Environmental pathways to autoimmune diseases: the cases of primary biliary cirrhosis and multiple sclerosis

The Role of the Unbinding Cycle on the Coordination Abilities of the Bi-Cyclopeptides toward Cu(II) Ions

Bicyclic peptides have attracted the interest of pharmaceutical companies because of their remarkable properties, putting them on a new path in medicine. Their conformational rigidity improves proteolytic stability and leads to rapid penetration into tissues via any possible route of administration. Moreover, elimination of renal metabolism is of great importance, for example, for people with a history of liver diseases. In addition, each ring can function independently, making bicyclic peptides extremely versatile molecules for further optimization. In this paper, we compared the potentiometric and spectroscopic properties studied by UV-vis, MCD, and EPR of four synthetic analogues of the bi-cyclic peptide c(PKKHP-c(CFWKTC)-PKKH) (BCL). In particular, we correlated the structural and spectral properties of complexes with coordinating abilities toward Cu(II) ions of MCL1 (Ac-PKKHPc(CFWKTC)PKKH-NH2) that contains the unbinding cycle and N- and C-terminal linear parts with two histidine residues, one per part; two monocyclic ligands containing one histidine residue, both in the N-terminal position, i.e., MCL2 (Ac-PKKHPc(CFWKTC)PKKS-NH2) and in the C-terminal position, i.e., MCL3 (Ac-PKKSPc(CFWKTC)PKKH-NH2), respectively; and the linear structure LNL (Ac-PKKHPSFWKTSPKKH-NH2). Potentiometric results have shown that the bicyclic structure promotes the involvement of the side chain imidazole donors in Cu(II) binding. On the other hand, the results obtained for the mono-cyclic analogues lead to the conclusion that the coordination of the histidine moiety as an anchoring group is promoted by its location in the peptide sequence further from the nonbinding cycle, strongly influencing the involvement of the amide donors in Cu(II) coordination.

Optimization of peptide synthesis time and sustainability using novel eco-friendly binary solvent systems with induction heating on an automated peptide synthesizer

On December 12th, 2023, the European Commission took regulatory action to amend Annex XVII of REACH, imposing restrictions on the use of N,N-dimethylformamide (DMF) within the EU market owing to its high toxicity. Historically, DMF has been widely considered the gold standard for solid-phase peptide synthesis (SPPS). Being urgent to propose alternative solvents, we tested the suitability of non-hazardous neat and mixed solvents. Notably, binary solvent mixtures containing dimethyl sulfoxide as one of the solvent partners demonstrated high efficacy in solubilizing reagents while maintaining the desired swelling characteristics of common resins. A series of binary solvent mixtures were tested in automated SPPS, both at room temperature and high temperature, employing the PurePep® Chorus synthesizer, which enabled controlled induction heating between 25 and 90°C with oscillation mixing. The performances were assessed in challenging peptide sequences, i.e., ACP (65-74), and in longer and aggregating sequences like SARS-CoV-2 RBM (436-507) and β-amyloid (1-42). Furthermore, as part of the proposed sustainable approach to minimize the utilization of hazardous solvents, we coupled the novel PurePep EasyClean catch-and-release purification technology. This work, addressing regulatory compliance, emphasizes the crucial role of green chemistry in advancing safer and more environmentally friendly practices in SPPS.

Extrahepatic autoimmune diseases in primary biliary cholangitis: Prevalence and significance for clinical presentation and disease outcome

BACKGROUND AND AIM

The prevalence and clinical significance of extrahepatic autoimmune diseases (EHAIDs) have not been evaluated in a large cohort of primary biliary cholangitis (PBC).

METHODS

The medical records of 1554 patients with PBC from 20 international centers were retrospectively reviewed. Development of decompensated cirrhosis (ascites, variceal bleeding, and/or hepatic encephalopathy) and hepatocellular carcinoma were considered clinical endpoints.

RESULTS

A total of 35 different EHAIDs were diagnosed in 440 (28.3%) patients with PBC. Patients with EHAIDs were more often female (92.5% vs 86.1%, P < 0.001) and seropositive for anti-mitochondrial antibodies (88% vs 84%, P = 0.05) and antinuclear antibodies and/or smooth muscle antibodies (53.8% vs 43.6%, P = 0.005). At presentation, patients with EHAIDs had significantly lower levels of alkaline phosphatase (1.76 vs 1.98 × upper limit of normal [ULN], P = 0.006), aspartate aminotransferase (1.29 vs 1.50 × ULN, P < 0.001), and total bilirubin (0.53 vs 0.58 × ULN, P = 0.002). Patients with EHAIDs and without EHAIDs had similar rates of GLOBE high-risk status (12.3% vs 16.1%, P = 0.07) and Paris II response (71.4% vs 69.4%, P = 0.59). Overall, event-free survival was not different in patients with and without EHAIDs (90.8% vs 90.7%, P = 0.53, log rank). Coexistence of each autoimmune thyroid diseases (10.6%), Sjögren disease (8.3%), systemic sclerosis (2.9%), rheumatoid arthritis (2.7%), systemic lupus erythematosus (1.7%), celiac disease (1.7%), psoriasis (1.5%), and inflammatory bowel diseases (1.3%) did not influence the outcome.

CONCLUSIONS

Our study confirms that EHAIDs are frequently diagnosed in patients with PBC. The presence of EHAIDs may influence the clinical phenotype of PBC at presentation but has no impact on PBC outcome.

Mesenchymal stem cells enhance autophagy of human intrahepatic biliary epithelial cells in vitro

Dysfunctional autophagy in intrahepatic biliary epithelial cells (IBECs) is the main mechanism underlying the pathogenesis of bile duct lesions in primary biliary cholangitis. Autophagy may be a key pathogenesis for aetiology of primary biliary cholangitis. Immunoblotting and immunofluorescence analyses were used for the evaluation of autophagy in human intrahepatic biliary epithelial cells (HiBECs) at various time points. Glycochenodeoxycholate (GCDC) induced autophagy in HiBECs; the ratio of microtubule-associated protein light chain 3-II/microtubule-associated protein light chain 3-I (LC3-II/LC3-I) expression markedly increased at 48 hours, and then declined. However, compared with cells treated with GCDC alone, the expression of LC3-II increased and the clearance of autophagosome enhanced in GCDC-treated cells cocultured with mesenchymal stem cells (MSCs). Furthermore, the level of phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) decreased in HiBECs cocultured with MSCs relative to those cultured without MSCs. Following STAT3 silencing, decreased expression of phosphorylated eukaryotic initiation factor 2α was consistently observed. The present data suggest that mesenchymal stem cells may enhance autophagic flux of HiBECs through the inhibition of STAT3 activity.

SIGNIFICANCE PARAGRAPH

The present findings constitute the first report that human umbilical cord-derived MSCs enhance autophagic flux in HiBECs through a STAT3-dependent way: MSCs enhance the autophagic flux by increasing the formation of autophagosome and autolysosome in GCDC-treated HiBECs. MSCs decrease the STAT3 activity and the expression of eIF2α in GCDC-treated HiBECs; in addition, MSCs increase the expression of PKR. With STAT3 silencing, MSCs enhance neither the levels of LC3II nor the expression of PKR in GCDC-treated HiBECs.

Delayed-type hypersensitivity to metals in connective tissue diseases and fibromyalgia

Rheumatic diseases include a group of autoimmune disorders with environmental and genetic etiology that are characterized as a subgroup of connective tissue diseases (CTD). Rheumatoid arthritis (RA) often involves the small joints of the hands in a symmetrical fashion that can lead to loss of joint function, and RA, as well as Sjögren's syndrome (SS) and other rheumatic diseases, are often accompanied by sensitivity to metals. Numerous investigations on metal sensitivity were evaluated in this review. A detailed metal exposure history was collected by different evaluation of studies. In all subjects, the main source of metal exposure was nickel, mercury, gold, palladium, titanium, and chromium. All of SLE (systemic lupus erythematosus), RA and SS patients appeared to have an increased frequency of metal delayed-type hypersensitivity (DTH) (Type IV allergy). As dental restorative materials release minor amounts of their metals (including mercury, gold, and nickel), many adults are commonly exposed to these metal ions by vapor or corrosion into saliva. Metal-related DTH in these patients will induce an inflammatory response. Such inflammations are important factors in CTD progress. It is hypothesized that metal-specific T cell reactivity can act as an etiological agent in the propagation and chronification of rheumatic inflammation. The key responses of metal delayed-type hypersensitivity in autoimmunity are precipitating as an appealing challenge for further investigations.

Association of vitamin D status and clinical and radiological outcomes in a treated MS population in Poland

BACKGROUND

Vitamin D influences the immune system significantly. Previous studies have found that vitamin D deficiency in adolescence can play a significant role in increasing the risk of developing autoimmune diseases including multiple sclerosis. The aim of this study was to investigate the relationship between the vitamin D status in serum and clinical and radiological outcomes in a treated population in Poland.

METHODS

Inclusion criteria met 83 adult patients aged 20-61 years with diagnosis of relapsing-remitting multiple sclerosis, who underwent immunomodulatory treatment which lasted at least 12 months. Levels of serum 25-hydroxyvitamin D were determined using radio-immuno assay. Magnetic resonance imaging of the brain and cervical part of a spinal cord was performed each time after 12 months of the treatment. Patients were assessed neurologically after 12 months of treatment, the level of disability was also assessed using Extended Disability Status Scale.

RESULTS

The largest group (63.8%) showed significant vitamin D deficiency (<20 ng/ml), 21.7% showed the suboptimal level of vitamin D (20-30 ng/ml). The normal level of 25(OH)D (>30 ng/ml) was observed in 14.5% of the patients. Statistically significant correlation was observed between the vitamin D status and frequency of relapses.

CONCLUSIONS

Our findings confirm that deficiency of vitamin D in patients with MS is correlated with clinical and radiological course of the disease.

Acute immunomodulatory changes during controlled ovarian stimulation: evidence from the first trial investigating the short-term effects of estradiol on biomarkers and B cells involved in autoimmunity

PURPOSE

The aim of the present study was to evaluate the in vivo immunomodulatory effects of an acute short-term estradiol (E(2)) increase on serum levels of B cell-activating factor (BAFF), immunoglobulins (Ig), anti-nuclear antibodies (ANA), and the peripheral B cell phenotype.

METHODS

We conducted, at the Infertility Center of the University of Padua, a prospective case-control study on a cohort of infertile normo-responder women (group-A, 63 patients) undergoing controlled ovarian stimulation (COS) compared with an age-matched cohort of normo-ovulatory healthy women (group-B, 39 patients). Three serial blood sample assays were conducted in both groups, at T0, hypothalamic suppression; T1, ovulation induction; and T2, βhCG test in group A, and at T0, 2nd day; T1, 14th day; and T2, 21st day of cycle in group B, and serum levels of E(2) and BAFF, BAFF/E(2) ratio, circulating IgM, IgG, and IgA, ANA titer, and peripheral B cell phenotype were measured. We compared group-A versus group-B in terms of absolute and E(2) normalized values of BAFF at baseline (T0) to verify for possible differences between healthy and infertile women, at T1 to verify for possible differences occurring after spontaneous ovulation versus COS, and at T2 to evaluate differences in serum BAFF levels between pregnant versus non-pregnant patients (considering only group-A) and between non-pregnant women after spontaneous versus COS cycles (group-B versus group-A). In group-A, we also evaluated IgM, IgG, IgA levels, ANA titer, and peripheral B cell phenotype at T0 versus T1 versus T2.

RESULTS

With the exception of E(2) levels at T1 (as expected), no significant differences were found between the two groups for all outcome measures. In group-A, BAFF at T0 positively correlated with IgM levels; marginal zone CD19+/CD27+/IgD+ memory B cell compartment tended to be expanded at T1 when compared with T0.

CONCLUSIONS

Despite several mechanistic and clinical studies supporting a stimulatory role of E(2) on autoimmunity, the acute increase of E(2) during COS for infertility treatment does not seem to have a major impact on the immune system.

Elevated levels of antibodies against xenobiotics in a subgroup of healthy subjects

In spite of numerous research efforts, the exact etiology of autoimmune diseases remains largely unknown. Genetics and environmental factors, including xenobiotics, are believed to be involved in the induction of autoimmune disease. Some environmental chemicals, acting as haptens, can bind to a high-molecular-weight carrier protein such as human serum albumin (HSA), causing the immune system to misidentify self-tissue as an invader and launch an immune response against it, leading to autoimmunity. This study aimed to examine the percentage of blood samples from healthy donors in which chemical agents mounted immune challenges and produced antibodies against HSA-bound chemicals. The levels of specific antibodies against 12 different chemicals bound to HSA were measured by ELISA in serum from 400 blood donors. We found that 10% (IgG) and 17% (IgM) of tested individuals showed significant antibody elevation against aflatoxin-HSA adduct. The percentage of elevation against the other 11 chemicals ranged from 8% to 22% (IgG) and 13% to 18% (IgM). Performance of serial dilution and inhibition of the chemical–antibody reaction by specific antigens but not by non-specific antigens were indicative of the specificity of these antibodies. Although we lack information about chemical exposure in the tested individuals, detection of antibodies against various protein adducts may indicate chronic exposure to these chemical haptens in about 20% of the tested individuals. Currently the pathological significance of these antibodies in human blood is still unclear, and this protein adduct formation could be one of the mechanisms by which environmental chemicals induce autoimmune reactivity in a significant percentage of the population.

Recent advances in understanding the pathogenesis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic autoimmune liver disease characterized by the destruction of small intrahepatic bile ducts and the presence of highly specific serum antimitochondrial antibodies (AMAs). The human leukocyte antigen (HLA) gene has been proved to have strongest association with PBC susceptibility, and non-HLA genes, including IL12A, IL12RB2, STAT4, IRF5-TNPO3, ORMDL3/IKZF3, MMEL1, SPIB, CTLA-4, FCRL3 and A2BP1, are also closely associated with PBC susceptibility. Four AMAs including anti-M2, anti-M4, anti-M8 and anti-M9, and antinuclear antibodies (ANAs), such as antinuclear dot antibodies (SP100, PML, NDP52, SP140), antinuclear pore antibodies (gp210, p62), antinuclear envelope antibodies (Lamin and Lamin B receptor), and anti-centromere antibodies, may also be involved in the pathogenesis of PBC. The imbalance between Th17 cells and regulatory T lymphocytes (Treg) may also play an important role in the pathogenesis of PBC. In addition, senescence, autophagy, apoptosis of biliary epithelial cells (BECs), and environmental factors, such as Epstein-Barr virus (EBV) infection and smoking, may also contribute to the pathogenesis of PBC. Understanding of the mechanisms responsible for the pathogenesis of PBC has important implications for the treatment of PBC.

Mechanisms and pathophysiology of autoimmune disease

The first textbook on autoimmunity was published by Ian Mackay and McFarland Burnett in 1963. It was the first attempt to summarize existing knowledge on human autoimmunity. Since that time, there have been tens of thousands of experimental papers and numerous textbooks that focus on the diagnosis and treatment of human autoimmunity. There have been at least as many, if not more, directed at similar issues in animal models. Enormous strides have been made not only in diagnosis, but also in the pathophysiology and especially in treatment. We have gone from the era of simple HLA typing to deep sequencing and, more recently, epigenetic analysis. We have gone from the era of white blood cell differentials to detailed lymphoid phenotyping. We have gone from the era of simple antinuclear antibodies to detailed and sophisticated immunodiagnosis with recombinant autoantigens and disease-specific epitopes. We have gone from the era of using only corticosteroids to selective biologic agents. Diseases that were previously considered idiopathic are now very much understood as autoimmune. We are in the era of autoinflammatory reactions and the concept of both innate versus adaptive immunity in mediating immunopathology. In this edition of Clinical Reviews in Allergy and Immunology, we focus on key and cutting-edge issues in the pathophysiology of autoimmunity. The issues are very much oriented and driven by hypothesis, i.e., a prediction of events expected to occur based on observations. It is not meant to be a complete summary of potential mechanisms of autoimmunity, but rather an attempt to accelerate discussion and better understanding. The primary goal is obviously to help our patients with autoimmune disease.

Mechanisms of environmental influence on human autoimmunity: a National Institute of Environmental Health Sciences expert panel workshop

The mechanisms leading to autoimmune diseases remain largely unknown despite numerous lines of experimental inquiry and epidemiological evidence. The growing number of genome-wide association studies and the largely incomplete concordance for autoimmune diseases in monozygotic twins support the role of the environment (including infectious agents and chemicals) in the breakdown of tolerance leading to autoimmunity via numerous mechanisms. The present article reviews the major theories on the mechanisms of the environmental influence on autoimmunity by addressing the different degrees of confidence that characterize our knowledge. The theories discussed herein include (i) the role of innate immunity mediated by toll-like receptors in triggering the autoimmune adaptive response characterizing the observed pathology; (ii) changes in spleen marginal zone B cells in autoantibody production with particular focus on the B10 subpopulation; (iii) Th17 cell differentiation and T regulatory cells in the aryl hydrocarbon receptor model; (iv) self antigen changes induced by chemical and infectious agents which could break tolerance by post-translational modifications and molecular mimicry; and finally (v) epigenetic changes, particularly DNA methylation, that are induced by environmental stimuli and may contribute to autoimmunity initiation. We are convinced that these working hypotheses, in most cases supported by solid evidence, should be viewed in parallel with animal models and epidemiological observations to provide a comprehensive picture of the environmental causes of autoimmune diseases.

Cutting-edge issues in organ-specific autoimmunity

There have been numerous methods and ways to classify autoimmune diseases. By far, the most traditional has been to separate immune-mediated pathology into organ-specific and organ-non-specific diseases. The classic systemic autoimmune diseases are, of course, rheumatoid arthritis and systemic lupus. The classic organ-specific autoimmune diseases have been autoimmune thyroiditis and autoimmune gastritis. However, as our understanding of the loss of tolerance has expanded, so has the long list of autoimmune diseases. In many cases, the distinction between organ-specific and organ-non-specific or systemic autoimmunity becomes a blur. In this issue, we discuss recent concepts in autoimmune pancreatitis, primary sclerosing cholangitis, Goodpasture's syndrome, myofasciitis, type I diabetes, polymyositis, autoimmune thyroid disease, IgA nephropathy, autoimmune uveitis, and ANCA-associated vasculitis. Common themes on both etiology and effector mechanisms are described throughout these papers with an attempt to provide a cutting-edge overview.