In vivo expression of stromelysin in synovium and cartilage of rabbits injected intraarticularly with interleukin-1 beta

OBJECTIVE

To examine the in vivo expression of the matrix metalloproteinase stromelysin in the synovium and articular cartilage of rabbits injected intraarticularly with recombinant human interleukin-1 beta (IL-1).

METHODS

The direct isolation of messenger RNA (mRNA) from articular cartilage without the prior isolation of chondrocytes is described. The in vivo expression of stromelysin was examined at the mRNA level by Northern blot analysis, and at the protein level by in situ immunolocalization and by enzyme-linked immunosorbent assay.

RESULTS

In the synovium of IL-1-injected joints, stromelysin mRNA levels were highest at 4 hours and declined to background levels within 24 hours. In the cartilage of IL-1-injected joints, stromelysin mRNA was elevated at 4 hours and continued to increase until 8 hours, before declining. Stromelysin mRNA expression preceded a similar increase in stromelysin protein levels in both synovium and cartilage.

CONCLUSION

Intraarticular injection of IL-1 induced the endogenous expression of stromelysin mRNA and protein in both synovium and cartilage. The kinetics of stromelysin expression correlated well with the accumulation of stromelysin and proteoglycan in synovial fluids. Therefore, the de novo synthesis of stromelysin in cartilage may have contributed to the loss of proteoglycan from that tissue.

Production, purification and characterization of canine prostromelysin

One of the best studied animal models of osteoarthritis is a dog model in which the anterior cruciate ligament of the hind limb stifle joint is transected (Pond-Nuki model). To determine whether stromelysin might play a role in this model, it was necessary to purify the enzyme for production of suitable probes. In the present study, dog synovial fibroblasts were stimulated to express a metalloproteinase that was demonstrated to be canine prostromelysin by Northern blot, protein purification and amino-terminal sequence analyses. Unlike rabbit synoviocytes, passaged dog synoviocytes did not express stromelysin mRNA in response to recombinant human IL-1, but expressed stromelysin mRNA only upon treatment with dog monocyte-conditioned medium (dMCM). The aminophenylmercuric acetate (APMA)-activatable metalloproteinase present in the culture supernatants of stimulated dog synoviocytes was purified using a combination of ion-exchange and dye matrix affinity chromatography. The purified canine metalloproteinase co-migrated on reducing SDS-PAGE with recombinant human prostromelysin-1 as a doublet with apparent molecular masses of 54 and 56 kDa. Similar to APMA-activated human prostromelysin-1, the APMA-activated canine metalloproteinase was inhibited by 1,10-phenanthroline or recombinant human tissue inhibitor of metalloproteinase (TIMP). The amino-terminal sequences of the canine pro- and APMA-activated enzymes were compared with those of human, rabbit and rat stromelysin. The striking homologies among the sequences demonstrated that the purified canine metalloproteinase was indeed canine prostromelysin. A rabbit anti-canine prostromelysin polyclonal antiserum was generated and used to localize the enzyme within cultured dog synoviocytes and articular cartilage stimulated with dMCM. The reagents developed in this study should be useful for examining the expression and distribution of prostromelysin in canine models of osteoarthritis.

[Modifications of the water balance and urinary excretion of sodium and potassium in obese subjects on a "single-meal" low-calorie diet]

Four obese patients were given a single-meal diet (684 kcal.) for two periods of three days each. Water-loss, according to Peter-Passmore formula, and urinary sodium and potassium excretion were measured at 4-hours intervals. A water-loss greater in the first than in the second and in the third day in both periods and a strong linear correlation between water-loss and sodium urinary excretion were found. Furthermore a circadian rhythm either is sodium or in potassium urinary excretion not modifiable by meal timing with both regiment was detected.

Self-assembling sequentially administered tumor targeted Split IL-12p35 and p40 subunits to improve the therapeutic index of systemically delivered IL-12 therapy for cancer

IL-12, also called IL-12p70, is a highly potent, proinflammatory heterodimeric cytokine that can mediate many beneficial anti-tumor effects. In preclinical studies, recombinant IL-12, as well as IL-12 gene therapies, have demonstrated notable anti-tumor results across various tumor types; however, IL-12 clinical benefit has been limited by its poor tolerability at potentially efficacious doses. We have developed a novel approach to mitigate the toxicity of IL-12 by engineering tumor-targeted split IL-12 that preferentially localizes IL-12 activity to the tumor microenvironment. The functionally inactive IL-12 subunits, p35 and p40, are separately fused to antibody fragments targeting a highly expressed tumor-associated antigen, uPAR. The goal of this strategy is to drive assembly and activity of the IL-12 heterodimer into the tumor site through sequential administration of the targeted subunits, reducing systemic exposure and thereby potentially reducing associated toxicities. We use in vitro activity assays along with in vivo pharmacokinetic and pharmacodynamic studies in mice and non-human primates to demonstrate that the split IL-12 anti-uPAR fusions are capable of assembly and activity in vivo. The targeted p35 and p40 subunits are capable of complexing to form IL-12p70 and inducing STAT4 phosphorylation when applied to cultured immune cells, indicating in vitro IL-12 activity. Furthermore, sequential administration of subunits in in vivo mouse models demonstrates rapid serum clearance of IL-12 while extending retention in the tumor. Finally, dosing in non-human primates shows molecules are functionally active in vivo. This is a unique strategy with great clinical promise to harness the therapeutic potential of IL-12 while potentially avoiding the toxicity associated with systemic delivery.

Induction of increased levels of proteoglycan fragments in synovial fluid (SF) and increased levels of stromelysin in cartilage, synovium and SF by intraarticular injection of canine monocyte conditioned medium into dogs

OBJECTIVE

To study the effects of the intraarticular injection of canine monocyte conditioned medium (cMCM) into dogs on proteoglycan fragment and stromelysin levels in the joint.

METHODS

cMCM was injected intraarticularly into dogs, and the levels of proteoglycan fragments in synovial fluid (SF) as well as stromelysin levels in cartilage, synovium, and SF were assessed after 12 h.

RESULTS

There was a 4-fold increase of proteoglycan fragment levels and a 6-fold increase in stromelysin levels in SF, and a 4.4-fold increase in stromelysin levels in cartilage extracts. Elevated mRNA levels were detected in both synovium and cartilage. By immunofluorescence staining, stromelysin was localized in chondrocytes throughout the cartilage and in synovial cells.

CONCLUSION

Intraarticular injection of cMCM stimulated the expression of stromelysin mRNA and protein in cartilage and synovium and caused marked increases in stromelysin protein and proteoglycan fragment levels in SF.

[Effects of a "single-meal" low calorie diet on the circadian variation of serum cortisol, insulin and somatotropin and urinary excretion of catecholamines]

Four obese patients were given a single-meal diet for two periods of three days each. Blood samples were drawn every four hours for serum determinations of growthormone, cortisol and insulin. At same times urinary samples for urinary cathecholamines determination were collected. Cortisolemia showed a firm circadian rhythm in both regimens: there was a marked over-lap of the two confidences ellipsis so we could conclude for the independence of cortisol rhythm whith both regimes, but there occurred a significant difference in the acrofases between the two regimens. This could mean that meal-timing can play a major role in syncronizing catecholamines urinary excretion as far as subjects in supine position are concerned. No circadian rhythm was detected either in serum insulin or in HGH values.

[Variations in carbohydrate, lipid and protein oxidation evaluated by indirect calorimetry in obese subjects on a "single-meal" low-calorie diet]

Four obese patients were given a single-meal diet (Kcal, 684) for two periods of three days each. CO2 production and 02 consumption were measured every four hours for 30'. At the same times urine samples were collected for nitrogen evaluations. By Consolatio's formulas the amount of carbohydrates, lipids and proteins oxidated in the three days of both periods was calculated. No changes in carbohydrate and lipid oxidation rates were found during the three days with meal at h.10, while a progressive increase in lipid oxidation and a progressive decrease in carbohydrates oxidation could be observed with meal at h. 18. No change with both regimes could be observed in protein oxidation. Furthermore a circadian rhythm of lipid and carbohydrate oxidation with both regimens was observed, while protein oxidation showed a circadian rhythm only with meal at h.10.