[Induction of histidine decarboxylase in inflammation and immune responses]

Histamine index and clinical expression of rheumatoid arthritis activity

BACKGROUND/AIM

Many arguments prove the pathophysiologic role of histamine in the process of remodeling and joint destruction in rheumatoid arthritis. The aim of our study was to find out if there was a relation between histamine concentration in synovial fluid and blood with clinical expression of disease activity.

METHODS

Histamine concentration in synovial fluid and blood was determinated in 19 patients with rheumatoid arthritis. Histamine concentration measurement was based on the Shore's fluorometric method. Histamine index (HI) was evaluated as a ratio between histamine concentration in synovial fluid and blood. Disease activity score, DAS 28 (3), with three variables (erythrocyte sedimentation rate, the number of swelled joints and the number of tender joints) was also evaluated.

RESULTS

Our results showed that there was no significant difference in concentration of histamine in synovial fluid and blood related to disease activity. However, there was a significiant difference in the histamine index which was increased proportionally with disease activity.

CONCLUSION

Our study indicates that histamine index could be useful in estimation of rheumatoid arthritis activity.

Anti-inflammatory evaluation of Coronopus didymus in the pleurisy and paw oedema models in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Mastrunço (Coronopus didymus--CD) is currently considered as a medicinal specie often used in Brazil, especially in southeast region, for the treatment of several diseases in which pain and inflammation are common. Treatment with the plant can be done by infusion, decoction, or through food. The aim of this study was: to investigate the anti-inflammatory effect of hydroalcoholic extract obtained from the leaves of CD following the traditional procedure.

MATERIALS AND METHODS

The anti-inflammatory activity was determined using mouse of pleurisy and paw oedema models, both process being induced by different flogistic agents such as: carrageenan (Cg), bradykinin (BK), histamine (HIS), substance P (SP), dextran (DEX) or prostaglandin E(2) (PGE(2)). We evaluated the effect of CD (200-600 mg/kg) administered by oral route (p.o.) upon leukocytes migration, myeloperoxidase (MPO), and adenosine-deaminase (ADA) activities and nitric oxide (NO) levels.

RESULTS

CD (200-600 mg/kg) inhibited the leukocytes by 60.0+/-1.42%, neutrophils by 82.75+/-1.29%, MPO by 42.30+/-4.23%, and ADA activities by 57.89+/-1.94%, as well as NO levels by 64.28+/-2.15% in Cg induced pleurisy. CD also inhibited total and differential leukocytes in the pleurisy induced by BK (1.30+/-0.11/0.29+/-0.02), HIS (1.20+/-0.09/0.42+/-0.05) and SP (0.74+/-0.06/0.14+/-0.01). In addition, CD was effective in reducing paw oedema induced by Cg by 72.79+/-1.13%, SP by 68.26.+/-0.78%, BK by 66.66.+/-0.77%, PGE(2) by 53.346.+/-1.18 and DEX by 65.14+/-2.35%.

CONCLUSION

Several mechanisms, including the inhibition of enzymes (MPO and ADA) and mediators (BK, HIS, SP, NO and PGE(2)) release and/or action, appear to account for the anti-inflammatory effect of Coronopus didymus.

Anti-inflammatory evaluation of Solidago chilensis Meyen in a murine model of pleurisy

The aim of this study was to investigate the anti-inflammatory effects and the mechanism of action of the aqueous extracts obtained from rhizomes, leaves and inflorescences of Solidago chilensis in the mouse model of pleurisy. The extracts were prepared by infusion and were lyophilized.

RESULTS

The aqueous extracts of rhizomes, leaves or inflorescences inhibited leukocytes, neutrophils and exudation (P<0.05) in the inflammation induced by carrageenan. The rhizomes aqueous extract, butanolic and aqueous residual fractions inhibited leukocytes, neutrophils, myeloperoxidase, adenosine-deaminase, and tumor necrosis factor alpha levels in the inflammation induced by carrageenan (P<0.05). The rhizome aqueous extract and butanolic fraction also inhibited exudation, nitric oxide, and interleukin-1 beta levels (P<0.05). The rhizomes aqueous extract and its two derived fractions reduced leukocytes and mononuclears in the pleurisy induced by bradykinin, histamine, or substance P (P<0.05) and neutrophils in the pleurisy induced by histamine or substance P (P<0.05). Only aqueous residual fraction inhibited neutrophils induced by bradykinin (P<0.05).

CONCLUSION

Solidago chilensis aqueous extracts from leaves, inflorescences and rhizomes demonstrated an important anti-inflammatory effect, inhibiting cells in the inflammation caused by carrageenan. In addition, the rhizomes aqueous extract and its derived fractions also decreased pro-inflammatory mediators release into the site of the inflammatory process. The rhizomes aqueous extract and the butanolic fraction showed more evident anti-inflammatory actions.

L-histidine decarboxylase as a probe in studies on histamine

Because the Falck-Hillarp formaldehyde fluorescence method, which was superbly applied to identify catecholaminergic and serotonergic neurons, is not applicable to histamine, the first author (T.W.) developed an antibody to L-histidine decarboxylase (HDC) for identification of the histaminergic neuron system in the brain. The anti-HDC antibody was of great use for mapping the location and distribution of this histaminergic neuron system. (S)-alpha-fluoromethylhistidine, a specific and potent irreversible inhibitor of HDC, was also very useful in studies on functions of the neuron system. The activity of HDC is increased by various agents, treatments, and physiological conditions. We found new compounds that increased HDC activity (i.e., tetradecanoylphobol acetate (TPA), other tumor promoters, and staphylococcal enterotoxin A); and using mast cell-deficient mutant (W/W(v)) mice, we obtained evidence that this increase occurred in macrophages. To further characterize the mechanism of increases in HDC activity, the second author (H.O.) cloned human HDC cDNA and a human HDC gene. In studies on the regulation mechanism of the HDC gene, which is expressed only in limited types of cells such as mast cells, enterochromaffin-like cells in the stomach, cells in the tuberomammillary nucleus of the brain, and macrophages, CpG islands in the promoter region of the HDC gene were found to be demethylated in cells expressing the gene, whereas they are methylated in other cells that do not express the HDC gene. In collaboration with many other researchers, we developed HDC knockout mice. The resulting research is producing a lot of interesting findings in our laboratory as well as in others. In summary, HDC has been and will be useful in studies on functions of histamine.

Quantitative Determination of Histamine in Tears during Conjunctivitis by a Novel HPLC Method

The histamine content of tears of healthy sex- and age-matched subjects and patients affected by allergic or nonallergic inflammatory ocular diseases was determined through a new competitive reverse-phase high-performance liquid chromatography (HPLC) method. Tear samples from 50 healthy subjects, 30 patients affected by seasonal allergic conjunctivitis, 12 patients with bacterial conjunctivitis associated with Haemophilus influenzae and 8 patients with bacterial conjunctivitis associated with Streptococcus pneumoniae were analyzed for histamine concentration by O-phthaldialdehyde precolumn derivatization-based HPLC. In physiological conditions, the tear histamine content was low (2.26 ng/ml) and did not vary in relation to age and sex. Histamine levels were significantly higher in all the patients studied, to a greater extent in those affected by allergic (23.61 ng/ml) or Haemophilus influenzae-associated (21.53 ng/ml) conjunctivitis.