Patients who develop inflammatory polyarthritis (IP) after immunization are clinically indistinguishable from other patients with IP

Musculoskeletal symptoms may occur following various types of immunization, and it has also been suggested that, like infection, immunization may act as a trigger for rheumatoid arthritis (RA). A total of 48 of 898 (5.3%) patients with early inflammatory polyarthritis (IP) referred to the Norfolk Arthritis Register reported an immunization in the 6 weeks prior to symptom onset. There were no important clinical or demographic differences between the 48 immunized patients and 185 consecutive patients who did not report prior immunization. In addition, the frequencies of HLA-DRB1*01. *04 and the shared epitope in 33 of the immunized patients were similar to those in the 185 non-immunized patients and to those in 136 healthy controls. Further results from a case-control study suggest that the rate of immunization is higher amongst cases (5.5%) than age- and sex-matched controls (2.8%). In a small number of susceptible individuals, immunization may thus act as a trigger for RA.      

Effect of natural killer cells on syngeneic bone marrow: in vitro and in vivo studies demonstrating graft failure due to NK cells in an identical twin treated by bone marrow transplantation

Bone marrow transplantation for severe idiopathic aplastic anemia was undertaken in a patient, using his monozygotic twin brother as the donor. In spite of the use of syngeneic bone marrow, failure of engraftment occurred on two occasions. In vitro studies demonstrated that natural killer (NK) cells from the recipient markedly inhibited the growth of donor bone marrow granulocyte progenitor cells. On a third attempt, successful bone marrow engraftment was achieved following high-dose cyclophosphamide, which has previously been shown to be inhibitory to NK cells. We conclude that NK cell activity may play an important role in bone marrow failure as well as being responsible for at least some cases of aplastic anemia.     

Novel role of macrophage migration inhibitory factor in angiotensin II regulation of neuromodulation in rat brain

Previously we determined that angiotensin II (Ang II) activates neuronal AT(1) receptors, located in the hypothalamus and the brainstem, to stimulate noradrenergic pathways. To link Ang II to the regulation of norepinephrine metabolism in neurons cultured from newborn rat hypothalamus and brainstem we have used cDNA arrays for high throughput gene expression profiling. Of several genes that were regulated, we focused on macrophage migration inhibitory factor (MIF), which has been associated with the modulation of norepinephrine metabolism. In the presence of the selective AT(2) receptor antagonist PD123,319 (10 microM), incubation of cultures with Ang II (100 nM; 1-24 h) elicited an increase in MIF gene expression. Western immunoblots further revealed that Ang II (100 nM; 1-24 h) increased neuronal MIF protein expression. This effect was inhibited by the AT(1) receptor antagonist losartan (10 microM), the PLC inhibitor U-73122 (10 or 25 microM), the PKC inhibitor chelerythrine (10 microM), and the Ca(2+) chelator 1,2-bis-[2-aminophenoxy]-ethane-N,N,N',N'-tetraacetic acid tetrakis acetoxymethyl ester (10 microM). Taken together with our observation that MIF is expressed in the terminal fields of noradrenergic neurons (hypothalamus) and that Ang II increases the expression of MIF in this region in vivo, our data may suggest a novel role of Ang II in norepinephrine metabolism.     

Leukemia inhibitory factor upregulates cytokine expression by a murine stromal cell line enabling the maintenance of highly enriched competitive repopulating stem cells

Attempts to maintain or expand primitive hematopoietic stem cells in vitro without the concomitant loss of their differentiative and proliferative potential in vivo have largely been unsuccessful. To investigate this problem, we compared the ability of three cloned bone marrow (BM) stromal cell lines to support the growth of primitive Thy- 1lo Sca-1+H-2Khi cells isolated by fluorescence-activated cell sorting from the BM of Ly-5.2 mice treated 1 day previously with 5-fluo- rouracil. Sorted cells were highly enriched in cobblestone area-forming cells (CAFC), but their frequency was dependent on the stromal cell lines used in this assay (1 per 45 cells on SyS-1; 1 per 97 cells on PA6). In the presence of recombinant leukemia inhibitory factor (LIF), CAFC cloning efficiency was increased to 1 per 8 cells on SyS-1 and 1 per 11 cells on PA6, thus showing the high clonogenicity of this primitive stem cell population. More primitive stem cells with competitive repopulating potential were measured by injecting the sorted cells into lethally irradiated Ly-5.1 mice together with 10(5) radioprotective Ly-5.1 BM cells whose long-term repopulating ability has been "compromised" by two previous cycles of marrow transplantation and regeneration. Donor-derived lymphocytes and granulocytes were detected in 66% of animals injected with 50 sorted cells. To quantitate the maintenance of competitive repopulating units (CRU) by stromal cells, sorted cells were transplanted at limiting dilution before and after being cultured for 2 weeks on adherent layers of SyS-1, PA6, or S17 cells. CRU represented 1 per 55 freshly sorted cells. CRU could be recovered from cocultures supported by all three stromal cell lines, but their numbers were approximately-sevenfold less than on day 0. In contrast, the addition of LIF to stromal cultures improved CRU survival by 2.5-fold on S17 and PA6 cells (approximately two-fold to threefold decline), and enabled their maintenance on SyS-1. LIF appeared to act indirectly, because alone it did not support the proliferation of Thy- 1lo Sca-1+H-2Khi cells in stroma-free cultures. Polymerase chain reaction (RT-PCR) analysis revealed that Interleukin-1beta (IL-1 beta) IL-2, IL-6, granulocyte-colony stimulating factor, granulocyte macrophage-colony stimulating factor, transforming growth factors, LIF, and Steel Factor (SLF) mRNAs were upregulated in SyS-1 within 1 to 6 hours of LIF-stimulation. To determine if increased expression of SLF by LIF-stimulated SyS-1 cells could account for their capacity to support stem cells, sorted calls were cocultured on simian CV-E cells that were transfected with an expression vector encoding membrane-bound SLF, or supplemented with soluble SLF. In both cases, SLF synergized with IL-6 produced endogenously by CV-E cells enabling CAFC growth equivalent to that on LIF-stimulated SyS-1. CAFC development on LIF- stimulated SyS-1 could also be completely abrogated by an anti-SLF antibody. These data provide evidence for a role of LIF in the support of long-term repopulating stem cells by indirectly promoting cytokine expression by BM stroma. Furthermore, we have used quantitative assays to show a maintenance of CRU numbers, with retention of in vivo function following ex vivo culture.     

Angiotensin II receptor subtypes are coupled with distinct signal-transduction mechanisms in neurons and astrocytes from rat brain.

Both neurons and astrocytes contain specific receptors for angiotensin II (AII). We used selective ligands for the AT1 and AT2 types of AII receptors to investigate the expression of functional receptor subtypes in astrocyte cultures and neuron cultures from 1-day-old (neonatal) rat brain. In astrocyte cultures, competition of 125I-labeled AII (125I-AII) specific binding with AT1 (DuP753) or AT2 (PD123177, CGP42112A, [Phe(p-NH2)6]AII) selective receptor ligands revealed a potency series of AII greater than DuP753 much greater than CGP42112A greater than [Phe(p-NH2)6]AII greater than PD123177. These results suggest a predominance of the AT1 receptor subtype in neonatal astrocytes. Also, in astrocyte cultures, AII stimulated increases in inositolphospholipid hydrolysis that were significantly reduced by the AT1 receptor antagonist DuP753 but not altered by the AT2 receptor antagonist PD123177. In neonatal neuron cultures, competition of 125I-AII specific binding with the above ligands revealed a potency series of CGP42112A = AII greater than [Phe(p- NH2)6]AII greater than PD123177 much greater than DuP753. 125I-AII specific binding to neonate neuronal cultures was reduced 73-84% by 1 microM PD123177, and the residual 125I-AII specific binding was eliminated by DuP753. Also, in neuron cultures, AII induced decreases in basal cGMP that were completely blocked by PD123177 or CGP42112A but not by DuP753. Our results suggest that astrocyte cultures from neonatal rat brains contain predominantly AT1 receptors that are coupled to a stimulation of inositophospholipid hydrolysis. In contrast, neuron cultures from neonatal rat brain contain mostly AT2 receptors that are coupled to a reduction in basal cGMP levels, but a smaller population of AT1 receptors is also present in these neurons.     

The safety of anticholinergic bronchodilators for the treatment of chronic obstructive pulmonary disease

Introduction: Poorly absorbable quaternary ammonium-inhaled muscarinic antagonists both as the short-acting ipratropium and as long-acting (12 – 24 h) agents (tiotropium, glycopyrronium, aclidinium and umeclidinium) have all demonstrated statistically and clinically significant efficacy in chronic obstructive pulmonary disease compared with placebo. However, controversy has arisen concerning the safety of this class of agents principally regarding their association with both fatal and nonfatal cardiovascular toxicity.

Areas covered: The safety of both ipratropium and the long-acting muscarinic antagonists is reviewed with a major emphasis on potential cardiovascular toxicity, based on published clinical trials data and results of analyses of pooled data, meta-analyses, and observational studies. Since glycopyrronium, aclidinium, and umeclidinium have become available only relatively recently, more emphasis will be placed on the more extensive literature concerning the safety of the older anticholinergic compounds, the short-acting ipratropium, and the long-acting tiotropium in its dry powder formulation, as well as its newer soft mist inhaler delivery device.

Expert opinion: Pooled analyses and meta-analyses of randomized controlled trials (RCTs) of tiotropium in both its dry powder and soft mist formulations, as well as some observational studies, have implicated this agent as increasing the risk of nonfatal and fatal cardiovascular events. However, the most robust evidence based on large-scale randomized controlled trials (RCTs) of relatively long duration specifically designed to evaluate the cardiovascular safety of tiotropium have not confirmed these safety concerns. Because of the relatively limited amount of safety data for the newer long-acting muscarinic antagonists compared to the far more extensive experience with tiotropium, it will be important to accumulate additional safety information from post-marketing pharmacovigilance for these newer agents.     

Selective activation of angiotensin AT2 receptors attenuates progression of pulmonary hypertension and inhibits cardiopulmonary fibrosis

Background and Purpose

Pulmonary hypertension (PH) is a devastating disease characterized by increased pulmonary arterial pressure, which progressively leads to right-heart failure and death. A dys-regulated renin angiotensin system (RAS) has been implicated in the development and progression of PH. However, the role of the angiotensin AT₂ receptor in PH has not been fully elucidated. We have taken advantage of a recently identified non-peptide AT₂ receptor agonist, Compound 21 (C21), to investigate its effects on the well-established monocrotaline (MCT) rat model of PH.

Experimental Approach

A single s.c. injection of MCT (50 mg·kg⁻¹) was used to induce PH in 8-week-old male Sprague Dawley rats. After 2 weeks of MCT administration, a subset of animals began receiving either 0.03 mg·kg⁻¹ C21, 3 mg·kg⁻¹ PD-123319 or 0.5 mg·kg⁻¹ A779 for an additional 2 weeks, after which right ventricular haemodynamic parameters were measured and tissues were collected for gene expression and histological analyses.

Key Results

Initiation of C21 treatment significantly attenuated much of the pathophysiology associated with MCT-induced PH. Most notably, C21 reversed pulmonary fibrosis and prevented right ventricular fibrosis. These beneficial effects were associated with improvement in right heart function, decreased pulmonary vessel wall thickness, reduced pro-inflammatory cytokines and favourable modulation of the lung RAS. Conversely, co-administration of the AT₂ receptor antagonist, PD-123319, or the Mas antagonist, A779, abolished the protective actions of C21.

Conclusions and Implications

Taken together, our results suggest that the AT₂ receptor agonist, C21, may hold promise for patients with PH.