Splenic Function Research Articles

Fast Determination of Projected Surface Area in Red Blood Cells from Splenectomised Patients with Imaging Flow Cytometry

The spleen is one of the few organs that can be entirely removed (or that can become severely dysfunctional) without major impact on immediate survival. In the long term however, splenectomised or asplenic patients are at risk of severe complications such as severe infections (mostly by encapsulated organisms), deep venous thrombosis, pulmonary embolism, solid tumor and hematologic malignancies (Sabatini 2011 Lancet, Jais Thorax 2005, Kristinsson Haematologica 2014). The spleen contributes to the efficient circulation of RBC in small vessels, a process essential for life. Stiff or sticky RBC are indeed cleared by the spleen before they would clog small vessels in other organs. We have previously shown that the deformability of RBC is mildly but significantly altered in splenectomised patients, even in those without preexisting RBC disease (Prendki et al. 2012). We hypothesized that loss of splenic filtration results in the presence in circulation of RBC subpopulations that could be associated with complications.To explore this hypothesis, we assessed RBC morphology and deformability and markers of splenic function (pitted cells and Howell-Joly bodies) with a panel of reference tools and with innovative methods that we have developed (Buffet et al. 2006 ; Deplaine et al. 2011 ; Roussel et al. 2017) in 14 splenectomised patients and 10 healthy controls. RBC morphology and dimensions, numeration of pitted cells and of Howell-Joly bodies were assessed using imaging flow cytometry (AMNIS), differential interference contrast microscopy and blood smear. Deformability was determined by ektacytometry (LORRCA) and microsphiltration (Deplaine et al 2011). Reticulocyte count was done using cresyl blue and retic count.The mean concentration of RBC containing Howell-Jolly bodies on Giemsa-stained smears was 0.71% (range 0.05-1.56) in splenectomised patients versus 0.03% (range 0-0.09) in controls (Fig 1). The mean concentration of RBC containing “pits” or vacuoles (pitted or pocked cells) visible with differential interference contrast (DIC) microscopy was 30.73% (range 18.94-43.24) and 1 % (0.48-1.52%) in patients and controls respectively (Fig 2). Imaging flow cytometry showed that splenectomised patients exhibit higher RBC projected surface area than do control subjects (Fig 3). Mean surface area was 78.18 µm2 (range 63.1-88.3) and 73.56µm2 in patients and controls respectively. This increase in surface area was associated with numerous morphological alterations in RBC including the presence of echinocytes, spheroechinocytes and spherocytes (Typical example is shown in Fig 4). These alterations were not observed in controls. Ecktacytometry confirmed the mild alteration of RBC deformability in splenectomised patients. Reticulocyte count showed no significative differences between patients and controls.These observations confirmed that splenectomised patients exhibit morphological and deformability alterations that could contribute to complications (especially thrombo-embolic events). These alterations may also be new markers of splenic dysfunction and are currently been quantified in a larger number of patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Macrophage-fibroblast circuits in the spleen.

Macrophages are an integral part of all organs in the body, where they contribute to immune surveillance, protection, and tissue-specific homeostatic functions. This is facilitated by so-called niches composed of macrophages and their surrounding stroma. These niches structurally anchor macrophages and provide them with survival factors and tissue-specific signals that imprint their functional identity. In turn, macrophages ensure appropriate functioning of the niches they reside in. Macrophages thus form reciprocal, mutually beneficial circuits with their cellular niches. In this review, we explore how this concept applies to the spleen, a large secondary lymphoid organ whose primary functions are to filter the blood and regulate immunity. We first outline the splenic micro-anatomy, the different populations of splenic fibroblasts and macrophages and their respective contribution to protection of and key physiological processes occurring in the spleen. We then discuss firmly established and potential cellular circuits formed by splenic macrophages and fibroblasts, with an emphasis on the molecular cues underlying their crosstalk and their relevance to splenic functionality. Lastly, we conclude by considering how these macrophage-fibroblast circuits might be impaired by aging, and how understanding these changes might help identify novel therapeutic avenues with the potential of restoring splenic functions in the elderly.

Splenectomy and risk of COVID-19 infection, hospitalisation, and death

Objectives Splenectomy is a common surgical procedure, and splenectomized patients have shown to be severely more affected by certain infections than patients with a preserved splenic function. We investigated the risk of COVID-19 infection and subsequent hospitalisation and death in splenectomized patients. Methods We conducted a case-control study of all individuals with a microbiologically verified COVID-19 infection in Denmark through December 31, 2020. To each case, we matched three controls on age, sex, and region of residence. We examined the association between previous splenectomy and the risk of COVID-19 infection, hospitalisation, and death using a logistic regression model. Results We identified 165,623 individuals with a positive COVID-19 test and 493,300 matched controls. Mean age was 38 years. 130 and 422 splenectomies were performed in the COVID-19 positive individuals and controls, respectively. Splenectomized patients did not have a higher risk of COVID-19 infection than non-splenectomized patients (adjusted OR: 0.89; 95% CI: 0.73-1.08). Among COVID-19 positive individuals, splenectomized patients may have an increased risk of hospitalisation or death (adjusted OR for combined endpoint: 1.44; 95% CI: 0.79–2.61). Conclusions Splenectomized patients are not at an increased risk of COVID-19 infection, but they may have a higher risk of hospitalisation or death among COVID-19 positive individuals. This may be attributed to higher comorbidity levels.

Ageratina adenophora Inhibits Spleen Immune Function in Rats via the Loss of the FRC Network and Th1-Th2 Cell Ratio Elevation.

The objective of this study was to determine the impact of Ageratina adenophora (A. adenophora) on splenic immune function in a rat model. Rats were fed with 10 g/100 g normal feed and an experimental feed, which was composed of 3:7 A. adenophora powder and normal feed for 60 days. On days 14, 28, and 60, subsets of rats (n = 8 rats/group/time point) were selected for blood and spleen tissue sample collection. The results showed that the proportion of CD3+ T cells in the spleen was decreased at day 60 (vs. control). Also, mRNA and protein expression of chemokines CCL21 and CCL19 and functional protein gp38 in spleen decreased significantly versus the control at day 60. In addition, ER-TR7 antigen protein expression was also decreased at day 60. Levels of T-helper (Th)1 cells significantly increased, whereas those of Th2 cells decreased significantly versus the control at day 60 in spleen. The finding revealed that A. adenophora could affect splenic immune function in rats by altering the fibroblast reticulocyte (FRC) network, as well as by causing an imbalance in Th1/Th2 cell ratios. This research provides new insights into potential mechanisms of spleen immunotoxicity due to exposures to A. Adenophora.

Regulation of splenic monocyte homeostasis and function by gut microbial products

SummarySplenic Ly6Chigh monocytes are innate immune cells involved in the regulation of central nervous system-related diseases. Recent studies have reported the shaping of peripheral immune responses by the gut microbiome via mostly unexplored pathways. In this study, we report that a 4-day antibiotic treatment eliminates certain families of the Bacteroidetes, Firmicutes, Tenericutes, and Actinobacteria phyla in the gut and reduces the levels of multiple pattern recognition receptor (PRR) ligands in the serum. Reduction of PRR ligands was associated with reduced numbers and perturbed function of splenic Ly6Chigh monocytes, which acquired an immature phenotype producing decreased levels of inflammatory cytokines and exhibiting increased phagocytic and anti-microbial abilities. Addition of PRR ligands in antibiotic-treated mice restored the number and functions of splenic Ly6Chigh monocytes. Our data identify circulating PRR ligands as critical regulators of the splenic Ly6Chigh monocyte behavior and suggest possible intervention pathways to manipulate this crucial immune cell subset.

Splenic artery embolization with N-butyl cyanoacrylate in patients with blunt abdominal trauma

Introduction Splenic artery embolization (SAE) has been shown to be safe and effective for non-operative management of patients with splenic trauma while preserving splenic function. A variety of coils, plugs, particles and liquid embolics have all been used. NBCA (n-butyl cyanoacrylate) is used less frequently than other modalities but is effective. Methods A retrospective review of all patients who underwent SAE with NBCA for blunt abdominal trauma at a single tertiary medical center over a six-year period. Results Out of 123 SAE patients, 7 utilized NBCA; 6 patients had intraparenchymal splenic artery pseudoaneurysms, 2 had intraparenchymal arteriovenous fistulas, and 5 had active extravasation from the spleen on CT imaging. There was 100% technical success rate. There were no acute post-op complications or complications at 30-day and 90-day follow up. One patient died 2 days following SAE secondary to worsening subdural hematoma unrelated to SAE. Conclusions NBCA is safe and effective in treating patients with splenic injury particularly in patients with high grade splenic injury demonstrating extensive intraparenchymal vascular injury and/or intraprocedural extravasation in distal locations.

Exposure of pregnant rats to staphylococcal enterotoxin B increases offspring splenic Treg number and function via decreasing FoxP3 methylation

Staphylococcus aureus is an infectious pathogen that is relatively common, but that can cause severe disease in pregnant women and their fetus. We previously demonstrated that exposing pregnant rats to staphylococcal enterotoxin B (SEB) altered splenic CD4/CD8 T cell frequencies in their offspring. Whether prenatal SEB exposure impacts Tregs in these offspring, however, remains to be determined. As such, in this study, we intravenously injected pregnant rats with 15 μg of SEB on gestational day 16. Splenic tissue was then harvested from 1-, 3-, and 5-day-old neonatal rats and analyzed via flow cytometry to assess Treg numbers. In addition, FoxP3 expression levels were assessed via qPCR and western blotting, while FoxP3 methylation status was evaluated via methyl-DNA immunoprecipitation qPCR. Immunosuppression assays were additionally used to gauge Treg suppressive functionality. We found that exposing pregnant rats to SEB resulted in a significant increase in Treg numbers, FoxP3 expression, and Treg suppressive capacity in the spleens of both neonatal and adult offspring. In addition, total T cell, CD4+T cell, and non-Treg CD4+ T cell numbers were elevated in the spleens of offspring following prenatal SEB exposure. We additionally determined that SEB exposure resulted in a significant reduction in FoxP3 DNA methylation. Together, our results indicate that prenatal SEB exposure can markedly enhance offspring splenic Treg numbers and functionality at least in part by decreasing FoxP3 methylation.

Retained Splenic Function in an Indian Population with Homozygous Sickle Cell Disease May Have Important Clinical Significance.

Background and Objectives:To determine whether the persistence of splenomegaly characteristic of the Asian haplotype of homozygous sickle cell (SS) disease is associated with continued splenic function, a comparison of patients from Odisha, India, and Jamaica.Materials and Methods:Indian patients were examined in a cross-sectional study and compared with the Jamaican Cohort Study from birth. Splenomegaly was assessed in both populations with standard methods. Splenic function was assessed in both by counts of pitted red blood cells determined by differential interference contrast microscopy in the same laboratory.Results:In Jamaica, the spleen became palpable in 55% of patients during the 1st year of life and the prevalence declined thereafter, whereas in Indian patients, the prevalence rose steeply after the age of 4 years. Raised pitted red cell counts, consistent with loss of splenic function, were common after 2 years in Jamaicans but did not increase in Indians until after the age of 5 years.Interpretation and Conclusions:The maximal risk of invasive pneumococcal infection in SS disease falls sharply after the age of 3 years, and persistence of splenic function in Odisha patients beyond this age may explain the apparent absence of pneumococcal septicemia in Indian patients and questions the role of pneumococcal prophylaxis.

Laparoscopic Partial Splenectomy with Distal Pancreatectomy Preserves Splenic Function

Introduction: Distal Pancreatectomy often requires splenectomy, for oncologic reasons, or because splenic vessels are involved. The immune function of the spleen is increasingly recognized, and many national guidelines suggest long term antibiotics following splenectomy.

Late Splenic Sequestration: A Consequence of Early Hydroxyurea Use?

Background: Acute splenic sequestration is a potentially life-threatening complication in patients with sickle cell disease. It is the second leading cause of death in young children with hemoglobin SS/Sβ0 thalassemia (SCD). The incidence approaches 35% during the first two years of life in SCD. Although splenic sequestration can occur in patients with any sickle phenotype, patients with SCD tend to be significantly younger when compared to patients with hemoglobin SC disease. Splenic function may be preserved in children treated with hydroxyurea. We recommend hydroxyurea for all SCD patients diagnosed via newborn screening, with a goal of starting therapy before 12 months of age. With this aggressive approach and potential for maintaining some splenic function, this study evaluates acute splenic sequestration in this young cohort and compares this to institutional and historical controls Methods: We performed a retrospective search of electronic medical records at Children's Minnesota from 1/1/1999 through 12/31/2019 to identify patients with SCD and splenic sequestration. We used a broad array of ICD-9 an ICD-10 codes in order to capture all appropriate patients. Following this initial search, in-depth chart review was performed to identify patients with SCD and confirmed splenic sequestration. Data collected includes age, sex, hydroxyurea use, splenectomy, and hematologic results including hemoglobin F percentage, if available. Student t-tests for independent samples were performed to compare cohorts. This study was granted exemption by our Institutional Review Board. Results: Over this 21 year period, the initial search revealed 151 patients. Of those, 74 had SCD. In-depth chart review found 38 (24M, 14F) of these children were confirmed to have splenic sequestration. Twelve patients started hydroxyurea before 2 years of age at a mean age of 12.6 months, median 11 months (cohort A). Of these, six started hydroxyurea during infancy at a mean and median age of 6.5 months (cohort B). The remaining 26 patients were not on hydroxyurea at the time of splenic sequestration (cohort C). Children in cohorts A and B were significantly older at the time of splenic sequestration compared to patients in cohort C (mean 58 and 45.8 months vs. 14.9 months, p< 0.0001). Conclusions: Children with SCD who start hydroxyurea at a young age may develop splenic sequestration much later in life than previously expected. More study is needed to confirm this finding. It will be important to educate families and healthcare providers about this potential unintended consequence of early hydroxyurea use. Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: Hydroxyurea use in children with sickle cell disease < 2 years of age

Hydroxyurea to Reduce Stroke Risk in Tanzanian Children with Sickle Cell Anemia

Introduction: Sickle cell anemia (SCA) is highly prevalent in sub-Saharan Africa with >300,000 annual births, and substantial morbidity and mortality due to limited resources. The burden of stroke in this population is of particular concern, given the devastating clinical and neurocognitive sequelae of these events. Hydroxyurea, a potent disease modifying therapy for SCA, is safe and feasible for low-resource and malarial endemic countries within sub-Saharan Africa and when used at maximum tolerated dose (MTD), decreases the incidence of acute painful vaso-occlusive events, infections, malaria, transfusions, hospitalizations, and death. Whether hydroxyurea can prevent primary stroke in SCA within Africa has not yet been determined, due in part to lack of stroke screening programs using transcranial Doppler (TCD) ultrasonography. If effective, hydroxyurea would have even more therapeutic benefits for children with SCA, particularly in settings where blood is not available, affordable, or safe. We designed the Stroke Prevention with Hydroxyurea Enabled through Research and Education (SPHERE) trial to determine the stroke risk among Tanzanian children using TCD screening and to investigate the effects of hydroxyurea to reduce that risk. Methods: The SPHERE trial (NCT03948867) is a single center prospective phase 2 open-label screening and treatment pilot study at Bugando Medical Centre, a teaching and referral hospital in Mwanza, Tanzania. Children 2-16 years old with SCA consented to TCD screening by locally trained and certified examiners; recent febrile illness, red cell transfusion, or hospitalization were temporary exclusions. Study participants with maximum Time-Averaged Mean Velocity (TAMV) on TCD exam categorized as conditional (170-199 cm/sec) or abnormal (≥200 cm/sec) are offered hydroxyurea with escalation to MTD, while those with normal TCD screening exams will be rescreened annually. Hydroxyurea is initiated at ~20 mg/kg/day using 500 mg capsules and a weekly dosing calculator, then escalated every 8 weeks by 5 mg/kg/day up to 35 mg/kg/day. Children on hydroxyurea are seen monthly during dose escalation and every 3 months after reaching MTD. The primary endpoint is change in TCD velocity after 12 months of hydroxyurea therapy. Secondary endpoints include changes in splenic volume and filtrative function; change in renal function; incidence of infection, especially malaria; hydroxyurea pharmacokinetics; and genetic modifiers of disease including pharmacogenomics. Results: From April 2019 to April 2020, a total of 202 children underwent TCD screening, exceeding the projected enrollment pace and goal (Figure). The average age (mean ± SD) at enrollment was 6.8 ± 3.5 years, and 53% were female. A majority had previous dactylitis (75%), painful vaso-occlusive episode (93%), blood transfusion (68%), and malaria (89%). Recurrent hospitalization was common with 30% having >5 previous hospitalizations. Only 4% had previously used hydroxyurea. Baseline labs included hemoglobin = 7.8 ± 1.3 g/dL, HbF = 9.3 ± 5.4 %, and ANC = 5.5 ± 2.4 x 109/L. Baseline assessment revealed a palpable spleen in 46 children (23%), and most of these (29) were ≥5 cm below the costal margin. Abdominal ultrasonography documented splenic tissue in 91% of children with an average volume of 101 ± 123 mL (range 8-1045). TCD examinations were performed in all children at enrollment with average TAMV of 148 ± 27 cm/sec [median 144, IQR 130-169 cm/sec] with 76% normal, 21% conditional, 2% abnormal, and 1% inadequate exams. Of 47 children eligible for hydroxyurea for elevated TCD velocities, 45 successfully initiated treatment, while 1 lived too far away for regular visits, and 1 had low blood counts from acute splenic sequestration and died before initiating study treatment. Conclusion: Children with SCA in Tanzania have a high risk for primary stroke. Identification of elevated TCD velocities through screening by local trained certified examiners, coupled with initiation of hydroxyurea treatment with dose escalation to MTD, offers a feasible and affordable means by which to lower TCD velocities and reduce primary stroke risk. Now fully enrolled, SPHERE has built local clinical capacity, research infrastructure and high-quality TCD screening, and will prospectively determine the benefits of hydroxyurea for stroke prevention, as a prelude for expanding hydroxyurea access for children with SCA in Tanzania. Figure Disclosures No relevant conflicts of interest to declare.

Effectiveness of Comprehensive Newborn Screening Program of Sickle Cell Disease on the Childhood Morbidity and Mortality of the Disease: A Systematic Review and Meta-Analysis

Sickle cell disease is a multisystem disorder associated with severe complications and premature death. To address the morbidity, disability, and mortality of inherited disorders, the implementation of newborn screening programmes are considered pivotal public health service intervention. Due to ethical consideration there are no RCTs that prove the benefits of comprehensive newborn screening (Lees, Davies and Dezateux, 2000). However, many evidences suggested early diagnosis and treatment can improve outcomes and survival of patients (Gaston et al., 1986; King et al., 2007). As such, an economic analysis reviewed many studies, cited that the pre-clinical diagnosis of SCD had twofold cost-effectiveness compared to symptomatic diagnosis (Grosse, Olney and Baily, 2005). The aim of this study was to assess the impact of the newborn screening program on the morbidity and mortality of disease among the children by assembling results from cohort studies. DESIGN AND METHODS The systematic review was performed in accordance with the PRISMA guidelines. Medline, EMBASE, and Cochrane Library were searched for cohort studies that addressed the sickle cell disease morbidity and mortality of the disease among children will consider eligible. The phenomena of interest were mortality, infection, stroke PICO have been translated to keywords and MeSH terms with search limit under 18 years old and date set until July 2020. Two reviewers assessed the quality of included cohort studies individually using Newcastle-Ottawa scale (NOS). Subsequently, the data were extracted in Microsoft Word. In case of disagreement, were settled by discussion. The incidence rates per 100 patient year and 95% confidence intervals were pooled to random-effects meta-analysis using RevMan5.4. Studies' heterogeneity identified by chi-squared test and the I2 statistic. RESULTS Eight studies included that met inclusion criteria two studies were from USA (Quinn et al., 2008 and Gill et al., 1995) , 1 from UK (Telfer et al., 2007), 1 from Belgium(Lê et al., 2010), 1 from Jamaica (King et al 2007), 1 from Africa (Rahimy et al, 2003), 1 from India (Upadhye et al., 2016) and 1 from Brazil (Rezende et al., 2018). The total number of participants in the 8 cohort studies were 2377 SCD patients (mean 297.1 and SE 73.9), that includes patients with the four common SCD genotypes: HbSS, HbSC, Hb Sβ+ and HbSβ0. The median age was 6.5 year (IQR: 4.95), with 9623 total years of follow up. The pooled incidence rate of SCD associated mortality per 100 patient year was 0.65 (95%CI 0.35-0.94; I2= 89%; p < 0.00001). While the infection incidence rate 17.74 (95%CI; 11.57-23.91; I2= 100%; p< 0.00001), Stroke 1.04(95% CI 0.60-1.47; I2= 78%; p< 0.0001), Acute chest syndrome 12.55(95% CI; 7.70-17.41; I2 =97%; p< 0.00001), Acute splenic sequestration crisis 1.95 (95% CI 1.31-2.59; I2= 69%; p=0.003) and Vaso-occlusive crisis 52.45(95% CI 45.67-59.14; I2= 92%; p< 0.00001). DISCUSSION In this systematic review and meta-analysis combining 8 cohort studies, pooled mortality rate was 0.65 per 100 patient-year, similar to (0.64) meta-analysis of 15 studies reported previously (Wastnedge, 2018). Furthermore, our study reported that the total infection rate was 17.7 per 100 patient-year. However, this result of infection cannot be considered a true gold standard and due to the variation in definitions used and other methodological heterogeneity. For example, Africa-based cohort study reported 23.2 per 100 patient-year attacks of malaria and fatal pneumococcal meningitis despite the use of antimalarial prophylaxis and anti-pneumococcal vaccine (Rahimy et al., 2003). Another notable result, Hemoglobin SC cohort study stated that the incidence of infections was, 62.2 episodes (59.8-64.6) per 100 patient-years. They assumed that might be due to higher impaired splenic function in HbSC patients compared to HbSS (Rezende et al., 2018). CONCLUSION This first systematic review and meta-analysis of cohort studies provided evidence supporting the sickle cell newborn screening program. However, still infection and pain episodes are the highest incidence symptoms. Despite children survival increasingly improved, disease burden remains at a peak in developing countries. One limitation of this study is high heterogeneity and this mainly due to countries disparity of included studies and variance in definition of events, particularly infection. Table Disclosures Inusa: Novartis: Honoraria, Other: Steering committee participation, Research Funding, Speakers Bureau; Global Blood Therapeutics: Honoraria, Other: Steering committee participation, Research Funding, Speakers Bureau; Bluebird bio: Research Funding; AstraZeneca: Honoraria, Other: Steering committee participation, Research Funding, Speakers Bureau; Vertex: Research Funding.

Associations between spleen volume and exercise capacity in advanced heart failure patients with left ventricular assist device

Abstract Background The spleen has been recognized as an important organ with several functions such as a reservoir of blood volume, and an involvement in iron metabolism by processing of aged red blood cells and recycling iron. During exercise, spleen contracts, and red blood cells pooled in the spleen are recruited into the systemic circulation. So far, we reported that spleen size changed in advanced heart failure (HF) with left ventricular assist device (LVAD). In addition, spleen volume was related to pulmonary capillary wedge pressure (PCWP) or right atrial pressure (RAP) as parameters of cardiac preload. However, it remains unclear about the relationship between spleen volume and exercise capacity in advanced HF with LVAD. Purpose The purpose of this study was to investigate the associations between spleen volume and exercise capacity in advanced HF patients with LVAD. Methods We enrolled 27 HF patients (21 males, 45±12 years) with LVAD (HeartMate II™; Abbott, Chicago, IL, USA) for use as a bridge to heart transplantation. All patients underwent blood test, echocardiography, right heart catheterization, computed tomography (CT) and cardiopulmonary exercise testing (CPET). Spleen size was measured by CT volumetry. We excluded patients with splenic infarction or aortic valve closure surgery. Results At baseline, body mass index, blood brain natriuretic peptide levels, hemoglobin levels, left ventricular ejection fraction were 21.4±3.1 kg/m2, 73.8 (51.9–165.8) pg/mL, 12.1 (10.6–13.4) g/dL, 24.8±14.7%, respectively. Total cardiac output (CO), the sum of pump flow and CO of native heart was 4.6±0.9 L/min, and spleen volume was 184.9±48.8 mL. As for parameters of CPET, peak heart rate (HR), peak VO2, and peak O2 pulse were 128±25 beats/min, 14.2±3.3 mL/kg/min, and 6.6±1.9 mL/beat. At rest, there were significant correlations between spleen volume and PCWP (r=0.382, p=0.049), RAP (r=0.406, p=0.035) or pulsatility index (r=0.384, p=0.047), despite no correlations with total CO or pump flow. During exercise, there were significant interrelations of spleen volume with peak VO2 (r=0.451, p=0.018) and peak O2 pulse (r=0.427, p=0.026). Furthermore, peak VO2 was interrelated with peak HR (r=0.481, p=0.011) or hemoglobin levels (r=0.649, p<0.001). Remarkably, spleen volume was significantly correlated with hemoglobin levels (r=0.391, p=0.043) (Figure). Interpreting these results based on Fick's formula, the proportion of native CO to total CO is very small at rest, but increases during exercise. The spleen during exercise may contribute to increased native CO, especially stroke volume. Moreover, the spleen may be related to both cardiac preload and oxygen carrying capacity, resulting in a significant association between spleen volume and peak VO2. Conclusion Spleen volume could be a useful predictor of exercise capacity in advanced HF patients with LVAD, reflecting splenic function to modulate cardiac preload and blood hemoglobin levels. Spleen volume and exercise parameters Funding Acknowledgement Type of funding source: None

Laparoscopic Central Splenectomy for Littoral Cell Angioma

BackgroundSplenic littoral cell angioma (LCA) is a rare vascular tumor with malignant potential originating from the red pulp of the spleen.1,2 Although laparoscopic splenectomy is the treatment choice for LCA,3 patients suffer from long-term complications of sepsis, thrombosis, and tumor.4,5 Laparoscopic central splenectomy (LCS) for LCA is a technically challenging operation mainly due to the risk of intraoperative hemorrhage. However, it can be a valuable alternative particularly for adolescent patients in whom maximum preservation of splenic function outweighs the risks associated with organ preservation. MethodsA 15-year-old young man was admitted with left upper abdominal dull pain for 1 month. Laboratory tests and enhanced abdominal CT scans were performed. Laboratory test results were all normal, as follows: complete blood count showed normal WBC: 5.74 × 109/l, platelets: 173 × 109/l, Hb: 151 g/l, tumor markers (CEA: 1.62 ng/ml, CA19–9: 10.30 U/ml, AFP: 1.13 ng/ml) which were within normal limits. CT scan showed that a 5 × 5.9-cm solid tumor was discovered in the middle part of the spleen during diagnosis, and the density of this tumor was high in the early artery phase and low in the late portal venous phase of contrast-enhanced CT. LCS was performed where the trunk of the splenic artery was intermittently occluded and several branches of the vessels were freed from the tumor which was then resected. The splenic parenchyma was dissected by following a line 0.5 cm from demarcation line. The tumor was completely removed with the activity of the splenic parenchyma being preserved to the maximum extent. Total operation time was 175 min, with an estimated blood loss of 200 ml; thus, no blood transfusion was required. Intraoperative frozen section suggested vascular tumor-like lesions, and then the tumor was completely removed with the resection margin being free of tumor involvement. ResultsThe patient was fully recovered after a 7-day hospital stay. The reason for the 7-day hospital stay is that the patient maintains normal ambulating independent assistance on POD-3 and can eat without intravenous fluids on POD-4. Meanwhile, the patient needs to remove the drainage tube after the abdominal CT scan on POD-6, rather than postoperative complications. Diagnosis of LCA was confirmed using histology, and the symptoms disappearing after the operation was done. A total of 86·laparoscopic partial splenectomy (LPS) procedures were performed at the Department of Pancreatic Surgery, West China Hospital and Department of Hepatopancreatobiliary Minimal Invasive Surgery, Chengdu ShangJin NanFu Hospital from May 2011 to May 2020. Five patients among the total number of patients were diagnosed with LCA of which LPS was performed in four patients and LCS performed for one patient. The mean duration of surgery for LPS was 100 min (range of 80-120 min) while the mean estimated blood loss was 125 ml (range of 100-200 ml). On the other hand, the mean length of hospital stay was 7.5 days (range of 5-11 days) and the mean tumor diameter was 5.1 cm (range of 3.2-7 cm). All patients recovered without complications. In addition, there were no signs of immune insufficiency, thrombosis, and tumor recurrence during the follow-up which had a mean of 31.2 months (range from 10 to 53 months). ConclusionLCS is a technically feasible technique for a select group of patients with centrally located LCA. The technique helps to maximize preservation of splenic function and maintains the advantages of minimally invasive surgery.

Innate Antiviral Specialization of Ly6C+CD45+ Splenic Red Pulp Stroma Instilled by Subset-Specific Regulation of Cellular Sensitivity to Type I Interferons

Our understanding of splenic stromal cell composition and function remains incomplete. Here, we uncover that splenic red pulp stroma is phenotypically Ly6C+CD45+, due to acquisition of hematopoietic-derived CD45 via intercellular transfer in situ. Using a rectified gating strategy to integrate stroma with surface CD45 expression, we transcriptionally profiled the entire splenic mesenchymal cell compartment with single-cell resolution at steady state and upon viral infection. We show extensive functional heterogeneity of the white pulp-, red pulp- and perivascular stromal cell components and identify striking differences in innate antiviral response potential of distinct stromal subsets. We demonstrate that Ly6C+CD45+ red pulp stromal cells are selectively sensitized by tonic type I interferon signals, which licenses them with enhanced sensitivity to interferon stimulation in vivo and with vigorous antiviral gene response upon systemic infection. These results highlight a specialized contribution of stroma to the innate immune function of the splenic red pulp.

Physical Activity and Breast Cancer Prevention: Possible Role of Immune Mediators.

There is strong evidence that physical activity (PA) reduces risk, recurrence, and mortality from breast cancer. Emerging data suggest that PA induces changes in inflammatory and immune mediators that may contribute to beneficial effects on breast cancer outcomes. Thus, the goal of this review was to evaluate the evidence linking the protective benefit of PA to modulation of immune responses in breast cancer. A literature search was conducted to identify studies that evaluated the impact of PA on tumor and immune outcomes in breast cancer patients and in mammary tumor models. Nineteen studies investigated the effect of PA interventions on cancer immune outcomes using preclinical breast cancer models. Tumor growth was reduced in 11 studies, unchanged in three studies, and increased in one study. Spontaneous metastasis was reduced in two studies and survival was improved in four studies. Frequently assessed immune outcomes include splenic cell number and function, circulating inflammatory cytokines, and intratumoral immune cells and inflammatory markers. Circulating inflammatory cytokine responses were heterogeneous in preclinical models. Within the tumor microenvironment (TME), several studies documented a change in the infiltration of immune cells with an increase in effector cells and a reduction in immune suppressive cells. Twenty-three studies investigated the effect of PA interventions on immune outcomes in breast cancer patients. Thirteen studies used aerobic PA interventions and 10 studies used a combination of aerobic and resistance exercise interventions. Cycling and treadmill activities were the most commonly used PA modalities. Circulating immune cells and inflammatory cytokines were the most frequently assessed immune outcomes in the clinical studies. Among the 19 studies that evaluated a PA intervention during the post treatment period, 10 reported a reduction in the levels of at least one inflammatory cytokine. No inflammatory cytokines were quantified in the three studies that evaluated a PA intervention during treatment with chemotherapy. Immune outcomes within the tumor were assessed in only one study performing a PA intervention prior to surgery. Results from preclinical and clinical studies suggest that PA exerts heterogeneous effects on inflammatory cytokines, but may alter the gene expression profile and immune infiltrates in the tumor which may result in a reduction in immunosuppressive factors. However, additional studies are needed to better understand the effect of PA on immune outcomes in the TME.

Decellularized Splenic Matrix as a Scaffold for Spleen Bioengineering.

The spleen is considered a non-essential organ. However, its importance is increasingly clear, given the serious disorders caused by its absence or dysfunction, e.g., greater susceptibility to infections, thromboembolism and cancer. Surgical techniques to preserve the spleen and maintain splenic function have become increasingly common. However, the morbidity and mortality associated with its absence and dysfunction are still high. We used the decellularization technique to obtain a viable splenic scaffold for recellularization in vitro and propose the idea of bioengineered spleen transplantation to the host. We observed the maintenance of important structural components such as white pulp, marginal zone and red pulp, in addition to the network of vascular ducts. The decellularized scaffold presents minimal residual DNA and SDS, which are essential to prevent immunogenic responses and transplantation failure. Also, the main components of the splenic matrix were preserved after decellularization, with retention of approximately 72% in the matrisomal protein content. The scaffold we developed was partially recellularized with stromal cells from the spleen of neonatal rats, demonstrating adhesion, proliferation and viability of cells. Therefore, the splenic scaffold is very promising for use in studies on spleen reconstruction and transplantation, with the aim of complete recovery of splenic function.

NONTYPEABLE HAEMOPHILUS INFLUENZAE VENTRICULITIS COMPLICATED BY HYDROCEPHALUS IN A PATIENT WITH SICKLE CELL DISEASE

SESSION TITLE: Fellows Critical Care Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Community-acquired purulent ventriculitis is very rare. We present a case of community-acquired purulent nontypeable Haemophilus influenzae meningitis with ventriculitis requiring cerebrospinal fluid diversion. CASE PRESENTATION: 46-year-old female with sickle cell disease presented in late fall with two days of headache, fever, and confusion. On arrival, she was febrile to 103F. On exam, she was agitated and unable to follow commands. Laboratory studies showed a white blood cell count of 23,000 (94% neutrophils), and procalcitonin 36 mg/dL. Blood and urine cultures were collected. The patient was given dexamethasone, vancomycin, meropenem (anaphylactic to penicillin), acyclovir, and doxycycline for community-acquired meningoencephalitis. CT Brain was consistent with cerebral edema. The patient required intubation for airway protection. Lumbar puncture showed purulent cerebrospinal fluid with opening pressure 21. CSF protein was 900, glucose 1, and 24,000 neutrophils. Gram stain showed numerous gram negative coccobacilli. MRI Brain showed layering debris within the ventricles and hydrocephalus. Due to intracranial hypertension, mannitol was given and an external ventricular drain placed. Blood and CSF cultures grew non-type B Haemophilus influenzae. The patient completed 14 days of ceftriaxone and was eventually extubated and ventriculostomy removed. DISCUSSION: Anatomical and functional asplenia poses high risk for invasive infections with encapsulated organisms such as S. pneumoniae, N. meningitidis, and H. influenzae. However, we present a case of community-acquired nontypeable H influenza meningitis with associated ventriculitis requiring CSF diversion. Nontypeable Haemophilus species lack a polysaccharide capsule for which splenic function provides less immunity. Serotype B was a common invasive pathogen prior to the institution of Hib vaccination in 1987. Nontypeable H influenzae is a common pathogen in otitis media in children and exacerbations of COPD in adults. Invasive diseases such as bacteremia and pneumonia are mostly seen at the extremes of age. Our patient is also unique in that she developed purulent ventriculitis complicated by hydrocephalus. Hydrocephalus complicates community-acquired bacterial meningitis in about 5% of cases and is associated with high mortality. H influenza ventriculitis is a rare condition and is mostly described in children and patient’s after neurosurgical CNS manipulation. CONCLUSIONS: We present a case of community-acquired nontypeable Haemophilus influenzae meningitis with ventriculitis. This case is unique in that the patient had purulent ventriculitis required CSF diversion. Community-acquired purulent ventriculitis is very rare without neurosurgical manipulation or indwelling CSF drainage catheters. Also, nontypeable H flu is an uncommon pathogen in the central nervous system and usually affects the respiratory tract. Reference #1: Eldere, J.V., Slack, M, Ladhani,Shamez, Cripps, A. Non-typeable Haemophilus infl uenzae, an under-recognised pathogen.Lancet Infect Dis 2014; 14: 1281–92. Reference #2: Bakaletz, L, Novotny, L. NontypeableHaemophilusinfluenzae(NTHi). Trends in Microbiology, August 2018,Vol. 26,No.8. Reference #3: Langereis, J, Jonge, M. Invasive Disease Caused by Nontypeable Haemophilus influenzae. Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 21, No. 10, October 2015. DISCLOSURES: No relevant relationships by Andrew Holt, source=Web Response No relevant relationships by Scott Sinclair, source=Web Response

Changes in splenic uptake pattern associated with X-ray irradiation

PurposeTo evaluate the splenic uptake function after irradiation with high-energy X-rays. Materials and methodsFourteen male Wistar rats were distributed into three groups. Group 1 (n = 6) – control, non-irradiated; Group 2 (n = 4) – animals that were irradiated and studied 24 h after irradiation; and Group 3 (n = 4) – animals that were irradiated and studied 48 h after irradiation. The animals were irradiated with 8 Gy X-rays in the abdominal region. According with the groups, after 24 or 48 h, 1 ml/kg of a 50% colloidal carbon solution was injected in the left internal jugular vein. After 40 min, the spleens were removed for histological studies. Macrophages containing carbon pigments in their cytoplasms were counted in 16 consecutive microscopic fields, and their means were considered as the uptake pattern of each animal. ResultsIn the control groups, carbon pigments were captured by macrophages in the red and white pulps, while in the irradiated groups, the uptake in the marginal zone, around the white pulp, was enhanced. There was no disorder on the splenic parenchyma or necrosis in histological analyzes. Qualitatively rare apoptotic events were observed, with no difference between control and irradiated animals. ConclusionThe high-energy X-ray, used in radiotherapy, modifies the splenic clearance, enhancing the amount of marginal zone macrophages containing colloid particles. This radiation was not associated with morphological changes, nor with necrosis or apoptosis of splenic tissue.

THU139 - Impaired splenic function in liver cirrhosis: a study in 69 patients with cirrhosis from outpatient hepatology clinic in a tertiary hospital in northern Greece

THU139 - Impaired splenic function in liver cirrhosis: a study in 69 patients with cirrhosis from outpatient hepatology clinic in a tertiary hospital in northern Greece