Rheumatoid arthritis synovial microenvironment induces metabolic and functional adaptations in dendritic cells.

Rheumatoid arthritis (RA) is a chronic autoimmune disease which causes degradation of cartilage and bone. It is well appreciated that the pathogenic hallmark of RA is the mass influx of inflammatory cells into the joint. However, the role that dendritic cells (DC) may play in this inflammatory milieu is still relatively unexplored. Moreover, the contribution this unique synovial microenvironment has on DC maturation is still unknown. Using monocyte-derived DC (MoDC), we established an in-vitro model to recapitulate the synovial microenvironment to explore DC maturation. MoDC treated with conditioned media from ex-vivo synovial tissue biopsy cultures [explant-conditioned media (ECM)] have increased expression of proinflammatory cytokines, chemokines and adhesion molecules. ECM DC have increased expression of CD83 and CC-chemokine receptor (CCR)7 and decreased expression of CCR5 and phagocytic capacity, suggestive of heightened DC maturation. ECM-induced maturation is concomitant with altered cellular bioenergetics, whereby increased expression of glycolytic genes and increased glucose uptake are observed in ECM DC. Collectively, this results in a metabolic shift in DC metabolism in favour of glycolysis. These adaptations are in-part mediated via signal transducer and activator of transcription-3 (STAT-3), as demonstrated by decreased expression of proinflammatory cytokines and glycolytic genes in ECM DC in response to STAT-3 inhibition. Finally, to translate these data to a more in-vivo clinically relevant setting, RNA-seq was performed on RA synovial fluid and peripheral blood. We identified enhanced expression of a number of glycolytic genes in synovial CD1c+ DC compared to CD1c+ DC in circulation. Collectively, our data suggest that the synovial microenvironment in RA contributes to DC maturation and metabolic reprogramming.

Tofacitinib regulates synovial inflammation in psoriatic arthritis, inhibiting STAT activation and induction of negative feedback inhibitors.

BACKGROUND: Psoriatic arthritis (PsA) is a chronic inflammatory disease, characterised by synovitis and destruction of articular cartilage/bone. Janus-kinase and signal transducer and activator of transcription (JAK-STAT) signalling pathway is implicated in the pathogenesis of PsA. OBJECTIVES: To examine the effect of tofacitinib (JAK inhibitor) on proinflammatory mechanisms in PsA. METHODS: Primary PsA synovial fibroblasts (PsAFLS) and ex vivo PsA synovial explants were cultured with tofacitinib (1 µM). PhosphoSTAT3 (pSTAT3), phosphoSTAT1 (pSTAT1), suppressor of cytokine signaling-3 (SOCS3), protein inhibitor of activated Stat3 (PIAS3) and nuclear factor kappa B cells (NFκBp65) were quantified by western blot. The effect of tofacitinib on PsAFLS migration, invasion, Matrigel network formation and matrix metallopeptidase (MMP)2/9 was quantified by invasion/migration assays and zymography. Interleukin (IL)-6, IL-8, IFN-gamma-inducible protein 10 (IP-10) monocyte chemoattractant protein (MCP)-1, IL-17, IL-10, MMP3 and tissue inhibitor of metalloproteinases 3 (TIMP3) were assessed by ELISA. RESULTS: Tofacitinib significantly decreased pSTAT3, pSTAT1, NFκBp65 and induced SOCS3 and PIAS3 expression in PsAFLS and synovial explant cultures (p<0.05). Functionally, PsAFLS invasion, network formation and migration were inhibited by tofacitinib (all p<0.05). In PsA explant, tofacitinib significantly decreased spontaneous secretion of IL-6, IL-8, MCP-1, MMP9/MMP2, MMP3 (all p<0.05) and decreased the MMP3/TIMP3 ratio (p<0.05), with no effect observed for IP-10 or IL-10. CONCLUSIONS: This study further supports JAK-STAT inhibition as a therapeutic target for the treatment of PsA.

Dysregulated bioenergetics: a key regulator of joint inflammation.

OBJECTIVES: This study examines the relationship between synovial hypoxia and cellular bioenergetics with synovial inflammation. METHODS: Primary rheumatoid arthritis synovial fibroblasts (RASF) were cultured with hypoxia, dimethyloxalylglycine (DMOG) or metabolic intermediates. Mitochondrial respiration, mitochondrial DNA mutations, cell invasion, cytokines, glucose and lactate were quantified using specific functional assays. RASF metabolism was assessed by the XF24-Flux Analyzer. Mitochondrial structural morphology was assessed by transmission electron microscopy (TEM). In vivo synovial tissue oxygen (tpO2 mmHg) was measured in patients with inflammatory arthritis (n=42) at arthroscopy, and markers of glycolysis/oxidative phosphorylation (glyceraldehyde 3-phosphate dehydrogenase (GAPDH), PKM2, GLUT1, ATP) were quantified by immunohistology. A subgroup of patients underwent contiguous MRI and positron emission tomography (PET)/CT imaging. RASF and human dermal microvascular endothelial cells (HMVEC) migration/angiogenesis, transcriptional activation (HIF1α, pSTAT3, Notch1-IC) and cytokines were examined in the presence of glycolytic inhibitor 3-(3-Pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO). RESULTS: DMOG significantly increased mtDNA mutations, mitochondrial membrane potential, mitochondrial mass, reactive oxygen species and glycolytic RASF activity with concomitant attenuation of mitochondrial respiration and ATP activity (all p<0.01). This was coupled with altered mitochondrial morphology. Hypoxia-induced lactate levels (p<0.01), which in turn induced basic fibroblast growth factor (bFGF) secretion and RASF invasiveness (all p<0.05). In vivo glycolytic markers were inversely associated with synovial tpO2 levels <20 mm Hg, in contrast ATP was significantly reduced (all p<0.05). Decrease in GAPDH and GLUT1 was paralleled by an increase in in vivo tpO2 in tumour necrosis factor alpha inhibitor (TNFi) responders. Novel PET/MRI hybrid imaging demonstrated close association between metabolic activity and inflammation. 3PO significantly inhibited RASF invasion/migration, angiogenic tube formation, secretion of proinflammatory mediators (all p<0.05), and activation of HIF1α, pSTAT3 and Notch-1IC under normoxic and hypoxic conditions. CONCLUSIONS: Hypoxia alters cellular bioenergetics by inducing mitochondrial dysfunction and promoting a switch to glycolysis, supporting abnormal angiogenesis, cellular invasion and pannus formation.

Dysregulated cytokine expression in lesional and nonlesional skin in hidradenitis suppurativa.

BACKGROUND: There is a dearth of information on the precise pathogenesis of hidradenitis suppurativa (HS), but immune dysregulation is implicated. OBJECTIVES: To determine the nature of the immune response in HS. METHODS: Skin biopsies - lesional, perilesional (2 cm away) and uninvolved (10 cm away) - were obtained from patients with HS and healthy controls. The expression of various cytokines was determined by enzyme-linked immunosorbent assay, flow cytometry and real-time polymerase chain reaction. RESULTS: The expression of the inflammatory cytokines interleukin (IL)-17, IL-1ß and tumour necrosis factor-α was enhanced in lesional skin of patients with HS. In addition, IL17A and IL1B mRNA were enhanced in clinically normal perilesional skin. CD4(+) T cells produced IL-17 in HS, while CD11c(+) CD1a(-) CD14(+) cells were sources of IL-1ß. Activated caspase-1 was detected in HS skin and was associated with enhanced expression of NLRP3 and IL18. Inhibition of caspase-1 decreased IL-1ß and IL-18 production, suggesting that the caspase-1 pathway participates in IL-1ß and IL-18 expression in HS. Abnormal cytokine expression was detected in perilesional and uninvolved skin, which may suggest that subclinical inflammation is present in HS skin prior to the formation of an active lesion. CONCLUSIONS: This study demonstrates that CD4(+) T cells produce IL-17 in HS and that the IL-17 pathway may be important in HS pathogenesis. CD11c(+) CD1a(-) CD14(+) cells are a source of IL-1ß in HS, the production of which was shown to be mediated, in part, via a caspase-1-dependent pathway. These results suggest that IL-17 and the caspase-1-associated cytokines IL-1ß and IL-18 may play a role in the pathogenesis of HS.

Intracellular distribution and degradation of immunoglobulin G and immunoglobulin G fragments injected into HeLa cells.

Intact rabbit immunoglobulin G molecules (IgGs) and their papain or pepsin fragments were radio-iodinated and injected into HeLa cells. Whole IgGs, Fab2, and Fc fragments were degraded with half-lives of 60-90 h, whereas half-lives of Fab fragments were 110 h. These results indicate that proteolytic cleavage in the hinge region of the IgG molecule is not the rate-limiting step in its intracellular degradation. The hingeless human myeloma protein, Mcg, was degraded at the same rate as bulk human IgG, providing further evidence that the proteolytically susceptible hinge region is not important for intracellular degradation of IgG molecules. SDS acrylamide gel analysis of injected rabbit IgG molecules revealed that heavy and light chains were degraded at the same rate. Injected rabbit IgGs and rabbit IgG fragments were also examined on isoelectric focusing gels. Fab, Fab2, and Fc fragments were degraded without any correlation with respect to isoelectric point. Positively charged rabbit IgGs disappeared more rapidly than their negative counterparts, contrary to the trend reported for normal intracellular proteins. The isoelectric points of two mouse monoclonal antibodies were essentially unchanged after injection into HeLa cells, suggesting that the altered isoelectric profile observed for intact rabbit IgG resulted from degradation and not protein modification. The intracellular distributions of IgG fragments and intact rabbit IgG molecules were determined by autoradiography of thin sections through injected cells. Intact IgG molecules were excluded from HeLa nuclei whereas both Fab and Fc fragments readily entered them. Thus, for some proteins, entry into the nuclear compartment is determined primarily by size.

Identification of a vertebrate sister-chromatid separation inhibitor involved in transformation and tumorigenesis.

A vertebrate securin (vSecurin) was identified on the basis of its biochemical analogy to the Pds1p protein of budding yeast and the Cut2p protein of fission yeast. The vSecurin protein bound to a vertebrate homolog of yeast separins Esp1p and Cut1p and was degraded by proteolysis mediated by an anaphase-promoting complex in a manner dependent on a destruction motif. Furthermore, expression of a stable Xenopus securin mutant protein blocked sister-chromatid separation but did not block the embryonic cell cycle. The vSecurin proteins share extensive sequence similarity with each other but show no sequence similarity to either of their yeast counterparts. Human securin is identical to the product of the gene called pituitary tumor-transforming gene (PTTG), which is overexpressed in some tumors and exhibits transforming activity in NIH 3T3 cells. The oncogenic nature of increased expression of vSecurin may result from chromosome gain or loss, produced by errors in chromatid separation.

Caspase-3-generated fragment of gelsolin: effector of morphological change in apoptosis.

The caspase-3 (CPP32, apopain, YAMA) family of cysteinyl proteases has been implicated as key mediators of apoptosis in mammalian cells. Gelsolin was identified as a substrate for caspase-3 by screening the translation products of small complementary DNA pools for sensitivity to cleavage by caspase-3. Gelsolin was cleaved in vivo in a caspase-dependent manner in cells stimulated by Fas. Caspase-cleaved gelsolin severed actin filaments in vitro in a Ca2+-independent manner. Expression of the gelsolin cleavage product in multiple cell types caused the cells to round up, detach from the plate, and undergo nuclear fragmentation. Neutrophils isolated from mice lacking gelsolin had delayed onset of both blebbing and DNA fragmentation, following apoptosis induction, compared with wild-type neutrophils. Thus, cleaved gelsolin may be one physiological effector of morphologic change during apoptosis.

Systematic identification of mitotic phosphoproteins.

BACKGROUND: Cyclin-dependent kinases (CDKs) are thought to initiate and coordinate cell division processes by sequentially phosphorylating key targets; in most cases these substrates remain unidentified. RESULTS: Using a screen that scores for phosphorylation of proteins, which were translated from pools of cDNA plasmids in vitro, by either phosphoepitope antibody recognition or electrophoretic mobility shifts, we have identified 20 mitotically phosphorylated proteins from Xenopus embryos, 15 of which have sequence similarity to other proteins. Of these proteins, five have previously been shown to be phosphorylated during mitosis (epithelial-microtubule associated protein-115, Oct91, Elongation factor 1gamma, BRG1 and Ribosomal protein L18A), five are related to proteins postulated to have roles in mitosis (epithelial-microtubule associated protein-115, Schizosaccharomyces pombe Cdc5, innercentrosome protein, BRG1 and the RNA helicase WM6), and nine are related to transcription factors (BRG1, negative co-factor 2alpha, Oct91, S. pombe Cdc5, HoxD1, Sox3, Vent2, and two isoforms of Xbr1b). Of 16 substrates tested, 14 can be directly phosphorylated in vitro by the mitotic CDK, cyclin B-Cdc2, although three of these may be physiological substrates of other kinases activated during mitosis. CONCLUSIONS: Examination of this broad set of mitotic phosphoproteins has allowed us to draw three conclusions about how the activation of CDKs regulates cell-cycle events. First, Cdc2 itself appears to directly phosphorylate most of the mitotic phosphoproteins. Second, during mitosis most of the substrates are phosphorylated more than once and a number may be targets of multiple kinases, suggesting combinatorial regulation. Third, the large fraction of mitotic phosphoproteins that are presumptive transcription factors, two of which have been previously shown to dissociate from DNA during mitosis, suggests that an important function of mitotic phosphorylation is to strip the chromatin of proteins associated with gene expression.

Comparison of the results of four users of a contemporary CAD/CAM system.

The objective of this study was to investigate the variation of measurements recorded when four different users of the TracerCAD system trace a model of known dimensions and volume. This complements a previous study where the accuracy and consistency of a single user was measured. Landmarks were added to indicate proximal, distal, anterior, medial and lateral regions of a specially manufactured cylindrical nylon 6.6 model. Four circumferential lines were added at regular intervals along the length of the cylinder with a view to calculating diameters and volumes relative to these landmarks. The model was measured using a comparator with guaranteed accuracy to one hundredth of a millimetre, and was traced using the TracerCAD system by four different users. The difference in mean volume between measured results and TracerCAD scans of differing users ranged to -3%. Individual trace volumes varied by up to -7.85%. In all volumes measured, 11 out of 12 maximum volume percentage differences measured greater than 2%, and of these, seven results showed maximum volume percentage difference to measure greater than 4%.

Disseminated histoplasmosis in the acquired immunodeficiency syndrome. Report of five cases from a nonendemic area.

Disseminated histoplasmosis is predominantly a disease of the immunocompromised. However, it has been reported infrequently in patients with the acquired immunodeficiency syndrome (AIDS), and then almost exclusively from patients residing in endemic areas. We report five cases of disseminated histoplasmosis in patients with AIDS in a nonendemic area. The initial diagnosis was made by fiberoptic bronchoscopy in three patients and by bone marrow and liver biopsy specimens in one patient each. All patients had fungemia, septic shock, and multiple organ involvement. Three patients had a fulminant course and died within four weeks. Two patients had more prolonged courses, with one survival period of ten months. We conclude that patients with AIDS are at high risk to contract disseminated histoplasmosis with an extremely high morbidity and mortality. This risk is not limited to residents of endemic areas.

Evaluation of a contemporary CAD/CAM system.

The objective of this study is to investigate the accuracy of the TracerCAD system in measuring a model of known dimensions and volumes. A cylindrical nylon 6.6 model was prepared. Landmarks were added to indicate proximal, distal, anterior, medial, and lateral. Four additional landmarks were added at regular intervals along the length of the cylinder with a view to calculating diameters and volumes relative to these landmarks. The model was measured using a comparator with a guaranteed accuracy of 0.01 mm and was traced using the TracerCAD system (Test 1). The test was repeated with the model rotated by 90 degrees (Test 2), to determine whether there were any effects related to the orientation of the model in relation to the transmitter. The difference in average volume between measured results and TracerCAD scans was between 0.20% and -1.96%. Individual trace volumes varied between -0.0085% and -4.50%. In all volumes measured in Tests 1 and 2, all maximum volume percentage differences measured greater than 3%.

Pneumatocele formation in adult pneumonia.

Pneumatocele formation is unusual in adult pneumonia, particularly in pneumococcal pneumonia. We report three cases of pneumatocele formation in adults, including one with probable pneumococcal pneumonia. All three patients were severely ill and two expired. Although they are usually asymptomatic, pneumatoceles may enlarge and compress the adjacent lung and mediastinum. This occurred in two patients causing respiratory insufficiency and cardiovascular compromise. The placement of a chest tube into the enlarging pneumatocele resulted in successful decompression.

Detection of herpes simplex virus by biotinylated DNA probes.

Clinical specimens from 159 patients suspected with herpes simplex virus (HSV) were examined by monoclonal antibody immunofluorescence (IF) and by a commercial biotinylated DNA probe kit following cell culture isolation. Herpes simplex virus was isolated from 57 samples. All cultures were positive by IF when the cytopathic effect (CPE) was less than 1+ but only 49 (86%) yielded positive reaction with the DNA probe when CPE was at least 1+. A total of 54 clinical specimens was also examined directly by immunoperoxidase histopathology (IHP), IF, and DNA hybridization. Of these, 16 were positive by IHP, 15 by IF, and only five by DNA probe. The DNA probe kit was found to be reasonably sensitive only after cell culture isolation of HSV. Compared to the IF procedure, the DNA probe kit was found to be costly, labor intensive, and time consuming.

A horse race between independent processes: evidence for a phantom point of no return in preparation of a speeded motor response.

Electromyographic (EMG) data show that a speeded elbow extension response can be interrupted at any time after its execution. Submaximal, or partial, EMG data are also observed in some cases, from which 2 alternatives were considered. The partial response might in fact be interrupted early in response production or, alternately, it might arise from stopping processes that incompletely suppress the response production processes prior to their execution. An interrupted response is easily accounted for by a horse race between independent response production and stopping processes, whereas a partial response can only be reconciled if leakage between the two processes is allowed for. If the distinction between an interrupted and a partial response is correct, then the data yielded evidence for a phantom point of no return that locates late in the premotor component of the response and, thus, prior to the onset of EMG activity.

Genetic control of heat resistance and thermotolerance by recA and uvrA in E. coli K12.

Several recA and uvrA derivatives of E. coli K12 AB1157 develop a transient increase in heat resistance, i.e. induced thermotolerance after a brief exposure to 43.5 degrees C (less than 1 h). Thermotolerance was identified from the appearance of an inflection in the survival curve or from the loss of heat resistance in the presence of chloramphenicol (CAM) or rifampicin. Heat resistance and induced thermotolerance were enhanced by recA and uvrA gene functions and their contribution was roughly as follows: AB1157 (recA+ uvrA+) greater than AB2463 (recA- uvrA+) greater than AB1886 (recA+ uvrA-) greater than AB2480 (recA- uvrA-). In heat resistance, uvrA and recA contributed approximately equally and their effects were additive. Induced thermotolerance developed sooner and was maintained at a higher level in the presence of uvrA as compared with recA. Since uvrA-dependent excision repair is scheduled prior to recA-dependent (postreplication) repair, induction of thermotolerance may be linked to DNA repair. Although recA and uvrA play a distinct role, they are not essential, and thermotolerance can develop in the absence of either one or both of these gene functions. Furthermore, since thermotolerance can be induced in recA mutants (AB2463 and AB2480), its biochemical pathway must be different from that of the recA-dependent SOS system.

Cytotoxicity of Khat (Catha edulis) extract on cultured mammalian cells: effects on macromolecule biosynthesis.

A chloroform extract of Khat (Catha edulis) leaves was used to study the cytotoxic activity on KB, 1BR.3, and XP2Bi cells. Log phase cell survival curves showed an LD50 of 40 ng/ml for KB cells. 1BR.3 and XP2Bi cells were biphasic in their response to the extract during log phase, with an LD50 of 20 and 75 ng/ml, respectively. Stationary phase cells were unaffected by the extract. DNA and RNA synthesis inhibition was studied using radiolabeled thymidine or uridine to measure the amount of extract that inhibits the synthesis to 50% of the untreated control cells. DNA synthesis was inhibited by 45, 60 and 200 ng/ml and RNA synthesis by 24, 17 and 58 ng/ml in 1BR.3, XP2Bi and KB cells, respectively. Protein synthesis was inhibited to 15-20% of untreated control cells by a dose of 40 ng/ml in all the cells studied. From this work, it is apparent that the main cause of cytotoxicity of Khat extract may be the inhibition of de novo RNA synthesis. Our results suggest that this effect is exerted on all cells used in this study and that KB cells demonstrate a higher resistance to the toxic component.

On-line control of a speeded motor response.

Evidence for a point of no return in a motor act has been reported to occur very late in its preparation and even to the point at which the response is executed. We report a qualitative example from electromyographic (EMG) data of an elbow-extension movement from 1 of 12 adults which suggests that the response can be stopped at any time up to its production, from which we conclude that the response is subject to on-line control at all times.

Implementation of groups for creative expression on a psychiatric inpatient unit.

Patients benefited from creativity group participation through expression of both positive and negative feelings, group acceptance, and acceptance of self in a non-competitive activity. Psychiatric nurses can lead creativity groups with a focus on creative expression, rather than psychotherapy. No specific training in the arts is required for these simple creative formats. It was found from using a variety of creative formats that, overall, patients received group projects better than individual projects done in a group setting.