Primary biliary cirrhosis is a generalized autoimmune epithelitis

Primary Sjögren's syndrome: new perspectives on salivary gland epithelial cells

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease primarily affecting exocrine glands such as the salivary glands, leading to impaired secretion and sicca symptoms. As the mainstay of salivation, salivary gland epithelial cells (SGECs) have an important role in the pathology of pSS. Emerging evidence suggests that the interplay between immunological factors and SGECs may not be the initial trigger or the sole mechanism responsible for xerostomia in pSS, challenging conventional perceptions. To deepen our understanding, current research regarding SGECs in pSS was reviewed. Among the extensive aberrations in cellular architecture and function, this review highlighted certain alterations of SGECs that were identified to occur independently of or in absence of lymphocytic infiltration. In particular, some of these alterations may serve as upstream factors of immuno-inflammatory responses. These findings underscore the significance of introspecting the pathogenesis of pSS and developing interventions targeting SGECs in the early stages of the disease.

Pharmacokinetics and ADME Characterization of Intravenous and Oral [14C]-Linerixibat in Healthy Male Volunteers

Linerixibat, an oral small-molecule ileal bile acid transporter inhibitor under development for cholestatic pruritus in primary biliary cholangitis, was designed for minimal absorption from the intestine (site of pharmacological action). This study characterized the pharmacokinetics, absorption, metabolism, and excretion of [¹⁴C]-linerixibat in humans after an intravenous microtracer concomitant with unlabeled oral tablets and [¹⁴C]-linerixibat oral solution. Linerixibat exhibited absorption-limited flip-flop kinetics: longer oral versus intravenous half-life (6-7 hours vs. 0.8 hours). The short intravenous half-life was consistent with high systemic clearance (61.9 l/h) and low volume of distribution (16.3 l). In vitro studies predicted rapid hepatic clearance via cytochrome P450 3A4 metabolism, which predicted human hepatic clearance within 1.5-fold. However, linerixibat was minimally metabolized in humans after intravenous administration: ∼80% elimination via biliary/fecal excretion (>90%-97% as unchanged parent) and ∼20% renal elimination by glomerular filtration (>97% as unchanged parent). Absolute oral bioavailability of linerixibat was exceedingly low (0.05%), primarily because of a very low fraction absorbed (0.167%; fraction escaping first-pass gut metabolism (fg) ∼100%), with high hepatic extraction ratio (77.0%) acting as a secondary barrier to systemic exposure. Oral linerixibat was almost entirely excreted (>99% recovered radioactivity) in feces as unchanged and unabsorbed linerixibat. Consistent with the low oral fraction absorbed and ∼20% renal recovery of intravenous [¹⁴C]-linerixibat, urinary elimination of orally administered radioactivity was negligible (<0.04% of dose). Linerixibat unequivocally exhibited minimal gastrointestinal absorption and oral systemic exposure. Linerixibat represents a unique example of high CYP3A4 clearance in vitro but nearly complete excretion as unchanged parent drug via the biliary/fecal route. SIGNIFICANCE STATEMENT: This study conclusively established minimal absorption and systemic exposure to orally administered linerixibat in humans. The small amount of linerixibat absorbed was eliminated efficiently as unchanged parent drug via the biliary/fecal route. The hepatic clearance mechanism was mispredicted to be mediated via cytochrome P450 3A4 metabolism in vitro rather than biliary excretion of unchanged linerixibat in vivo.

Epigenetic Modifications in Generalized Autoimmune Epithelitis: Sjögren's Syndrome and Primary Biliary Cholangitis

Sjögren's syndrome (SjS) and primary biliary cholangitis (PBC) can be classified as a model of generalized autoimmune epithelitis based on their frequent coexistence in clinical practice and the highly specific immune mediated injury of target epithelial cells. Both of these autoimmune diseases are characterized by female predominance, highly specific circulating autoantibodies, and immune-mediated destruction of the salivary and lachrymal glands and the biliary epithelial cells, respectively. Although the genetic predisposition has been well described for both diseases, genetic studies have failed to completely elucidate their pathogenesis. The recent integration of epigenetic data, analyzing the different cellular partners, opens new perspectives and allows for better understanding of these complex and still incurable diseases. Epigenetic studies on SjS have elucidated the role of DNA methylation alterations in disease pathogenesis, while epigenetic changes that influence expression of genes on the X chromosome have been implicated in the geo-variability and occurrence of PBC. The aim of this review is to describe the advances in epigenetics in the field of autoimmune epithelitis as well as to highlight how epigenetic changes could contribute to better understanding of disease pathogenesis and progression. These advances could yield insights on novel therapeutic interventions.

Autoimmune associations in a Mexican cohort with primary biliary cholangitis

INTRODUCTION

Several groups have reported associations of primary biliary cholangitis with other autoimmune entities, particularly Sjögren's syndrome and hypothyroidism. Its prevalence and characteristics in Mexican patients is unknown.

AIM

To determine the frequency and characteristics of autoimmune diseases in a Mexican cohort of patients with primary biliary cholangitis.

MATERIALS AND METHODS

The medical records of patients that presented with primary biliary cholangitis within the time frame of 2005 and 2012 were reviewed and assessed for other autoimmune diseases.

RESULTS

Seventy-eight patients, 75 women and 3 men, were included. Their mean age was 55.8 years. Seventy-three cases had positive antimitochondrial antibodies (94.8%) and disease was confirmed in 5 through liver biopsy. Five patients (8%) had anti-smooth muscle antibodies and 55/78 (70.5%) had antinuclear antibodies by indirect immunofluorescence. Forty-nine patients (62.8%) were positive for an autoimmune disease other than primary biliary cholangitis. Among those, 20 patients had one associated disease, 14 had 2, and 15 patients had 3 concomitant diseases. They included: Sjögren's syndrome in 23/78 patients (29.5%), dysthyroidism in 21/78 cases (26.9%), Raynaud syndrome in 11/78 (14.1%), CREST syndrome in 9/78 patients (11.4%), rheumatoid arthritis in 6/78 patients (7.7%), vitiligo in 5/78 (6.4%), scleroderma in 4/78 patients (5.1%), and other diseases in 8 patients. In 12/78 patients (15.4%), there was a documented family background of autoimmune disease.

CONCLUSIONS

The presence of autoimmune associations in our cohort was frequent, and similar in characteristics to the information reported by other groups. The clinical implications of those findings remain to be determined.

Hormonal contraception and the development of autoimmunity: A review of the literature

Estrogens and progestins are known to have profound effects on the immune system and may modulate the susceptibility to autoimmune diseases. A comprehensive literature search was carried out using PubMed for any of 153 autoimmune disease terms and the terms contraception, contraceptive, or their chemical components with limits of Humans + Title or Abstract. Over 1,800 titles were returned and scanned, 352 papers retrieved and reviewed in depth and an additional 70 papers retrieved from the bibliographies. Based on this review, substantial evidence exists linking the use of combined oral contraceptives to a lower incidence of hyperthyroidism, an increase in multiple sclerosis, ulcerative colitis, Crohn's disease, Systemic Lupus Erythematosus, and interstitial cystitis. Progesterone only contraceptives are linked to progesterone dermatitis and in one large developing world concurrent cohort study are associated with increases in arthropathies and related disorders, eczema and contact dermatitis, pruritis and related conditions, alopecia, acne, and urticaria. Hormonal contraceptives modulate the immune system and may influence the susceptibility to autoimmune diseases with significant increases in risk for several autoimmune diseases.

SUMMARY

Hormonal contraceptives (HCs), such as the "pill," Norplant, and vaginal rings, are very potent hormones that have effects on the immune system, which is made up of white blood cells and lymph nodes and normally defends the body against invading bacteria, viruses and parasites. This review looked at the association of HC use to the development of autoimmune diseases, where the immune system turns against the body and causes damage to organs. There is good evidence that HC use is associated with an increased risk of several serious autoimmune diseases such as Crohn's disease (which causes inflammation of the bowels), Lupus (which causes inflammation in many organs), and interstitial cystitis (which causes inflammation in the bladder). Several other rarer autoimmune diseases are also linked to HC use. People contemplating the use of HCs should be informed of these risks.

Infliximab as a treatment option for patients with rheumatoid arthritis and primary biliary cirrhosis

Rheumatoid arthritis (RA) is a chronic inflammatory systemic disease which commonly requires treatment with biologic agents targeting various inflammatory pathways. Tumor necrosis factor alpha is a proinflammatory cytokine which plays a pivotal role not only in the pathogenesis of RA but also in other autoimmune diseases such as primary biliary cirrhosis. The co-existence of more than one autoimmune disorder in the same individual is very challenging in the daily practice as therapy strategies applicable to one disease setting may cause clinical and/or biochemical relapse of the other clinical entity. As a result, treatment options able to control different diseases are highly desirable among rheumatologists and other specialties. In that respect, we present a case of a 61-year-old female patient with RA and concomitant primary biliary cirrhosis with poor clinical response to conventional disease-modifying drugs for RA. The introduction of tumor necrosis factor alpha antagonist infliximab led to significant clinical improvement of RA and to stabilization of liver function. In this case review study, we discuss aspects of pathophysiology of primary biliary cirrhosis associated with tumor necrosis alpha and we review the available data of similar published cases.