Down-regulation of miR-18b-5p protects against splenic hemorrhagic shock by directly targeting HIF-1α/iNOS pathway.

Splenic hemorrhagic shock is a typical emergency in surgery, seriously threatening human beings' life. Emerging evidence shows that microRNAs (miRNAs) are closely related to inflammation and immunity in the body. However, the detailed effects and underlying mechanisms of miRNAs on the immune function of splenic hemorrhagic shock have not been revealed yet. In the present study, we construct the rat hemorrhagic shock model, and the rats are further cured with splenic blood transport clipping recanalization (SBTCR). MiR-18b-5p was highly expressed in the spleen of hemorrhagic shock rats detected by the qRT-PCR assay. Functionally, down-regulation of miR-18b-5p notably inhibited the levels of SOD1, iNOS and IL-6 in macrophages isolated from splenic tissues detected by qRT-PCR and ELISA assays. In addition, inhibition of miR-18b-5p significantly decreased the M1/M2 ratio of macrophages. Besides, knockdown of miR-18b-5p obviously reduced the Th1/Th2 ratio of CD4+ T cells. Moreover, HIF-1α was predicted as a target gene of miR-18b-5p, which was further confirmed by dual-luciferase reporter assay, and HIF-1α was negatively associated with miR-18b-5p. Furthermore, overexpression of HIF-1α partially restored the effects of miR-18b-3p on inflammation and immunity in macrophages. Taken together, miR-18b-5p may be a novel therapeutic candidate target in splenic hemorrhagic shock treatment.

Preferable Transplant Site for Hepatocyte Transplantation in a Rat Model.

Intraportal injection is regarded as the current standard procedure of hepatocyte transplantation (HTx). In islet transplantation, which shares many aspects with HTx, recent studies have clarified that instant blood-mediated inflammatory reaction (IBMIR), characterized by strong innate immune responses, can cause poor engraftment, so other transplant sites to avoid such a reaction have been established. Although IBMIR was reported to occur in HTx, few reports have evaluated alternative transplant sites for HTx. In this study, we sought to determine the optimum transplant site for HTx. Rat hepatocytes (1.0 × 107) were transplanted at the 9 transplant sites (intraportal (IPO), intrasplenic (IS), liver parenchyma, subcutaneous, intraperitoneal, renal subcapsular, muscle, inguinal subcutaneous white adipose tissue, and omentum) of analbuminemic rats. The serum albumin levels, immunohistochemical staining (albumin, TUNEL, and BrdU), and in vivo imaging of the grafts were evaluated. The serum albumin levels of the IPO group were significantly higher than those of the other groups (p < .0001). The BrdU-positive hepatocyte ratio of liver in the IS group (0.9% ± 0.2%) was comparable to that of the IPO group (0.9% ± 0.3%) and tended to be higher than that of the spleen in the IS group (0.5% ± 0.1%, p = .16). Considering the in vivo imaging evaluation and the influence of splenectomy, the graft function in the IS group may be almost entirely achieved by hepatocytes that have migrated to the liver. The present study clearly showed that the intraportal injection procedure is more efficient than other procedures for performing HTx.

Cholinergic stimulation with pyridostigmine modulates a heart-spleen axis after acute myocardial infarction in spontaneous hypertensive rats.

The mechanisms regulating immune cells recruitment into the heart during healing after an acute myocardial infarction (AMI) have major clinical implications. We investigated whether cholinergic stimulation with pyridostigmine, a cholinesterase inhibitor, modulates heart and spleen immune responses and cardiac remodeling after AMI in spontaneous hypertensive rats (SHRs). Male adult SHRs underwent sham surgery or ligation of the left coronary artery and were randomly allocated to remain untreated or to pyridostigmine treatment (40 mg/kg once a day by gavage). Blood pressure and heart rate variability were determined, and echocardiography was performed at day six after MI. The heart and spleen were processed for immunohistochemistry cellular analyses (CD3+ and CD4+ lymphocytes, and CD68+ and CD206+ macrophages), and TNF levels were determined at day seven after MI. Pyridostigmine treatment increased the parasympathetic tone and T CD4+ lymphocytes in the myocardium, but lowered M1/M2 macrophage ratio towards an anti-inflammatory profile that was associated with decreased TNF levels in the heart and spleen. Treatment with this cholinergic agent improved heart remodeling manifested by lower ventricular diameters and better functional parameters. In summary, cholinergic stimulation by pyridostigmine enhances the parasympathetic tone and induces anti-inflammatory responses in the heart and spleen fostering cardiac recovery after AMI in SHRs.

Tonifying spleen and replenishing kidney method of traditional Chinese medicine for myasthenia gravis: A protocol for systematic review and meta-analysis.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune antibody-mediated disorder caused by dysfunction at the neuromuscular junction spreads. The main clinical features of this disease are fluctuating fatigue, and weakness of the skeletal muscles of the eyes and limbs. At present, the tonifying the spleen and replenishing the kidney method in traditional Chinese medicine has been widely used for MG. The present study was conducted to evaluate the efficacy and safety of the tonifying the spleen and replenishing the kidney method in traditional Chinese medicine for MG. METHODS: The following 10 databases were searched from inception to March 2021: PubMed, Cochrane Library, EMBASE, Web of Science, Springer, China National Knowledge Infrastructure (CNKI), Wan fang, VIP Chinese Science and Technique Journals Database, the Chinese Bio Medical Database (CBM), and Baidu Scholar. The language was limited to the Chinese and English language. Merely randomized controlled trials (RCTs) were included. The Cochrane Collaboration risk-of-bias tool was used for the methodological quality assessment and risk of bias. The meta-analysis was assessed using the Cochrane RevMan 5.3 software. RESULTS: In the present study, a meta-analysis was conducted, and RCTs that met the eligibility criteria were included. Furthermore, the different outcome indicators of different methods were objectively compared. The main outcome indicators included the effective rate, quantitative myasthenia gravis (QMG) scores, adverse events, and quality of life (QOL). The secondary outcome indicators included AchRAb, serum-related immune cells (such as CD3+CD4+cells and CD4+/CD8+cells), the traditional Chinese medicine syndrome score scale (TCMSSS), the serum interleukin-6 level, the level of IFN-γ and its mRNA, and the clinical score that contains the clinical absolute score (CAS) and clinical relative score (CRS). CONCLUSION: This study would provide credible evidence to determine whether the tonifying the spleen and replenishing the kidney method in traditional Chinese medicine is an effective treatment method for MG. TRIAL REGISTRATION NUMBER: INPLASY202110097.

Dynamic modulation of spleen germinal center reactions by gut bacteria during Plasmodium infection.

Gut microbiota educate the local and distal immune system in early life to imprint long-term immunological outcomes while maintaining the capacity to dynamically modulate the local mucosal immune system throughout life. It is unknown whether gut microbiota provide signals that dynamically regulate distal immune responses following an extra-gastrointestinal infection. We show here that gut bacteria composition correlated with the severity of malaria in children. Using the murine model of malaria, we demonstrate that parasite burden and spleen germinal center reactions are malleable to dynamic cues provided by gut bacteria. Whereas antibiotic-induced changes in gut bacteria have been associated with immunopathology or impairment of immunity, the data demonstrate that antibiotic-induced changes in gut bacteria can enhance immunity to Plasmodium. This effect is not universal but depends on baseline gut bacteria composition. These data demonstrate the dynamic communications that exist among gut bacteria, the gut-distal immune system, and control of Plasmodium infection.

Electroacupuncture facilitates M2 macrophage polarization and its potential role in the regulation of inflammatory response.

The underlying mechanism of electroacupuncture (EA) in relieving obesity, anti-inflammation and the interaction with metabolic pathways in obese mice has not been elaborated. The aim of this study was to investigate the regulation of EA on macrophage polarization in obesity tissue of diet-induced obesity mice. Mice were divided in 6 groups: normal control group, model group, EA-7 group, EA-14 group, EA-21 group and EA-28 group. Low-frequency EA was applied at "Tianshu (ST 25)", "Guanyuan (CV 4)", "Zusanli (ST 36)" and "Sanyinjiao (SP 6)" for 10 min. Adipose tissue was assessed with hematoxylin and eosin staining. Adipocytokines and pro-inflammatory factors expression was measured by ELISA. The protein and mRNA levels of macrophage markers were examined by immumohistochemical staining and RT-PCR, respectively. EA treatment was associated with a decrease of adipose tissue and large adipocytes, and an increase of small adipocytes. After EA treatment, the levels of Leptin, Chemerin, TNF-α, F4/80, iNOS, and CD11c decreased obviously in adipose tissue, while IL-4, IL-10 and CD206 levels increased significantly. Besides, TNF-α in spleen tissue was also downregulated, but IL-4 and IL-10 were upregulated. EA prevents weight gain through modulation inflammatory response and macrophage polarization in obese adipose tissues.

Liver-spleen axis in nonalcoholic fatty liver disease.

Introduction: NAFLD is often under-diagnosed, even though rates of its co-morbidities such as obesity and type2 diabetes mellitus, prominent statuses of inflammation, are significantly high. The spleen-liver axis is gaining much credit in the last years like other well-known organ axes.Areas covered: PubMed/MEDLINE was searched for relevant articles related to concomitant occurrence of NAFLD and spleen. Areas covered in this review include: (1) updated findings of spleen dimensions at ultrasonography, (2) discussion of current data on pathophysiological connections between obesity-related NAFLD and increased volume of the spleen, and (3) analysis of current immune-mediated mechanisms characterizing the so.called chronic low-grade inflammation leading to insulin resistance.Expert opinion: The advances in explaining mechanisms underlying the spleen involvement in immune regulation, coupled with research about the role of spleen in NAFLD, could impact real world outcomes through establishing better tools for a precocious diagnosis. Using both liver and spleen ultrasonography, technique largely dealt with in this review, could expand the possibility to cover an adequate diagnostic path toward NAFLD, reaching a good sensibility and specificity.

Splenic non-infarction volume determines a clinically significant hepatic venous pressure gradient response to partial splenic embolization in patients with cirrhosis and hypersplenism.

BACKGROUND: This study aimed to investigate changes in the hepatic venous pressure gradient (HVPG) by partial splenic embolization (PSE) and to identify the determinants of a clinically meaningful postoperative HVPG reduction. METHODS: Sixty-eight patients with cirrhosis and hypersplenism who underwent PSE at our department between September 2007 and June 2020 were included. The HVPG was evaluated pre- and immediately post-PSE. The patients were divided into three groups according to their preprocedural HVPG: low-HVPG (< 10 mmHg, n = 22), intermediate-HVPG (10 mmHg ≤ HVPG < 16 mmHg, n = 33), and high-HVPG (≥ 16 mmHg, n = 13). RESULTS: Overall, PSE significantly reduced HVPG from 12.2 ± 4.0 to 9.4 ± 3.6 mmHg (p < 0.01) with a relative decrease of 22.2 ± 20.4%. In addition, HVPG reductions were 19.4 ± 28.7%, 24.0 ± 15.9%, and 22.5 ± 13.3% in the low-, intermediate-, and high-HVPG groups, respectively, indicating no significant difference in HVPG reduction between the groups. An HVPG decrease of ≥ 20% from the baseline, defined in this study as a clinically significant HVPG response to PSE, was achieved in 55.9% of all patients. Multivariate logistic regression and receiver operating characteristic curve analyses identified splenic non-infarction volume as an independent determinant of a 20% decrease in HVPG (p < 0.05), with a cut-off of 139.2 cm3 (sensitivity, 76.3%; specificity, 60.0%; p < 0.05). CONCLUSIONS: The splenic non-infarction volume, namely the residual functional spleen volume, independently determines a clinically significant HVPG response to PSE in patients with cirrhosis and hypersplenism.

Therapeutic effect of Jianpi Liqi Fang combined with transcatheter arterial chemoembolization in patients with hepatocellular carcinoma and spleen deficiency syndrome.

OBJECTIVE: To investigate the therapeutic effect of the Jianpi Liqi Fang ( ，JPLQF) combined with transcatheter arterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC) and spleen deficiency syndrome (SDS) and identify a potential indicator of efficacy. METHODS: Ninety-nine patients with HCC who were diagnosed with SDS, non-spleen deficiency syndrome (NSDS), or no syndrome (NS) were treated with JPLQF combined with TACE for three periods. Therapeutic efficacy was compared among the groups. Plasma proteins were screened using label-free discovery analysis and verified via enzyme-linked immunosorbent assay (ELISA). Furthermore, receiver operating characteristic (ROC) curves were analyzed to evaluate therapeutic indicators. RESULTS: After treatment, the Karnofsky Performance Status was significantly improved in the SDS group and significantly better than that in the NS group. The Traditional Chinese Medicine (TCM) syndrome scores were lower in the SDS group after treatment and lower than those in the NSDS group. However, alanine aminotransferase, carbohydrate antigen 19-9, alpha-fetoprotein, and carcinoembryonic antigen levels and white blood cell and platelet counts did not differ among the groups. Serum aspartate aminotransferase levels in the SDS group were significantly lower after treatment than before treatment, and total bilirubin levels were significantly lower in the SDS group than in the NSDS group. Label-free analysis identified 24 differentially expressed proteins (DEPs) between the SDS and NS groups, including 17 and 7 upregulated and downregulated proteins, respectively. Fibulin-5 (FBLN5) displayed the largest difference in expression between the groups. ELISA confirmed that FBLN5 levels were significantly lower in the NSDS and NS groups than in the SDS group. Following treatment with JPLQF and TACE, FBLN5 expression was upregulated only in the SDS group. Furthermore, ROC curve analysis indicated that FBLN5 may serve as a potential indicator of the efficacy of JPLQF combined with TACE in patients with HCC and SDS. CONCLUSION: JPLQF combined with TACE improved quality of life, clinical TCM symptoms, and liver function in patients with HCC and SDS. FBLN5 expression was significantly altered by treatment with JPLQF and TACE in patients with HCC and SDS.

Association between splenic volume and pulsatility index in patients with left ventricular assist devices.

The spleen serves as a blood volume reservoir for systemic volume regulation in heart failure (HF) patients. Changes are seen in spleen size in advanced HF patients after left ventricular assist device (LVAD) implantation. The pulsatility index (PI) is an indicator of native heart contractility with hemodynamic changes in patients using LVAD. We hypothesized that the splenic volume was associated with the PI, reflecting the hemodynamics in advanced HF patients with LVADs. Herein, we investigated the relationship between splenic volume and PI in these patients. Forty-four patients with advanced HF underwent implantation of HeartMate II® (Abbott, Chicago, IL, USA) as a bridge to heart transplantation at the Nagoya University Hospital between October 2013 and June 2019. The data of 27 patients (21 men, median age 46 years) were analyzed retrospectively. All patients underwent blood tests, echocardiography, right heart catheterization, and computed tomography (CT). Spleen size was measured via CT volumetry; the splenic volume (median: 190 mL) correlated with right arterial pressure (r = 0.431, p = 0.025) and pulmonary capillary wedge pressure (r = 0.384, p = 0.048). On multivariate linear regression analysis, the heart rate (ß = -0.452, p = 0.003), pump power (ß = -0.325, p = 0.023), and splenic volume (ß = 0.299, p = 0.038) were independent determinants of PI. The splenic volume was associated with PI, reflecting the cardiac preload in advanced HF patients with LVADs. Thus, spleen measurement using CT may help estimate the systemic volume status and understand the hemodynamic conditions in LVAD patients.

Diagnostic value of conventional ultrasound and shear wave elastography in detecting transjugular intrahepatic portosystemic shunt dysfunction.

BACKGROUND: Transjugular intrahepatic portosystemic shunt (TIPS) dysfunction can cause recurrent portal hypertension (PH)-related complications such as ascites and gastroesophageal variceal bleeding. Portography is invasive and costly limits its use as a screening modality. PURPOSE: To assess the clinical value of conventional ultrasound in combination with point shear wave elastography (pSWE) to predict TIPS dysfunction. MATERIAL AND METHODS: A total of 184 patients with cirrhosis scheduled for TIPS implantation were enrolled in this study and evaluated retrospectively. The splenoportal venous blood flow parameter, liver stiffness (LS), and spleen stiffness (SPS) were measured. Outcome measures included differences in portal vein velocity (PVV), splenic vein velocity (SPVV), LS, and SPS. The accuracy of change in PVV (ΔPVV), SPVV (ΔSPVV), and SPS (ΔSPS) to diagnose TIPS dysfunction was investigated. RESULTS: TIPS dysfunction occurred in 28 of 184 patients (15.2%). Eighteen (64.3%) patients had shunt stenoses and 10 (35.7%) had shunt occlusion. Portal vein diameter (PVD), PVV, splenic vein diameter (SPVD), SPVV, LS, and SPS were not significantly different between the TIPS normal and TIPS dysfunction groups. Compared with the TIPS normal group, PVV and SPVV of the TIPS dysfunction group decreased significantly, whereas SPS increased significantly (P < 0.001). The values of areas under the receiver operating characteristic curves of ΔPVV, ΔSPVV, and ΔSPS for the diagnosis of TIPS dysfunction were 0.97, 0.96, and 0.87, respectively. CONCLUSION: pSWE showed a diagnostic efficacy comparable to conventional ultrasound for diagnosing TIPS dysfunction and can be used routinely after TIPS procedures.

Alterations in the non-neuronal cholinergic system induced by in-vitro exposure to diazoxon in spleen mononuclear cells of Nile tilapia (O. niloticus).

Organophosphate pesticides as diazinon disrupt the neuroimmune communication, affecting the innate and adaptive immune response of the exposed organisms. Since the target molecule of diazinon is typically the acetylcholinesterase enzyme (AChE), the existence of a non-neuronal cholinergic system in leukocytes makes them susceptible to alterations by diazinon. Therefore, the aim of this work was to evaluate the activity of AChE, acetylcholine (ACh) concentration, and the expression of nicotinic ACh receptors (nAChR) and muscarinic ACh receptors (mAChR) in spleen mononuclear cells (SMNC) of Nile tilapia (O. niloticus) exposed in vitro to diazoxon, a diazinon metabolite. SMNC were exposed in-vitro to 1 nM, 1 µM, and 10 µM diazoxon for 24 h. The enzyme activity of AChE was then evaluated by spectrophotometry, followed by ACh quantification by ultra-performance liquid chromatography. Finally, mAChR and nAChR expression was evaluated by RT-qPCR. The results indicate that AChE levels are significantly inhibited at 1 and 10 µM diazoxon, while the relative expression of (M3, M4, and M5) mAChR and (ß2) nAChR is reduced significantly as compared against SMNC not exposed to diazoxon. However, ACh levels show no significant difference with respect to the control group. The data indicate that diazoxon directly alters elements in the cholinergic system of SMNC by AChE inhibition or indirectly through the interaction with AChR, which is likely related to the immunotoxic properties of diazinon and its metabolites.

Esplenectomía laparoscópica en esplenomegalia masiva: a propósito de un caso / Laparoscopic splenectomy in massive splenomegaly. About a case

Introducción: el bazo constituye el órgano reticuloendotelial mayor del cuerpo. Este puede ser afectado por una serie de desórdenes primarios y secundarios indicativos de esplenectomía. Las primeras esplenectomías por técnicas de mínimo acceso fueron reportadas entre los años 1991 y 1992, encontrando entre sus ventajas una más pronta recuperación, mejores resultados estéticos, y menor sangrado intraoperatorio. Presentación del caso: paciente de 43 años de edad que es intervenida por esplenomegalia masiva secundaria a púrpura trombocitopénica inmunológica, realizándosele esplenectomía laparoscópica satisfactoria. Discusión: las esplenomegalias masivas son aquellas cuando el bazo supera los 20 cm de longitud entre sus polos superior e inferior, siendo este criterio contraindicación relativa para esplenectomía laparoscópica. Conclusiones: la extirpación exitosa del bazo por cirugía laparoscópica en aquellos pacientes con esplenomegalia masiva puede ser factible siempre que se cumplan una serie de condiciones elementales(AU)

Introduction: the spleen is the largest reticuloendothelial organ in the body. This can be affected by a series of primary and secondary disorders indicative of splenectomy. The first splenectomies using minimal access techniques were reported between 1991 and 1992, finding among their advantages a faster recovery, better aesthetic results, and less intraoperative bleeding. Case presentation: 43-year-old patient who underwent surgery for massive splenomegaly secondary to immunological thrombocytopenic purpura, undergoing satisfactory laparoscopic splenectomy. Discussion:massive splenomegalies are those when the spleen exceeds 20 cm in length between its upper and lower poles, this criterion being a relative contraindication for laparoscopic splenectomy. Conclusions: thesuccessful removal of the spleen by laparoscopic surgery in those patients with massive splenomegaly may be feasible provided that a series of elementary conditions are met(EU)

Spleen Stiffness Predicts Survival after Transjugular Intrahepatic Portosystemic Shunt in Cirrhotic Patients.

OBJECTIVES: Transjugular intrahepatic portosystemic shunt (TIPS) is an effective intervention for portal hypertensive complications. Little is known about the ability of spleen stiffness (SS) for predicting the survival of cirrhotic patients undergoing TIPS. This study is to evaluate the influence of SS detected by point shear wave elastography (pSWE) in predicting survival after TIPS. METHODS: This retrospective cohort study screened consecutive patients who underwent TIPS and reliable pSWE measurement between October 2014 and September 2017 from our prospectively maintained database. SS values were measured before TIPS. The primary endpoint was the overall survival after TIPS. The Cox regression analysis model was used for univariate and multivariate analyses. A receiver operating characteristic (ROC) curve analysis was performed to calculate the sensitivity, specificity, and positive and negative predictive values. RESULTS: A total of 89 patients were involved in the final analysis. 24 patients (27.0%) died during a median follow-up time of 31 m. Multivariable Cox regression analysis confirmed that higher SS value (P < 0.001), LS value (P = 0.008), diameter of shunt (P = 0.001), and older age (P < 0.001) were independent prognostic factors of survival after TIPS. The risk of death rose 57.440-fold for each SS unit (m/s) increase. SS was also correlated with liver failure after TIPS. ROC analysis showed that the best SS cutoff value was 3.60 m/s for predicting survival, with a sensitivity of 54.2% and specificity of 90.8%. CONCLUSIONS: The SS value determined by pSWE in cirrhotic patients was an independent predictive factor for survival after TIPS.

Evaluation of liver function using liver parenchyma, spleen and portal vein signal intensities during the hepatobiliary phase in Gd-EOB-D TPA-enhanced MRI.

BACKGROUND: Previous studies have used signal intensity (SI) to reflect liver function. However, few studies have evaluated liver function via the portal vein. Regarding the SI of the liver, spleen, and portal vein, no study has indicated which can best reflect liver function. Therefore, the aim of this study is to investigate whether these parameters can evaluate liver function in patients with cirrhosis and determine which is the best parameter. METHODS: 120 patients with normal livers (n = 41) or Child-Pugh class A (n = 50), B (n = 21) or C (n = 8) disease who had undergone Gd-EOB-DTPA-enhanced MRI were retrospectively reviewed. Comparisons of the MRI data (liver parenchyma SI, portal vein SI, and spleen SI and liver-to-portal vein contrast ratio (LPC), liver-to-spleen contrast ratio (LSC), and portal vein-to-spleen contrast ratio (PSC)) in the 15-min hepatobiliary phase images were performed among the groups, and the correlations among the liver function parameters (total bilirubin, direct bilirubin, indirect bilirubin, aspartate aminotransferase, alanine aminotransferase, albumin, creatinine, platelet count, prothrombin time and international normalized ratio), liver function scores and MRI data were also quantitatively analysed. RESULTS: Significant differences were observed in the liver parenchyma SI, LPC and LSC among the groups. These values all decreased gradually from normal livers to Child-Pugh class C cirrhotic livers (P < 0.001). The portal vein SI constantly and slightly increased from normal livers to Child-Pugh class C cirrhotic livers, but no differences were found among the groups in the portal vein SI and PSC (P > 0.05). LPC showed a stronger correlation with the Child-Pugh score and MELD score than LSC and the liver parenchyma SI. The order of the AUCs of these parameters, from largest to smallest, was as follows: LPC, LSC, and liver parenchyma SI (P > 0.05). CONCLUSION: The liver parenchyma SI, LSC and LPC may be used as alternative imaging biomarkers to assess liver function, while the portal vein SI and PSC do not reflect liver function. Furthermore, LPC values can more effectively distinguish severity among patients with cirrhosis than the liver parenchyma SI and LSC.

The intrinsic and extrinsic elements regulating inflammation.

Inflammation is a sophisticated biological tissue response to both extrinsic and intrinsic stimuli. Although the pathological aspects of inflammation are well appreciated, there are still rooms for understanding the physiological functions of the inflammation. Recent studies have focused on mechanisms, context and the role of physiological inflammation. Besides, there have been progress in the comprehension of commensal microbiota, immunometabolism, cancer and intracellular signaling events' roles that impact on the regulation of inflammation. Despite the fact that inflammatory responses are vital through tissue damage, understanding the mechanisms to turn off the finished or unnecessary inflammation is crucial for restoring homeostasis. Inflammation seems to be a smart process that acts like two edges of a sword, meaning that it has both protective and deleterious consequences. Knowing both edges and the regulation processes will help the future understanding and therapy for various diseases.

Hemolysis in the spleen drives erythrocyte turnover.

Red pulp macrophages (RPMs) of the spleen mediate turnover of billions of senescent erythrocytes per day. However, the molecular mechanisms involved in sequestration of senescent erythrocytes, their recognition, and their subsequent degradation by RPMs remain unclear. In this study, we provide evidence that the splenic environment is of substantial importance in facilitating erythrocyte turnover through induction of hemolysis. Upon isolating human spleen RPMs, we noted a substantial lack of macrophages that were in the process of phagocytosing intact erythrocytes. Detailed characterization of erythrocyte and macrophage subpopulations from human spleen tissue led to the identification of erythrocytes that are devoid of hemoglobin, so-called erythrocyte ghosts. By using in vivo imaging and transfusion experiments, we further confirmed that senescent erythrocytes that are retained in the spleen are subject to hemolysis. In addition, we showed that erythrocyte adhesion molecules, which are specifically activated on aged erythrocytes, cause senescent erythrocytes to interact with extracellular matrix proteins that are exposed within the splenic architecture. Such adhesion molecule-driven retention of senescent erythrocytes under low shear conditions was found to result in steady shrinkage of the cell and ultimately resulted in hemolysis. In contrast to intact senescent erythrocytes, the remnant erythrocyte ghost shells were prone to recognition and breakdown by RPMs. These data identify hemolysis as a key event in the turnover of senescent erythrocytes, which alters our current understanding of how erythrocyte degradation is regulated.