An insight in Salmonella typhi associated autoimmunity candidates' prediction by molecular mimicry

Autoimmune diseases develop when the immune system targets healthy cells and tissues of an individual. In developing countries, S. typhi (a gram-negative pathogenic bacteria) remains a major public health issue. This study aimed to employ bioinformatics analyses to determine the 3D structural-based molecular mimicry and sequence of S. typhi and human host proteins. In addition, to classify possible antigenic microbial peptides homologous to human peptides and comprehend the molecular basis of S. typhi-related autoimmune disorders. Protein sequences were obtained from the NCBI database, and redundancy was removed using the CD-HIT tool. The BLASTp comparative sequence analysis was followed for molecular mimicry identification of human and S. typhi protein sequences. The PathDIP database was utilized to simulate essential physical relationships between proteins and curated pathways for metabolic processes. Subsequently, the IEDB database was used to find cross-reactive MHC class-II binding epitopes that could trigger an autoimmune reaction. SPARKS-X computational biology resource was also used to determine the structural homology between human and S. typhi peptides. The BLASTp study showed that S. typhi and the human host have several proteins holding considerable sequence similarities based on a set threshold of e ≤ 10-6 and bit score ≥100. The PathDIP putatively identified that these proteins enriched in a total of 68 metabolic pathways by a significant P-value (P < 0.005). The PSORTb analysis predicted that 26 out of these proteins are cytosolic, 1 predicted to be periplasmic protein, and 1 predicted to be localized in the cytoplasmic membrane. IEDB data analysis predicted many S.typhi and human homologs epitopes as a good binder of human HLA, i.e. DRB1*01:01, DPA1*03:01/DPB1*04:02, and DQA1*01:02/DQB1*06:02 with IC₅₀ < 50 nM. Finally, the docking data demonstrated that homolog lead epitopes promisingly interact with HLA and immune TLR4 receptors by exhibiting the best docking scores and molecular interactions. The analyses ultimately identified several potential candidate proteins and peptides that could cause S.typhi infection-mediated autoimmune diseases in humans.

Molecular Interventions towards Multiple Sclerosis Treatment

Multiple sclerosis (MS) is an autoimmune life-threatening disease, afflicting millions of people worldwide. Although the disease is non-curable, considerable therapeutic advances have been achieved through molecular immunotherapeutic approaches, such as peptides vaccination, administration of monoclonal antibodies, and immunogenic copolymers. The main aims of these therapeutic strategies are to shift the MS-related autoimmune response towards a non-inflammatory T helper 2 (Th2) cells response, inactivate or ameliorate cytotoxic autoreactive T cells, induce secretion of anti-inflammatory cytokines, and inhibit recruitment of autoreactive lymphocytes to the central nervous system (CNS). These approaches can efficiently treat autoimmune encephalomyelitis (EAE), an essential system to study MS in animals, but they can only partially inhibit disease progress in humans. Nevertheless, modern immunotherapeutic techniques remain the most promising tools for the development of safe MS treatments, specifically targeting the cellular factors that trigger the initiation of the disease.

Targets and Mechanisms in Prevention of Parkinson's Disease through Immunomodulatory Treatments

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world; however, there is no cure for it. Current treatments only relieve some of the symptoms, without ceasing the disease, and lose efficacy with prolonged treatment. Considerable evidence shows that persistent inflammatory responses, involving T cell infiltration and glial cell activation, are common characteristics of human patients and play a crucial role in the degeneration of dopaminergic neurons. Therefore, it is important to develop therapeutic strategies that can impede or halt the disease through the modulation of the peripheral immune system by aiming at controlling the existing neuroinflammation. Most of the immunomodulatory therapies designed for the treatment of Parkinson's disease are based on vaccines using AS or antibodies against it; yet, it is of significant interest to explore other formulations that could be used as therapeutic agents. Several vaccination procedures have shown that inducing regulatory T cells in the periphery is protective in PD animal models. In this regard, the formulation glatiramer acetate (Copaxone^® ), extensively used for the treatment of multiple sclerosis, could be a suitable candidate due to its capability to increase the number and suppressor capacity of regulatory T cells. In this review, we will present some of the recent immunomodulatory therapies for PD including vaccinations with AS or glatiramoids, or both, as treatments of PD pathology.

Glatiramer acetate in treatment of multiple sclerosis: a toolbox of random co-polymers for targeting inflammatory mechanisms of both the innate and adaptive immune system?

Multiple sclerosis is a disease of the central nervous system, resulting in the demyelination of neurons, causing mild to severe symptoms. Several anti-inflammatory treatments now play a significant role in ameliorating the disease. Glatiramer acetate (GA) is a formulation of random polypeptide copolymers for the treatment of relapsing-remitting MS by limiting the frequency of attacks. While evidence suggests the influence of GA on inflammatory responses, the targeted molecular mechanisms remain poorly understood. Here, we review the multiple pharmacological modes-of-actions of glatiramer acetate in treatment of multiple sclerosis. We discuss in particular a newly discovered interaction between the leukocyte-expressed integrin α(M)β(2) (also called Mac-1, complement receptor 3, or CD11b/CD18) and perspectives on the GA co-polymers as an influence on the function of the innate immune system.

Macrophage-specific chemokines induced via innate immunity by amino acid copolymers and their role in EAE

The random amino acid copolymer poly(Y,E,A,K)_n (Copaxone®) is widely used in multiple sclerosis treatment and a second generation copolymer poly(Y,F,A,K)_n with enhanced efficacy in experimental autoimmune encephalomyelitis in mice has been described. A major mechanism through which copolymers function to ameliorate disease is the generation of immunosuppressive IL-10-secreting regulatory T cells entering the CNS. In addition, the antigen presenting cell to which these copolymers bind through MHC Class II proteins may have an important role. Here, both CCL22 (a Th2 cell chemoattractant) in large amounts and CXCL13 in much smaller amounts are shown to be secreted after administration of YFAK to mice and to a smaller extent by YEAK parallel to their serum concentrations. Moreover, bone marrow-derived macrophages secrete CCL22 in vitro in response to YFAK and to higher concentrations of YEAK. Strikingly, these chemokines are also secreted into serum of MHC Class II −/− mice, indicating that an innate immune receptor on these cells also has an important role. Thus, both the innate and the adaptive immune systems are involved in the mechanism of EAE amelioration by YFAK. The enhanced ability of YFAK to stimulate the innate immune system may account for its enhanced efficacy in EAE treatment.

Abnormal B-cell cytokine responses a trigger of T-cell-mediated disease in MS?

OBJECTIVE

To study antibody-independent contributions of B cells to inflammatory disease activity, and the immune consequences of B-cell depletion with rituximab, in patients with multiple sclerosis (MS).

METHODS

B-Cell effector-cytokine responses were compared between MS patients and matched controls using a 3-signal model of activation. The effects of B-cell depletion on Th1/Th17 CD4 and CD8 T-cell responses in MS patients were assessed both ex vivo and in vivo, together with pharmacokinetic/pharmacodynamic studies as part of 2 rituximab clinical trials in relapsing-remitting MS.

RESULTS

B Cells of MS patients exhibited aberrant proinflammatory cytokine responses, including increased lymphotoxin (LT):interleukin-10 ratios and exaggerated LT and tumor necrosis factor (TNF)-alpha secretion, when activated in the context of the pathogen-associated TLR9-ligand CpG-DNA, or the Th1 cytokine interferon-gamma, respectively. B-Cell depletion, both ex vivo and in vivo, resulted in significantly diminished proinflammatory (Th1 and Th17) responses of both CD4 and CD8 T cells. Soluble products from activated B cells of untreated MS patients reconstituted the diminished T-cell responses observed following in vivo B-cell depletion in the same patients, and this effect appeared to be largely mediated by B-cell LT and TNFalpha.

INTERPRETATION

We propose that episodic triggering of abnormal B-cell cytokine responses mediates 'bystander activation' of disease-relevant proinflammatory T cells, resulting in new relapsing MS disease activity. Our findings point to a plausible mechanism for the long-recognized association between infections and new MS relapses, and provide novel insights into B-cell roles in both health and disease, and into mechanisms contributing to therapeutic effects of B-cell depletion in human autoimmune diseases, including MS.

Prophylactic and therapeutic suppression of experimental autoimmune encephalomyelitis by a novel bifunctional peptide inhibitor

The objective was to optimize and evaluate the in vivo activities of our novel bifunctional peptide inhibitor (BPI), which alters immune response in autoimmune diseases by modulating the immunological synapse formation. Previously, we have designed PLP-BPI and GAD-BPI by conjugating myelin proteolipid protein (PLP)(139-151) and glutamic acid decarboxylase (GAD)(208-217), respectively, with CD11a(237-246) via a spacer peptide. PLP-BPI and GAD-BPI suppressed the disease progression in experimental autoimmune encephalomyelitis (EAE) and in type-1 diabetes, respectively. In this study, various PLP-BPI derivatives were synthesized and evaluated in the EAE model. Intravenous injections of PLP-BPI derivatives prevented the disease progression more efficiently than did unmodified PLP-BPI. Production of IL-17, a potent proinflammatory cytokine found commonly among MS patients, was significantly low in Ac-PLP-BPI-NH(2)-2-treated mice. Treatment given after the disease onset could dramatically ameliorate the disease. BPI induced anaphylactic responses at a lower incidence than PLP(139-151). In conclusion, PLP-BPI derivatives can effectively suppress the disease severity and morbidity of EAE by post-onset therapeutic treatment as well as prophylactic use.

Serum stability of peptides

Hospitals worldwide have lately reported a worrying increase in the number of isolated drug-resistant pathogenic microbes. This has to some extent fueled at least academic interest in design and development of new lead components for novel drug design. Much of this interest has been focused on antimicrobial peptides and peptides in general, primarily due to their natural occurrence and low toxicity. However, issues have been raised regarding the stability of peptide therapeutics for systemic use. The focus of this chapter is assays for measuring peptide stability in the presence of serum, both in vitro and in vivo.

Clinical response to glatiramer acetate correlates with modulation of IFN-γ and IL-4 expression in multiple sclerosis

Objective To determine whether glatiramer acetate (GA)-induced lymphoproliferation and IFN-γ and IL-4 modulation correlate with the clinical response in multiple sclerosis (MS).

Background GA therapy involves the induction of anti-inflammatory cytokine shifts. However, it is not known whether this response correlates with the clinical outcome.

Methods Thirty-six relapsing-remitting (RR) MS patients were treated with GA for at least two years, and classified clinically as GA-responders (GA-R=22) or hypo/non-responders (GA-HR/NR = 14). Proliferation of peripheral blood mononuclear cells (PBMC) to GA and Tetanus toxoid (TT), as well as IL-4 and IFN-γ ELISPOT, were performed.

Findings There was no difference in PBMC proliferation to GA or TT between GA-R and GA-HR/NR before and during treatment (P>0.05). The mean number of IFN-γ ELISPOTS in unstimulated, TT and anti-CD3/CD28-stimulated PBMC was lower among GA-R (unstimulated: GA-R =10.1±6.21 (n=22) versus GA-HR/NR=17.8±12.7 (n=14), P=0.04; TT-GA-R =12.2±4.06 (n=12) versus GA-HR/NR=26.8±21.0 (n=8), P=0.028; anti-CD-3/CD28 GA-R=217.3±140.4 (n=22) versus GA-HR/NR=368.5±170.1 (n=14), P=0.006). In contrast, the number of IL-4 ELISPOTS remained unchanged in the GA-R group, but was progressively reduced in the GA-HR/NR group during GA therapy (GA-HR/NR IL-4: pre-Rx: 59±34 versus 22±11 at 12 months (n =6), P=0.0429). The IL-4/ IFN-γ ratio in anti-CD3/CD28-stimulated PBMC was significantly higher among GA-R compared to GA-HR/NR (P=0.0474).

Interpretation Lymphoproliferation to GA did not differentiate GA-R from GA-HR/NR. However, reduced IFN-γ expression and stable IL-4 expression in anti-CD3/CD28-stimulated PBMC, and an increased IL-4/IFN-γ ratio was associated with favorable clinical response. More data are needed to validate the prospective use of IL-4/IFN-γ expression in PBMC as a biomarker of clinical response to GA for individual patients. Multiple Sclerosis 2007; 13: 754-762. http://msj.sagepub.com

Glatiramer acetate in multiple sclerosis: update on potential mechanisms of action

Glatiramer acetate is a synthetic random copolymer approved for the immunomodulatory therapy of relapsing-type multiple sclerosis (MS). Previous work has focused on the effects of this drug on T cells, especially the glatiramer-acetate-induced shift of the cytokine profile towards those characteristic of T-helper-2 (Th2) cells. Glatiramer acetate was thought to bring about this Th2 shift by acting like an altered peptide ligand but more recent work has shown that the drug notably affects the properties of antigen-presenting cells, such as monocytes and dendritic cells. These new observations might offer an explanation for the previously observed Th2 shift. In this review, we focus on these new findings. We address several controversial issues, including the possible neurotrophic effects of glatiramer acetate, the potential role of neutralising antibodies to the drug, and attempts to develop biomarkers of the treatment response. Finally, we will think about how a better understanding of glatiramer acetate might help the development of new immunomodulatory agents for MS.