Summary We analysed the proportions of different microparticles (MPs) in plasma from patients with rheumatoid arthritis (RA), and assessed their relationship with disease activity/therapy and their in‐vitro effect on proinflammatory cytokine release. Blood and urine samples were obtained from 55 patients with RA (24 untreated and 31 under conventional therapy) and 20 healthy subjects. Fourteen patients with systemic lupus erythematosus (SLE) were also studied. The proportions of CD3+, CD14+, CD19+, CD41+ and CD62E+ MPs were determined by flow cytometry analysis. The in‐vitro effect of plasma MPs on the release of interleukin (IL)‐1, IL‐6, IL‐17 and tumour necrosis factor (TNF)‐α was also analysed. We detected that the proportions of different types of annexin‐V+ MPs were enhanced in plasma (CD3+, CD14+, CD19+, CD41+ and CD62E+ MPs) and urine (CD14+, CD3+ and CD19+ MPs) from RA patients with high disease activity (DAS28 index > 5·1). Accordingly, a significant positive correlation was observed between the levels of MPs and DAS28 score, and these levels diminished significantly at week 4 of immunosuppressive therapy. Finally, MPs isolated from patients with high disease activity induced, in vitro, an enhanced release of IL‐1, IL‐17 and TNF‐α. In SLE, enhanced levels of different types of plasma MPs were also detected, with a tight correlation with disease activity. Our data further support that MPs have a relevant role in the pathogenesis of RA and suggest that the analysis of the proportions of these microvesicles in plasma could be useful to monitor disease activity and therapy response in patients with RA.

The blood-brain barrier (BBB) plays a significant pathophysiological role in multiple sclerosis (MS). Vasopressin (AVP) is released after brain injury and contributes to the inflammatory response. We propose that AVP may be modulating BBB permeability and hence affecting EAE clinical signs. Female Lewis rats were immunized s.c. with guinea-pig brain extract suspended in complete Freund's adjuvant. prior to that, animals were subjected to neurointermediate pituitary lobectomy (niL) or treated with AVP receptor antagonist (conivaptan). BBB permeability assays were performed. Western blot for claudin-5 and histological analysis were performed in conivaptan treated EAE rats. EAE increase in BBB permeability to Evans blue was reverted by the NIL surgery. AVP receptor blockade reverted the EAE BBB hyperpermeability to Evans blue and 10-kDa FITC-dextran in almost all brain regions. Both, AVP low levels and AVP receptor blockade attenuated EAE clinical signs. Conivaptan reduced perivascular cuffs in EAE rats. A decrease in claudin-5 expression was observed in EAE rats and conivaptan treatment partially restored normal levels. Our data indicate that V1a and V2 AVP receptors can modulate BBB permeability and consequently are involved in the CNS inflammatory process during EAE. Future research is required to characterize the utility of vasopressin antagonist in MS treatment.

IntroductionThe experimental autoimmune encephalomyelitis (EAE), the rat paradigm for the human multiple sclerosis (MS), are autoimmune diseases mediated by Th1 and Th17 cells and responsible of the nervous system demyelination and progressive paralysis. It is know that lymphocytes possess AVP receptors and that EAE increases AVP serum levels along the disease. Neurointermediate pituitary lobectomy (NIL) in rats causes AVP and oxytocin permanent low serum levels and decreased humoral and cell‐mediated immune responses. Nevertheless the role of AVP as a direct immune regulatory factor has not been well clarified.ObjectiveTo investigate the effects of AVP deficiency (by NIL), and the treatment with desmopressin (DP, a synthetic analog of AVP) and conivaptan (CNV, an AVP V1a‐V2 receptor antagonist) on the clinical symptoms of EAE, and to determine the serum levels of Interleukine‐2 (IL‐2), IL‐4, IL‐6, IL‐10, IL‐17A, INF‐γ and TNF‐α in the experimental groups.MethodsGroups of female Lewis rats were divided in: (1) Intact control (Control) (2) Control+EAE, (3) Sham‐operated (SHAM), (4) Control+CNV, (5) NIL and (6) NIL+DP. Except the Control the remaining groups were immunized for EAE three weeks post‐NIL. DP and CNV administrations started 3 days before EAE immunizations. Serum cytokines were analyzed by flow cytometry and EAE clinical symptoms were evaluated by a conventional numerical scale.ResultsEAE clinical symptoms, INF‐γ, TNF‐α, and the IL‐2, IL‐6 and IL‐17A were significantly decreased in both NIL and CNV groups, whereas the IL‐4 and IL‐10 increased in the CNV group. In NIL+DP group we found a significant increase in TNF‐α, whereas the IL‐4 was significantly decreased.Conclusions1) The present clinical and molecular findings demonstrate that AVP deficiency and the block of the AVP receptors decreased immune response, and that DP restores the susceptibility of the NIL animals to develop EAE. 2) The results strongly support that acting directly on the AVP receptors, AVP plays an important immuneregulatory role in the generation and maintenance of the immune‐competence, 3) AVP receptors may be therapeutic targets in the treatment of the human MS.Support or Funding InformationSupported by UAA‐PIFF14‐1 and CONACYT‐221262 (AQS). México.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

IntroductionHuman Multiple Sclerosis (MS) is a medically important disease. MS and its experimental autoimmune encephalomyelitis (EAE) paradigm are central nervous system demyelinizing diseases in which the immune system is directly involved. The pursuit for new treatments for MS still as an important goal for research. The use of the EAE animals to study the immune mechanisms that mediate the disease still being the best strategy to deep into the immune‐neuroendocrine interactions during the pathogenesis. Previously we have demonstrated that neurointermediate pituitary lobectomy (NIL) decreases humoral and cell‐mediated immune responses and that AVP is directly involved. Nevertheless, the role of AVP has not been entirely clarified.ObjectiveTo investigate the mechanism by which AVP deficiency (by NIL) and desmopressin (DP, a synthetic analog of AVP) affects the development of the clinical signs, the immune response and gene expression profile in the EAE.MethodsFemale Lewis rats were divided into intact control (IC), EAE immunized, NIL and NIL treated with desmopressin (NIL+DP). Except the IC, the remaining groups were immunized for EAE. The EAE was induced by encephalitogen subcutaneous injection. Animals were sacrificed at the peak of the disease (15 days after immunization). EAE clinical signs, cytokine serum profiles (IL‐17A, IL‐4, IL‐2, IL‐10, IL‐6, TNF‐α and INF‐γ) (flow cytometry) and spleen gene expression profile (microarray) were evaluated. DP treatment started 3 days before immunization.ResultsAs compared with the EAE group, NIL animals developed just a mild clinical signs of EAE and significant decreased IFN‐γ and IL‐17 levels. NIL+DP treated animals restored its susceptibility to EAE clinical signs, whereas no‐significant differences on cytokine levels occurred. Significant differences in gene expression profile among groups were evident; in the NIL group the expression pattern of the TGF‐β pathway was down‐regulated as compared with the EAE group, whereas in the NIL+DP group the same genes were up‐regulated.ConclusionsFindings add novel data indicating that directly AVP plays a crucial role in regulating the immune responses and suggests that AVP receptor blockers may be used for the MS treatment and possibly autoimmune diseases and other inflammatory processes.Support or Funding InformationSupported by UAA‐PIFF14‐1 and CONACYT‐221262 (AQS). México. VVB: CONACT Doctoral scholarship. NMS: CONACYT post doctoral Fellow. México.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The role of AVP controlling the mean arterial blood pressure (MBP) in basal conditions remains unclear. We described that neurointermediate pituitary lobectomy (NIL) in rats, induced an early but transient diabetes insipidus and low MBP (8 weeks after lobectomy). To elucidate the chronological effects of NIL, we evaluated the AVP serum levels, water intake and urine output (diabetes insipidus, DI), and MBP immediately (0 to 6 hours post NIL) and 3, 15, 45 and 90 days post NIL. The renin, angiotensin II and aldosterone system (RAAS) was assessed at 3 and 45 days post NIL. Values were compared with the respective SHAM operated groups. Results: NIL caused significant and permanent AVP serum level decrease (10.6 ± 0.8 vs 2.4 ± 0.16 pg/ml (SD), SHAM vs NIL), transient DI (15‐30 days of duration) and permanent decrease of the MBP in 70% of the NIL animals (106.8 ± 3.15 vs 73.8 ± 3.2 mmHg). Hypotension was apparent 20‐30 minutes after NIL. No significant differences in the RAAS were evident.ConclusionsWe propose that in non‐stressed animals, basal serum levels of AVP are required to maintain the hydro‐electrolytic balance and MBP. Further studies are needed to explain why some animals did not develop hypotension, and to determine how cardiovascular, renal and hormone adaptive mechanisms in the NIL group support their survival.Supported by UAA‐PIFF and CONACYT, México and the Jarislowsky and L. Carr‐Harris Foundations