Infectious agents and inflammation. The role of microbiota in autoimmune arthritis

In higher vertebrates, mucosal sites at the border between the internal and external environments, directly interact with bacteria, viruses, and fungi. Through co-evolution, hosts developed mechanisms of tolerance or ignorance toward some infectious agents, because hosts established "gain of function" interactions with symbiotic bacteria. Indeed, some bacteria assist hosts in different functions, among which are digestion of complex carbohydrates, and absorption and supply of vitamins. There is no doubt that microbiota modulate innate and acquired immune responses starting at birth. However, variations in quality and quantity of bacterial species interfere with the equilibrium between inflammation and tolerance. In fact, correlations between gut bacteria composition and the severity of inflammation were first described for inflammatory bowel diseases and later extended to other pathologies. The genetic background, environmental factors (e.g., stress or smoking), and diet can induce strong changes in the resident bacteria which can expose the intestinal epithelium to a variety of different metabolites, many of which have unknown functions and consequences. In addition, alterations in gut permeability may allow pathogens entry, thereby triggering infection and/or chronic inflammation. In this context, a local event occurring at a mucosal site may be the triggering cause of an autoimmune reaction that eventually involves distant sites or organs. Recently, several studies attributed a pathogenic role to altered oral microbiota in rheumatoid arthritis (RA) and to gut dysbiosis in spondyloarthritis (SpA). There is also growing evidence that different drugs, such as antibiotics and immunosuppressants, can influence and be influenced by the diversity and composition of microbiota in RA and SpA patients. Hence, in complex disorders such RA and SpA, not only the genetic background, gender, and immunologic context of the individual are relevant, but also the history of infections and the structure of the microbial community at mucosal sites should be considered. Here the role of the microbiota and infections in the initiation and progression of chronic arthritis is discussed, as well as how these factors can influence a patient's response to synthetic and biologic immunosuppressive therapy

B cells in SLE. Different biological drugs for different pathogenic mechanisms

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease characterized by a complex multi-factorial pathogenesis and a great clinical polymorphism. SLE is considered to be a B cell disease in which autoantibodies are the major players. Recently, the central role of B cells has been confirmed and it has been shown that that the relative frequency of B cells subsets is altered in SLE patients. Conventional immunosuppressive therapies such as azathioprine, cyclophosphamide or methotrexate, reduce disease activity and improves the patient's general health conditions. These treatments have possible side effects; in fact they could compromise liver function, fertility and innate and adaptive immune responses. Moreover, for unknown reasons a small group of SLE patients is refractory to immunosuppressive therapy. In these cases finding an effective treatment becomes a challenge. The progress in therapeutic antibody technology has led to the production of a wide array of humanized monoclonal antibodies, targeting specific cell types or pathways, initiating a new era in the treatment of autoimmune disorders. In contrast to general immuno-suppression, the availability of drugs interfering with specific pathogenetic pathways gives the possibility to choose therapies tailored to each disease in each patient. © 2007 Elsevier B.V. All rights reserved

Microbiota and chronic inflammatory arthritis. an interwoven link

Background: Only recently, the scientific community gained insights on the importance of the intestinal resident flora for the host's health and disease. Gut microbiota in fact plays a crucial role in modulating innate and acquired immune responses and thus interferes with the fragile balance inflammation versus tolerance. Main body: Correlations between gut bacteria composition and the severity of inflammation have been studied in inflammatory bowel diseases. More recently similar alterations in the gut microbiota have been reported in patients with spondyloarthritis, whereas in rheumatoid arthritis an accumulating body of evidence evokes a pathogenic role for the altered oral microbiota in disease development and course. In the context of dysbiosis it is also important to remember that different environmental factors like stress, smoke and dietary components can induce strong bacterial changes and consequent exposure of the intestinal epithelium to a variety of different metabolites, many of which have an unknown function. In this perspective, and in complex disorders like autoimmune diseases, not only the genetic makeup, sex and immunologic context of the individual but also the structure of his microbial community should be taken into account. Conclusions: Here we provide a review of the role of the microbiota in the onset, severity and progression of chronic inflammatory arthritis as well as its impact on the therapeutic management of these patients. Furthermore we point-out the complex interwoven link between gut-joint-brain and immune system by reviewing the most recent data on the literature on the importance of environmental factors such as diet, smoke and stress

Immunogenicity of viral vaccines in the italian military

Military personnel of all armed forces receive multiple vaccinations and have been doing so since long ago, but relatively few studies have investigated the possible negative or positive interference of simultaneous vaccinations. As a contribution to fill this gap, we analyzed the response to the live trivalent measles/mumps/rubella (MMR), the inactivated hepatitis A virus (HAV), the inactivated trivalent polio, and the trivalent subunits influenza vaccines in two cohorts of Italian military personnel. The first cohort was represented by 108 students from military schools and the second by 72 soldiers engaged in a nine-month mission abroad. MMR and HAV vaccines had never been administered before, whereas inactivated polio was administered to adults primed at infancy with a live trivalent oral polio vaccine. Accordingly, nearly all subjects had baseline antibodies to polio types 1 and 3, but unexpectedly, anti-measles/-mumps/-rubella antibodies were present in 82%, 82%, and 73.5% of subjects, respectively (43% for all of the antigens). Finally, anti-HAV antibodies were detectable in 14% and anti-influenza (H1/H3/B) in 18% of the study population. At mine months post-vaccination, 92% of subjects had protective antibody levels for all MMR antigens, 96% for HAV, 69% for the three influenza antigens, and 100% for polio types 1 and 3. An inverse relationship between baseline and post-vaccination antibody levels was noticed with all the vaccines. An excellent vaccine immunogenicity, a calculated long antibody persistence, and apparent lack of vaccine interference were observed

Right drug, right patient, right time: aspiration or future promise for biologics in rheumatoid arthritis?

Individualising biologic disease-modifying anti-rheumatic drugs (bDMARDs) to maximise outcomes and deliver safe and cost-effective care is a key goal in the management of rheumatoid arthritis (RA). Investigation to identify predictive tools of bDMARD response is a highly active and prolific area of research. In addition to clinical phenotyping, cellular and molecular characterisation of synovial tissue and blood in patients with RA, using different technologies, can facilitate predictive testing. This narrative review will summarise the literature for the available bDMARD classes and focus on where progress has been made. We will also look ahead and consider the increasing use of ‘omics’ technologies, the potential they hold as well as the challenges, and what is needed in the future to fully realise our ambition of personalised bDMARD treatment

BIOCHEMICAL CHARACTERIZATION OF AUTO-ADP-RIBOSYLATED NARE

Mono ADP-ribosylation is a post-translational modification, conserved in viruses, prokaryotes and eukaryotes. Several ADP-ribose transfer enzymes as ART2, ART5, ExoS and CT are able to modify themselves, changing their chemical and biological functions. Here we report that NarE (Neisseria ADP-ribosylating enzyme), a transferase identified in Nesseria meningitides, ADP-ribosylates itself. In vitro ADP-ribosylation assays using NAD as substrate clearly showed the ability of NarE to catalyze an auto-ADP-ribosylation reaction in dose and time dependent manner. Mass analysis further supported the presence of a single ADP-ribose moiety. The ADP-ribose-linkage was destroyed after incubation with hydroxylamine and NaOH indicating that arginine was likely the amino-acid where ADP-ribose was linked. Four arginine residues (R7, R33, R97, R124) are present in NarE sequence, therefore to identify the arginine target we mutated each single R to K. The mutant R7K does not bind ADP-ribose suggesting that R7 is likely the target of auto-modification. R7 is included in Region I, which is involved in NAD binding, therefore, we investigated whether the link of ADP-ribose to R7 alters the interaction with NAD. After auto-ADP-ribosylation NarE shows a reduced ability to bind NAD compared to control experiments. Moreover the auto-ADP-ribosylated protein evidenced a notable change in both its enzymatic activities. The transferase activity is decreased while the NAD-glycohydrolase activity is enanched after modification. So we conclude that the modified NarE is essentially a NAD-glycohydrolase enzyme. Auto ADP-ribosylation to R7 can behave as an intermolecular control mechanism for the enzymatic activities of NarE. Length Max 250 word

IDENTIFICATION OF A MECHANISM FOR ENZYMATIC REGULATION IN NARE

NarE (Neisseria ADP-ribosylating enzyme), identified in the virulent strain MC58 of Nesseria meningitidis, belongs to the family of bacterial ADP-ribosyltransferases [1]. These enzymes catalyze the transfer of the ADP-ribose unit from β-nicotinamide adenine dinucleotide (NAD+) to specific amino-acids (R, C, N, T, Q) with simultaneous release of nicotinamide (nam). In vitro assays showed that NarE is an arginine-specific ADP-ribosyltransferase and also possesses NAD-glycohydrolase (NADase) activity. Recently we showed that NarE contains an iron-sulfur cluster (Fe-S) [2] in which a single iron atom is coordinated with two C (C67 and C128) and two H (H46 and H57) [3]. The presence of a structured cluster is important for transferase activity, which is lost when the cluster is destroyed, while the NADase activity is only slightly decreased. Here we reported that NarE ADP-ribosylates itself in vitro in a dose and concentration dependent manner. Incubation with NH2OH and NaOH hydrolyzed the link between ADP-ribose and NarE suggesting arginine the ADP-ribose acceptor. Four arginine residues (R7, R33, R97, R124) are present in NarE, we mutated each single R to K to identify the modified residue. The mutant R7K does not bind ADP-ribose suggesting that R7 is likely the target of auto-modification. The ADP-ribose unit carries two negative charges and alters considerably the chemical property of the R-residue, which is involved in the binding of NAD and the protein substrate. So the auto-modification influences the NarE enzymatic activities, the ADP-ribosylated NarE decreases transferase activity while NADase proportionally enhances. These data provided evidence that the auto-modification is an intramolecular mechanism adopted by NarE to regulate the priority between the two enzymatic activities. [1] Masignani V. et al Mol. Microbiology (2003) 50(3), 1055-1067 [2] Del Vecchio M. et al. J Biol. Chem. (2009) 284(48):33040-7 [3] Koehler C. et al J Biol. Chem. (2011) in pres