhibitor, twice daily for 4 days, was without any inhibitory effect on paw swelling in 6-SAI arthritis but it caused increased serum levels of alpha 2 macroglobulin and Darcy's glycoprotein. Thus, spontaneous remission of 6-SAI arthritis occurring, despite continued administration of 6-SAI, seems hardly likely to be caused by acute-phase reactants, e.g. via protease inhibition. Evidence is presented which shows that spontaneous remission of 6-SAI arthritis could be due to local processes.

Purification and properties of rat alpha 2 acute-phase macroglobulin

Alpha 2 acute-phase macroglobulin was isolated from plasma of turpentine-injected rats. In the method conditions known to damage the biological activities of alpha 2 macroglobulin are avoided. The procedure successively involves: rivanol precipitation, concanavalin A-Sepharose chromatography and ion-exchange chromatography on DEAE-cellulose. Proteolytic activities were minimized throughout the purification. Thus alpha 2 macroglobulin was obtained in a 20% yield and was pure by biochemical and immunological criteria. Its molecular weight appeared to be 760 000 and it consisted of four subunits (Mr 190 000). The protein has an A1cm 1% = 8.8 and an isoelectric point = 4.8. The amino acid and carbohydrate compositions were determined. Our preparations bound 1 molecule of trypsin or 1 molecule of plasmin/molecule of alpha 2 macroglobulin. Kinetic parameters for alpha 2 macroglobulin-bound trypsin and plasmin were determined and compared with those of free trypsin and plasmin using butoxycarbonyl-L-valylglycyl-L-arginine-2-naphthylamide and benzoyl-L-arginine ethylester as substrates.

Serum concentrations of alpha-macrofeto-protein (acute-phase alpha2-macroglobulin), a proteinase inhibitor, in pregnant and neonatal rats and in rats with acute inflammation

Alpha macrofetoprotein (AMF) or acute-phase alpha2 macroglobulin serum concentrations are elevated in pregnant, fetal, and newborn rats and in rats with experimentally induced acute inflammation when quantitated using a double-antibody radioimmunoassay. Concentrations of AMF are 17 +/- 2 microgram/ml and 32 +/- 6 microgram/ml in normal adult rat sera. Both maternal (1.2 mg/ml) and neonatal (9.3 mg/ml) concentrations are maximal at term. AMF serum concentrations of rats injected with croton oil into the hind footpads are unchanged for the first 4 h after injection, then increase to a maximum of 10.5 mg/ml 36 h after injection. Serum AMF concentrations correlate directly with the dose of croton oil and the increase in size (swelling) of the injured foot, and remain elevated during the course of inflammation for at least two weeks. The possible function of AMF as an antiproteinase limiting the extent of inflammation after acute tissue injury is discussed.

The role of bacterial contamination in the isolation of apparent anti-inflammatory factors from rabbit anti-lymphocytic serum

1 Rabbit anti-guinea-pig lymphocytic serum was fractionated by gel filtration to obtain partially purified materials possessing anti-inflammatory activity. The pharmacological properties of these materials were then studied. 2 Two fractions were found which reproducibly contained significant activity. One of these activities caused inflammation at the site of injection and was associated with high molecular weight protein (2008000). The other activity was found in low molecular weight fraction but was shown to be due to small amounts of endotoxin from Gram negative bacteria. These organisms contaminated the fractions in spite of the recommended precautions for gel filtration having been taken. 3 The endotoxin-containing fraction completely abolished leucocyte infiltration into the rat foot which had been injected with kaolin. It had no apparent effect on circulating haemolytic complement. It caused maximal elevation of serum 11-hydroxycorticosteroid concentrations and was found to cause the release of pharmacologically active amines. Many of the previously reported naturally occurring anti-inflammatory substances have similar pharmacological properties to those of the endotoxin-containing fraction. 4 It was concluded that doubt will exist about the presence of anti-inflammatory factors in mammalian body fluids unless stringent precautions are taken to exclude measurable bacterial contamination. 5 These experiments also cast doubt on the validity of accepted procedures for excluding microbial growth from columns used in the fractionation of serum.

Inflammation inhibiting properties of rat alphaM foetoprotein (rat-alpha2 macroglobulin), an acute phase reactant

alphaMFoetoprotein of the rat (rat alpha2macroglobulin) is present in serum during foetal development. After birth, alphaMFP declines rapidly, but the protein returns after injury. The injury we used consisted of skin and muscle incision, laparotomy, BaSO4 i.p. The protein occurs also during liverregeneration, livercardinogenesis en during infections. Therefore, alphaMFP can be considered as an acute phase reactant. We found that this protein strongly inhibits inflammatory exudation caused by carrageenin, histamin, prostaglandin E2, 5HT and bradykinin. Furthermore, we found that alphaMFP suppresses completely inflammatory reactions during Ga1.N-hepatitis. In this condition, the primary biochemical lesion, consisting of liver UDPG depletion, does occur in spite of the protective effect of alphaMFP. Thus, the inflammatory inhibiting effects of alphaMFP seem to be an important mechanism reducing inflammatory reaction patterns.

The role of the acute phase reaction in inflammation

Inflammation and injury to tissue results in a variety of local and systemic events, however although the local events of oedema formation and cellular infiltration have received considerably more attention the systemic response to inflammation is no less profound. The particular systemic event which forms the substance of this communication is the change in the circulating levels of plasma proteins which occurs after inflammatory injury, and the manner in which these changes in plasma concentration are controlled by changes in plasma concentration are controlled by changes in the rate of synthesis. A discussion of the role of the liver in controlling inflammatory events, in relation to the synthesis of an anti-inflammatory protein has been given; the present work is an extension of this and describes the changes in concentration and synthesis rate of albumin, fibrinogen and alpha1 acid glycoprotein during adjuvant arthritis in the rat. The changes which occur are regulated at the liver by alteration of the rate of synthesis of the individual protein. For example albumin at the height of adjuvant arthritis falls to a third of its normal plasma level whereas the level of alpha1 acid glycoprotein increases up to twenty-fold; these changes are reflected by similar changes in their synthesis rate by the liver. The effect of the fall in albumin concentration on the plasma binding of anti-inflammatory drugs (and their toxicity) in relation to these findings will be discussed along with the biological role of the acute phase plasma proteins and hence the influence of the liver in the response to injury.