Extracellular chromatin, for example in the form of neutrophil extracellular traps (NETs), is an important element that propels the pathological progression of a plethora of diseases. DNA drives the interferon system, serves as autoantigen, and forms the extracellular scaffold for proteins of the innate immune system. An insufficient clearance of extruded chromatin after the release of DNA from the nucleus into the extracellular milieu can perform a secret task of moonlighting in immune-inflammatory and occlusive disorders. Here, we discuss (I) the cellular events involved in the extracellular release of chromatin and NET formation, (II) the devastating consequence of a dysregulated NET formation, and (III) the imbalance between NET formation and clearance. We include the role of NET formation in the occlusion of vessels and ducts, in lung disease, in autoimmune diseases, in chronic oral disorders, in cancer, in the formation of adhesions, and in traumatic spinal cord injury. To develop effective therapies, it is of utmost importance to target pathways that cause decondensation of chromatin during exaggerated NET formation and aggregation. Alternatively, therapies that support the clearance of extracellular chromatin are conceivable.

Phagocytosis, degranulation, and neutrophil extracellular traps (NETs) formation build the armory of neutrophils for the first line of defense against invading pathogens. All these processes are modulated by the microenvironment including tonicity, pH and oxygen levels. Here we investigated the neutrophil infiltration in cardiac tissue autopsy samples of patients with acute myocardial infarction (AMI) and compared these with tissues from patients with sepsis, endocarditis, dermal inflammation, abscesses and diseases with prominent neutrophil infiltration. We observed many neutrophils infiltrating the heart muscle after myocardial infarction. Most of these had viable morphology and only few showed signs of nuclear de-condensation, a hallmark of early NET formation. The abundance of NETs was the lowest in acute myocardial infarction when compared to other examined diseases. Since cardiac oxygen supply is abruptly abrogated in acute myocardial infarction, we hypothesized that the resulting tissue hypoxia increased the longevity of the neutrophils. Indeed, the viable cells showed increased nuclear hypoxia inducible factor-1α (HIF-1α) content, and only neutrophils with low HIF-1α started the process of NET formation (chromatin de-condensation and nuclear swelling). Prolonged neutrophil survival, increased oxidative burst and reduced NETs formation were reproduced under low oxygen tensions and by HIF-1α stabilization in vitro. We conclude that nuclear HIF-1α is associated with prolonged neutrophil survival and enhanced oxidative stress in hypoxic areas of AMI.

Background The COVID-19 pandemic caused a global health crisis in 2020. This pandemic also had a negative impact on standard procedures in general surgery. Surgeons were challenged to find the best treatment plans for patients with acute cholecystitis. The aim of this study is to investigate the impact of the COVID-19 pandemic on the outcomes of laparoscopic cholecystectomies performed in a tertiary care hospital in Germany. Patients and methods We examined perioperative outcomes of patients who underwent laparoscopic cholecystectomy during the pandemic from March 22, 2020 (first national lockdown in Germany) to December 31, 2020. We then compared these to perioperative outcomes from the same time frame of the previous year. Results A total of 182 patients who underwent laparoscopic cholecystectomy during the above-mentioned periods were enrolled. The pandemic group consisted of 100 and the control group of 82 patients. Subgroup analysis of elderly patients (> 65 years old) revealed significantly higher rates of acute [5 (17.9%) vs. 20 (58.8%); p = 0.001] and gangrenous cholecystitis [0 (0.0%) vs. 7 (20.6%); p = 0.013] in the “pandemic subgroup”. Furthermore, significantly more early cholecystectomies were performed in this subgroup [5 (17.9%) vs. 20 (58.8%); p = 0.001]. There were no significant differences between the groups both in the overall and subgroup analysis regarding the operation time, intraoperative blood loss, length of hospitalization, morbidity and mortality. Conclusion Elderly patients showed particularly higher rates of acute and gangrenous cholecystitis during the pandemic. Laparoscopic cholecystectomy can be performed safely in the COVID-19 era without negative impact on perioperative results. Therefore, we would assume that laparoscopic cholecystectomy can be recommended for any patient with acute cholecystitis, including the elderly.