Pharmacologic Interventions for Preventing Chondrocyte Apoptosis in Rheumatoid Arthritis and Osteoarthritis

Chronic inflammation drives the progression of rheumatoid arthritis (RA) and osteoarthritis (OA) to synovial joint failure. The inflammatory state in both musculoskeletal diseases is associated with significantly elevated levels of pro-inflammatory cytokines in joint synovial fluid, which is best exemplified by increases in interleukin-1β (IL-1β), IL-6, IL-17, tumor necrosis factor-α, among others, as well as increased activity of soluble mediators such as nitric oxide and certain growth factors including vascular endothelial growth factor and fibroblast growth factor. The multitude of these factors activate chondrocyte signal transduction pathways resulting in programmed cell death, otherwise known as apoptosis as well as compromising chondrocyte autophagy. Importantly, chondrocyte apoptosis causes a loss of articular cartilage vitality which dampens cartilage repair mechanisms because at present, the possibility that chondrocyte progenitor cells could replace those differentiated chondrocytes lost via apoptosis remains debatable. Certain pharmacologic interventions which have been proven to induce apoptosis in various cancer cell studies in vitro suggest the possibility that drugs could be developed to specifically suppress or completely inhibit chondrocyte apoptosis in RA and OA cartilage. This review supports that contention and indicates that apoptosis can be inhibited by identifying novel cellular targets which promote apoptosis and autophagy

Myeloid-Related Protein Activity in Rheumatoid Arthritis

SA100A8, SA100A9, and SA100A12 are members of the myeloid-related protein class. SA100A8 and SA100A9, also known as MRP-8 and MRP-14, respectively, are intracellular Ca2+-binding proteins produced mainly by neutrophils and monocytes where they exist as a heterodimeric complex in the cytosol. The MRP-8/-14 complex has been shown to promote chronic inflammation associated with rheumatoid arthritis (RA). In that regard, MRP-8 and MRP-14 regulate the inflammatory response through their capacity to recruit neutrophils and monocytes to target tissues resulting in attachment to endothelium. MRPs also activate the signal transduction pathway principally involving the stress-activated/mitogen-activated protein kinases. MRP-8/MRP-14 also increased nitric oxide synthesis. Most recently, the MRP-8/MRP-14 complex was shown to be a novel ligand for the toll-like receptors (TLRs) and TLR-4, in particular. Engagement of TLRs by the MRP-8/-14 complex may be particularly important for activating antigen-presenting dendritic cells which regulate critical autoimmune responses that promote chronic synovitis characteristic of RA

Biological Basis for the Use of Botanicals in Osteoarthritis and Rheumatoid Arthritis: A Review

Osteoarthritis (OA) of the knee and hip is a debilitating disease affecting more women than men and the risk of developing OA increases precipitously with aging. Rheumatoid arthritis (RA), the most common form of inflammatory joint diseases, is a disease of unknown etiology and affects ∼1% of the population worldwide, and unlike OA, generally involves many joints because of the systemic nature of the disease. Non-steroidal anti-inflammatory drugs (NSAIDs) are the first drugs of choice for the symptomatic treatment of both OA and RA. Because of the risks associated with the use of NSAIDs and other limitations, the use of alternative therapies, such as acupuncture and medicinal herbs, is on the rise and according to reports ∼60–90% of dissatisfied arthritis patients are likely to seek the option of complementary and alternative medicine (CAM). This paper reviews the efficacy of some of the common herbs that have a history of human use and their anti-inflammatory or antiarthritic properties have been evaluated in animal models of inflammatory arthritis, in studies employing well defined and widely accepted in vitro models that use human chondrocytes/cartilage explants or in clinical trials. Available data suggests that the extracts of most of these herbs or compounds derived from them may provide a safe and effective adjunctive therapeutic approach for the treatment of OA and RA. This, in turn, argues for trials to establish efficacy and optimum dosage of these compounds for treating human inflammatory and degenerative joint diseases

Age-related changes in Serum Growth Hormone, Insulin-like Growth Factor-1 and Somatostatin in System Lupus Erythematosus

BACKGROUND: Systemic lupus erythematosus is an age- and gender-associated autoimmune disorder. Previous studies suggested that defects in the hypothalamic/pituitary axis contributed to systemic lupus erythematosus disease progression which could also involve growth hormone, insulin-like growth factor-1 and somatostatin function. This study was designed to compare basal serum growth hormone, insulin-like growth factor-1 and somatostatin levels in female systemic lupus erythematosus patients to a group of normal female subjects. METHODS: Basal serum growth hormone, insulin-like growth factor-1 and somatostatin levels were measured by standard radioimmunoassay. RESULTS: Serum growth hormone levels failed to correlate with age (r(2 )= 3.03) in the entire group of normal subjects (i.e. 20 – 80 years). In contrast, serum insulin-like growth factor-1 levels were inversely correlated with age (adjusted r(2 )= 0.092). Of note, serum growth hormone was positively correlated with age (adjusted r(2 )= 0.269) in the 20 – 46 year range which overlapped with the age range of patients in the systemic lupus erythematosus group. In that regard, serum growth hormone levels were not significantly higher compared to either the entire group of normal subjects (20 – 80 yrs) or to normal subjects age-matched to the systemic lupus erythematosus patients. Serum insulin-like growth factor-1 levels were significantly elevated (p < 0.001) in systemic lupus erythematosus patients, but only when compared to the entire group of normal subjects. Serum somatostatin levels differed from normal subjects only in older (i.e. >55 yrs) systemic lupus erythematosus patients. CONCLUSIONS: These results indicated that systemic lupus erythematosus was not characterized by a modulation of the growth hormone/insulin-like growth factor-1 paracrine axis when serum samples from systemic lupus erythematosus patients were compared to age- matched normal female subjects. These results in systemic lupus erythematosus differ from those previously reported in other musculoskeletal disorders such as rheumatoid arthritis, osteoarthritis, fibromyalgia, diffuse idiopathic skeletal hyperostosis and hypermobility syndrome where significantly higher serum growth hormone levels were found. Somatostatin levels in elderly systemic lupus erythematosus patients may provide a clinical marker of disease activity in these patients

Defective T-Cell Apoptosis and T-Regulatory Cell Dysfunction in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, progressive, systemic autoimmune disease that mostly affects small and large synovial joints. At the molecular level, RA is characterized by a profoundly defective innate and adaptive immune response that results in a chronic state of inflammation. Two of the most significant alterations in T-lymphocyte (T-cell) dysfunction in RA is the perpetual activation of T-cells that result in an abnormal proliferation state which also stimulate the proliferation of fibroblasts within the joint synovial tissue. This event results in what we have termed &#8220;apoptosis resistance&#8222;, which we believe is the leading cause of aberrant cell survival in RA. Finding therapies that will induce apoptosis under these conditions is one of the current goals of drug discovery. Over the past several years, a number of T-cell subsets have been identified. One of these T-cell subsets are the T-regulatory (Treg) cells. Under normal conditions Treg cells dictate the state of immune tolerance. However, in RA, the function of Treg cells become compromised resulting in Treg cell dysfunction. It has now been shown that several of the drugs employed in the medical therapy of RA can partially restore Treg cell function, which has also been associated with amelioration of the clinical symptoms of RA

Recent advances in neutralizing the IL-6 pathway in arthritis

Charles J MalemudDivision of Rheumatic Diseases, Case Western Reserve University, School of Medicine and University Hospitals Case Medical Center, Cleveland, Ohio, USAAbstract: Recent advances in understanding the mechanism(s) of how IL-6 trans-signaling regulates immune cell function and promotes inflammation in autoimmune arthritis are critically reviewed. Serum and/or synovial fluid (SF) IL-6 is markedly elevated in adult and juvenile rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis (AS) and osteoarthritis (OA). IL-6, in concert with IL-17, determines the fate of CD4+ lymphocytes and therefore TH17 cell differentiation. IL-6 also plays a critical role in modulating B-lymphocyte activity. The recognition that IL-6 trans-signaling regulates inflammation resulted in the development of tocilizumab, a fully humanized monoclonal antibody that neutralizes the biological activity of the IL-6-receptor (IL-6R). Significant clinical benefit was demonstrated as well as reduced serum IL-6 levels with suppression of X-ray progression of disease in several clinical trials in which juvenile or adult RA patients were treated with tocilizumab monotherapy or tocilizumab plus methotrexate. However, levels of serum and/or SF IL-6 cytokine protein superfamily members, adiponectin, oncostatin M, pre-B-cell colony enhancing factor/visfatin and leukemia inhibitory factor are also elevated in RA. Additional studies will be required to determine if anti-IL-6 trans-signaling inhibition strategies with tocilizumab or recombinant soluble IL-6R reduce the level of these cytokines.Keywords: interleukin-6, interleukin-6/interleukin-6 receptor/glycoprotein 130, JAK/STAT pathway, SAP/MAPK pathway, osteoarthritis, rheumatoid arthriti