Regulatory effect and mechanisms of carbon monoxide-releasing molecule II on hepatic energy metabolism in septic mice

An Overview of the Potential Therapeutic Applications of CO-Releasing Molecules

Carbon monoxide (CO) has long been known as the “silent killer” owing to its ability to form carboxyhemoglobin—the main cause of CO poisoning in humans. Its role as an endogenous neurotransmitter, however, was suggested in the early 1990s. Since then, the biological activity of CO has been widely examined via both the direct administration of CO and in the form of so-called “carbon monoxide releasing molecules (CORMs).” This overview will explore the general physiological effects and potential therapeutic applications of CO when delivered in the form of CORMs.

Ultraviolet-A1 irradiation therapy for systemic lupus erythematosus

Systemic lupus erythematosus (lupus, SLE) is a chronic autoimmune disease characterized by the production of autoantibodies, which bind to antigens and are deposited within tissues to fix complement, resulting in widespread systemic inflammation. The studies presented herein are consistent with hyperpolarized, adenosine triphosphate (ATP)-deficient mitochondria being central to the disease process. These hyperpolarized mitochondria resist the depolarization required for activation-induced apoptosis. The mitochondrial ATP deficits add to this resistance to apoptosis and also reduce the macrophage energy that is needed to clear apoptotic bodies. In both cases, necrosis, the alternative pathway of cell death, results. Intracellular constituents spill into the blood and tissues, eliciting inflammatory responses directed at their removal. What results is “autoimmunity.” Ultraviolet (UV)-A1 photons have the capacity to remediate this aberrancy. Exogenous exposure to low-dose, full-body, UV-A1 radiation generates singlet oxygen. Singlet oxygen has two major palliative actions in patients with lupus and the UV-A1 photons themselves have several more. Singlet oxygen depolarizes the hyperpolarized mitochondrion, triggering non-ATP-dependent apoptosis that deters necrosis. Next, singlet oxygen activates the gene encoding heme oxygenase (HO-1), a major governor of systemic homeostasis. HO-1 catalyzes the degradation of the oxidant heme into biliverdin (converted to bilirubin), Fe, and carbon monoxide (CO), the first three of these exerting powerful antioxidant effects, and in conjunction with a fourth, CO, protecting against injury to the coronary arteries, the central nervous system, and the lungs. The UV-A1 photons themselves directly attenuate disease in lupus by reducing B cell activity, preventing the suppression of cell-mediated immunity, slowing an epigenetic progression toward SLE, and ameliorating discoid and subacute cutaneous lupus. Finally, a combination of these mechanisms reduces levels of anticardiolipin antibodies and protects during lupus pregnancy. Capping all of this is that UV-A1 irradiation is an essentially innocuous, highly manageable, and comfortable therapeutic agency.

Neuropathological Correlates of Hyperglycemia During Prolonged Polymicrobial Sepsis in Mice

Glucose toxicity may play a crucial role in evoking neurologic complications of critical illness. We studied whether the neuropathological alterations in fatal human critical illness observed under hyperglycemia are present and can be attenuated by maintaining normoglycemia in a mouse model of prolonged sepsis induced by cecal ligation and puncture. Mice were randomized to moderate hyperglycemia (>8.3 mmol/L, n = 8) or normoglycemia (4.4-6.7 mmol/L, n = 8). After 5 days, hippocampus and frontal cortex from septic mice were compared with those from healthy controls (n = 8). Blood glucose was 7.8 ± 1.3 mmol/L in hyperglycemic and 6.1 ± 0.7 mmol/L in normoglycemic critically ill mice (P = 0.007). The percentage of damaged neurons was twofold higher in frontal cortex (P = 0.01) and hippocampus (P = 0.06) of hyperglycemic ill mice than that of healthy mice. In frontal cortex, neuronal damage was attenuated under normoglycemia (P = 0.04). Critical illness reduced astrocyte density and activation status fourfold in hippocampus (P ≤ 0.02), but not in frontal cortex, irrespective of glycemic control. Microglia were twofold to fourfold more abundant in both brain areas of hyperglycemic critically ill mice (P ≤ 0.002), but only in frontal cortex were they reduced in number with normoglycemia (P = 0.0008). The density of apoptotic cells and abundance of carbonylated proteins were significantly higher than normal in frontal cortex of hyperglycemic ill mice only (P = 0.05). In a mouse model of prolonged polymicrobial sepsis, remarkable neuropathological changes develop with neuronal damage, impaired astrocyte activation, increased microglia, apoptosis, and accumulation of carbonylated proteins. These changes were partially prevented or attenuated when hyperglycemia was prevented with insulin. Frontal cortex appeared more vulnerable to hyperglycemic insults than hippocampus.