Alasdair R. Fraser

Bio: Alasdair R. Fraser is an academic researcher from Scottish National Blood Transfusion Service. The author has contributed to research in topics: Chemokine & T cell. The author has an hindex of 24, co-authored 45 publications receiving 2379 citations. Previous affiliations of Alasdair R. Fraser include University of Salford & University of Glasgow.

MicroRNA-155 as a proinflammatory regulator in clinical and experimental arthritis

Abstract: MicroRNA (miRNA) species (miR) regulate mRNA translation and are implicated as mediators of disease pathology via coordinated regulation of molecular effector pathways. Unraveling miR disease-related activities will facilitate future therapeutic interventions. miR-155 recently has been identified with critical immune regulatory functions. Although detected in articular tissues, the functional role of miR-155 in inflammatory arthritis has not been defined. We report here that miR-155 is up-regulated in synovial membrane and synovial fluid (SF) macrophages from patients with rheumatoid arthritis (RA). The increased expression of miR-155 in SF CD14+ cells was associated with lower expression of the miR-155 target, Src homology 2-containing inositol phosphatase-1 (SHIP-1), an inhibitor of inflammation. Similarly, SHIP-1 expression was decreased in CD68+ cells in the synovial lining layer in RA patients as compared with osteoarthritis patients. Overexpression of miR-155 in PB CD14+ cells led to down-regulation of SHIP-1 and an increase in the production of proinflammatory cytokines. Conversely, inhibition of miR-155 in RA synovial CD14+ cells reduced TNF-α production. Finally, miR-155–deficient mice are resistant to collagen-induced arthritis, with profound suppression of antigen-specific Th17 cell and autoantibody responses and markedly reduced articular inflammation. Our data therefore identify a role of miR-155 in clinical and experimental arthritis and suggest that miR-155 may be an intriguing therapeutic target.

IL-33 exacerbates antigen-induced arthritis by activating mast cells

Abstract: IL-33, a cytokine of the IL-1 family, is closely associated with type II T cell responses. Here, we report an unexpected proinflammatory role of IL-33 in inflammatory arthritis. IL-33 was expressed in synovial fibroblasts from patients with rheumatoid arthritis (RA). Expression was markedly elevated in vitro by inflammatory cytokines. Mice lacking ST2, the IL-33 receptor alpha-chain, developed attenuated collagen-induced arthritis (CIA) and reduced ex vivo collagen-specific induction of proinflammatory cytokines (IL-17, TNFalpha, and IFNgamma), and antibody production. Conversely, treatment of wild-type (WT) but not ST2(-/-) mice with IL-33 exacerbated CIA and elevated production of both proinflammatory cytokines and anti-collagen antibodies. Mast cells expressed high levels of ST2 and responded directly to IL-33 to produce a spectrum of inflammatory cytokines and chemokines in vitro. In vivo, IL-33 treatment exacerbated CIA in ST2(-/-) mice engrafted with mast cells from WT but not from ST2(-/-) mice. Disease exacerbation was accompanied by elevated expression levels of proinflammatory cytokines. Our results demonstrate that IL-33 is a critical proinflammatory cytokine for inflammatory joint disease that integrates fibroblast activation with downstream immune activation mainly via an IL-33-driven, mast-cell-dependent pathway. Thus, this IL-1 superfamily member represents a therapeutic target for RA.

Suppression, subversion and escape: the role of regulatory T cells in cancer progression

Abstract: Regulatory T cells (Tregs) are crucial in mediating immune homeostasis and promoting the establishment and maintenance of peripheral tolerance. However, in the context of cancer their role is more complex, and they are thought to contribute to the progress of many tumours. As cancer cells express both self- and tumour-associated antigens, Tregs are key to dampening effector cell responses, and therefore represent one of the main obstacles to effective anti-tumour responses. Suppression mechanisms employed by Tregs are thought to contribute significantly to the failure of current therapies that rely on induction or potentiation of anti-tumour responses. This review will focus on the current evidence supporting the central role of Tregs in establishing tumour-specific tolerance and promoting cancer escape. We outline the mechanisms underlying their suppressive function and discuss the potential routes of Tregs accumulation within the tumour, including enhanced recruitment, in-situ or local proliferation, and de-novo differentiation. In addition, we review some of the cancer treatment strategies that act, at least in part, to eliminate or interfere with the function of Tregs. The role of Tregs is being recognized increasingly in cancer, and controlling the function of these suppressive cells in the tumour microenvironment without compromising peripheral tolerance represents a significant challenge for cancer therapies.

Enumeration and phenotypical analysis of distinct dendritic cell subsets in psoriatic arthritis and rheumatoid arthritis

Abstract: Dendritic cells (DCs) comprise heterogeneous subsets of professional antigen-presenting cells, linking innate and adaptive immunity. Analysis of DC subsets has been hampered by a lack of specific DC markers and reliable quantitation assays. We characterised the immunophenotype and functional characteristics of psoriatic arthritis (PsA)-derived and rheumatoid arthritis (RA)-derived myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) to evaluate their potential role in arthritis. Circulating peripheral blood (PB) pDC numbers were significantly reduced in PsA patients (P = 0.0098) and RA patients (P = 0.0194), and mDCs were significantly reduced in RA patients (P = 0.0086) compared with healthy controls. The number of circulating mDCs in RA PB was significantly inversely correlated to C-reactive protein (P = 0.021). The phenotype of both DC subsets in PsA PB and RA PB was immature as compared with healthy controls. Moreover, CD62L expression was significantly decreased on both mDCs (PsA, P = 0.0122; RA, P = 0.0371) and pDCs (PsA, P = 0.0373; RA, P = 0.0367) in PB. Both mDCs and pDCs were present in PsA synovial fluid (SF) and RA SF, with the mDC:pDC ratio significantly exceeding that in matched PB (PsA SF, P = 0.0453; RA SF, P = 0.0082). pDCs isolated from RA SF and PsA SF displayed an immature phenotype comparable with PB pDCs. RA and PsA SF mDCs, however, displayed a more mature phenotype (increased expression of CD80, CD83 and CD86) compared with PB mDCs. Functional analysis revealed that both SF DC subsets matured following toll-like receptor stimulation. pDCs from PB and SF produced interferon alpha and tumour necrosis factor alpha on TLR9 stimulation, but only SF pDCs produced IL-10. Similarly, mDCs from PB and SF produced similar tumour necrosis factor alpha levels to TLR2 agonism, whereas SF mDCs produced more IL-10 than PB controls. Circulating DC subset numbers are reduced in RA PB and PsA PB with reduced CD62L expression. Maturation is incomplete in the inflamed synovial compartment. Immature DCs in SF may contribute to the perpetuation of inflammation via sampling of the inflamed synovial environment, and in situ presentation of arthritogenic antigen.

Safety profile of autologous macrophage therapy for liver cirrhosis.

Abstract: Therapies to reduce liver fibrosis and stimulate organ regeneration are urgently needed. We conducted a first-in-human, phase 1 dose-escalation trial of autologous macrophage therapy in nine adults with cirrhosis and a Model for End-Stage Liver Disease (MELD) score of 10-16 (ISRCTN 10368050). Groups of three participants received a single peripheral infusion of 107, 108 or up to 109 cells. Leukapheresis and macrophage infusion were well tolerated with no transfusion reactions, dose-limiting toxicities or macrophage activation syndrome. All participants were alive and transplant-free at one year, with only one clinical event recorded, the occurrence of minimal ascites. The primary outcomes of safety and feasibility were met. This study informs and provides a rationale for efficacy studies in cirrhosis and other fibrotic diseases.

Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury

Abstract: Acute kidney injury (AKI) is a complex disorder for which currently there is no accepted definition. Having a uniform standard for diagnosing and classifying AKI would enhance our ability to manage these patients. Future clinical and translational research in AKI will require collaborative networks of investigators drawn from various disciplines, dissemination of information via multidisciplinary joint conferences and publications, and improved translation of knowledge from pre-clinical research. We describe an initiative to develop uniform standards for defining and classifying AKI and to establish a forum for multidisciplinary interaction to improve care for patients with or at risk for AKI. Members representing key societies in critical care and nephrology along with additional experts in adult and pediatric AKI participated in a two day conference in Amsterdam, The Netherlands, in September 2005 and were assigned to one of three workgroups. Each group's discussions formed the basis for draft recommendations that were later refined and improved during discussion with the larger group. Dissenting opinions were also noted. The final draft recommendations were circulated to all participants and subsequently agreed upon as the consensus recommendations for this report. Participating societies endorsed the recommendations and agreed to help disseminate the results. The term AKI is proposed to represent the entire spectrum of acute renal failure. Diagnostic criteria for AKI are proposed based on acute alterations in serum creatinine or urine output. A staging system for AKI which reflects quantitative changes in serum creatinine and urine output has been developed. We describe the formation of a multidisciplinary collaborative network focused on AKI. We have proposed uniform standards for diagnosing and classifying AKI which will need to be validated in future studies. The Acute Kidney Injury Network offers a mechanism for proceeding with efforts to improve patient outcomes.

The pathogenesis of rheumatoid arthritis.

Abstract: The increased understanding of the immune mechanisms of rheumatoid arthritis has led to the development of a considerable number of new therapeutic agents that alter the natural history of the disease and reduce mortality.

Neutrophils in the activation and regulation of innate and adaptive immunity

Abstract: Neutrophils have long been viewed as the final effector cells of an acute inflammatory response, with a primary role in the clearance of extracellular pathogens. However, more recent evidence has extended the functions of these cells. The newly discovered repertoire of effector molecules in the neutrophil armamentarium includes a broad array of cytokines, extracellular traps and effector molecules of the humoral arm of the innate immune system. In addition, neutrophils are involved in the activation, regulation and effector functions of innate and adaptive immune cells. Accordingly, neutrophils have a crucial role in the pathogenesis of a broad range of diseases, including infections caused by intracellular pathogens, autoimmunity, chronic inflammation and cancer.

The IL-1 family: regulators of immunity

Abstract: Over recent years it has become increasingly clear that innate immune responses can shape the adaptive immune response. Among the most potent molecules of the innate immune system are the interleukin-1 (IL-1) family members. These evolutionarily ancient cytokines are made by and act on innate immune cells to influence their survival and function. In addition, they act directly on lymphocytes to reinforce certain adaptive immune responses. This Review provides an overview of both the long-established and more recently characterized members of the IL-1 family. In addition to their effects on immune cells, their involvement in human disease and disease models is discussed.