Ionising Radiation Suppresses rAPC-Induced NLRP3 Expression and Associated Signaling in Rat Brain: Evidence for a Radiation-Sensitive Molecular Phenotype

Abstract

Arka Plan ve Amaç: Rekombinant aktif protein C (rAPC), yaygın olarak anti-enflamatuar ve sitoprotektif bir ajan olarak kabul edilmektedir; ancak, ışınlanmış merkezi sinir sistemindeki moleküler etkileri yeterince karakterize edilmemiştir. Bu çalışma, sıçan beyninde rAPC tarafından tetiklenen gen ekspresyon profilini karakterize etmeyi ve iyonlaştırıcı radyasyonun bu moleküler (apoptotik ve nöroenflamatuar) yanıtları nasıl değiştirdiğini değerlendirmeyi amaçlamaktadır. Yöntemler: Erkek Wistar Albino sıçanlar rastgele dört deney grubuna ayrıldı: tedavi edilmemiş kontrol, tüm vücut ışınlaması (9 Gy, TBI), tek başına rAPC ( 0,4 mg/kg, intravenöz) ve TBI'yi takiben rAPC. Apoptotik, nöroenflamasyon ve oksidatif stresle ilgili belirteçlerin gen ekspresyon analizi için beyin dokusu toplandı. Sonuçlar: Beş gen önemli genel etkiler gösterdi. BAX ekspresyonu (ε² = 0,62) hem ışınlama hem de tek başına rAPC ile anlamlı derecede azalmıştır; kombinasyon grubu, sadece ışınlama grubuna göre daha yüksek BAX göstermiştir, bu da rAPC tarafından kısmi bir restorasyonu düşündürmektedir. BCL-2 ışınlama ile azalmış ve p53 sadece rAPC ile azalmıştır (η² = 0,38). Dikkat çekici bir şekilde, tek başına rAPC, ışınlanmış gruplarda bulunmayan pro-enflamatuar aktivasyon imzası olan TNF-α'da tutarlı bir yönlü artışla birlikte NLRP3 inflamozom ekspresyonunu seçici olarak yukarı düzenlemiştir (p = 0,023). Oksidatif stres belirteçlerinde, COX-2, FGFR veya CASP3'te anlamlı bir değişiklik gözlenmemiştir. Sonuç: Bu bulgular, sıçan beyin dokusunda rAPC için radyasyona duyarlı bir moleküler fenotipi ortaya koymaktadır. rAPC tek başına NLRP3 inflamatuar sinyallemesini aktive ederken aynı zamanda p53 ve BAX ekspresyonunu azaltır ve ışınlanmış ortamda önemli ölçüde değişen çok yönlü bir moleküler profil tanımlar. Bu sonuçlar, rAPC için tek tip anti-inflamatuar aktivite varsayımını sorgular ve iyonlaştırıcı radyasyonu, merkezi sinir sistemindeki gen ekspresyon profilinin temel belirleyicisi olarak tanımlar.

Keywords

• rekombinant aktif protein C
• iyonlaştırıcı radyasyon;
• tüm vücut ışınlaması;
• nöroenflamasyon;
• NLRP3 inflamazomu
• BAX
• BCL-2
• TNF-α

Ethical Statement

Çalışma, Erciyes Üniversitesi Hayvan Deneyleri Yerel Etik Kurulu tarafından onaylanmıştır (26/065).

Thanks

Katılımcılara katkılarından dolayı teşekkür ederiz.

Ionising Radiation Suppresses rAPC-Induced NLRP3 Expression and Associated Signaling in Rat Brain: Evidence for a Radiation-Sensitive Molecular Phenotype

Abstract

Purpose: Recombinant activated protein C (rAPC) is widely regarded as an anti-inflammatory and cytoprotective agent; however, its molecular effects in the irradiated central nervous system remain poorly characterized. This study aims to characterize the gene expression profile triggered by rAPC in the rat brain and to evaluate how ionizing radiation alters these molecular (apoptotic and neuroinflammatory) responses. Material and Methods: Male Wistar Albino rats were randomly assigned to four experimental groups: untreated control, total body irradiation (9 Gy, TBI), rAPC (0.4 mg/kg, intravenous) alone, and TBI followed by rAPC. Brain tissue was collected for gene expression analysis of apoptosis, neuroinflammation, and oxidative stress-related markers. Results: Five genes showed significant omnibus effects. BAX expression (ε² = 0.62) was significantly reduced by both irradiation and rAPC alone; the combination group showed higher BAX than the irradiation-only group, suggesting partial restoration by rAPC. BCL-2 was reduced by irradiation and p53 was reduced by rAPC alone (η² = 0.38). Strikingly, rAPC alone selectively upregulated NLRP3 inflammasome expression (p = 0.023) with a consistent directional increase in TNF-α, a pro-inflammatory activation signature absent in irradiated groups. No significant changes were observed in oxidative stress markers, COX-2, FGFR, or CASP3. Conclusion: These findings reveal a radiation-sensitive molecular phenotype for rAPC in rat brain tissue. rAPC alone upregulates Nlrp3 expression and associated signaling while simultaneously reducing P53 and Bax expression, defining a multifaceted molecular profile that is substantially modified in the irradiated context.

Keywords

• recombinant activated protein C
• ionizing radiation
• total body irradiation
• neuroinflammation
• NLRP3 inflammasome
• BAX
• BCL-2
• TNF-α

Ethical Statement

The study was approved by the Erciyes University Animal Experiments Local Ethics Committee (26/065)

Thanks

We thank the participants for their contribution.

References

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