Interleukin-1 and Tumor Necrosis Factor- Produce ...

Vet Pathol 41:235–243 (2004)

Interleukin-1␤ and Tumor Necrosis Factor-␣ Produce Distinct, Time-dependent Patterns of Acute Arthritis in the Rat Knee1 B. BOLON, G. CAMPAGNUOLO, L. ZHU, D. DURYEA, D. ZACK,

AND

U. FEIGE

Departments of Pathology (BB, DD) and Inflammation Research (GC, LZ, DZ, UF), Amgen, Inc., One Amgen Center Drive, M/S 29-M-B, Thousand Oaks, CA Abstract. Interleukin-1␤ (IL-1␤) and tumor necrosis factor-␣ (TNF-␣) synergistically induce and sustain arthritis. Two competing hypotheses of arthritis induction are 1) that TNF preferentially mediates inflammation, whereas IL-1 impels bone destruction, or 2) that either cytokine controls the entire process. In this study, these propositions were tested in two experiments by instilling IL-1␤ or TNF-␣ into one knee of Lewis rats (n ⫽ 6/ group) to incite arthritis, after which semiquantitative scores for inflammation, bone resorption, osteoclasts, and cartilage integrity were acquired. In the induction study, IL-1␤ or TNF-␣ (3, 10, or 30 ␮g) was given once to incite arthritis. After 2 days, IL-1␤ induced significant, dose-dependent increases in inflammation (mild to marked), bone resorption (minimal to moderate), and osteoclasts (minimal to moderate). In contrast, TNF-␣ induced minimal to mild inflammation but had little impact on resorption or osteoclasts. Both IL-1 and TNF (ⱖ10 ␮g) yielded mild cartilage degeneration. Most lesion scores in TNF-treated rats were significantly lower than those in animals given the same dose of IL-1␤. In the persistence study, rats were injected once with IL1 or TNF (10 ␮g) and maintained for 2, 3, or 7 days. IL-1␤ significantly enhanced inflammation (all 3 days), bone resorption (days 2 and 3), osteoclasts (days 2 and 3), and cartilage matrix loss (days 2 and 3), whereas TNF-␣ augmented inflammation (days 2 and 3) and cartilage degeneration (day 2) but not bone resorption or osteoclasts. Thus, both IL-1␤ and TNF-␣ can launch inflammation, but IL-1␤ drives skeletal destruction. Key words:

Arthritis; cytokine; IL-1; intra-articular; TNF.

Arthritis is initiated and sustained by the release of myriad proinflammatory cytokines (reviewed by Arend and Dayer1 and Taylor37). In patients with rheumatoid arthritis, the dominant proinflammatory cytokines are interleukin-1 (IL-1) (chiefly the inducible ␤ form) and tumor necrosis factor-␣ (TNF-␣).2,7 Inhibition of IL-1␤ or TNF-␣ (or both) reduces the extent of inflammation in rheumatoid arthritis9,33 and lessens inflammation and bone destruction in various experimental models of arthritis.15,21,23,44,45 Therefore, biologic agents that specifically inhibit the action of these two cytokines are gaining rapid acceptance as early, aggressive treatments for rheumatoid arthritis.6,10 IL-1␤ and TNF-␣ act synergistically to induce and maintain inflammation and skeletal erosion in arthritis.8 Given the extensive coexpression of these two cytokines in joints with both acute27 and advanced disease,14,22,25 the precise role that each molecule plays in directing the early pathogenesis of arthritis remains unA part of this study was presented at a symposium on ‘‘Immune Mechanisms and Disease’’ (sponsored jointly by the New York Academy of Sciences and the Henry Kunkel Society) at St. Georges, Grenada, West Indies, on 14–17 April 2002 (extended abstract published in Ann NY Acad Sci 987:295–298, 2003). 1

clear. Two competing propositions are that TNF-␣ preferentially drives acute inflammation, whereas IL1␤ impels later bone destruction,20,21,25 or that either IL-1␤ or TNF-␣ alone can control both inflammation and skeletal destruction.15 The present experiments explored these competing hypotheses using direct intraarticular injection of purified cytokines. We selected this strategy so that the acute effects of each molecule could be studied in relative isolation from those related to the plethora of proinflammatory cytokines that are produced during the induction and progression of arthritis. Materials and Methods Experimental design The current studies were designed to examine the respective functions of IL-1␤ and TNF-␣ in controlling the induction and maintenance of acute joint inflammation. These two cytokines were selected for study because they profoundly influence the course of rheumatoid arthritis,2,7 where they participate both directly and indirectly (through induction of other proinflammatory molecules) in sustaining the disease. Two experiments were completed in series (Table 1): 1) an induction study assessing the impact of acute exposure to either IL-1␤ or TNF-␣; and 2) a persistence study to define the time course during which intra- and periarticular lesions

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Table 1. studies.

Group

Vet Pathol 41:3, 2004

Experimental design for cytokine instillation

IL-1␤ (␮g) TNF-␣ (␮g)

No. Injections

Necropsy Time (days after injection)

Experiment 1 2 3 4 5 6 7

1: arthritis — 3 10 30 — — —

induction — — — — 3 10 30

1 1 1 1 1 1 1

2 2 2 2 2 2 2

Experiment 1 2 3 4 5 6 7 8

2: arthritis — 0 10 — 10 — 10 —

persistence — 0 — 10 — 10 — 10

0 1 1 1 1 1 1 1

2 2 2 2 3 3 7 7

regress after a limited acute exposure to either IL-1␤ or TNF-␣. Both cytokines were given once, as described below. The soluble mature forms of circulating IL-1␤ and TNF-␣ are both 17 kd,32 so the two cytokines were given on an equimolar basis. The range of doses was extrapolated from previously reported data12,18 to ensure a rapid and florid arthritic reaction. These experiments were conducted in accordance with federal animal care guidelines and were preapproved by the Amgen Institutional Animal Care and Use Committee. Animals and husbandry Young, adult male Lewis rats (6–7 weeks and 175–200 g; Charles River, Wilmington, MA) were randomly assigned to treatment groups (n ⫽ 6/cohort) and housed two per filtercapped cage (room temperature 23 ⫾ 2 C, relative humidity 50 ⫾ 20%, 12-hour light-dark cycle). This strain was selected because of its demonstrated utility in arthritis investigations. Animals were given tap water and pelleted chow (#8640, Harlan Teklad, Madison, WI) ad libitum. Cytokine instillation Each rat was anesthetized with isoflurane (3%) in oxygen (4 liter/minute). Using a 28-gauge needle, the left knee was injected once through the infrapatellar ligament with 50 ␮l of filter-sterilized phosphate-buffered saline (PBS) containing either IL-1␤ or TNF-␣. In a pilot study, we confirmed that the instillate was confined to the joint space by injecting Evan’s blue dye (unpublished). The recombinant human proteins (Amgen Inc., Thousand Oaks, CA) were expressed in Escherichia coli and purified by standard methods. Recombinant human versions were used for these experiments because of the high degree of

Fig. 1. Knee (frontal section); normal rat. Abbreviations: F ⫽ femur; L ⫽ cruciate ligament; M ⫽ meniscus; T ⫽ tibia. Boxes denote regions shown at higher magnification in figures below. Anti-CK immunohistochemistry with HE counterstain. Bar ⫽ 1 mm. homology between the human and rodent proteins32 and the proinflammatory actions of either human IL-1␤12,13,24,36,43 or TNF-␣24,35,39,43 toward rat cells in vitro and in vivo. Endotoxin contamination was held below 10 EU (20 ng) per milligram protein because the lipopolysaccharide component is a potent inducer of both IL-1 and TNF-␣. Induction experiment Either IL-1␤ or TNF-␣ was instilled once at 3, 10, or 30 ␮g. Rats were maintained for 2 days to study the dose response for initiation of joint lesions that develop in acute arthritis. This time point was selected based on a previous study demonstrating that joint damage peaks 2 days after cytokine injection.41 An untreated normal control group was used rather than a vehicle-treated cohort for the first study. This labor-saving choice was deemed reasonable because in our experience normal young rats almost never have joint lesions (unpublished). Persistence experiment IL-1␤, TNF-␣ (10 ␮g), or vehicle was injected once. Rats were kept for 2, 3, or 7 days to evaluate the progression of arthritis after a limited insult. A dose of 10 ␮g was chosen because results of the dose-response study indicated that,

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Roles of IL-1 and TNF in Acute Arthritis


Table 2.

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Histopathology criteria for arthritis lesion scores.

Lesion/Grades

Location of Assessment/Criteria for Grades

Inflammation 0 1 2 3 4 Bone resorption 0 1 2

Assessment made for intra-articular and periarticular soft tissues Normal Few inflammatory cells Mild inflammation Moderate inflammation Marked inflammation (generally diffuse) Assessment made for subchondral bone on distal femur and proximal tibia Normal Minimal increase in the depth of resorption lacunae (scallops) in subchondral bone Mild increase in the depth or number of resorption lacunae (or both) in subchondral bone Moderate increase in the depth or number of resorption lacunae (or both) in subchondral bone Assessment made for distal femur and proximal tibia Normal Minimal increase in osteoclasts (crescentic) lining subchondral bone Mild increase in osteoclasts (oval ⬍ crescentic) lining subchondral bone Moderate increase in osteoclasts (crescentic ⬍ oval) lining subchondral bone Marked increase in osteoclasts (oval) lining subchondral bone Osteoclast morphology: crescentic ⫽ resting, oval ⫽ activated Assessment made for articular cartilage on distal femur and proximal tibia Normal Minimal (loss of toluidine blue staining in superficial layer) Mild (loss of toluidine blue extending up to 25% of cartilage depth) Moderate (loss of toluidine blue extending up to 75% of cartilage depth) Marked (loss of toluidine blue extending to the tide mark)

3 Osteoclasts 0 1 2 3 4 Cartilage 0 1 2 3 4

when given alone, both IL-1␤ and TNF-␣ induced biologically significant lesions at this level. A single administration was elected to limit secondary production of other cytokines, thereby allowing the effects of IL-1␤ and TNF-␣ to be studied in relative isolation. Tissue processing At necropsy, injected knees were separated from the foot and thigh, fixed intact by immersion in 70% ethanol, and then decalcified in a 1 : 1 mixture of 8 N formic acid and 1 N sodium formate. Almost all knees naturally assumed an angle of between 135⬚ and 150⬚ because severing the leg muscles prevented postmortem contraction. Next, knees were trimmed in the frontal plane by progressively removing tissue (in layers of 2 to 4 mm) from the rostral margin until the joint cavity and menisci were visible (internal landmarks, as shown in Fig. 1); the proper orientation was maintained by holding the razor blade parallel to the tibia when cutting the knee. For the few knees (about 5%) that contracted during fixation, the fascia and tendon insertions on the caudal surface were cut just above and below the joint so that the knee could be flexed to a 140⬚ angle for trimming. Specimens were embedded in paraffin (rostral face down in cassette) and sectioned serially at 5 ␮m. One section was stained with toluidine blue because it imparts a uniform, deep purple color to normal cartilage. The other was subjected to an automated, indirect immunoperoxidase technique to label the osteoclast marker cathepsin K (CK) and

then counterstained with hematoxylin and eosin (HE).5 The immunohistochemical method used sequential incubations in CAS Block (Zymed Laboratories, San Francisco, CA) for 10 minutes, PBS containing a proprietary rabbit monoclonal anti-human CK antibody (1 ␮g/ml; Amgen) for 60 minutes, PBS with biotinylated goat polyclonal anti-rabbit antibody (1 : 200; Vector, Burlingame, CA) for 25 minutes, and peroxidase blocking solution (DAKO Corporation, Carpenteria, CA) for 25 minutes. An avidin–biotin–complex bridge was developed for 25 minutes using standard reagents (ABC Elite kit; Vector) and visualized using diaminobenzidine (DAB⫹ Substrate/Chromagen System; DAKO) for 3 minutes. Morphologic analysis Four lesions were scored in each joint using tiered, semiquantitative criteria (Table 2). Cartilage degeneration was examined in toluidine-blue–stained sections. The other three changes—leukocyte infiltration, bone resorption, and subchondral osteoclasts—were evaluated in CK/HE–stained sections. These lesions were selected for analysis because such measures of inflammation, joint erosion, and cartilage matrix integrity commonly are assessed in animal models of arthritis. Separate scores for osteoclasts and bone resorption were acquired because we postulated that a rise in the population of bone-eroding cells was likely to precede actual bone damage in this acute arthritis model. Both sections for each animal were read consecutively (CK/HE followed by


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Fig. 2. Knee; normal rat. Frontal section magnifying the meniscus (M) and associated periarticular tissues (left [vertical] box, Fig. 1). Anti-CK with HE. Bar ⫽ 400 ␮m. Fig. 3. Knee; normal rat. Frontal section of the joint cartilage and subchondral bone of the femoral (F) epiphysis (right [oblique] box, Fig. 1). Resting osteoclasts are rare, and resorption (Howship’s) lacunae are shallow (arrowhead). Anti-CK with HE. Bar ⫽ 400 ␮m. Fig. 4. Knee; normal rat. Frontal section of opposing femoral (F) and tibial (T) joint cartilages (right [oblique] box, Fig. 1), showing uniform staining intensity of the cartilage matrix in all zones. The tip of the meniscus (M) routinely exhibits less intense labeling. Toluidine blue stain for cartilage matrix integrity. Bar ⫽ 150 ␮m. Fig. 5. Knee; rat given IL-1␤ (10 ␮g) 2 days previously, demonstrating extensive inflammation in the periarticular soft tissues and joint cavity. Anti-CK with HE. Bar ⫽ 400 ␮m. Fig. 6. Knee; rat given IL-1␤ (10 ␮g) 2 days previously. The number and depth of resorption lacunae in the subchondral bone is increased, and the osteoclast population is both expanded and activated (as shown by their larger size and more rounded contours). Anti-CK with HE. Bar ⫽ 400 ␮m. Fig. 7. Knee; rat given IL-1␤ (30 ␮g) 2 days previously, revealing degeneration (loss of staining intensity [defined by arrowheads]) of the superficial matrix of the tibial joint cartilage. In this case, this change is associated with intra-articular accumulation of leukocytes (arrow). Toluidine blue. Bar ⫽ 150 ␮m. Fig. 8. Knee; rat given TNF-␣ (10 ␮g) 2 days previously. Note the extremely modest infiltration of leukocytes into the periarticular soft tissues relative to an equimolar IL-1␤ dose (Fig. 5). Anti-CK with HE. Bar ⫽ 400 ␮m. Fig. 9. Knee; rat given TNF-␣ (10 ␮g) 2 days previously, showing increases in both resorption lacunae and osteoclasts. The osteoclast phenotype (fusiform to stellate conformation) suggests that these cells are differentiating but not yet fully activated (cf. Fig. 6). Anti-CK with HE. Bar ⫽ 400 ␮m. Fig. 10. Knee; rat given TNF-␣ (10 ␮g) 2 days previously, showing the essentially normal staining pattern observed in joints exposed acutely to lower doses of either cytokine. Toluidine blue. Bar ⫽ 150 ␮m.




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toluidine blue) so that data from each animal could be interpreted together. A ‘‘blinded’’ design was used to avoid bias because the three indices for scoring skeletal damage were based on subtle differentiations between grades. Statistical analyses The histopathologic lesion scores (ordinal variables) were analyzed by the chi-square test using commercially available software (JMP, v. 4.0; SAS Institute, Cary, NC). A P value of 0.05 was used to define significant differences between groups.

Results Lesion character

The most prominent lesion induced by cytokine exposure was inflammation (Fig. 5). Two days after cytokine instillation, the reaction included neutrophils, with fewer lymphocytes and macrophages, and was most extensive in the periarticular soft tissues. Aggregates of neutrophils or fibrin (or both) were seen in some joints, particularly within recesses near the cruciate ligaments and beneath the patella. Over time, inflamed joints contained more mononuclear cells and less fibrin, but the neutrophil content remained high. The primary skeletal changes seen in the inflamed joints were subchondral bone resorption accompanied by an enhanced subchondral population of activated osteoclasts (Fig. 6). Resorption was distinguished by more and deeper resorption (Howship’s) lacunae lining the subchondral bone in both the femur and tibia. Osteoclasts filled most lacunae. The large osteoclasts (Fig. 6) in severely inflamed joints that had been injected with a cytokine typically had oval contours and multiple nuclei (an ‘‘activated’’ phenotype).4 In contrast, osteoclasts from control knees (Fig. 3) or joints exhibiting a more modest inflammatory response (Fig. 9) generally had a fusiform or stellate conformation (a ‘‘resting’’ phenotype).4 The appearance of the bone lesion and osteoclast population was similar at all time points after a single cytokine instillation. Cartilage degeneration was induced in some joints after acute exposure to either cytokine. This change was exemplified by focal to multifocal loss of toluidine blue staining in the superficial cartilage matrix (Fig. 7); however, many cytokine-exposed joints remained unaffected (Fig. 10). The extent and severity of this lesion was higher in joints with more extensive inflammation—especially if the leukocyte infiltrate was present within the joint cavity. The degree of degeneration did not change with time after a single cytokine injection. Arthritis induction

Relative to uninjected joints (Figs. 2–4), both IL-1␤ (Figs. 5–7) and TNF-␣ (Figs. 8–10) led to substantial

Fig. 11. Inflammation. Fig. 12. Bone resorption. Fig. 13. Osteoclast expansion. Fig. 14. Cartilage degeneration. Induction of acute arthritis by a single intra-articular instillation of IL-1␤ or TNF-␣ (3, 10, or 30 ␮g of purified protein) 2 days previously. Numbers inside the bars or just above the error bars indicate the group mean inflammation score. ‘‘1’’ denotes a significantly greater lesion (P ⱕ 0.05) relative to untreated control rats and ‘‘2’’ a significant difference (P ⱕ 0.05) between the changes induced by equimolar doses of IL-1␤ and TNF-␣.

inflammation, subchondral bone resorption, and osteoclast expansion as well as some cartilage matrix degeneration 2 days after instillation. The rise in the lesion score severity was dose dependent for both cytokines. All three IL-1␤ doses elicited significant increases in inflammation (Fig. 11), bone resorption (Fig. 12), and osteoclasts (Fig. 13). The increase in inflammation was mild to marked, whereas those for bone resorption and osteoclasts were minimal to moderate. The cartilage score was enhanced significantly to a minimal degree for IL-1␤ doses ⱖ10 ␮g (Fig. 14). In contrast, all three TNF-␣ doses induced significant but minimal to mild inflammation (Fig. 11) but did not affect bone resorption (Fig. 12) or osteoclasts (Fig. 13). The cartilage score was enhanced significantly to a minimal degree for TNF-␣ at 10 ␮g (Fig. 14). For a given dose, IL-1–treated rats had significantly greater scores for


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gree at 2 and 3 days after instillation but not after 7 days; minimal cartilage degeneration occurred in this same pattern (Fig. 18). In contrast, TNF-␣ induced minimal to mild inflammation only at the two early time points (Fig. 15). The only other lesion of significance elicited by TNF was minimal loss of cartilage matrix after 2 days (Fig. 18). A single TNF exposure did not affect bone resorption (Fig. 16) or osteoclasts (Fig. 17). IL-1␤ generated significantly greater inflammation, bone resorption, and osteoclasts than did TNF␣ 3 days after cytokine treatment. Discussion

Fig. 15. Inflammation. Fig. 16. Bone resorption. Fig. 17. Osteoclast expansion. Fig. 18. Cartilage degeneration. Persistance of acute arthritis by a single intra-articular instillation of IL-1␤ or TNF-␣ (10 ␮g of purified protein). Numbers inside the bars or just above the error bars indicate the group mean lesion score. ‘‘1’’ denotes a significantly greater lesion (P ⱕ 0.05) relative to untreated control rats and ‘‘2’’ a significant difference (P ⱕ 0.05) between the changes induced by equimolar doses of IL-1␤ and TNF-␣. Abbreviation: d ⫽ days after injection.

inflammation (doses ⱖ10 ␮g), bone resorption (all doses), and osteoclasts (all doses) 2 days after treatment than did animals injected with TNF. Arthritis persistence

IL-1␤ or TNF-␣ (10 ␮g) produced significant, sustained increases in scores for inflammation (both cytokines), bone resorption (IL-1 only), osteoclast expansion (IL-1 only), and cartilage matrix degeneration (both cytokines) 2, 3, or 7 days after instillation into the femorotibial joint cavity. Lesions induced by both cytokines regressed during the 7-day course of this experiment, indicating that arthritis induced by a limited cytokine exposure is self-limiting. For IL-1␤, the extent of inflammation was mild 2 and 3 days after injection and minimal after 7 days (Fig. 15). IL-1␤ also enhanced bone resorption (Fig. 16) and osteoclasts (Fig. 17) to a minimal to mild de-

Inflammation and skeletal destruction in arthritis are determined by interactions between numerous pro- and anti-inflammatory molecules. On the proinflammatory side, two major players are IL-1␤ and TNF-␣. Importantly, many studies indicate that IL-1␤ and TNF-␣ act cooperatively to promote joint inflammation. For example, IL-1 and TNF-␣ exhibit synergism in vitro when inducing production of plasminogen activator by human articular chondrocytes,11 or collagenase and prostaglandin E2,3,26 IL-6,16 or IL-831 by human synovial fibroblasts. In vivo, IL-1 and TNF-␣ act synergistically to recruit leukocytes into rabbit joints.18 In like manner, molecules that bind IL-1 or TNF-␣—thereby blocking signal transduction through these two pathways—exhibit synergistic efficacy in decreasing the severity of inflammation and bone destruction in the Lewis rat model of adjuvant arthritis.15 The synergism between IL-1␤ and TNF-␣ has been suggested to result from reciprocal positive feedback cycles by which IL1 induces TNF-␣19 and TNF-␣ induces IL-1;38 IL-1 has also been shown to induce itself.34 Given the extensive colocalization of these two molecules in advanced disease,14,22,25 the precise role that each molecule plays in the pathogenesis of acute arthritis in vivo remains unclear. We undertook the present study to compare the effects elicited by IL-1␤ and TNF-␣ during the induction and early maintenance phases of acute arthritis. In particular, we sought evidence to select between two contending postulates: preferential control of inflammation by TNF-␣ and bone damage by IL-1␤21,42 or coregulation of both inflammation and bone destruction by the actions of either IL-1 or TNF-␣.15,30 Our present data show that one exposure to equimolar doses of either IL-1␤ or TNF-␣ initiates acute arthritis, thus demonstrating that both cytokines can launch disease. Interestingly, however, our findings also show that IL1␤ impels joint lesions to a substantially greater degree and for a longer time than does an equivalent dose of TNF-␣. Taken together, these data provide support for the second hypothesis. Still, IL-1␤ was a more potent stimulus for subchondral bone resorption and osteo-




clast expansion than was TNF-␣. Thus, in this respect, our data also confirm the first hypothesis because IL1␤ clearly plays a greater role in the genesis of arthritis-associated skeletal destruction. One potential criticism of the current experiments is that the cytokine levels used in this study were high relative to those needed to initiate a limited arthritic response. For example, IL-1 induces proteoglycan loss in cartilage matrix and leukocyte infiltration when injected into knees of mice or rabbits17,28 at doses of 25 ng or less. In like manner, intra-articular injection of proarthritic materials yields local production of IL-1 and TNF-␣ at picogram levels.29,40 However, we purposely selected the cytokine doses for the present study based on the relative insensitivity of the rat knee to the proinflammatory influence of IL-1 as arthritis reportedly is initiated in this joint only if the intraarticular dose of recombinant human IL-1 exceeds 90 ␮g.12 An additional consideration was that administration of a high dose reasonably would be expected to overwhelm the effects of other proinflammatory molecules induced by IL-1␤ or TNF-␣, thereby allowing the true proarthritic potential of each cytokine to be assessed. Our data show that the range of doses we chose to administer produced a modest, self-limiting arthritis, which shows that a single IL-1␤ or TNF-␣ exposure of ⱕ30 ␮g was not sufficient to induce the secondary cytokine cascades necessary to sustain the inflammatory process. A potential explanation for the divergent proarthritic responses between IL-1 and TNF in the present study is that human IL-1␤ can stimulate rat-derived inflammatory cells, whereas human TNF-␣ cannot. This contention is supported in a general sense by data on rats showing that the stimulatory effect of human IL-1␤ toward the hypothalamic-pituitary-adrenal axis exceeds that engendered by human TNF-␣.43 The maximum cytokine dose used in the endocrine study (3 ␮g/ rat) was 10-fold lower than the highest dose given during the present experiments (30 ␮g/rat); furthermore, the endocrine study used intravenous delivery, which would have greatly diluted the cytokine levels at the target tissue relative to our localized intra-articular injection. A review of recent literature amply demonstrates that human IL-1␤ and human TNF-␣ can enhance the activity of proinflammatory pathways in ratderived cells and tissues,13,36,39 which supports our interpretation that the discrepancy between the acute proarthritic responses of these two molecules in our rat intra-articular injection model represents a true biologic effect. However, with the exception of our present experiments, the functional consequences of exposing tissues from rat joints to recombinant human versions of IL-1␤ or TNF-␣ apparently have not been tested in a head-to-head experiment under either in vi-

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tro or in vivo conditions. Additional work with this and other arthritis models using various cytokine doses should provide considerable assistance in elucidating the specific in vivo functions of IL-1␤ versus TNF-␣, as well as for comparing the effects of additional proand anti-inflammatory molecules in the onset and progression of acute arthritis. References 1 Arend WP, Dayer JM: Cytokines and cytokine inhibitors or antagonists in rheumatoid arthritis. Arthritis Rheum 33:305–315, 1990 2 Arend WP, Dayer JM: Inhibition of the production and effects of interleukin-1 and tumor necrosis factor ␣ in rheumatoid arthritis. Arthritis Rheum 38:151–160, 1995 3 Berenbaum F, Jacques C, Thomas G, Corvol MT, Bereziat G, Masliah J: Synergistic effect of interleukin-1␤ and tumor necrosis factor ␣ on PGE2 production by articular chondrocytes does not involve PLA2 stimulation. Exp Cell Res 222:379–384, 1996 4 Bolon B, Campagnuolo G, Feige U: Duration of bone protection afforded by a single injection of recombinant osteoprotegerin (OPG) in male Lewis rats with adjuvant arthritis. Cell Mol Life Sci 59:1569–1576, 2002 5 Bolon B, Morony S, Cheng Y, Hu Y-L, Feige U: Osteoclast numbers in Lewis rats with adjuvant-induced arthritis: identification of preferred sites and parameters for rapid quantitative analysis. Vet Pathol 41:30–36, 2004 6 Breedveld FC: Future trends in the treatment of rheumatoid arthritis: cytokine targets. Rheumatology 38:11– 13, 1999 7 Brennan FM, Field M, Chu CQ, Feldmann M, Maini RN: Cytokine expression in rheumatoid arthritis. Br J Rheumatol 30:76–80, 1991 8 Brennan FM, Maini RN, Feldmann M: Role of pro-inflammatory cytokines in rheumatoid arthritis. Springer Semin Immunopathol 20:133–147, 1998 9 Bresnihan B, Alvaro-Gracia JM, Cobby M, Doherty M, Domljan Z, Emery P, Nuki G, Pavelka K, Rau R, Rozman B, Watt I, Williams B, Aitchison R, McCabe D, Musikic P: Treatment of rheumatoid arthritis with recombinant human interleukin-1 receptor antagonist. Arthritis Rheum 41:2196–2204, 1998 10 Calabrese LH: Molecular differences in anticytokine therapies. Clin Exp Rheumatol 21:241–248, 2003 11 Campbell IK, Piccoli DS, Roberts MJ, Muirden KD, Hamilton JA: Effects of tumor necrosis factor ␣ and ␤ on resorption of human articular cartilage and production of plasminogen activator by human articular chondrocytes. Arthritis Rheum 33:542–552, 1990 12 Chandrasekhar S, Harvey AK, Hrubey PS, Bendele AM: Arthritis induced by interleukin-1 is dependent on the site and frequency of intraarticular injection. Clin Immunol Immunopathol 55:382–400, 1990 13 Chandrasekhar S, Panetta JA, Bendele AM: Inhibition of IL-1 induced articular inflammation of rats by 4-aminothiazolidines, LY 221068 and LY 269415. Agents Actions 42:67–70, 1994 14 Chu CQ, Field M, Allard S, Abney E, Feldmann M, Mai-


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20

21

22

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25


ni RN: Detection of cytokines at the cartilage/pannus junction in patients with rheumatoid arthritis: implications for the role of cytokines in cartilage destruction and repair. Br J Rheumatol 31:653–661, 1992 Feige U, Hu Y-L, Gasser J, Campagnuolo G, Munyakazi L, Bolon B: Anti-interleukin-1 and anti-tumor necrosis factor-␣ synergistically inhibit adjuvant arthritis in Lewis rats. Cell Mol Life Sci 57:1457–1470, 2000 Harigai M, Hara M, Kitani A, Norioka K, Hirose T, Hirose W, Suzuki K, Kawakami M, Masuda K, Shinmei M, Kawago M, Nakamura H: Interleukin 1 and tumor necrosis factor-␣ synergistically increase the production of interleukin 6 in human synovial fibroblasts. J Clin Lab Immunol 34:107–113, 1991 Henderson B, Pettipher ER: Comparison of the in vivo inflammatory activities after intra-articular injection of natural and recombinant IL-1␣ and IL-1␤ in the rabbit. Biochem Pharmacol 37:4171–4176, 1988 Henderson B, Pettipher ER: Arthritogenic actions of recombinant IL-1 and tumour necrosis factor ␣ in the rabbit: evidence for synergistic interactions between cytokines in vivo. Clin Exp Immunol 75:306–310, 1989 Ikejima T, Okusawa S, Ghezzi P, van der Meer JW, Dinarello CA: Interleukin-1 induces tumor necrosis factor (TNF) in human peripheral blood mononuclear cells in vitro and a circulating TNF-like activity in rabbits. J Infect Dis 162:215–223, 1990 Joosten LA, Helsen MM, Saxne T, van de Loo FA, Heinegard D, van den Berg WB: IL-1␣␤ blockade prevents cartilage and bone destruction in murine type II collageninduced arthritis, whereas TNF-␣ blockade only ameliorates joint inflammation. J Immunol 163:5049–5055, 1999 Joosten LA, Helsen MM, van de Loo FA, van den Berg WB: Anticytokine treatment of established type II collagen-induced arthritis in DBA/1 mice. A comparative study using anti-TNF␣, anti-IL-1␣␤, and IL-1Ra. Arthritis Rheum 39:797–809, 1996 Kaneko M, Tomita T, Nakase T, Ohsawa Y, Seki H, Takeuchi E, Takano H, Shi K, Takahi K, Kominami E, Uchiyama Y, Yoshikawa H, Ochi T: Expression of proteinases and inflammatory cytokines in subchondral bone regions in the destructive joint of rheumatoid arthritis. Rheumatology 40:247–255, 2001 Kuiper S, Joosten LA, Bendele AM, Edwards CK III, Arntz OJ, Helsen MM, van de Loo FA, van den Berg WB: Different roles of tumour necrosis factor ␣ and interleukin 1 in murine streptococcal cell wall arthritis. Cytokine 10:690–702, 1998 Lorenzo JA, Sousa SL, Alander C, Raisz LG, Dinarello CA: Comparison of the bone-resorbing activity in the supernatants from phytohemagglutinin-stimulated human peripheral blood mononuclear cells with that of cytokines through the use of an antiserum to interleukin 1. Endocrinology 121:1164–1170, 1987 Marinova-Mutafchieva L, Williams RO, Mason LJ, Mauri C, Feldmann M, Maini RN: Dynamics of proinflammatory cytokine expression in the joints of mice with collagen-induced arthritis (CIA). Clin Exp Immunol 107: 507–512, 1997


26 Meyer FA, Yaron I, Yaron M: Synergistic, additive, and antagonistic effects of interleukin-1␤, tumor necrosis factor ␣, and ␥-interferon on prostaglandin E, hyaluronic acid, and collagenase production by cultured synovial fibroblasts. Arthritis Rheum 33:1518–1525, 1990 27 Palmblad K, Erlandsson-Harris H, Tracey KJ, Andersson U: Dynamics of early synovial cytokine expression in rodent collagen-induced arthritis: a therapeutic study using a macrophage-deactivating compound. Am J Pathol 158:491–500, 2001 28 Pettipher ER, Henderson B, Moncada S, Higgs GA: Leucocyte infiltration and cartilage proteoglycan loss in immune arthritis in the rabbit. Br J Pharmacol 95:169–176, 1988 29 Pettipher ER, Salter ED: Resident joint tissues, rather than infiltrating neutrophils and monocytes, are the predominant sources of TNF-␣ in zymosan-induced arthritis. Cytokine 8:130–133, 1996 30 Probert L, Plows D, Kontogeorgos G, Kollias G: The type I interleukin-1 receptor acts in series with tumor necrosis factor (TNF) to induce arthritis in TNF-transgenic mice. Eur J Immunol 25:1794–1797, 1995 31 Rathanaswami P, Hachicha M, Wong WL, Schall T, McColl SR: Synergistic effect of interleukin-1␤ and tumor necrosis factor ␣ on interleukin-8 gene expression in synovial fibroblasts. Evidence that interleukin-8 is the major neutrophil-activating chemokine released in response to monokine activation. Arthritis Rheum 36: 1295–1304, 1993 32 R&D Systems. Cytokine Mini-Reviews: Interleukin-1 and Tumor Necrosis Factor Family. Web page: http:// www.rndsystems.com. Accessed November 12, 2003. 33 Richard-Miceli C, Dougados M: Tumour necrosis factor␣ blockers in rheumatoid arthritis—review of the clinical experience. BioDrugs 15:251–259, 2001 34 Schindler R, Ghezzi P, Dinarello CA: IL-1 induces IL-1. IV. IFN-␥ suppresses IL-1 but not lipopolysaccharideinduced transcription of IL-1. J Immunol 144:2216– 2222, 1990 35 Stevens T, Janssen PL, Tucker A: Acute and long-term TNF-␣ administration increases pulmonary vascular reactivity in isolated rat lungs. J Appl Physiol 73:708–712, 1992 36 Suzuki Y, Tanihara M, Ichikawa Y, Osanai A, Nakagawa M, Ide M, Mizushima Y: Periarticular osteopenia in adjuvant induced arthritis: role of interleukin-1 in decreased osteogenic and increased resorptive potential of bone marrow cells. Ann Rheum Dis 54:484–490, 1995 37 Taylor PC: Anti-cytokines and cytokines in the treatment of rheumatoid arthritis. Curr Pharm Des 9:1095–1106, 2003 38 Turner M, Chantry D, Buchan G, Barrett K, Feldmann M: Regulation of expression of human IL-1␣ and IL-1␤ genes. J Immunol 143:3556–3561, 1989 39 Utsunomiya I, Ito M, Watanabe K, Tsurufuji S, Matsushima K, Oh S: Infiltration of neutrophils by intrapleural injection of tumour necrosis factor, interleukin-1, and interleukin-8 in rats, and its modification by actinomycin D. Br J Pharmacol 117:611–614, 1996 40 van de Loo AA, Arntz OJ, Bakker AC, van Lent PL,




Jacobs MJ, van den Berg WB: Role of interleukin 1 in antigen-induced exacerbations of murine arthritis. Am J Pathol 146:239–249, 1995 41 van de Loo AAJ, Arntz OJ, Otterness IG, van den Berg WB: Proteoglycan loss and subsequent replenishment in articular cartilage after a mild arthritic insult by IL-1 in mice: impaired proteoglycan turnover in the recovery phase. Agents Actions 41:200–208, 1994 42 van den Berg WB: Uncoupling of inflammatory and destructive mechanisms in arthritis. Semin Arthritis Rheum 30:7–16, 2001 43 van der Meer MJ, Sweep CG, Rijnkels CE, Pesman GJ,

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Tilders FJ, Kloppenborg PW, Hermus AR: Acute stimulation of the hypothalamic-pituitary-adrenal axis by IL1␤, TNF␣ and IL-6: a dose response study. J Endocrinol Invest 19:175–182, 1996 44 Wooley PH, Dutcher J, Widmer MB, Gillis S: Influence of a recombinant human soluble tumor necrosis factor receptor Fc fusion protein on type II collagen-induced arthritis in mice. J Immunol 151:6602–6607, 1993 45 Wooley PH, Whalen JD, Chapman DL, Berger AE, Richard KA, Aspar DG, Staite ND: The effect of an interleukin-1 receptor antagonist protein on type II collagen-induced arthritis and antigen-induced arthritis in mice. Arthritis Rheum 36:1305–1314, 1993

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