Leukotriene involvement in pathologic processes

Leukotriene involvement pathologic processes A. W. Ford-Hutchinson,

in

Ph.D. Pointe Claire-Dorval,

Quebec, Canada

Leukotrienes (LTs) have potent biologic properties, suggesting a role in human disease. LTBl release has been detected in inflammatory exudates in the rat. LTCl release has been detected ajier antigen challenge of lung tissue in vitro and in tear fluid in man in vivo. There is some evidence to suggest that LTB4 is a mediator of ulcerative colitis in man and considerable evidence to suggest that LTB4, LTC4, and L,TDl may be involved in the pathogenesis of psoriasis. (J ALLERGYCLIN IMMUNOL 74:437, 1984.)

LTs are products of arachidonic acid oxygenation formed through the Uipoxygenase enzymepathway.’ They have important biologic properties and, largely on the basis of circumstantial evidence, they have been proposed as mediators of various pathologic processes.LTB, is a dibydroxy-eicosatetraenoic acid with a precise stereochemical configuration. It is a potent chemotactic and chemokinetic agent for leukocytesZe4and in vivo it produces leukocyte accumulation,“. 3 modulates pain responses,’ and induces changesin vascular permeability through a leukocytedependentmechanism.7, * LTB, is thus consideredto be a potentially important mediator of inflammatory processes.3LTC4, LTD,, and LTEl are peptidolipid conjugates that collectively account for the biologic activity known as slowreacting substanceof anaphylaxis.’ They are potent smooth muscle contracting agents, particularly in regard to pulmonary smooth muscle, and hence are thought to be important mediators of asthma and other hypersensitivity reactions. Two major difficulties have limited evaluation of the role of LTs in pathologic processes:the lack of any specific antagonistsof actions or inhibitors of LT synthesis that can be used in vivo, and the lack of sensitive assaysfor determining LT levels in biologic fluids. The latter problem has been resolved with the development of specific, sensitive radioimmunoassays for C6 peptidolipid LTs and LTB4.g, lo Together with the development of sensitive bioassays, some preliminary studies have now been published indicating that LTs may be generatedin vivo. The evidence

Reprint requests: A. W. Ford-Hutchinson, Ph.D., Merck Frosst Canada Inc., P.O. Box 1005, Pointe Claire-Dorval, Quebec, H9R 4P8, Canada.

for LT involvement in various pathologic conditions is summarizedbelow. LT production

within

inflammatory

exudates

Inflammatory exudatesmay be readily produced in the rat by the implantation of polyester sponges.” With this technique, LTBl has been detected in sponges soaked in either saline solution or carrageenan.I2 In this model, LT production correlates with the influx of PMN leukocytes; this cell appearsto be the source of the LT.12 These results have been confirmed and a close correlation between LTB, levels and leukocyte migration after the application of various different irritants to the sponge has been observed.l3 However, application of LTB, to the sponge produced no significant leukocyte accumulation, despite the fact that LTBl levels could still be determined in the exudate 5 hours later. These results suggest that LTBl levels within the exudatedo not greatly influence subsequent leukocyte migration. In these studies, LTCl immunoreactivity was also determined within the sponges. Low levels were measured, but after analysis by HPLC, observed immunoreactivity did not correlate with retention times of known LTs. LTB4 has been reported to be present in synovial fluid from patients with rheumatoid arthritis and spondylarthritis .I4 Subsequentstudieshave confirmed the presence of low levels of LTB, in rheumatoid arthritis,15 with evidence of increased levels in patients with gouty artbriti~.‘~ 437

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bT release after atlergen

challenge

When ltmg slicers obtained from actively sensitized

guinea pigs or rats are challenged with antigen in i:itro. the release of both LTC.$ and LTB, can be de:ccted by radioimmunoassay.* Release is related to t,hc dose of antigen, and 10 times more LTs are proc.iuced in rats with nonspecific bronchial hyperrc;tctivitq as compared to that produced in normal ;w,. Studies on human bronchi from patients with bnrch pollen--sensitive asthma have implicated LTC,. i.TD.,, and L,TEA as important mediators of bronchial ::ontraction after challenge with specific allergen.” In ;Iddition, purified human lung mast cells have been ;hown to release LTs after allergen challenge.“’ LT ~.adioimmunoassays are sufficiently sensitive to meaore LTs directly in fluids such as plasma.” However. preliminary studies in which LTC’, levels were derermined in plasma from either patients with asthma after antigen challenge+ or rat plasma after antigen challenge; have failed to show increases in Level< of I.TC,. These studies suggest that if LTCl is released into circulation during antigen provocation in viva ~ rhen mechanisms exist for the rapid removal and/or metabolism of LTs. ffowever, SRS-A LTs may be detectable in fluids other than plasma, such as in bronchial lavages from neonates with hypoxia and pulmonary hypertension’!’ and in sputum samples from patients with cystic fibrosis.‘!” In this context. l.TC,-like immunoreactivity has been detected in tear fluid from subjects with amnestic grass pollen rhino.con.junctivitis after application of specific allergen to the eye .zi LTs and psoriasis There is considerable evidence to suggest that LTs and other lipoxygenase products may have a role in skin diseases such as psoriasis The evidence is 3s follows. 1, I .TB, causeh neutrophil accumulation when injected into human skit? or when applied in skin chambers over abrasions on the human forearm.’ -.’ Topical application of LTB, to normal human skin results in the production of intraepidermal misroabscesses histologically similar to lesions observed it1 pustlllar

psoriasis:‘:

.J. NeuXrophil accumulation is an important aspect of the pathology of this skin disease and has been reported to be one of the earliest pathologic events

occurring before the development of a prepapillary lesion.“’ 4. When stimulated with the calcium ionophore A23 Ii87, human keratinocytes can produce LTB,*.“;’ 5. LTB, can be recovered from psoriatic lesions in man.“’ Recent studies with LT radioimmunoassays have demonstrated the presence of both LTB4 and I.TC’, immunoreactivity in fluids obtained from skin chambers applied to lesional skin in patients with psoriasis.:‘: 6. Abnormalities in arachidonic acid metabolism in psoriasis have been demonstrated. In particular. these include elevated levels of arachidonic acid as well as the lipoxygenase product 12-hydroxy-eicosatetraenoic acid.‘“: This circumstantial evidence summarized above suggests that LTB., may be an important mediator of neutrophil accumulation in psoriasis and that LTC,% contributes to pathology by increasing blood flow. Peptidolipid LTs have been reported to be very potent vasodilators in human skin.“’ It will obviously be of considerable interest to study the effects of ti-lipoxygenase enzyme inhibitors in this human disease. Ulcerative

oh

colitis

ln common with psoriasis, neutrophil accumulation 1san important histologic feature of ulcerative colitis. Analysis of mucosal samples from patients with ulcerative colitis has shown elevated levels of LTBI as well as an elevated capacity to synthesize both 5hydroxy-eicosatetraenoic acid and LTB,.:‘O Together with an analysis of the effects of therapeutic agents in rhis disease, it has been suggested that lipoxygenase products, in particular LTB,. may be important mediators of this human disease. Conclusions LTs have irnportant biologic properties that suggest they may be mediators of various pathologic processes. Some evidence for LT release in various diseases has now been obtained. Final definitive proof for the involvement of LTs in various pathologic processes will depend on the development of specific inhibitors of the production of LT3 or of antagonists of their action and the correlation of therapeutic utility of such drugs with effects on production of LTs in vivo. REFERENCES I

’ hlrunet G, Ford-Hutchinson A%. Cbarleson S. Unpublished servationb Hayes I: Ilnpublished obscrvation~. Zlnrnci K. F~trd. Hutr:hinson A& t+q)ubli?hrd obsefiations

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c’

Samuelwn B Leukotriene\: Mediators pericrr\lti~. it! reaction\ .md inflammation. ii)83 Ford-Hutchmson AW, Bray M.4, Doig

of immediate hyScience 2X):568, MV,

Shipley

Smith MJH: Leukotriene B: A potent chemokinetic gregating substance released from polymorphonuclear iyytt:a Karurc 2X6:264. ?9Xn

ME,

and agleuko-

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3. Smith MJH, Ford-Hutchinson AW, Bray MA: Leukotriene B: A potential mediator of inflammation. J Pharm Pharmacol 32:517. 1980 4. Goetzl EJ, Pickett WC: The human PMN leukocyte chemotactic activity of complex hydroxy-eicosatetraenoic acids (HETEs). J Immunol 125:1789, 1980 5. Bray MA, Cunningham FM, Ford-Hutchinson AW, Smith MJH: Leukotriene B,: An inflammatory mediator in viva. Br J Pharmacol 22:483, 1981 6. Rackham A, Ford-Hutchinson AW: Inflammation and pain sensitivity: effects of leukotrienes D4, B, and prostaglandin E, in the rat paw. Prostaglandins 25: 193, 1983 7. Bray MA, Cunningham FM, Ford-Hutchinson AW, Smith MJH: Leukotriene B,: A mediator of vascular permeability Br J Pharmacol 72:483, 1981 8. Wedmore CV, Williams TJ: The control of vascular permeability by polymorphonuclear leukocytes in inflammation. Nature 284:646, 1980 9. Hayes EC, Lombard0 DL, Girard Y, Maycock AL, Rokach J, Rosenthal AS, Young RN, Egan RW, Zweerink HJ: Measuring leukotrienes of slow-reacting substance of anaphylaxis: development of a specific radioimmunoassay. J Immunol 131:429, 1983 10. Young RN, Zamboni R, Rokach J: Studies on the conjugation of leukotriene B, with proteins for development of a radioimmunoassay for leukotriene B,. Prostaglandins 26605, 1983 11. Ford-Hutchinson AW, Walker JR, Smith MJH: Assessment of antiinflammatory activity by sponge implantation techniques. J Pharmacol Methods 1:3, 1978 12. Simmons PA, Salmon JA, Moncada S: The release of leukotriene B, during experimental inflammation. Biochem Pharmacol 32:1353, 1983 13. Ford-Hutchinson AW, Brunet G, Savard P, Charleson S: Leukotriene B,, polymorphonuclear leukocytes and inflammatory exudates in the rat. Prostaglandins (in press) 14. Klickstein LB, Shapleigh C, Goetzl EJ: Lipoxygenation of arachidonic acid as a source of polymorphonuclear leukocyte chemotactic factors in synovial fluid and tissue in rheumatoid arthritis and spondyloarthritis. J Clin Invest 66: 1166, 1980 15. Davidson EM, Rae SA, Smith MJH: Leukotriene B, in synovial fluid. J Pharm Pharmacol 34225, 1982 16. Rae SA, Davidson EM, Smith MJH: Leukotriene B,: an inflammatory mediator in gout. Lancet 2: 1122, 1982 17. DahlCn S, Hansson G, Hedqvist P, Bjarck T, Granstriim E, Dahltn B: Allergen challenge of lung tissues from asthmatics elicits bronchial contraction that correlates with the release of leukotrienes C4, D4 and E,. Proc Nat1 Acad Sci USA 80: 17 12, 1983 18. MacGlashan DW, Schleimer RP, Peters SP, Schulman ES, Adams GK, Newball HH, Lichtenstein LM: Generation of leukotrienes by purified human lung mast cells. J Clin Invest 70:747, 1982 19. Stenmark KR, James SL, Vodkel NF, Toews WH, Reeves JT, Murphy RC: Leukotriene C, and D4 in neonates with hypoxemia and pulmonary hypertension. N Engl J Med 309:77, 1983 20. Cromwell 0, Walport MJ, Morris H, Taylor GW, Hodson ME, Batten J, Kay AB: Identification of leukotrienes D and B in sputum from cystic fibrosis patients. Lancet 2: 164, 198 1 21. Bisgaard H, Ford-Hutchinson AW, Charleson S, Taudorf E: Detection of leukotriene &like immunoreactivity in tear fluid from subjects challenged with specific allergen. Prostaglandins 27369-74, 1984 22. Camp RDR, Coutts AA, Greaves MW, Kay AB, Walport MJ: Responses of human skin to intradermal injection of leukotrienes Cd, D, and B,. Br J Pharmacol 75: 168, 1982

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23. Camp R, Jones RR, Brain S, Wollard P, Greaves M: Production of intraepidermal micro-abscesses by topical application of leukotriene B,-a potential experimental model of psoriasis. J Invest Dermatol (in press) 24. Choweniec 0, Jablonska S: Pre-pinpoint papule cnanges preceding pinpoint lesions in psoriasis. Acta Derma Venerol 59:39, 1979 25. Brain SD, Camp RDR, Leigh IM, Ford-Hutchinson AW: Synthesis of leukotriene B,-like material by cultured human keratinocytes. J Invest Dermatol 78:328, 1982 26. Brain SD, Camp RDR, Dowd RM, Kobza-Black A, Wollard PM, Mallet AI, Greaves MW: Psoriasis and leukotriene B,. Lancet 2:762, 1982 2?. Brain SD, Camp RDR, Kobza-Black A, Ford-Hutchinson AW, Charleson S, Greaves MW: The release of leukotrienes C, and D, in psoriatic lesions (submitted for publication) 28. Hammarstriim S, Hamberg M, Samuelsson B, Duel1 EA, Stamski M, Voorhees JJ: Increased concentrations of nonesterified arachidonic acid, 12L-hydroxy-5,8,10,16eicosatetraenoic acid, prostaglandin E,, and prostaglandin F,a in epidemis of psoriasis. Proc Nat1 Acad Sci USA 72::~130, 1975 29. Bisgaard H, Kristensen J, Sondergaard J: The effect of leukotriene Cq and D, on cutaneous blood flow in humans. Prostaglandins 23:797, 1982 30. Sharon P, Stenson WF: Production of leukotrienes by colonic mucosa from patients with inflammatory bowel disease. Gastroenterology 84: 1306, 1983

DISCUSSION Marc Goldyne: Did the LTC, immunoreactivity in allergen-challenged tear fluid migrate with standard LTC, on HPLC analysis? Could you comment on yout concepts regarding the PMN leukocyte as a potential source of LTs in the epidermis in psoriasis? Anthony Ford-Hutchinson: The quantities of tear fluid obtained are so small that, unfortunately, it has not been possible to confirm the identity of the LTs by HPLC. The important finding for the skin is that keratinocytes can produce LTs. Priscilla Piper: Did you implant sponges under the skin of hyperreactive rats? If so, did they show any differences from normal rats? A. Ford-Hutchinson: It would appear that there is a reduced LTB4 content in sponges implanted in hyperreactive rats, in contrast to the enhanced production in the lung. I cannot explain this finding. P. Piper: Has anyone put LTs into the nose and measured nasal secretion? A. Ford-Hutchinson: No. Michael Bach: If one calculated

total sulfidopeptide LT production in rats, taking into consideration the amount of LTEI made and the low sensitivity of the radioimmunoassay to LTE,, how would the numbers compare to LTB., production and to sulfidopeptide production in guinea pigs‘? A. Ford-Hutchinson: If one recalculates the results to allow for conversion to LTEI, then rats produce a!, much or more LTs than the guinea pig and sulfidopeptide LT production exceeds that of LTBI. Sven HammarstrGm: Which LTs were present in nasal washings? A. Ford-Hutchinson: LTC( and possibly LTDl as well.

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Robert Lewis: DO pulmonary parenchymal strips from your hyperreactive rats respond to- sulfidopeptide LTs better than those from normal rats’? If so. do their responses to LT5, model-monophasic or biphasic curves‘? A. Ford-Hut&ii: The parenchymal strips, but not the tracheal rings. from hyperreactive rats respond to LTs. In contrast, tissue from Fischer rats fails to respond to LTs. In vivo LT aerosols decrease dynamie compliance in hyperreactive bur not in Fischer rats. We do not see the biphasic response that one Sees in rats or guinea pigs. Witlim Seaman: With regard to keratinocyte preparations. is there evidence concerning which cell peppdations

CLIN IMMUNOL. SEPTEMBER 1984

can make LTs? Could this be accounted for entirely by Langerhans cells and contaminating white blood cells’? A. Ford-Hutchinson: These other cells certainly are minor contaminants of the keratinocyte preparations. Cultured keratinocytes will help to answer this question. Eva Cramer: Is the amount of LTB4 formed by keratinocytes comparable to the amount formed by PMN leukocytes? A. Ford-Hutchinson: Probably. Dr. Czametski’s data with freshly suspended keratinocytes support this conclusion