Does COVID-19 cause an increase in spleen dimensions? Possible effects of immune activation, hematopoietic suppression and microthrombosis

AMG487 alleviates influenza A (H1N1) virus-induced pulmonary inflammation through decreasing IFN-γ-producing lymphocytes and IFN-γ concentrations

BACKGROUND AND PURPOSE

Severe influenza virus-infected patients have high systemic levels of Th1 cytokines (including IFN-γ). Intrapulmonary IFN-γ increases pulmonary IFN-γ-producing T lymphocytes through the CXCR3 pathway. Virus-infected mice lacking IP-10/CXCR3 demonstrate lower pulmonary neutrophilic inflammation. AMG487, an IP-10/CXCR3 antagonist, ameliorates virus-induced lung injury in vivo through decreasing viral loads. This study examined whether AMG487 could treat H1N1 virus-induced mouse illness through reducing viral loads or decreasing the number of lymphocytes or neutrophils.

EXPERIMENTAL APPROACH

Here, we studied the above-mentioned effects and underlying mechanisms in vivo.

KEY RESULTS

H1N1 virus infection caused bad overall condition and pulmonary inflammation characterized by the infiltration of lymphocytes and neutrophils. From Day-5 to Day-10 post-virus infection, bad overall condition, pulmonary lymphocytes, and IFN-γ concentrations increased, while pulmonary H1N1 viral titres and neutrophils decreased. Both anti-IFN-γ and AMG487 alleviated virus infection-induced bad overall condition and pulmonary lymphocytic inflammation. Pulmonary neutrophilic inflammation was mitigated by AMG487 on Day-5 post-infection, but was not mitigated by AMG487 on Day-10 post-infection. H1N1 virus induced increases of IFN-γ, IP-10, and IFN-γ-producing lymphocytes and activation of the Jak2-Stat1 pathways in mouse lungs, which were inhibited by AMG487. Anti-IFN-γ decreased IFN-γ and IFN-γ-producing lymphocytes on Day-5 post-infection. AMG487 but not anti-IFN-γ decreased viral titres in mouse lung homogenates or BALF. Higher virus load did not increase pulmonary inflammation and IFN-γ concentrations when mice were treated with AMG487.

CONCLUSION AND IMPLICATIONS

AMG487 may ameliorate H1N1 virus-induced pulmonary inflammation through decreasing IFN-γ-producing lymphocytes rather than reducing viral loads or neutrophils.

Exploring the Correlation Between Splenomegaly and Lung Involvement in COVID-19: A Retrospective Study

Background Coronavirus disease 2019 (COVID-19), resulting from the severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), has not only shown substantial effects on the respiratory system but also on extrapulmonary systems, including cardiovascular, gastrointestinal, hematological, and immune responses, notably spleen enlargement. The connection between the enlargement of the spleen and pulmonary complications in individuals with COVID-19 is still not well elucidated, with current studies offering divergent conclusions. Objective This study aims to elucidate the correlation between splenomegaly, as assessed by computed tomography (CT) imaging, and the extent of lung involvement (LI) in COVID-19 patients, thereby offering insights into potential prognostic indicators. Methodology A hospital-based, cross-sectional, retrospective study was conducted involving 1058 symptomatic COVID-19 patients confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR), aged 18 years and above. CT imaging was utilized to evaluate spleen size and LI. Statistical analyses, including Pearson correlation and simple linear regression, were performed to explore the relationship between spleen size and LI. Results The study cohort exhibited a mean spleen size of 9.49 cm and a mean LI score of 0.272. The Pearson correlation coefficient was calculated at 0.0495, indicating a marginal positive correlation between spleen size and LI. Regression analysis demonstrated a minimal impact of spleen size on LI, with spleen size accounting for only 0.2% of the variance in LI scores. Conclusions The study found a slight, statistically non-significant correlation between splenomegaly and LI in COVID-19 patients, suggesting that while splenic enlargement may reflect systemic disease involvement, it is not a strong independent predictor of lung damage extent. The findings highlight the complexity of extrapulmonary manifestations and highlight the need for additional research to fully understand the implications of splenic involvement in COVID-19.

African Americans Possessed High Prevalence of Comorbidities and Frequent Abdominal Symptoms, and Comprised A Disproportionate Share of Covid-19 Mortality among 9,873 Us- Hospitalized Patients Early in the Pandemic

Background and aim

Identifying clinical characteristics and outcomes of different ethnicities in the US may inform treatment for hospitalized COVID-19 patients. Aim of this study is to identify predictors of mortality among US races/ethnicities.

Design Setting and participants

We retrospectively analyzed de-identified data from 9,873 COVID-19 patients who were hospitalized at 15 US hospital centers in 11 states (March 2020-November 2020). Main Outcomes and Measures: The primary outcome was to identify predictors of mortality in hospitalized COVID-19 patients.

Results

Among the 9,873 patients, there were 64.1% African Americans (AA), 19.8% Caucasians, 10.4% Hispanics, and 5.7% Asians, with 50.7% female. Males showed higher in-hospital mortality (20.9% vs. 15.3%, p=0.001). Non- survivors were significantly older (67 vs. 61 years) than survivors. Patients in New York had the highest in-hospital mortality (OR=3.54 (3.03 - 4.14)). AA patients possessed higher prevalence of comorbidities, had longer hospital stay, higher ICU admission rates, increased requirement for mechanical ventilation and higher in-hospital mortality compared to other races/ethnicities. Gastrointestinal symptoms (GI), particularly diarrhea, were more common among minority patients. Among GI symptoms and laboratory findings, abdominal pain (5.3%, p=0.03), elevated AST (n=2653, 50.2%, p=<0.001, OR=2.18), bilirubin (n=577, 12.9%, p=0.01) and low albumin levels (n=361, 19.1%, p=0.03) were associated with mortality. Multivariate analysis (adjusted for age, sex, race, geographic location) indicates that patients with asthma, COPD, cardiac disease, hypertension, diabetes mellitus, immunocompromised status, shortness of breath and cough possess higher odds of in-hospital mortality. Among laboratory parameters, patients with lymphocytopenia (OR2=2.50), lymphocytosis (OR2=1.41), and elevations of serum CRP (OR2=4.19), CPK (OR2=1.43), LDH (OR2=2.10), troponin (OR2=2.91), ferritin (OR2=1.88), AST (OR2=2.18), D-dimer (OR2=2.75) are more prone to death. Patients on glucocorticoids (OR2=1.49) and mechanical ventilation (OR2=9.78) have higher in-hospital mortality.

Conclusion

These findings suggest that older age, male sex, AA race, and hospitalization in New York were associated with higher in-hospital mortality rates from COVID-19 in early pandemic stages. Other predictors of mortality included the presence of comorbidities, shortness of breath, cough elevated serum inflammatory markers, altered lymphocyte count, elevated AST, and low serum albumin. AA patients comprised a disproportionate share of COVID-19 death in the US during 2020 relative to other races/ethnicities.

Deep learning, 3D ultrastructural analysis reveals quantitative differences in platelet and organelle packing in COVID-19/SARSCoV2 patient-derived platelets

Platelets contribute to COVID-19 clinical manifestations, of which microclotting in the pulmonary vasculature has been a prominent symptom. To investigate the potential diagnostic contributions of overall platelet morphology and their α-granules and mitochondria to the understanding of platelet hyperactivation and micro-clotting, we undertook a 3D ultrastructural approach. Because differences might be small, we used the high-contrast, high-resolution technique of focused ion beam scanning EM (FIB-SEM) and employed deep learning computational methods to evaluate nearly 600 individual platelets and 30 000 included organelles within three healthy controls and three severely ill COVID-19 patients. Statistical analysis reveals that the α-granule/mitochondrion-to-plateletvolume ratio is significantly greater in COVID-19 patient platelets indicating a denser packing of organelles, and a more compact platelet. The COVID-19 patient platelets were significantly smaller -by 35% in volume - with most of the difference in organelle packing density being due to decreased platelet size. There was little to no 3D ultrastructural evidence for differential activation of the platelets from COVID-19 patients. Though limited by sample size, our studies suggest that factors outside of the platelets themselves are likely responsible for COVID-19 complications. Our studies show how deep learning 3D methodology can become the gold standard for 3D ultrastructural studies of platelets.

Atraumatic splenic rupture associated with COVID-19

Atraumatic splenic rupture (ASR) is a rare but life-threatening condition. Several underlying pathologies have been associated with a splenic rupture in the absence of trauma, most often malignant-haematological disorders, viral infections or local inflammatory disorders. The management of ASR is similar to traumatic splenic rupture and includes early risk stratification of patients to determine those eligible for non-operative treatment versus those who need immediate surgical intervention. In this report, we discuss a rare case of a non-operatively managed ASR in an otherwise healthy young patient with SARS-CoV-2 as the likely aetiology. The multisystemic nature of the ongoing novel COVID-19 is evident, but not all manifestations are yet known. This case report underlines the challenge for physicians in terms of recognising and treating emergent complications of this new disease.

Intrapulmonary IFN-γ instillation causes chronic lymphocytic inflammation in the spleen and lung through the CXCR3 pathway

Some patients with chronic refractory cough have high levels of pulmonary IFN-γ and IFN-γ-producing T lymphocytes. Pulmonary IFN-γ administration causes acute airway lymphocytic inflammation and cough hypersensitivity by increasing the number of pulmonary IFN-γ-producing T lymphocytes, but these lymphocytes may be recruited from other organs. Intraperitoneal IFN-γ injection can increase the spleen weight of mice. It remains elusive whether pulmonary IFN-γ can induce chronic airway lymphocytic inflammation and cough hypersensitivity by stimulating the proliferation of IFN-γ -producing T lymphocytes in the spleen. Here, we found that pulmonary IFN-γ administration induced chronic airway inflammation and chronic cough hypersensitivity with an increased number of IFN-γ-producing T lymphocytes in the spleen, blood and lung. Pulmonary IFN-γ administration also increased 1) the proliferation of spleen lymphocytes in vivo and 2) the IP-10 level and CXCR3+ T lymphocyte numbers in the spleen and lung of mice. IP-10 could promote the proliferation of spleen lymphocytes in vitro but not blood lymphocytes or lung-resident lymphocytes. AMG487, a potent inhibitor of binding between IP-10 and CXCR3, could block pulmonary IFN-γ instillation-induced chronic airway lymphocytic inflammation and the proliferation of IFN-γ-producing T lymphocytes in mouse spleens. In conclusion, intrapulmonary IFN-γ instillation may induce the proliferation of splenic IFN-γ-producing T lymphocytes through IP-10 and the CXCR3 pathway. The IFN-γ-producing T lymphocytes in blood, partly released from the mouse spleen, may be partly attracted to the lung by pulmonary IP-10 through the CXCR3 pathway. IFN-γ-producing T lymphocytes and IFN-γ in the lung may cause chronic airway lymphocytic inflammation and chronic cough hypersensitivity.

Splenomegaly versus pathological lung volume during COVID-19 infection with or without cytokine storm; a linear regression analysis using CT volumetry

Background

Due to the paucity of scientific evidence, it is unclear among pulmonologists and physicians in critical care units if and when splenomegaly in novel coronavirus disease (2019) (COVID-19) patients is worrisome. This study aims to evaluate the significance of splenic volume during COVID-19 infection with or without cytokine storm and correlates splenic volume to the volume of pathological lung changes through linear regression analysis.

Results

A retrospective study collected 509 polymerase chain reaction proved COVID-19 patients (399 males, 110 females; mean age 48 years, age range 24–78 years) between June and November 2021, without a history of splenic pathology. A control group of age and sex-matched 509 healthy subjects was used and analyzed according to the splenic volume. Five consulting radiologists evaluated initial and follow-up computed tomography (CT) examinations using lung CT volumetry and splenic volume calculation in consensus. Three consulting pulmonologists correlated the severity of clinical and laboratory findings, including oxygen requirements and interleukin-6 (IL-6) levels. The T test results for comparison between the COVID-19 patients and the healthy subjects control group regarding the splenic volume were significant (T value was − 4.731452 and p value was 0.00002). There was no significant correlation between the severity of the disease and normal-sized spleen (26% of patients, p = 0.916) or splenomegaly (24% of patients, p = 0.579). On the other hand, all patients with a small spleen or progressive splenomegaly during serial follow-up imaging had clinically severe disease with a statistically significant correlation (p = 0.017 and 0.003, respectively). Ninety-seven percent of patients with clinically mild disease and splenomegaly had 0–20% lung involvement (CT-severity score 1) while all patients with clinically severe disease and splenomegaly had 27–73% lung involvement (CT-severity score 2 and 3) (r = 0.305, p = 0.030).

Conclusions

Splenomegaly is a non-specific sign that may be found during mild and severe COVID-19 infection, it was not statistically correlated with the clinical severity and a weak positive relationship was found between the splenic size and the CT-severity score of the pathological lung volume. On the other hand, the presence of splenic atrophy or progressive splenomegaly was correlated with severe COVID-19 presentation and “cytokine storm”. Therefore, the splenic volume changes should not be overlooked in COVID-19 serial CT examinations, particularly in severe or critically ill patients with cytokine storms.

Targeting the Complement-Sphingolipid System in COVID-19 and Gaucher Diseases: Evidence for a New Treatment Strategy

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2)-induced disease (COVID-19) and Gaucher disease (GD) exhibit upregulation of complement 5a (C5a) and its C5aR1 receptor, and excess synthesis of glycosphingolipids that lead to increased infiltration and activation of innate and adaptive immune cells, resulting in massive generation of pro-inflammatory cytokines, chemokines and growth factors. This C5a-C5aR1-glycosphingolipid pathway- induced pro-inflammatory environment causes the tissue damage in COVID-19 and GD. Strikingly, pharmaceutically targeting the C5a-C5aR1 axis or the glycosphingolipid synthesis pathway led to a reduction in glycosphingolipid synthesis and innate and adaptive immune inflammation, and protection from the tissue destruction in both COVID-19 and GD. These results reveal a common involvement of the complement and glycosphingolipid systems driving immune inflammation and tissue damage in COVID-19 and GD, respectively. It is therefore expected that combined targeting of the complement and sphingolipid pathways could ameliorate the tissue destruction, organ failure, and death in patients at high-risk of developing severe cases of COVID-19.

Coronavirus Disease in the Abdomen

Numerous abdominal manifestations have been reported in patients with coronavirus disease 2019 (COVID-19), including involvement of the luminal gastrointestinal (GI) tract, hepatobiliary system, pancreas, kidneys, spleen, and blood vessels. Although most of the associated radiological abnormalities are nonspecific without distinguishing imaging features to suggest COVID-19, unique presentations such as findings of bowel ischemia preceding gross findings of bowel necrosis have been reported. Awareness of the spectrum of abdominal manifestations of COVID-19 allows radiologists to optimize their search pattern and to raise the possibility of this etiology when appropriate. Awareness of the possible abdominal manifestations of COVID-19 should enhance detection by radiologists and improve patient care. This review provides a comprehensive overview with illustrative imaging examples of COVID-19 in the abdomen.

Development of transgenic models susceptible and resistant to SARS-CoV-2 infection in FVB background mice

Coronavirus disease (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), is currently spreading globally. To overcome the COVID-19 pandemic, preclinical evaluations of vaccines and therapeutics using K18-hACE2 and CAG-hACE2 transgenic mice are ongoing. However, a comparative study on SARS-CoV-2 infection between K18-hACE2 and CAG-hACE2 mice has not been published. In this study, we compared the susceptibility and resistance to SARS-CoV-2 infection between two strains of transgenic mice, which were generated in FVB background mice. K18-hACE2 mice exhibited severe weight loss with definitive lethality, but CAG-hACE2 mice survived; and differences were observed in the lung, spleen, cerebrum, cerebellum, and small intestine. A higher viral titer was detected in the lungs, cerebrums, and cerebellums of K18-hACE2 mice than in the lungs of CAG-hACE2 mice. Severe pneumonia was observed in histopathological findings in K18-hACE2, and mild pneumonia was observed in CAG-hACE2. Atrophy of the splenic white pulp and reduction of spleen weight was observed, and hyperplasia of goblet cells with villi atrophy of the small intestine was observed in K18-hACE2 mice compared to CAG-hACE2 mice. These results indicate that K18-hACE2 mice are relatively susceptible to SARS-CoV-2 and that CAG-hACE2 mice are resistant to SARS-CoV-2. Based on these lineage-specific sensitivities, we suggest that K18-hACE2 mouse is suitable for highly susceptible model of SARS-CoV-2, and CAG-hACE2 mouse is suitable for mild susceptible model of SARS-CoV-2 infection.

Multiorgan Involvement in SARS-CoV-2 Infection: The Role of the Radiologist from Head to Toe

Radiology plays a crucial role for the diagnosis and management of COVID-19 patients during the different stages of the disease, allowing for early detection of manifestations and complications of COVID-19 in the different organs. Lungs are the most common organs involved by SARS-CoV-2 and chest computed tomography (CT) represents a reliable imaging-based tool in acute, subacute, and chronic settings for diagnosis, prognosis, and management of lung disease and the evaluation of acute and chronic complications. Cardiac involvement can be evaluated by using cardiac computed tomography angiography (CCTA), considered as the best choice to solve the differential diagnosis between the most common cardiac conditions: acute coronary syndrome, myocarditis, and cardiac dysrhythmia. By using compressive ultrasound it's possible to study the peripheral arteries and veins and to exclude the deep vein thrombosis, directly linked to the onset of pulmonary embolism. Moreover, CT and especially MRI can help to evaluate the gastrointestinal involvement and assess hepatic function, pancreas involvement, and exclude causes of lymphocytopenia, thrombocytopenia, and leukopenia, typical of COVID-19 patients. Finally, radiology plays a crucial role in the early identification of renal damage in COVID-19 patients, by using both CT and US. This narrative review aims to provide a comprehensive radiological analysis of commonly involved organs in patients with COVID-19 disease.

Imaging of Hematological Patients in the Era of COVID-19

The COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), resulted in changes in management and imaging routines for patients with hematological malignancies. Treating physicians had to familiarize themselves with a new disease, with distinct imaging manifestations, sometimes overlapping with other infections prevalent in this patient population. In some aspects, infected hematological patients might exhibit a different disease course, and routine imaging in asymptomatic hematological patients may result in unexpected COVID-19 findings, implying covert infection, that should be further explored. Furthermore, some complications of hematological diseases and treatments may present with findings similar to COVID-19 manifestations, and treating physicians must consider both possibilities in the differential diagnosis. In this review, we aimed to present the influence the COVID-19 pandemic had on hematological malignancy imaging.