Early Local Inhibition of Club Cell Protein 16 Following Chest Trauma Reduces Late Sepsis-Induced Acute Lung Injury

Abstract

Blunt thoracic trauma (TxT) deteriorates clinical post-injury outcomes. Ongoing inflammatory changes promote the development of post-traumatic complications, frequently causing Acute Lung Injury (ALI). Club Cell Protein (CC)16, a pulmonary anti-inflammatory protein, correlates with lung damage following TxT. Whether CC16-neutralization influences the inflammatory course during ALI is elusive. Ninety-six male CL57BL/6N mice underwent a double hit model of TxT and cecal ligation puncture (CLP, 24 h post-TxT). Shams underwent surgical procedures. CC16 was neutralized by the intratracheal application of an anti-CC16-antibody, either after TxT (early) or following CLP (late). Euthanasia was performed at 6 or 24 h post-CLP. Systemic and pulmonary levels of IL-6, IL-1β, and CXCL5 were determined, the neutrophils were quantified in the bronchoalveolar lavage fluid, and histomorphological lung damage was assessed. ALI induced a significant systemic IL-6 increase among all groups, while the local inflammatory response was most prominent after 24 h in the double-hit groups as compared to the shams. Significantly increased neutrophilic infiltration upon double hit was paralleled with the enhanced lung damage in all groups as compared to the sham, after 6 and 24 h. Neutralization of CC16 did not change the systemic inflammation. However, early CC16-neutralization increased the neutrophilic infiltration and lung injury at 6 h post-CLP, while 24 h later, the lung injury was reduced. Late CC16-neutralization increased neutrophilic infiltration, 24 h post-CLP, and was concurrent with an enhanced lung injury. The data confirmed the anti-inflammatory potential of endogenous CC16 in the murine double-hit model of ALI.

Early increase in anti-inflammatory biomarkers is associated with the development of multiple organ dysfunction syndrome in severely injured trauma patients

“…In this study, mice were treated with anti-CC-16 antibodies or IgG directly after trauma. Early anti-CC-16 treatment was associated with more neutrophil infiltration and more damaged lung tissue compared with IgG vehicle-treated mice 40. Taken together, in the present study MODS seemed more related to anti-inflammatory proteins than to proinflammatory proteins.…”

Early local neutralization of CC16 in sepsis‑induced ALI following blunt chest trauma leads to delayed mortality without benefitting overall survival

“…For TxT, mice underwent general mask anesthesia with 3% isoflurane (Baxter Deutschland GmbH), according to partly-modified standardized protocols described previously ( 7 , 9 , 10 , 27 ). Briefly, the mice were placed in the supine position under a cylinder.…”

“…Consistent with the findings of other researchers, it was found that isolated experimental lung trauma induced a profound inflammatory reaction; however, it was insufficient to establish the ongoing pathological pulmonary changes associated with ALI ( 7 , 8 ). However, secondary CLP following TxT, as applied herein, reflected the human etiology of indirect lung damage ending in ALI ( 7 , 9 - 11 ). Another murine 'double-hit' model that includes CLP, followed by inducing pneumonia via Pseudomonas aeruginosa 4-7 days later, significantly improved survival when pneumonia was induced after 7 days.…”

“…However, CC16 may also play a pathological role in immunoparalysis with concomitant post-traumatic infectious complications ( 25 ). This role was addressed in a recent study by the authors, which demonstrated the anti-inflammatory effects of CC16 on CLP-induced ALI following TxT in mice ( 9 ). While the early intrapulmonary inhibition of CC16 following TxT reduced lung damage, the later inhibition of CC16 deteriorated lung damage after 24 h. However, it remains questionable whether the latter may have been followed by reduced lung damage in a prolonged observational period.…”

Acute Respiratory Distress Syndrome (ARDS): Pathophysiological Insights and Lung Imaging

“…Störmann and colleagues [17] studied a biomarker named club cell protein 16 (CC16) deriving from lung epithelial club cells that has anti-inflammatory tasks. The systemic concentrations of CC correlate with the extent of pulmonary contusion in traumatized patients.…”