The Concentration of Tumor Necrosis Factor Alpha in Periapical Lesions

Jelena Popović1, Tatjana Cvetković2, Tanja Džopalić3, Aleksandar Mitić1, Marija Nikolić1, Radomir Barac1, Slavoljub Živković4 Department for Restorative Dentistry and Endodontics, Department of Dentistry, Faculty of Medicine, University of Niš, Niš, Serbia; Institute of Biochemistry, Faculty of Medicine, University of Niš, Niš, Serbia; Institute of Immunology, Faculty of Medicine, University of Niš, Niš, Serbia; Department of Restorative Odontology and Endodontics, School of Dental Medicine, University of Belgrade, Belgrade, Serbia


INTRODUCTION
Periapical lesions represent inflammatory and immune diseases affecting periapical tissue and surrounding bone.These periapical processes are primarily caused by bacterial infection of the root canal.Their existence, progression to chronic lesions and destruction of bony structures are the result of host defense inability to eliminate infection [1,2].
Cytokine network plays an important role in specific and non-specific immune responses.A number of studies have investigated cytokine production in periapical lesions at the level of gene expression, in tissue homogenate or cell cultures and have found that in some cases the balance between pro-inflammatory and immunoregulatory cytokines is disrupted [3,4].
Tumor necrosis factor α (TNF-α) plays an important role in the initiation and coordination of cellular events in the response of immune system to infection.It is a soluble mediator released by immune cells in the process of inflammation.It is produced mainly by macrophages, as well as lymphoid cells, mastocysts, endothelial cells, myocytes, adipocytes, fibroblasts and neural tissue.Large amounts of TNF-α are released under the influ-ence of lipopolysaccharide and other bacterial products and interleukin-1 (IL-1) [5,6].TNF is the only molecule, beside IL-1 that can activate osteoclasts.It induces calcium release from bone in vitro and may play a role in various stages of inflammatory diseases including bone resorption.The presence of TNF-α has been shown in human periapical lesions and exudates from root canals with apical periodontitis [6,7,8].
The aim of this study was to determine the concentration of TNF-α in the tissue homogenates of periapical lesions and analyze its levels in relation to the symptomatology and the size of lesions.

MATERIAL AND METHODS
The study involved 93 patients from the Dental Clinic, Faculty of Medicine, Nis, who had diagnosed chronic periapical lesions using clinical and radiographic methods.Periapical lesions were collected from teeth that were determined as non treatable and extracted.Other inclusion criteria were healthy patients not suffering from acute or chronic diseases that could lead to immunodeficiency, who were not taking antibiotics and anti-inflammatory medications previous two months.Only teeth with periapical lesions which did not show moderate or severe form of marginal periodontitis were included in the study.
According to subjective symptoms lesions were divided into two groups-symptomatic and asymptomatic.Clinically symptomatic lesions were characterized by swelling, pain, discomfort when chewing or sensitivity to percussion and palpation whereas asymptomatic lesions showed no symptoms.The size of periapical lesions was measured in millimeters using a ruler and divided into two groups: small (≤5 mm) and large (≥6 mm) (Table 1).Since periapical lesions contain granulomatous inflammatory tissue that replaces normal bone there was no equivalent tissue that could be used as negative control.
Before administering local anesthetics, teeth, gingiva and mucosa around the tooth were cleaned using 0.12% chlorhexidine and a patient rinsed mouth with 0.12% chlorhexidine for 30 seconds.Samples of periapical lesions removed from the root apex were collected immediately after the extraction using sterile scalpel, then washed in sterile saline, dried using sterile cotton, placed in a sterile plastic Eppendorf tubes and frozen at -70°C.Using teflon crusher in an iced phosphate buffer at pH 7.4 samples were homogenized with volume adapted to weight of the tissue obtaining the final concentration of 10%.Larger debris was sedimented by centrifugation at 1400 rpm for 1 minute at -40°C.The supernatant was frozen at -70°C until further analysis was performed.
The concentration of TNF-α was measured using ELISA test (R&D Systems Inc.Minneapolis, USA) according to the manufacturer's instructions.The sensitivity of ELISA test for TNF-α was from 0.5 to 5.5 pg/ml and the concentration of cytokines was analyzed in relation to the size and symptomatology of periapical lesions.
Statistical analysis was performed using the Mann-Whitney Rank Sum test using software Sigmastat and Origin.The results were expressed as mean ± standard deviation.P<0.05 was considered as statistically significant.

RESULTS
TNF-α was present in all analysed periapical lesions in significant concentrations.Graph 1 shows the concentrations of TNF-α in all samples, and the average values were analyzed with respect to the size and symptomatology.In the group of symptomatic lesions the average concentra-tion was 15.08 pg/ml while in the group of asymptomatic lesions the average value was 8.24 pg/ml.There was a statistically significant difference in the concentration of TNF-α between symptomatic and asymptomatic lesions (p<0.001).In the group of large lesions the average TNF-α concentration was 13.24 pg/ml whereas in the group of small lesions the average value was 9.61 pg/ml.There was a statistically significant difference between TNF-α concentrations in large and small lesions (p<0.01).
Graph 2 shows the mean values of TNF-α within the groups of symptomatic and asymptomatic lesions.In the group of symptomatic lesions, the average concentration of TNF-α was analyzed in large and small lesions.The average concentration of TNF-α in symptomatic large lesions was 17.67 pg/ml, while in small symptomatic lesions it was 12.07 pg/ml.The analysis of the average values showed significantly higher concentrations of TNF-α in symptomatic large lesions (p<0.05).Also, in the group of asymptomatic lesions there was statistically significant Graph 2. TNF-α concentration of sympthomatic and asympthomatic periapical lesions Grafikon 2. Koncentracija TNF-α u okviru grupa simptomatskih i asimptomatskih lezija difference in the concentrations of TNF-α in relation to the size of lesions.The average concentration of TNF-α in asymptomatic large lesions was 8.96 pg/ml, while it was 7.58 pg/ml in asymptomatic small lesions (p<0.01).
Graph 3 shows the concentration of TNF-α within the groups of large and small lesions where statistical significance was analyzed in relation to the symptomatology.The analysis showed statistically significant difference in the concentration of TNF-α in large symptomatic lesions (17.67 pg/ml) compared to large asymptomatic lesions (8.96 pg/ml) (p<0.001).Statistically significant difference was noticed in small lesions where the concentration of TNF-α in small symptomatic lesions was 12.07 pg/ml, while it was 7.58 pg/ml in small asymptomatic lesions (p<0.001).

DISCUSSION
Host response to antigen stimulation in chronic inflammatory processes is mainly controlled by the balance between proinflammatory and anti-inflammatory cytokines.While proinflammatory cytokines, such as IL-1, IL-6, TNF-α, TNF-β, chemokines and Th1 cytokines promote inflammation in the periapical tissue and activate osteoclastic bone resorption [1,2], the role of anti-inflammatory cytokines is important for the suppression of inflammatory processes and beginning of healing process [3,9,10].This specific role of cytokines was studied in the research of Gazivoda et al. [4] which showed that inflammatory cells from periapical lesions produced significant levels of pro-inflammatory (IL-1β, IL-6, IL-8 and TNF-α) and immunoregulatory (IL-10 and TGF-β) cytokines in vitro.The authors investigated whether the production of cytokines was associated with clinical symptoms and the composition of infiltrating cells.In accordance with previous results [10,11] they found that symptomatic lesions contained higher portion of neutrophils.The recruitment of granulocytes in these lesions was probably caused by re-infection of the root canal space and further reactivation of chronic periapical process [1,2].Granulocytes present together with activated and infiltrating macro-phages produce a number of soluble mediators, including proinflammatory cytokines [12].
IL-1, predominantly produced by mononuclear phagocytes, polymorphonuclear leukocytes and connective tissue cells in periapical lesions, has been considered as primary stimulator of periapical bone destruction [9,13,14,15].Production of IL-1 in periapical lesions is regulated by cytokines originating from Th1 cells, such as interferon gamma (IFN-γ).IFN-γ as a potent activator of macrophages, stimulates the expression of IL-1 and TNF-α by these cells.TNF-α induces the production of IL-1 whereas IL-1 alone stimulates its own synthesis by positive feedback mechanism [2].
The current study analyzed the concentration of proinflammatory cytokine TNF-α in the tissue homogenates of chronic periapical lesions in relation to the symptoms and the size of the lesions.Results demonstrated that the level of TNF-α was significantly higher in symptomatic lesions compared to asymptomatic and in large lesions compared to small.Therefore, TNF-α can be considered responsible for mediation of development and progression of periapical lesions.The research of Gazivoda et al. [4] showed no significant difference in the level of TNF-α between symptomatic and asymptomatic lesions.According to their study, increased secretion of TNF-α in large lesions may be associated with a different composition of infiltrating cells.Danin et al. [3] suggested that activated macrophages may be the main source of TNF-α.In contrast, Ma et al. [16] reported decreased numbers of macrophages in large lesions.The reason for this finding is not clear, however, the study of Artese et al. [7] showed that although 41% of mononuclear cells in periapical lesions are macrophages, only 2-3% of them produced IL-1β and TNF-α.Danin et al. [3] found significant levels of TNF-α in only two patients with periapical lesions out of 25 while Safavi and Rossomando [6] and Pezelj-Ribarić et al. [17] found TNF-α in all samples of periapical exudates.Brekalo-Pršo et al. in their study [5] demonstrated high concentrations of TNF-α in all symptomatic and asymptomatic lesions.Slightly higher concentration of TNF-α was observed in symptomatic lesions but the difference was not statistically significant.Such differences may occur due to the different state of activating macrophages depending on the clinical case but also as a result of different origin of produced cytokines due to various experimental approaches (tissue extracts or culture supernatants of inflammatory cells).

CONCLUSION
Symptomatic lesions showed increased production of TNF-α compared to asymptomatic.Higher concentration of TNF-α was demonstrated in large lesions compared to small.Large symptomatic lesions showed greater concentration of TNF-α than small symptomatic lesions and large asymptomatic lesions showed higher concentration of cytokines compared to asymptomatic small lesions.
Based on these results it can be concluded that TNF-α is an important factor responsible for the progression of periapical lesions.

KRATAK SADRŽAJ
Uvod Ba lans iz me đu pro in fla ma tor nih i an ti in fla ma tor nih ci to ki na igra va žnu ulo gu u pa to ge ne zi hro nič nih pe ri a pek snih le zi ja.Cilj ove stu di je je bio da se od re di kon cen tra ci ja fak to ra ne kro ze tu mo ra al fa (TNF-α) u ho mo ge na ti ma tki va pe ri a pek snih le zi ja i re zul ta ti ana li zi ra ju u po gle du simp to ma to lo gi je tih le zi ja kod pa ci je na ta, od no sno ve li či ne le zi je.Ma te ri jal i me to de ra da Is pi ta na su 93 uzor ka hro nič nih pe ri a pek snih le zi ja do bi je nih na kon eks trak ci je zu ba.Uzor ci le zi ja su, pre ma simp to ma to lo gi ji pa ci je na ta, po de lje ni na simp to mat ske i asimp to mat ske, a pre ma ve li či ni na ve li ke i ma le.Kon cen tra ci ja TNF-α u uzor ku is pi ti va na je po mo ću te sta ELI SA.Re zul ta ti Kod kli nič ki simp to mat skih le zi ja uoče no je po ve ća no stva ra nje TNF-α u od no su na asimp to mat ske.Ve ća kon cen traci ja TNF-α je do ka za na i u ve li kim le zi ja ma u od no su na ma le.Ve li ke simp to mat ske le zi je su po ka za le ve ću kon cen tra ci ju TNF-α u od no su na ma le simp to mat ske le zi je, dok su ve li ke asimp to mat ske le zi je ima le ve ću ko li či nu ovog ci to ki na u od no su na ma le asimp to mat ske le zi je.Za klju čak Ve ća kon cen tra ci ja TNF-α u ve li kim i u le zi ja ma s po ja ča nim kli nič kim simp to mi ma po ka zu je da je TNF-α va žan fak tor od go vo ran za na pre do va nje le zi je.Ključ ne re či: pe ri a pek sne le zi je; ci to ki ni; TNF-α; simp to mat ska; asimp to mat ska UVOD Pe ri a pek sne le zi je su in fla ma tor no-imun ska obo lje nja ko ja zahva ta ju pe ri a pek sna tki va i okol nu kost.Ova kvi pe ri ra dik sni pro ce si su pri mar no iza zva ni bak te rij skom in fek ci jom iz ka na la ko re na.Nji ho vo odr ža va nje, raz voj u hro nič ne le zi je i de struk cija ko šta nih struk tu ra po sle di ca su ne mo guć no sti me ha ni za ma od bra ne do ma ći na da su zbi ju in fek ci ju [1,2].
Mre ža ci to ki na igra zna čaj nu ulo gu u spe ci fič nim i ne speci fič nim imun skim od go vo ri ma.Mno ge stu di je su pro u ča va le pro iz vod nju ci to ki na u pe ri a pek snim le zi ja ma na ni vou genske eks pre si je, tkiv nih ho mo ge na ta ili u će lij skim kul tu ra ma, te usta no vi le da je u od re đe nim uslo vi ma ba lans iz me đu proin fla ma tor nih i imu no re gu la tor nih ci to ki na po re me ćen [3,4].
Fak tor ne kro ze tu mo ra al fa (TNF-α) igra va žnu ulo gu u inici ja ci ji i ko or di na ci ji će lij skih do ga đa ja i od go vo ru imu nskog si ste ma na in fek ci ju.On je so lu bil ni me di ja tor ko jeg oslo ba đaju imu no kom pe tent ne će li je u pro ce su za pa lje nja.Pro iz vo de ga uglav nom ma kro fa gi, ali i lim fo id ne će li je, ma sto ci ti, en dotel ne će li je, mi o ci ti, adi po ci ti, fi bro bla sti i ner vno tki vo.Ve li ke ko li či ne TNF-α se oslo ba đa ju pod uti ca jem li po po li sa ha ri da i dru gih bak te rij skih pro izvoda i in ter le u ki na 1 (IL-1) [5,6].TNF-α je, po red IL-1, je di ni mo le kul ko ji ima funk ci ju oste oklast ne ak ti va ci je.On in du ku je oslo ba đa nje kal ci ju ma iz ko sti in vi tro i mo že igra ti zna čaj nu ulo gu u raz li či tim sta di ju mi ma in fla ma tor nih obo lje nja, uklju ču ju ći ko šta nu re sorp ci ju.Pri sustvo TNF-α je do ka za no u hu ma nim apek snim pa ro don tal nim le zi ja ma i eks u da ti ma iz ka na la ko re na zu ba s apek snim pa rodon ti ti ma [6,7,8].
Cilj ove stu di je je bio da se od re di kon cen tra ci ja TNF-α u ho mo ge na ti ma tki va pe ri a pek snih le zi ja i re zul ta ti ana li zi ra ju u od no su na simp to ma to lo gi ju tih le zi ja kod pa ci je na ta, od nosno ve li či nu le zi je.

MATERIJAL I METODE RADA
U is tra ži va nje su uklju če na 93 pa ci jen ta Kli ni ke za sto ma tolo gi ju Me di cin skog fa kul te ta Uni ver zi te ta u Ni šu kod ko jih je kli nič kim i ra di o graf skim me to da ma po sta vlje na di jag no za hro nič ne pe ri a pek sne le zi je.Pe ri a pek sne le zi je su uzi ma ne sa ko re no va zu ba ko ji su zbog ne mo guć no sti le če nja in di ko va ni za eks trak ci ju.Po red pe ri a pek sne le zi je, uslov za uklju če nje pa ci je na ta u stu di ju bio je da ne bo lu ju od akut nih ili hro nič nih obo lje nja ko ja do vo de do sta nja imu no de fi ci jen ci je i da u prethod na dva me se ca ni su uzi ma li an ti bi ot sku i an ti in fla ma tor nu te ra pi ju.U is tra ži va nje su uklju či va ne pe ri a pek sne le zi je onih zu ba ko ji ni su po ka zi va li ume ren ili te žak ob lik mar gi nal nog pa ro don ti ti sa.
Is pi ti va ne le zi je su po de lje ne u dve gru pe pre ma su bjek tivnim simp to mi ma pa ci je na ta: simp to mat ske i asimp to mat ske le zi je.Kli nič ki su se simp to mat ske le zi je od li ko va le oto kom, bo lom, ne la god no šću pri žva ka nju ili ose tlji vo šću na per ku siju i pal pa ci ju, dok asimp to mat ske le zi je ni su po ka zi va le znake ili simp to me u vre me stu di je.Pe ri a pek sne le zi je su me re ne mi li me tar skim le nji rom i u od no su na ve li či nu svr sta ne u dve gru pe: ma le (≤ 5 mm) i ve li ke (≥6 mm) (Ta be la 1).Bu du ći da pe ri a pek sne le zi je ob u hva ta ju re ak tiv no tki vo ko je se sa sto ji uglav nom od gra nu lo ma to znog in fla ma tor nog tki va ko je za menju je nor mal nu kost, ni je po sto jao pra vi tkiv ni ekvi va lent ko ji bi slu žio kao ne ga tiv na kon tro la.
Pre pri me ne lo kal nog ane ste ti ka zu bi, gin gi va i slu zo ko ža oko zu ba su oči šće ni hlor hek si di nom u kon cen tra ci ji od 0,12%, a pa ci jent je is pi rao usta istim ras tvo rom 30 se kun di.Uzor ci peri a pek snih le zi ja su od mah po eks trak ci ji ste ril nim skal pe lom od stra nje ni s vr ha ko re na zu ba, is pra ni u ste ril nom fi zi o lo škom ras tvo ru, pro su še ni na ste ril noj va ti, sta vlje ni u ste ril nu pla stičnu epen dorf epru ve tu i za mr za va ni na -70°C.Ho mo ge ni za ci ja je vr še na te flon skim tuč kom u le de nom fos fat nom pu fe ru vrednosti pH od 7,4, či ja je za pre mi na pri la go đe na te ži ni tki va, ta ko da fi nal na kon cen tra ci ja ho mo ge na ta iz no si 10%.Krup ni ji detri tus je se di men ti ran cen tri fu gi ra njem na 1.400 obr ta ja to kom jed nog mi nu ta na -4°C.Su per na tant je na kon to ga za mr znut na -70°C do iz vo đe nja od go va ra ju ćih ana li za.
Kon cen tra ci ja TNF-α je od re đi va na ELI SA te stom (R&D Systems Inc.Mi ne a po lis, SAD) pre ma uput stvu pro iz vo đa ča.Sen zi tiv nost te sta ELI SA za TNF-α bi la je 0,5-5,5 pg/ml, a koncen tra ci ja ci to ki na je ana li zi ra na u po gle du simp to ma to lo gi je i ve li či ne pe ri a pek snih le zi ja.
Sta ti stič ka ana li za je ura đe na po mo ću Man-Vit ni je vog (Mann-Whit ney) te sta su me ran go va ko ri šće njem pro gra ma Sig ma stat i Ori gin.Re zul ta ti su iz ra ža va ni u vi du sred nje vredno sti sa stan dard nom de vi ja ci jom.Sta ti stič ki zna čaj nim raz lika ma su sma tra ne one ko je su bi le pri p<0,05.

REZULTATI
Is pi ti va nje kon cen tra ci je TNF-α u tki vu pe ri a pek snih le zi ja po ka za lo je sta ti stič ki zna čaj nu kon cen tra ci ju ci to ki na u svim uzor ci ma.Na gra fi ko nu 1 pri ka za na je kon cen tra ci ja TNF-α kod svih uzo ra ka, a pro seč ne vred no sti su ana li zi ra ne u od nosu na simp to ma to lo gi ju i ve li či nu.U gru pi simp to mat skih le zi ja pro seč na kon cen tra ci ja je bi la 15,08 pg/ml, a u gru pi asimp tomat skih le zi ja 8,24 pg/ml.Raz li ka je bi la sta ti stič ki zna čaj na (p<0,001).U gru pi ve li kih le zi ja pro seč na kon cen tra ci ja TNF-α je bi la 13,24 pg/ml, a u gru pi ma lih 9,61 pg/ml.Raz li ka je i izme đu ove dve po sma tra ne gru pe uzo ra ka ta ko đe bi la sta ti stič ki zna čaj na (p<0,01).
Na gra fi ko nu 2 pri ka za ne su pro seč ne vred no sti kon cen traci je TNF-α u okvi ru gru pa simp to mat skih i asimp to mat skih le zi ja.U gru pi simp to mat skih le zi ja ana li zi ra na je pro seč na kon cen tra ci ja TNF-α iz me đu ve li kih i ma lih le zi ja.Ona je kod ve li kih le zi ja bi la 17,67 pg/ml, a kod ma lih 12,07 pg/ml.Raz li ka je bi la sta ti stič ki zna čaj na (p<0,05).I u gru pi asimp to mat skih le zi ja za pa že na je sta ti stič ki zna čaj na raz li ka u kon cen tra ci jama TNF-α u od no su na ve li či nu le zi ja.Pro seč na kon cen tra ci ja TNF-α kod ve li kih le zi ja bi la je 8,96 pg/ml, a kod ma lih 7,58 pg/ml (p<0,01).
Na gra fi ko nu 3 pri ka za na je kon cen tra ci ja TNF-α u okvi ru gru pa ve li kih i ma lih le zi ja, gde je sta ti stič ka zna čaj nost anali zi ra na u od no su na simp to ma to lo gi ju.Ana li za je po ka za la sta ti stič ki zna čaj no ve ću (p<0,001) kon cen tra ci ju TNF-α u ve li kim simp to mat skim le zi ja ma (17,67 pg/ml) u od no su na ve li ke asimp to mat ske lezije (8,96 pg/ml).Sta ti stič ki zna čaj na raz li ka je uoče na i kod ma lih le zi ja, gde je kod simp to mat skih kon cen tra ci ja TNF-α bi la 12,07 pg/ml, a kod asimp to mat skih 7,58 pg/ml (p<0,001).

DISKUSIJA
Ba lans iz me đu pro in fla ma tor nih i an ti in fla ma tor nih ci to ki na u ve li koj me ri kon tro li še od go vo re do ma ći na na an ti ge nu stimu la ci ju kod hro nič nih za pa ljenj skih pro ce sa.Dok pro in fla mator ni ci to ki ni, kao što su IL-1, IL-6, TNF-α, TNF-β, he mo ki ni i Th1 ci to ki ni, pro pa gi ra ju in fla ma ci ju u pe ri a pek snim tki vi ma i ak ti vi ra ju oste o klast nu re sorp ci ju ko sti [1,2], ulo ga an ti in flama tor nih ci to ki na je va žna za su pre si ju in fla ma tor nih pro ce sa i pro ce se za ra sta nja unu tar pe ri a pek snih le zi ja [3,9,10].Ta kva ulo ga ci to ki na je pro u ča va na u stu di ji Ga zi vo de i sa rad ni ka [4], gde je do ka za no da in fla ma tor ne će li je iz pe ri a pek snih le zi ja stva ra ju zna čaj ne ni voe pro in fla ma tor nih (IL-1β, IL-6, IL-8 i TNF-α) i imu no re gu la tor nih (IL-10 i TGF-β) ci to ki na in vi tro.Kao zna čaj ne in di vi du al ne raz li ke ko je su po sma tra ne, auto ri su is pi ti va li da li je pro iz vod nja ci to ki na po ve za na s kli nič kim od li ka ma le zi ja i sa sta vom in fil tri ra ju ćih će li ja.U skla du s prethod nim re zul ta ti ma [10,11] uoče no je da simp to mat ske le zi je sa dr že ve ći pro ce nat ne u tro fil nih gra nu lo ci ta.Re gru to va nje granu lo ci ta u le zi ju je ve ro vat no iza zva no re in fek ci jom iz ka na la ko re na i da ljom re ak ti va ci jom hro nič nog pe ri a pek snog pro ce sa [1,2].Gra nu lo ci ti, za jed no s ak ti vi ra nim pri sut nim i in fil trira ju ćim ma kro fa gi ma, pro iz vo de broj ne so lu bil ne me di ja to re, uklju ču ju ći pro in fla ma tor ne ci to ki ne [12].
Kao pri mar ni sti mu la tor pe ri a pek sne ko šta ne de struk ci je na vo di se IL-1 [9,13], ci to kin ko ji pre do mi nant no stva ra ju mono nu kle ar ni fa go ci ti, po li mor fo nu kle ar ni le u ko ci ti i ve ziv notkiv ne će li je u pe ri a pek snim le zi ja ma [14,15].Pro iz vod nja IL-1 u pe ri a pek snim le zi ja ma je re gu li sa na ci to ki ni ma ko ji po ti ču od Th1 će li ja, ka kav je in ter fe ron ga ma (IFN-γ).IFN-γ, kao moć ni ak ti va tor ma kro fa ga, re gu li še eks pre si ju IL-1 i TNF-α od stra ne ovih će li ja.TNF-α iza zi va stva ra nje IL-1, dok sam IL-1 sti mu li še sop stve nu sin te zu me ha ni zmom po zi tiv ne povrat ne spre ge [2].
U ovom is tra ži va nju ana li zi ra ne su kon cen tra ci je pro in flama tor nog ci to ki na TNF-α u tkiv nim ho mo ge na ti ma hro nič nih pe ri a pek snih le zi ja u od no su na simp to ma to lo gi ju i ve li či nu le zi ja.Re zul ta ti stu di je, ko ji po ka zu ju da su ni voi TNF-α bi li sta ti stič ki zna čaj no vi ši u simp to mat skim le zi ja ma u od no su na asimp to mat ske i u ve li kim le zi ja ma u od no su na ma le, go vo re da je TNF-α me di ja tor od go vo ran za raz voj i na pre do va nje peri a pek snih le zi ja.U is tra ži va nju Ga zi vo de i sa rad ni ka [4] ni je uoče na zna čaj na raz li ka u ni vou TNF-α iz me đu simp to mat skih i asimp to mat skih le zi ja.Pre ma nji ho vom tu ma če nju, po ve ća no lu če nje TNF-α u ve li kim le zi ja ma mo že bi ti u ve zi s raz li či tim sa sta vom in fil tri ra ju ćih će li ja.Pre ma Da ni nu (Da nin) i sa radni ci ma [3], ak ti vi ra ni ma kro fa gi se sma tra ju glav nim iz vo rom TNF-α.Su prot no to me, Ma (Ma) i sa rad ni ci [16] su ob ja vi li da u ve li kim le zi ja ma ima ma nje ma kro fa ga.Raz log za ta kve na la ze ni je ja san, ali stu di ja Ar te za (Ar te se) i sa rad ni ka [7] je po ka za la da, iako 41% mo no nu kle ar nih in fla ma tor nih će li ja u pe ri a pek snim le zi ja ma či ne ma kro fa gi, sa mo 2-3% njih proiz vo di IL-1β i TNF-α.Da nin i sa rad ni ci [3] su pro na šli značaj ne ni voe TNF-α kod sa mo dva pa ci jen ta od 25 is pi ta ni ka s pe ri a pek snim le zi ja ma, dok su Sa fa vi (Sa fa vi) i Ro so man do (Ros so man do) [6] i Pe zelj-Ri ba ri će va i sa rad ni ci [17] ot kri li TNF-α u svim uzor ci ma pe ri a pek snih eks u da ta.U is tra ži va nju autor ke Bre ka lo-Pr šo i sa rad ni ka [5] utvr đe ne su vi so ke koncen tra ci je TNF-α u svim simp to mat skim i asimp to mat skim le zi ja ma.Ne što ve ća kon cen tra ci ja je uoče na u simp to mat skim le zi ja ma, me đu tim, raz li ka ni je bi la sta ti stič ki zna čaj na.Ovakve raz li ke mo gu na sta ti usled raz li či tih ak ti vi ra ju ćih sta nja ma kro fa ga u za vi sno sti od kli nič kih si tu a ci ja, ali i kao re zul tat raz li či tog po re kla stvo re nog ci to ki na zbog raz li či tih eks pe rimen tal nih pri stu pa (tkiv ni eks trakt ili kul tur ni su per na tan ti in fla ma tor nih će li ja).

ZAKLJUČAK
Kli nič ki simp to mat ske le zi je se ma ni fe stu ju po ve ća nom pro izvod njom TNF-α u od no su na asimp to mat ske.Ve ća kon cen tra ci ja TNF-α je do ka za na i u ve li kim le zi ja ma u od no su na ma le.Ve li ke simp to mat ske le zi je su po ka za le ve ću kon cen tra ci ju TNF-α u odno su na ma le simp to mat ske le zi je, dok su ve li ke asimp to mat ske le zi je ima le ve ću ko li či nu ovog ci to ki na u od no su na asimp to matske ma le le zi je.Na osno vu ova kvih re zul ta ta mo že se za klju či ti da je TNF-α va žan fak tor od go vo ran za na pre do va nje le zi je.