Methane Admixture Protects Liver Mitochondria and Improves Graft Function after Static Cold Storage and Reperfusion

Mitochondria are targets of cold ischemia-reperfusion (IR), the major cause of cell damage during static cold preservation of liver allografts. The bioactivity of methane (CH4) has recently been recognized in various hypoxic and IR conditions as having influence on many aspects of mitochondrial biology. We therefore hypothesized that cold storage of liver grafts in CH4-enriched preservation solution can provide an increased defence against organ dysfunction in a preclinical rat model of liver transplantation. Livers were preserved for 24 h in cold histidine–tryptophan–ketoglutarate (HTK) or CH4-enriched HTK solution (HTK-CH4) (n = 24 each); then, viability parameters were monitored for 60 min during normothermic isolated reperfusion and perfusate and liver tissue were collected. The oxidative phosphorylation capacity and extramitochondrial Ca2+ movement were measured by high resolution respirometry. Oxygen and glucose consumption increased significantly while hepatocellular damage was decreased in the HTK-CH4 grafts compared to the HTK group. Mitochondrial oxidative phosphorylation capacity was more preserved (128.8 ± 31.5 pmol/s/mL vs 201.3 ± 54.8 pmol/s/mL) and a significantly higher Ca2+ flux was detected in HTK-CH4 storage (2.9 ± 0.1 mV/s) compared to HTK (2.3 ± 0.09 mV/s). These results demonstrate the direct effect of CH4 on hepatic mitochondrial function and extramitochondrial Ca2+ fluxes, which may have contributed to improved graft functions and a preserved histomorphology after cold IR

Molecular and Functional Characterization of Hv1 Proton Channel in Human Granulocytes

Voltage-gated proton current (IHv) has been characterized in several cell types, but the majority of the data was collected in phagocytes, especially in human granulocytes. The prevailing view about the role of IHv in phagocytes is that it is an essential supporter of the intense and sustained activity of Nox2 (the core enzyme of the phagocyte NADPH oxidase complex) during respiratory burst. Recently Hv1, a voltage-gated proton channel, was cloned, and leukocytes from Hv1 knockout mice display impaired respiratory burst. On the other hand, hardly anything is known about Hv1 in human granulocytes. Using qPCR and a self made antibody, we detected a significant amount of Hv1 in human eosinophil and neutrophil granulocytes and in PLB-985 leukemia cells. Using different crosslinking agents and detergents in reducing and non-reducing PAGE, significant expression of Hv1 homodimers, but not that of higher-order multimers, could be detected in granulocytes. Results of subcellular fractionation and confocal imaging indicate that Hv1 is resident in both plasmalemmal and granular membrane compartments of resting neutrophils. Furthermore, it is also demonstrated that Hv1 accumulates in phagosome wall during zymosan engulfment together with, but independently of Nox2. During granulocytic differentiation early and parallel upregulation of Hv1 and Nox2 expression was observed in PLB-985 cells. The upregulation of Hv1 or Nox2 expression did not require the normal expression of the other molecule. Using RNA interference, we obtained strong correlation between Hv1 expression and IHv density in PLB-985 cells. It is also demonstrated that a massive reduction in Hv1 expression can limit the Nox2 mediated superoxide production of PLB-985 granulocytes. In summary, beside monomers native Hv1 forms stable proton channel dimer in resting and activated human granulocytes. The expression pattern of Hv1 in granulocytes is optimized to support intense NADPH oxidase activity

Mitochondrial Side Effects of Surgical Prophylactic Antibiotics Ceftriaxone and Rifaximin Lead to Bowel Mucosal Damage

Despite their clinical effectiveness, a growing body of evidence has shown that many classes of antibiotics lead to mitochondrial dysfunction. Ceftriaxone and Rifaximin are first choice perioperative antibiotics in gastrointestinal surgery targeting fundamental processes of intestinal bacteria; however, may also have negative consequences for the host cells. In this study, we investigated their direct effect on mitochondrial functions in vitro, together with their impact on ileum, colon and liver tissue. Additionally, their impact on the gastrointestinal microbiome was studied in vivo, in a rat model. Rifaximin significantly impaired the oxidative phosphorylation capacity (OxPhos) and leak respiration in the ileal mucosa, in line with increased oxidative tissue damage and histological changes following treatment. Ceftriaxone prophylaxis led to similar changes in the colon mucosa. The composition and diversity of bacterial communities differed extensively in response to antibiotic pre-treatment. However, the relative abundances of the toxin producing species were not increased. We have confirmed the harmful effects of prophylactic doses of Rifaximin and Ceftriaxone on the intestinal mucosa and that these effects were related to the mitochondrial dysfunction. These experiments raise awareness of mitochondrial side effects of these antibiotics that may be of clinical importance when evaluating their adverse effects on bowel mucosa

Hypermucinosus és kehelysejtszegény, gyulladásos bélbetegséghez társult, non-conventionalis dysplasia colorectalis adenocarcinoma mellett [Hypermucinous and goblet cell-deficient, IBD-associated, non-conventional dysplasia besides colorectal adenocarcinoma]

A gyulladásos bélbetegséggel (IBD) élő betegekben a colorectalis carcinoma kialakulásának esélye az átlagpopulációban észleltek kétszerese. Az invazív daganatokat megelőzően ezekben a betegekben nagyobb a rizikó dysplasia kialakulására is. Az utóbbi években számos, IBD-hez társult, ún. non-conventionalis dysplasia altípust azonosítottak, melyekről a jelenleg is zajló kutatásoknak köszönhetően egyre több információval rendelkezünk. Egy 62 éves, 14 éve relabáló colitis ulcerosával diagnosztizált és kezelt nőbeteg subtotalis colectomiás preparátumában colitis ulcerosa mellett a sigmabélben invazív adenocarcinomát azonosítottunk mucinosus területekkel. A daganat közvetlen környezetében kehelysejtszegény, valamint hypermucinosus IBD-hez társult, non-conventionalis dysplasiát észleltünk, az utóbbinak intestinalis és foveolaris altípusa is elkülöníthető volt. A felhalmozódó ismeretek tükrében az IBD-hez társult, non-conventionalis dysplasiák ismerete több szempontból is fontos lehet a diagnosztikában és a klinikai ellátásban, ugyanis ezek a laesiók makroszkóposan laposak vagy láthatatlanok lehetnek, megnehezítve a dysplasia endoszkópos szűrését. Ismeretük a patológus számára kiemelten fontos, hiszen a reaktív és reparatív folyamatoktól való elkülönítésük sokszor nagy kihívást jelent. Továbbá, a hagyományos típusoknál gyakrabban társultak ’high-grade’ dysplasiával, valamint colorectalis carcinomával. Molekuláris hátterüket tekintve, sokkal gyakrabban észlelhető bennük aneuploidia. Mindezen ismeretek a hagyományos neoplasiákhoz képest rosszabb prognózis rizikót vetítenek elő, és az esetlegesen nehezen azonosítható endoszkópos képüket is figyelembe véve felismerésük után az IBD-s betegek szorosabb utánkövetése és esetleges véletlenszerű biopsziás mintavétel mérlegelendő. Orv Hetil. 2023; 164(51): 2039–2044

Methane Admixture Protects Liver Mitochondria and Improves Graft Function after Static Cold Storage and Reperfusion

Mitochondria are targets of cold ischemia-reperfusion (IR), the major cause of cell damage during static cold preservation of liver allografts. The bioactivity of methane (CH4) has recently been recognized in various hypoxic and IR conditions as having influence on many aspects of mitochondrial biology. We therefore hypothesized that cold storage of liver grafts in CH4-enriched preservation solution can provide an increased defence against organ dysfunction in a preclinical rat model of liver transplantation. Livers were preserved for 24 h in cold histidine–tryptophan–ketoglutarate (HTK) or CH4-enriched HTK solution (HTK-CH4) (n = 24 each); then, viability parameters were monitored for 60 min during normothermic isolated reperfusion and perfusate and liver tissue were collected. The oxidative phosphorylation capacity and extramitochondrial Ca2+ movement were measured by high resolution respirometry. Oxygen and glucose consumption increased significantly while hepatocellular damage was decreased in the HTK-CH4 grafts compared to the HTK group. Mitochondrial oxidative phosphorylation capacity was more preserved (128.8 ± 31.5 pmol/s/mL vs 201.3 ± 54.8 pmol/s/mL) and a significantly higher Ca2+ flux was detected in HTK-CH4 storage (2.9 ± 0.1 mV/s) compared to HTK (2.3 ± 0.09 mV/s). These results demonstrate the direct effect of CH4 on hepatic mitochondrial function and extramitochondrial Ca2+ fluxes, which may have contributed to improved graft functions and a preserved histomorphology after cold IR

Mitochondrial Side Effects of Surgical Prophylactic Antibiotics Ceftriaxone and Rifaximin Lead to Bowel Mucosal Damage

Despite their clinical effectiveness, a growing body of evidence has shown that many classes of antibiotics lead to mitochondrial dysfunction. Ceftriaxone and Rifaximin are first choice perioperative antibiotics in gastrointestinal surgery targeting fundamental processes of intestinal bacteria; however, may also have negative consequences for the host cells. In this study, we investigated their direct effect on mitochondrial functions in vitro, together with their impact on ileum, colon and liver tissue. Additionally, their impact on the gastrointestinal microbiome was studied in vivo, in a rat model. Rifaximin significantly impaired the oxidative phosphorylation capacity (OxPhos) and leak respiration in the ileal mucosa, in line with increased oxidative tissue damage and histological changes following treatment. Ceftriaxone prophylaxis led to similar changes in the colon mucosa. The composition and diversity of bacterial communities differed extensively in response to antibiotic pre-treatment. However, the relative abundances of the toxin producing species were not increased. We have confirmed the harmful effects of prophylactic doses of Rifaximin and Ceftriaxone on the intestinal mucosa and that these effects were related to the mitochondrial dysfunction. These experiments raise awareness of mitochondrial side effects of these antibiotics that may be of clinical importance when evaluating their adverse effects on bowel mucosa