Exacerbated autoimmune hepatitis successfully treated with leukocytapheresis and bilirubin adsorption therapy

Nrf2/ARE axis signalling in hepatocyte cellular death

The Nrf2-ARE transcriptional pathway plays an important role amongst cellular defence systems regulating and ensuring adequacy of redox responses and oxidant signalling factors. Hepatocyte cellular death and injury is a prominent feature underlying liver pathologies. Diverse endogenous molecules and targets contribute to the outcome of cell survival and the consequent mode of cell death. Several research efforts focused on the confirmation of Nrf2 presence in cell death and its vital necessity against cell compromise, however, little they comprehend of such participation. Hepatocyte cell death modes discussed in this review including autophagy, apoptosis, necrosis, ferroptosis, pyroptosis, fibrosis and others, vary in response of the stimuli burdened. The current review presents a handful of highlights and crosstalk involved in the communication of Nrf2 signalling network with the "up to date" reported hepatocyte cell death modes and their underling mechanisms, and addressing key cellular networks of hepatocyte fate, through a perspective of Nrf2 as a critical transcriptional factor. Collectively, labelling the cross-transduction of Nrf2-ARE axis with key cell execution pathways could provide insights to therapeutic interventions and better research outcomes.

An Overview of Nrf2 Signaling Pathway and Its Role in Inflammation

Inflammation is a key driver in many pathological conditions such as allergy, cancer, Alzheimer’s disease, and many others, and the current state of available drugs prompted researchers to explore new therapeutic targets. In this context, accumulating evidence indicates that the transcription factor Nrf2 plays a pivotal role controlling the expression of antioxidant genes that ultimately exert anti-inflammatory functions. Nrf2 and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH- associated protein 1 (Keap1), play a central role in the maintenance of intracellular redox homeostasis and regulation of inflammation. Interestingly, Nrf2 is proved to contribute to the regulation of the heme oxygenase-1 (HO-1) axis, which is a potent anti-inflammatory target. Recent studies showed a connection between the Nrf2/antioxidant response element (ARE) system and the expression of inflammatory mediators, NF-κB pathway and macrophage metabolism. This suggests a new strategy for designing chemical agents as modulators of Nrf2 dependent pathways to target the immune response. Therefore, the present review will examine the relationship between Nrf2 signaling and the inflammation as well as possible approaches for the therapeutic modulation of this pathway.

Autoimmune hepatitis: Standard treatment and systematic review of alternative treatments

Autoimmune hepatitis is a rare chronic inflammatory liver disease, affecting all ages, characterised by elevated transaminase and immunoglobulin G levels, positive autoantibodies, interface hepatitis at liver histology and good response to immunosuppressive treatment. If untreated, it has a poor prognosis. The aim of this review is to summarize the evidence for standard treatment and to provide a systematic review on alternative treatments for adults and children. Standard treatment is based on steroids and azathioprine, and leads to disease remission in 80%-90% of patients. Alternative first line treatment has been attempted with budesonide or cyclosporine, but their superiority compared to standard treatment remains to be demonstrated. Second-line treatments are needed for patients not responding or intolerant to standard treatment. No randomized controlled trials have been performed for second-line options. Mycophenolate mofetil is the most widely used second-line drug, and has good efficacy particularly for patients intolerant to azathioprine, but has the major disadvantage of being teratogenic. Only few and heterogeneous data on cyclosporine, tacrolimus, everolimus and sirolimus are available. More recently, experience with the anti-tumour necrosis factor-alpha infliximab and the anti-CD20 rituximab has been published, with ambivalent results; these agents may have severe side-effects and their use should be restricted to specialized centres. Clinical trials with new therapeutic options are ongoing.

Nrf2 signaling pathway: Pivotal roles in inflammation

Inflammation is the most common feature of many chronic diseases and complications, while playing critical roles in carcinogenesis. Several studies have demonstrated that Nrf2 contributes to the anti-inflammatory process by orchestrating the recruitment of inflammatory cells and regulating gene expression through the antioxidant response element (ARE). The Keap1 (Kelch-like ECH-associated protein)/Nrf2 (NF-E2 p45-related factor 2)/ARE signaling pathway mainly regulates anti-inflammatory gene expression and inhibits the progression of inflammation. Therefore, the identification of new Nrf2-dependent anti-inflammatory phytochemicals has become a key point in drug discovery. In this review, we discuss the members of the Keap1/Nrf2/ARE signal pathway and its downstream genes, the effects of this pathway on animal models of inflammatory diseases, and crosstalk with the NF-κB pathway. In addition we also discuss about the regulation of NLRP3 inflammasome by Nrf2. Besides this, we summarize the current scenario of the development of anti-inflammatory phytochemicals and others that mediate the Nrf2/ARE signaling pathway.

The Role of Nrf2 in Cellular Innate Immune Response to Inflammatory Injury

Nuclear factor erythroid derived 2-related factor-2 (Nrf2) is a master transcription regulator of antioxidant and cytoprotective proteins that mediate cellular defense against oxidative and inflammatory stresses. Disruption of cellular stress response by Nrf2 deficiency causes enhanced susceptibility to infection and related inflammatory diseases as a consequence of exacerbated immuneediated hypersensitivity and autoimmunity. The cellular defense capacity potentiated by Nrf2 activation appears to balance the population of CD4⁺ and CD8⁺ of lymph node cells for proper innate immune responses. Nrf2 can negatively regulate the activation of pro-inflammatory signaling molecules such as p38 MAPK, NF-KB, and AP-1. Nrf2 subsequently functions to inhibit the production of pro-inflammatory mediators including cytokines, chemokines, cell adhesion molecules, matrix metalloprotein-ases, COX-2 and iNOS. Although not clearly elucidated, the antioxidative function of genes targeted by Nrf2 may cooperatively regulate the innate immune response and also repress the expression of proinflammatory mediators.

A protective role of nuclear factor-erythroid 2-related factor-2 (Nrf2) in inflammatory disorders

Nuclear factor-erythroid 2-related factor-2 (Nrf2) is a key transcription factor that plays a central role in cellular defense against oxidative and electrophilic insults by timely induction of antioxidative and phase-2 detoxifying enzymes and related stress-response proteins. The 5'-flanking regions of genes encoding these cytoprotective proteins contain a specific consensus sequence termed antioxidant response element (ARE) to which Nrf2 binds. Recent studies have demonstrated that Nrf2-ARE signaling is also involved in attenuating inflammation-associated pathogenesis, such as autoimmune diseases, rheumatoid arthritis, asthma, emphysema, gastritis, colitis and atherosclerosis. Thus, disruption or loss of Nrf2 signaling causes enhanced susceptibility not only to oxidative and electrophilic stresses but also to inflammatory tissue injuries. During the early-phase of inflammation-mediated tissue damage, activation of Nrf2-ARE might inhibit the production or expression of pro-inflammatory mediators including cytokines, chemokines, cell adhesion molecules, matrix metalloproteinases, cyclooxygenase-2 and inducible nitric oxide synthase. It is likely that the cytoprotective function of genes targeted by Nrf2 may cooperatively regulate the innate immune response and also repress the induction of pro-inflammatory genes. This review highlights the protective role of Nrf2 in inflammation-mediated disorders with special focus on the inflammatory signaling modulated by this redox-regulated transcription factor.

Features associated with treatment failure in type 1 autoimmune hepatitis and predictive value of the model of end-stage liver disease

Autoimmune hepatitis may fail to respond to corticosteroid therapy, but the frequency and bases for this outcome are uncertain. We aimed to determine the frequency and nature of treatment failure in patients with type 1 autoimmune hepatitis, define features associated with its occurrence, and assess if the model for end-stage liver disease can predict this outcome. Patients failing conventional corticosteroid regimens were compared to patients who responded to similar regimens. Fourteen of 214 patients (7%) failed corticosteroid treatment. Patients who failed therapy were younger (33 +/- 3 years versus 48 +/- 1 years, P = 0.0008), had higher serum levels of bilirubin at accession (4.1 +/- 0.9 mg/dL versus 2.3 +/- 0.2 mg/dL, P = 0.02), presented acutely more frequently (43% versus 14%, P = 0.01), and had a higher frequency of HLA (human leukocyte antigen) DRB1*03 (93% versus 53%, P = 0.004) than did patients who achieved remission. An alternative disease (fatty liver disease) emerged in only 1 patient who failed therapy (7%). Scores determined by the model of end-stage liver disease at presentation of patients who failed treatment were higher than those of who achieved remission (16 +/- 1 versus 10 +/- 0.3 points, P < 0.0001), and score greater than 12 points had greater sensitivity (97%) and specificity (68%) for treatment failure than did HLA DRB1*03 or other features.

CONCLUSION

Onset at an early age, acute presentation, hyperbilirubinemia, and presence of HLA DRB1*03 characterize patients who fail corticosteroid treatment. The model for end-stage liver disease may be a useful instrument for identifying patients prone to this outcome.

Leukocytapheresis (LCAP) in the management of chronic active ulcerative colitis--results of a randomized pilot trial

Recent studies suggest that leukocytapheresis with Cellsorba is a valuable therapy for ulcerative colitis after failure of conventional treatment. In this study the potential of leukocytapheresis to induce remission in refractory chronic colitis under the conditions of European treatment guidelines was investigated. The therapeutic benefit of leukocytapheresis in the maintenance of remission was additionally elucidated. Twenty patients were treated weekly for 5 weeks. A significant decrease in the activity index was observed. Fourteen patients achieved clinical remission, and mucosal healing was observed endoscopically in six patients. After randomization these 14 patients in remission entered a second period of either monthly leukocytapheresis or no further treatment. In both groups steroids were tapered down. After 6 months, only one patient in the control group remained in remission, in contrast to five of eight patients in the leukocytapheresis group. In conclusion, leukocytapheresis may offer a therapeutic option in the induction and the maintenance of remission in chronic active ulcerative colitis.

Autoimmune liver disease

The incidence and prevalence of autoimmune hepatitis are greater than expected among white northern Europeans. Patients with type 2 autoimmune hepatitis have different HLA frequencies than patients with type 1 disease and HLA-DRB1*07 may be an important risk factor. Hepatitis C virus can trigger autoimmune hepatitis after needlestick inoculation. Elderly patients have milder disease than young patients and they are frequently untreated. Cryptogenic chronic hepatitis is indistinguishable from autoimmune hepatitis and it responds as well to corticosteroids. Variant syndromes are common and the degree of cholestasis influences the treatment response. Endomysial antibodies indicate celiac sprue in asymptomatic patients, and multiple endocrinopathies in individuals with type 2 disease may reflect molecular mimicries and cross-reacting autoantibodies. Phase I (cytochromes P-450) and phase II (uridine diphosphate glucuronosyltransferases) drug-metabolizing enzymes are the autoantigens of syndromes characterized by liver/kidney microsomal autoantibodies. T-cell vaccination prevents the occurrence of experimental hepatitis in mice and it can also treat the disease. Liver transplantation can be complicated by recurrent disease, frequent allograft rejection, and de novo autoimmune hepatitis.

Complications of leukocytapheresis

Recently leukocytapheresis (LCAP) has attracted attention as a new therapy for ulcerative colitis. We reviewed the complications associated with LCAP carried out in our department during the period from December 1992 to September 1997. There were side effects during 195 (9.9%) of the 1,978 sessions performed, involving 47 (51.1%) of the 92 patients treated. Moderate reactions, which caused considerable discomfort to the patients and required the transient interruption of the administration or some medical treatment depending on the state, occurred during 31 (1.6%) of all therapy sessions, involving 15 (16%) patients. All patients recovered soon and never fell into a life-threateningly severe state. They also did not have any symptoms afterwards. The common side effects were nausea, vomiting, fever, chills, and nasal obstruction. Reactions such as palpitations, respiratory distress, or chest oppressions were common, especially when heparin sodium (HS) was used as the anticoagulant. The type and frequency of side effects depended somewhat on the length of the therapy series or the duration of one session. Other complications such as clotting in the leukocyte removal filter and/or blood line during administration were encountered frequently. These latter problems occurred during 46% of all sessions, but most of them had little significance. Sessions in which HS was used as the anticoagulant showed more severe clotting than those in which nafamostat mesilate (NM) was used. In our series, we experienced a relatively low rate of serious complications. We require, of course, careful observation during and after each session.

Therapeutic cytapheresis for inflammatory bowel disease

Cytapheresis therapy has recently been investigated as a treatment for several diseases, especially autoimmune related diseases such as rheumatoid arthritis, systemic lupus erythematosus, and inflammatory bowel disease. The removal of leukocyte components has been performed by the centrifugal method; however, using fiber technology or column technology, leukocyte components can be removed simply, and these technologies are more effective than the centrifugal method in removing numbers of cells. Each of 3 types of leukocytapheresis methods removes a different kind of cell in its therapeutic principle. Thus, if we understand what kind of cells should be removed, we can choose the best method for removing leukocytes. For this reason, the authors propose an international standard for unifying names. The therapy that makes use of a centrifuge to selectively remove about 40% of neutrophils and more than 60% of lymphocytes may be called a lymphocyte removal therapy, lymphocytapheresis (LCA). Using cellulose acetate beads in a G-1 granulocyte removal column, granulocytes and monocytes are removed but not lymphocytes, so we suggest calling this granulocytapheresis (GCAP). In addition, using a leukocyte removal filter, the Cellsorba leukocyte removal filter, 99% of both granulocytes and monocytes and about 70% of lymphocytes are removed. We propose calling this leukocytapheresis (LCAP). In the near future, we hope that we will be able to select one of these methods for cytapheresis for each disease pathogenesis or cellular immune abnormality. Presently, a lot of research is on-going to analyze how cytapheresis is effective for the immune related diseases. The mechanism of cytapheresis will be clarified by investigators. We strongly believe that cytapheresis therapies offer good news to those patients suffering from incurable diseases as well as their physicians.