Time-courses of plasma IL-6 and HMGB-1 reflect initial severity of clinical presentation but do not predict poor neurologic outcome following subarachnoid hemorrhage

Time-cou ses o plasma IL-6 and HMGB-1 eflec ini ial se e i y o clinical p esen a ion bu do no p edic poo neu ologic ou come ollowing suba achnoid hemo hage Heikki Kiiski a, ⁎, Jaakko Långsjö a , Jy ki Tenhunen a,b , Ma ika Ala-Peija i a , Heini Huh ala c ,Ma iHämäläinen d , Ee a Moilanen d ,JuhaÖhman e , Jukka Pel ola a C i ical Ca e Medicine Resea ch G oup, Depa men o In ensi e Ca e, Tampe e Uni e si y Hospi al, Tampe e, Finland b Depa men o Su gical Sciences, Di ision o Anes hesiology and In ensi e Ca e, Uppsala Uni e si y, Uppsala, Sweden c School o Heal h Sciences, Uni e si y o Tampe e, Tampe e, Finland d The Immunopha macology Resea ch G oup, Uni e si y o Tampe e School o Medicine and Tampe e Uni e si y Hospi al, Tampe e, Finland e Depa men o Neu osu ge y, Uni e si y o Tampe e and Tampe e Uni e si y Hospi al, Tampe e, Finland Depa men o Neu ology, Uni e si y o Tampe e and Tampe e Uni e si y Hospi al, Tampe e, Finland abs ac a icle in o A icle his o y: Recei ed 6 No embe 2016 Accep ed 28 No embe 2016 A ailable online 2 Decembe 2016 Objec i e: Pa ien s wi h aneu ysmal suba achnoid hemo hage (aSAH) expe ience high mo ali y and mo bidi y. Neu oinflamma ion causes b ain damage expansion a e aSAH. Due o he complexi y o he inflamma o y e- sponse mul iple bioma ke s a e needed o e alua e i s' p og ession. We s udied inflamma o y p ocess a e aSAH by measu ing wo inflamma o y bioma ke s, in e leukin-6 (IL-6) and high-mobili y g oup box 1 (HMGB1) a simul aneous ime-poin s a e aSAH. Me hods: In his p ospec i e popula ion-based s udy, IL-6 and HMGB1 we e measu ed in aSAH pa ien s (n = 47) o up o fi e days. Plasma concen a ions o IL-6 and HMGB1 we e measu ed a 0, 12 and 24 h a e hospi al ad- mission, and he ea e daily o up o fi e days o un il he pa ien was ans e ed om he in ensi e ca e uni (ICU). The pa ien s' neu ological ou comes we e e alua ed wi h he modified Rankin Scale a six mon hs a e aSAH. Resul s: A high IL-6 le el du ing he fi s day a e aSAH was associa ed wi h a se e e ini ial clinical p esen a ion (p = 0.002) and in ec ion du ing ollow-up (p = 0.031). The HMGB1 le el did no associa e wi h hese pa am- e e s. The e was no co ela ion be ween IL-6 and HMGB1 le els a any ime poin du ing he ollow-up. The concen a ions o IL-6 and HMGB1 we e no associa ed wi h neu ological ou come. Conclusions: High ini ial IL-6 alues seem o eflec he in ensi y o he inflamma o y esponse bu no he b ain damage pe se. An ea ly inflamma o y esponse migh e en be beneficial since al hough ele a ed IL-6 le els we e obse ed in pa ien s wi h a mo e se e e ini ial clinical p esen a ion, hey we e no associa ed wi h neu ological ou come. The lack o co ela ion be ween IL-6 and HMGB1 ques ions he ole o mac ophages in he p ocess o he sec e ion o hese inflamma o y ma ke s a e aSAH, ins ead poin ing o he ac i a ion o al e na i e p o- inflamma o y pa hways. © 2016 The Au ho s. Published by Else ie B.V. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/). Keywo ds: Aneu ysmal suba achnoid hemo hage Bioma ke s Neu oinflamma ion Inflamma o y esponse Il-6 HMGB1 1. In oduc ion Despi e ecen ad ances in he managemen o aneu ysmal sub- a achnoid hemo hage (aSAH), i emains a de as a ing disease wi h a mo ali y app oaching 50% and ewe han 60% o he su i o s achie - ing unc ional independence [1]. The b ain inju y de eloping a e aSAH occu s in mul iple phases. The e is e idence sugges ing ha a e he p ima y insul , an addi ional b ain inju y is e oked by ea ly b ain inju y (EBI) and delayed ce eb al ischemia (DCI). The e a e epo s ha he de elopmen o DCI doubles he isk o poo ou come in aSAH [2,3]. Ea ly b ain inju y e e s o he acu e e ec s o blood in he suba ach- noid space and he ansien global ischemia caused by acu e ele a ion in he in ac anial p essu e. Delayed ce eb al ischemia is a mul i ac o ial phenomenon in ol ing angiog aphic asospasm, mic oci cula o y asocons ic ion, mic o ascula h ombosis, co ical sp eading depola - iza ion and blood-b ain ba ie dys unc ion. I is also hough ha p ocesses ac i a ed du ing EBI con ibu e o he de elopmen o DCI [2,4,5]. Va ious bioma ke s ha e been examined in aSAH pa ien s bu hus a , he e a e no clinically eliable bioma ke s o p edic ing DCI o eNeu ologicalSci 6 (2017) 55–62 ⁎Co esponding au ho : Depa men o In ensi e Ca e, Tampe e Uni e si y Hospi al, PL 2000, Tampe e, Finland. E-mail add ess: heikki.kiiski@fimne .fi(H. Kiiski). h p://dx.doi.o g/10.1016/j.ensci.2016.11.010 2405-6502/© 2016 The Au ho s. Published by Else ie B.V. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/). Con en s lis s a ailable a ScienceDi ec eNeu ologicalSci jou nal homepage: h p://ees.else ie .com/ensci/ p ognosis [6]. Recen findings om ou g oup suppo he hypo hesis ha UCH-L1 could be use ul in p edic ing pa ien ou come a e aSAH al hough no associa ion be ween UCH-L1and DCI was ound[7]. Ne e - heless, he e is accumula ing e idence ha inflamma ion con ibu es o hede elopmen o DCI [2,8–10]. Knowledge abou he neu al con ol mechanisms o inflamma ion is accumula ing apidly [11]. A numbe o cy okines and p oinflamma o y ma ke s ha e been associa ed wi h a poo ou come in aSAH [6]. In e leukin-6 (IL-6) and high-mobili y g oup box 1 (HMGB1) a e wo impo an inflamma o y bioma ke s; hei pe iphe al blood concen a ions ha e been associa ed wi h a poo ou come in aSAH [12–14]. I has been pos ula ed ha he inflamma o y esponse displays bi- phasic ea u es in EBI and DCI [2,15]. The biphasic esponse e e s o he double-edged e ec s o he inflamma o y esponse which can be de imen al a some phase o he disease bu alle ia ing a ano he . The biphasic p ope ies o mul iple molecula pa hways ha e been p o- posed o con ibu e o he seconda y b ain inju y also in o he ypes o acu e s okes [16,17]. The pu a i e biphasic e ec s o he inflamma o y esponse highligh he need o a be e unde s anding o he mecha- nisms and imescale o he esponse in aSAH. The de elopmen o eli- able bioma ke s ac ing as su oga es o he esponse could help o achie e his goal. The aim o he p esen s udy was o analyze he ole o wo bio- ma ke s in a g oup o pa ien s wi h ecen aSAH. We e alua ed whe he he e was any co ela ion be ween IL-6 and HMGB1 le els. By compa - ing he concen a ions o hese wo inflamma o y bioma ke s a he same ime poin s, we wan ed o de e mine whe he he changes in hei concen a ions could o e mo e specific in o ma ion abou he in- flamma o y pa hways and possible mechanisms leading o he neu al inju y de eloping a e aSAH. In addi ion, we assessed hei associa ion wi h neu ological ou come and selec ed clinical condi ions. 2. Me hods Following he app o al o he ins i u ional e hics commi ee, we conduc ed a p ospec i e, obse a ional, single-cen e clinical s udy in Tampe e Uni e si y Hospi al (Tampe e, Finland). The hospi al is one o fi e e ia y e e al cen e s in Finland se ing a popula ion o ap- p oxima ely 1 million inhabi an s and hus p o iding ca e o all pa- ien s su e ing om suba achnoid hemo hage in he a ea. The s udy coho consis ed o 61 consecu i e aSAH pa ien s admi - ed o ou cen e om Ma ch2013 o Decembe 2013. W i en in o med consen was ob ained om each pa ien o om hei nex o kin. The ime o he onse o symp oms associa ed wi h aSAH was egis e ed om he pa ien eco ds. We excluded pa ien s wi h an unknown ime o onse o symp oms as well as pa ien s whose samples o he IL-6 and HMGB1 assays we e no collec ed wi hin he fi s 24 h a e he onse o symp oms. All pa ien s we e ea ed acco ding o s anda d- ized in-house guidelines. In o al, 47 pa ien s we e conside ed eligible and we e hus included in he s udy. These e i y o he ini ial clinical p esen a ion was e alua ed acco d- ing o he Wo ld Fede a ion o Neu ological Su geons (WFNS) and Hun & Hess g ading scales. The ex en o he p ima y hemo hage on he CT scan was g aded wi h Fishe scale. WFNS and Hun & Hess we e dicho - omized in o non-se e e (WFNS 1–3/Hun & Hess 1–3) o se e e (WFNS 4–5 / Hun & Hess 4–5). The Fishe g ade was dicho omized in o non- se e e (Fishe 1–2) o se e e (Fishe 3–4). The neu ological ou come was e alua ed wi h he modified Rankin Scale (mRS) six mon hs a e aSAH based on a s uc u ed in e iew pe o med by elephone o du - ing an ou pa ien clinic isi . mRS was dicho omized in o a a o able ou come (mRS 0–2) o an un a o able ou come (mRS 3–6). De ailed ca ego iza ions o WFNS, Hun & Hess, Fishe and mRS a e p esen ed in a Supplemen a y able. Addi ionally, we assessed he incidence o in- ec ion, which was defined as he need o an imic obial medica ion du ing he ollow-up pe iod. Plasma concen a ions o IL-6 and HMGB1 we e measu ed in he samples collec ed a 0, 12 and 24 h a e he admission, and he ea e a e e y 24 h o up o fi e days o un il he pa ien was ans e ed om he ICU. Be o e he s a is ical analysis, he IL-6 and HMGB1 mea- su emen s we e di ided in o consecu i e 24 h in e als s a ing om he onse o symp oms. I IL-6 and HMGB1 we e measu ed mo e han once pe in e al, he mean concen a ion was used. In a subg oup o 22 pa ien s who had up o fi e days' ollow-up, we also checked i he pa ien had been ea ed o DCI. T ea men o DCI was ini ia ed based on he clinical e alua ion. Blood samples we e collec ed in o EDTA-con aining ubes om an a e ial cannula ha had been ou inely inse ed o in asi e blood p essu e moni o ing as well as o blood sampling. A e collec ion, he sample was immedia ely deli e ed o he labo a o y whe e i was cen- i uged o 10 min a 2000g( oom empe a u e). A e cen i uga ion, he plasma was collec ed and kep a - 70 °C. IL-6 and HMBG1 Fig. 1. IL6 le els measu ed wi hin he fi s 24 h a e aSAH in ela ion o he ini ial clinical p esen a ion. Pa ien s wi h mo e se e e clinical p esen a ions had significan ly highe IL-6 le els (p = 0.002). Black ci cles ep esen ou lie s. 56 H. Kiiski e al. / eNeu ologicalSci 6 (2017) 55–62 concen a ions in he plasma samples we e measu ed by ELISA wi h e- agen s om eBioscience Inc. (San Diego, CA, USA) and IBL In e na ional (Hambu g, Ge many), espec i ely. Assay p o ocols a e desc ibed in he ollowing da ashee s: h p://www.ebioscience.com/media/pd / ds/88/88-7066.pd (IL-6) h p://www.ibl-in e na ional.com/media/ca alog/p oduc /S/T/ ST51011_IFU_EU_en_HMGB1_ELISA_V2011-01_sym4.pd (HMGB1) The abso bance was measu ed wi h Vic o 3 Mul ilabel Coun e (Pe kin Elme , Finland) and he esul s we e calcula ed agains a s anda d cu e using he smoo hed spline me hod wi h Mul iCalcTM (Pe kin Elme , Finland). S a is ical analyses we e pe o med wi h R ( e sion 3.3.0 o Mac OS X). Fishe 's exac es was used o he ca ego ical a iables and Mann- Whi ney U es o con inuous a iables. Linea eg ession was used o he ime in e al analysis. Spea man's co ela ion was used o es ima e whe he IL-6 and HMGB1 le els co ela ed 3. Resul s The pa ien s wi h a se e e ini ial clinical p esen a ion o aSAH (WFNS 4–5/Hun & Hess 4–5) had a highe plasma IL-6 concen a ion du ing he fi s 24 h ollowing aSAH han he pa ien s wi h a non- se e e (WFNS 1–3, p = 0.002/Hun & Hess 1–3, p = 0.019) p esen a- ion (Fig. 1,Table 1). In addi ion, he adminis a ion o an imic obial medica ion was associa ed wi h ele a ed plasma IL-6 le els (Fig. 2, Table 1, p = 0.031). Finally, plasma IL-6 concen a ions ended o be highe in pa ien s wi h se e e aSAH acco ding o Fishe scale (Fig. 3, p = 0.051). The plasma HMGB1 concen a ion du ing he fi s 24 h a e aSAH was no associa ed wi h he se e i y o aSAH (Table 2). IL-6 and HMGB1 concen a ions measu ed du ing he fi s 24 h we e no associa ed wi h neu ological ou come. The desc ip i e s a is ics o IL-6 and HMGB1 concen a ions measu ed du ing he fi s 24 h a e aSAH a e p esen ed in Tables 1 and 2. The linea eg ession analysis e- ealed no associa ion be ween neu ological ou come and IL-6 o HMGB1 concen a ions du ing he fi e-day ollow-up (Fig. 4). Plasma IL-6 and HMGB1 concen a ions did no co ela e wi h each o he a any o he ime poin s du ing he fi e-day ollow-up (Fig. 5, Table 3). In he subg oup o hose pa ien s ollowed o up o fi e days, IL-6 o HMGB1 concen a ions du ing he fi s 24 h did no p edic he de elopmen o DCI. In addi ion, he p esen a ion o DCI did no as- socia e wi h IL-6 o HMGB1 concen a ions measu ed on day fi e (Table 4). 4. Discussion In he p esen s udy, we examined he p ognos ic po en ial and in- e dependence o wo inflamma o y bioma ke s IL-6 and HMGB1 a e aSAH. Ou s udy sugges s ha a high plasma IL-6 concen a ion du ing he fi s 24 h a e aSAH is s ongly associa ed wi h a se e e clinical p esen- a ion as well as wi h he de elopmen o in ec ion du ing he fi e-day ollow-up pe iod. Howe e , nei he IL-6 no HMGB1 le els we e associ- a ed wi h neu ological ou come in pa ien s su e ing om aSAH. Thus, ou s udy ailed o suppo he findings o some p e ious s udies i.e. ha he e would be an associa ion be ween inc eased concen a ions o hese bioma ke s and poo neu ological ou come. Zhu e al. claimed ha he ea ly plasma HMGB1 concen a ion was associa ed wi h one- yea mo ali y and poo neu ological ou come as de e mined by he Glasgow Ou come Scale. These in es iga o s applied s ic e exclusion c i e ia, o example, pa ien s wi h sys emic diseases such as hype en- sion, diabe es and ch onic hea o lung disease we e excluded om he s udy [13]. Höllig e al. desc ibed an associa ion be ween ea ly se um and ce eb ospinal fluid IL-6 concen a ion wi h poo neu ological Table 1 IL-6 concen a ion du ing he fi s 24 h a e aSAH (n = 47). IL-6 (pg/ml) Mean SD Median IQR p-Value mRS 0.334 0–2 (n = 16) 9.92 6.51 8.93 4.84–13.28 3–6 (n = 31) 13.96 12.20 8.85 6.30–18.35 WFNS 0.002 1–3 (n = 28) 8.19 4.77 7.45 4.93–9.93 4–5 (n = 19) 19.07 13.58 16.30 8.88–24.05 Hun & Hess 0.019 1–3 (n = 35) 11.21 11.04 7.70 5.13–10.63 4–5 (n = 12) 16.93 9.33 16.18 9.90–21.10 Fishe 0.051 1–2 (n = 14) 11.27 14.03 6.53 4.44–9.30 3–4 (n = 33) 13.15 9.14 10.00 7.15–17.70 In ec ion 0.031 Yes (n = 14) 14.84 8.63 11.40 9.34–19.38 No (n = 33) 11.63 11.46 7.50 5.00–12.35 Mann-Whi ney U es was used. Fig. 2. IL6 le els measu ed wi hin he fi s 24 h a e aSAH in ela ion o clinically suspec ed in ec ion du ing ICU ollow-up. Ea ly IL-6 le els a e significan ly highe in pa ien s wi h in ec ion du ing ollow-up (p = 0.031). Black ci cles ep esen ou lie s. 57H. Kiiski e al. / eNeu ologicalSci 6 (2017) 55–62 ou comea discha ge, bu no a six mon hs a e aSAH. They conside ed his lack o co ela ion a six mon hs o be caused pa ly by he high d op-ou a e (27%) a e discha ge [14]. Kao e al. obse ed an associa- ion be ween ea ly IL-6 concen a ion measu ed om he aneu ysmal o ifice and pe iphe al eins wi h a poo neu ological ou come a one mon h a e aSAH. They included only pa ien s who had unde gone endo ascula coiling while pa ien s wi h su gically liga ed aneu ysm we e excluded om he s udy [12]. The disc epan findings be ween hese p e ious s udies and he p esen s udy may be pa ly explained by he di e ences in he s udy p o ocols, he pa ien selec ion and he di e en ime-poin s used o measu e neu ological ou come. As s a ed by Höllig e al. [14], i is also essen ial o app ecia e ha an ele a ed IL-6 concen a ion is a non-specificfinding which can eflec he inflam- ma o y esponse o a ious pa hologies occu ing a e aSAH. Fo exam- ple, pneumonia is common a e aSAH since pa ien s wi h dep essed le el o consciousness a e suscep ible o aspi a ion o gas ic con en s un il he ai way is secu ed. In asi e mechanical en ila ion p edisposes pa ien s o en ila o -associa ed pneumonia and need o en iculos omy c ea es a possibili y o en iculi is. All o hese in ec- ions may lead o inc eased le els o inflamma o y bioma ke s. The sec e ion o IL-6 and HMGB1 as a pa o he inflamma o y e- sponse is a complex p ocess. One well known mechanism in ol es he elease o hese bioma ke s o a he , media o s, om monocy es and mac ophages [18–20]. In his s udy, an ele a ed IL-6 concen a ion was associa ed wi h he clinical se e i y a e aSAH. Fu he mo e, a nea ly s a is ically significan end o ele a ions in IL-6 was obse ed in pa ien s wi h mo e se e e aSAH on he p ima y CT. On he o he hand, he HMGB1 le el was no associa ed wi h ei he clinical se e i y o he CT findings. Fu he mo e, he IL-6 and HMGB1 concen a ions did no co ela e wi h each o he a any ime poin du ing he fi e-day ollow-up. Based on hese findings, i would be emp ing o specula e ha he sec e ion o IL-6 a e aSAH is media ed h ough a pa hway un- ela ed o hei sec e ion by monocy es and mac ophages. Inflamma ion has been associa ed wi h DCI [2,9] and poo ou come a e aSAH [12,14]. In ou s udy, high concen a ions o IL-6 immedia ely a e aSAH we e associa ed wi h se e e ini ial clinical p esen a ion and head CT findings. On he o he hand, linea eg ession did no e eal any mass inc ease in plasma IL-6 concen a ions du ing ollow-up and he e was no di e ence be ween IL-6 concen a ions in pa ien s wi h a o - able and non- a o able neu ological ou comes. Mo eo e , IL-6 le els we e no associa ed wi h he de elopmen o DCI. Thus, ou findings aise ques ions abou he biphasic p ope ies o IL-6 in inflamma o y e- sponse a e aSAH, sugges ing ha he ea ly inflamma o y esponse migh no be de imen al o he pa ien 's ou come. Plasma HMGB1, as a la e phase cy okine, was no associa ed wi h he ini ial se e i y o aSAH o wi h he neu ological ou come. In addi ion o sec e ion om mac ophages du ing inflamma o y esponse, HGMB1 is also eleased om cells i hey die by nec osis bu no when hey unde go apop osis [21]. Apop osis has been associa ed wi h EBI and DCI [2,4]. The ela i ely low concen a ions o HMGB1 sugges ha he e had no been ex ensi e issue nec osis in ou pa ien s and suppo he hypo hesis ha cell dea h du ing EBI and DCI occu s by apop osis. This s udy has some limi a ions. The sample size is ela i ely small o make i possible o d aw defini e conclusions abou he p ognos ic po- en ial o he s udied bioma ke s. Howe e , he s udy is well powe ed o ule ou he possibili y ha he e would be a significan co ela ion be ween IL-6 and HMGB1 le els du ing he fi e-day ollow-up. We measu ed IL-6 and HMGB1 in pe iphe al blood so he specific mecha- nisms in ol ed in hei sec e ion emain elusi e. S ill, he lack o co e- la ion be ween he s udied bioma ke s aises in e es ing ques ions o Fig. 3. IL6 le els measu ed wi hin he fi s 24 h a e aSAH in ela ion o he se e i y o aSAH in p ima y CT. The e is a end owa ds highe IL-6 le els in pa ien s wi h mo e se e e CT findings bu s a is ical significance is no eached by a na ow ma gin (p = 0.051). Black ci cles ep esen ou lie s. Table 2 HMGB1 concen a ion du ing he fi s 24 h a e aSAH (n = 47). HMGB1 (ng/ml) Mean SD Median IQR p-Value mRS 0.486 0–2 (n = 16) 7.87 4.13 6.85 5.59–8.67 3–6 (n = 31) 6.85 2.94 6.27 4.55–8.61 WFNS 0.502 1–3 (n = 28) 6.83 2.78 6.04 5.39–7.72 4–5 (n = 19) 7.73 4.13 6.95 5.04–8.73 Hun & Hess 0.097 1–3 (n = 35) 6.61 2.70 5.83 4.55–7.87 4–5 (n = 12) 8.87 4.62 8.04 6.34–10.10 Fishe 0.771 1–2 (n = 14) 6.95 2.34 6.85 5.52–8.78 3–4 (n = 33) 7.30 3.76 6.27 4.61–8.59 In ec ion 0.693 Yes (n = 14) 6.84 3.11 6.33 4.38–8.32 No (n = 33) 7.35 3.53 6.62 5.44–8.62 Mann-Whi ney U es was used. 58 H. Kiiski e al. / eNeu ologicalSci 6 (2017) 55–62 Fig. 4. IL-6and HMGB1 le els o pa ien s (n = 22) wi h he ICU ollow-up las ing o fi e days (n = 22). Ci cles ep esen indi idual pa ien alues. Values a e g ouped in o a o able and non- a o able neu ological ou come. Linea eg ession shows no significan change be ween baseline alues o IL-6 (mRS 0–2: p- alue 0.084, be a −1.048/mRS 3–6: p- alue 0.515, be a −0.879) o HMGB1 (mRS 0–2: p- alue 0.454, be a 0.183/mRS 3–6: p- alue 0.776, be a 0.106) du ing he ollow-up. Ou lie s a e no shown. 59H. Kiiski e al. / eNeu ologicalSci 6 (2017) 55–62 u u e s udies in es iga ing mo e specific cellula and molecula mech- anisms o inflamma o y esponse du ing aSAH. He e, we defined in ec- ion as he use o an imic obial medica ion du ing ollow-up. Al hough, ex eme cau ion is adop ed in ou uni wi h espec o he use o an imi- c obial medica ion in o de o a oid unnecessa y ea men , i is s ill possible ha in a small numbe o pa ien s, an ibio ic he apy had Fig. 5. Sca e plo s displaying he co ela ion o indi idual pa ien alues o IL-6 agains hose o HGMB1 a di e en ime poin s du ing he ICU ollow-up. Ou lie s a e no shown. 60 H. Kiiski e al. / eNeu ologicalSci 6 (2017) 55–62 been ini ia ed o p ophylaxis o simply based on s ong clinical suspi- cion o in ec ion. High ini ial IL-6 concen a ions in pa ien s wi h a se e e clinical p e- sen a ion a e aSAH seem o eflec he in ensi y o he “inflamma o y eflex”[11] a he han he neu onal inju y i sel . Thus, he exp ession o IL-6 di e s om ha o UCH-L1, which in ou p e ious s udy was shown o co ela e wi h he neu onal inju y caused by aSAH [7].Acco d- ing o ecen e idence, inflamma ion seems o be a significan con ib- u ing ac o o DCI. I is plausible ha inflamma ion can exe bo h de imen al o beneficial e ec s depending on he phase o he second- a y inju y p ocess in aSAH [2]. The pu a i e biphasic e ec s o he inflamma o y esponse highligh he need o cla i ying he specificin- flamma o y pa hways and imescales in which hey a e ac i a ed a e aSAH. This knowledge would be o pa amoun impo ance o a ge ing an i-inflamma o y he apies o app op ia e pa ien s a alid ime poin s.Ass a edbyHöllige al.[14],a“sil e -bulle ”o “b ain oponin” migh no exis due o he ex eme complexi y o physiological p ocess- es in ol ed in aSAH. Ou findings highligh he complexi y o inflamma- o y esponse and pa hophysiology o DCI in aSAH . The e o e, u u e s udies should es mul iple bioma ke s o p e e ably panels o di e se bioma ke s measu ed a he same ime-poin s in o de o gain a be e unde s anding o pa hophysiology unde pinning he inflamma o y e- sponse in aSAH. 5. Conclusion High ini ial IL-6 alues seem o eflec he in ensi y o he inflamma- o y esponse associa ed wi h ini ial clinical p esen a ion bu no he e en ual b ain damage pe se. An ea ly inflamma o y esponse migh e en be beneficial since al hough ele a ed IL-6 le els we e obse ed in pa ien s wi h a mo e se e e ini ial clinical p esen a ion, hey we e no associa ed wi h neu ological ou come. The lack o co ela ion be ween IL-6 and HMGB1 aises ques ions abou he ole o mac o- phages in he p ocess o he sec e ion o hese inflamma o y ma ke s a e aSAH, ins ead poin ing o he ac i a ion o al e na i e p o- inflamma o y pa hways. Funding s a emen The s udy was financially suppo ed by Academy o Finland (G an numbe 138402) and he Compe i i e S a e Resea ch Financing o he Expe Responsibili y a ea o Tampe e Uni e si y Hospi al. E hics app o al The s udy was conduc ed wi h he app o al o he Tampe e Uni e - si y Hospi al E hics Commi ee. Conflic o in e es None. Acknowledgemen s Ms. Meiju Kukkonen and Te hi Salonen a e acknowledged o hei excellen echnical assis ance. Appendix A. Supplemen a y da a Supplemen a y da a o his a icle can be ound online a h p://dx. doi.o g/10.1016/j.ensci.2016.11.010. Re e ences [1] B.E. Zacha ia, Z.L. Hickman, B.T. G obelny, e al., Epidemiology o aneu ysmal sub- a achnoid hemo hage, Neu osu g. Clin. N. 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Mean SD Median IQR p-Value IL-6 (pg/ml) Day 1 DCI 12.07 8.87 8.93 6.33–12.79 0.155 NO DCI 21.73 17.56 18.35 10.94–21.75 Day 5 DCI 14.48 13.08 11.65 6.43–17.50 0.914 NO DCI 11.48 3.94 10.70 9.50–11.30 HMGB-1 (ng/ml) Day 1 DCI 6.03 2.46 5.48 4.17–7.59 0.197 NO DCI 7.67 3.42 7.14 6.49–8.95 Day 5 DCI 6.92 3.04 6.33 5.20–9.29 0.507 NO DCI 6.07 2.70 5.50 4.83–7.56 Mann-Whi ney U es was used. 61H. Kiiski e al. / eNeu ologicalSci 6 (2017) 55–62 [18] H. E landsson Ha is, U. Ande sson, Mini- e iew: he nuclea p o ein HMGB1 as a p oinflamma o y media o , Eu . J. Immunol. 34 (2004) 1503–1512, h p://dx.doi. o g/10.1002/eji.200424916. [19] M.E. Bianchi, A.A. Man edi, How mac ophages ing he inflamma ion ala m, P oc. Na l. Acad. Sci. U. S. A. 111 (2014) 2866–2867, h p://dx.doi.o g/10.1073/pnas. 1324285111. [20] M. Rincon, In e leukin-6: om an inflamma o y ma ke o a a ge o inflamma o y diseases, T ends Immunol. 33 (2012) 571–577, h p://dx.doi.o g/10.1016/j.i .2012. 07.003. [21] A. Raucci, R. Palumbo, M.E. Bianchi, HMGB1: a signal o nec osis, Au oimmuni y 40 (2009) 285–289, h p://dx.doi.o g/10.1080/08916930701356978. 62 H. Kiiski e al. / eNeu ologicalSci 6 (2017) 55–62