COVID-19-associated hypertriglyceridemia and impact of treatment

Background

Coronavirus disease 2019 (COVID-19) associated hypertriglyceridemia was observed among patients admitted to intensive care units (ICU) in Qatar. This study aimed to describe COVID-19-associated-hypertriglyceridemia in ICU patients and the impact of treating hypertriglyceridemia on clinical outcomes.

Methods

A retrospective observational cohort study of adult patients who were admitted to the ICU with a confirmed diagnosis of COVID-19 pneumonia according to the World Health Organization criteria. Hypertriglyceridemia was defined as triglyceride level of 1.7 mmol/L (≥150 mg/dL) and severe hypertriglyceridemia as fasting TG of ≥5.6 mmol/L (≥500 mg/dL).

Results

Of 1,234 enrolled patients, 1,016 (82.3%) had hypertriglyceridemia. Median age was 50 years and 87.9% were males. Patients with hypertriglyceridemia showed significantly longer time to COVID-19 recovery, ICU and hospital stay, and time to death (29.3 vs. 16.9 days) without a difference in mortality between groups. Of patients with hypertriglyceridemia, 343 (33.8%) received treatment (i.e., fibrate and/or omega-3). Patients in treatment group showed longer time to COVID-19 recovery and hospital stay with no difference in death rates in comparison with those in no-treatment group. Relatively older patients were less likely to experience hypertriglyceridemia (odd ratio (OR) 0.976; 95% CI: 0.956, 0.995) or to receive treatment (OR 0.977; 95% CI: 0.960, 0.994). Whereas patients who received tocilizumab were more likely to experience high TG level (OR 3.508; 95% CI: 2.046, 6.015) and to receive treatment for it (OR 2.528; 95% CI: 1.628, 3.926).

Conclusion

Hypertriglyceridemia associated with COVID-19 did not increase death rate, but prolonged time to death and length of stay. Treating hypertriglyceridemia did not translate into improvement in clinical outcomes including mortality.

Adding colchicine to tocilizumab in hospitalized patients with severe COVID-19 pneumonia: An open-label randomized controlled trial

INTRODUCTION

Colchicine acts upstream in the cytokines cascade by inhibiting the nod-like receptor protein 3 (NLRP3) inflammasome while interleukin 6 (IL-6) receptor antagonists, such as tocilizumab, block the end result of the cytokines cascade. Hence, adding colchicine to tocilizumab with the aim of blocking the early and end products of the cytokines cascade, might reduce the risk of developing cytokine storm.

METHODS AND ANALYSIS

We aim to conduct an open-label randomized controlled trial to evaluate the efficacy and safety of adding colchicine to tocilizumab among patients with severe COVID-19 pneumonia to reduce the rate of invasive mechanical ventilation and mortality. We will include patients with severe COVID-19 pneumonia who received tocilizumab according to our local guidelines. Enrolled patients will be then randomized in 1:1 to colchicine versus no colchicine. Patients will be followed up for 30 days. The primary outcome is the rate of invasive mechanical ventilation and will be determined using Cox proportional hazard model.

DISCUSSION

Given colchicine's ease of use, low cost, good safety profile, and having different anti-inflammatory mechanism of action than other IL-6 blockade, colchicine might serve as a potential anti-inflammatory agent among patients with severe COVID-19 pneumonia. This study will provide valuable insights on the use of colchicine in severe COVID-19 when added to IL-6 antagonists.

ETHICS AND DISSEMINATION

The Medical Research Center and Institutional Review Board at Hamad Medical Corporation in Qatar approved the study protocol (MRC-01-21-299). Results of the analysis will be submitted for publication in a peer-reviewed journal.

Chest X-ray Findings and Hyponatremia in COVID-19 Pneumonia Patients

Background: The World Health Organization declared the coronavirus disease-2019 (COVID-19) a pandemic in December 2019. COVID-19 can affect most organs of the body but predominantly affects the lungs. Chest infection is associated with hyponatremia primarily due to inappropriate ectopic secretion of antidiuretic hormone. We conducted a six-month retrospective observational study to evaluate the relationship between chest X-ray (CXR) radiological findings and serum sodium levels. Our secondary goal was to assess the relationship between CXR findings and patient outcomes.

Aim of the Study: To assess the relationship between the initial CXR findings, hyponatremia severity, and outcome in COVID-19 infected patients.

Materials and methods: We conducted a retrospective review of CXR findings of COVID-19 patients aged > 18 years. The patients were healthy and had no history of hyponatremia before COVID-19 infection. All recruited patients were admitted to one of four hospitals in Qatar (Hazm Mebaireek General Hospital, Communicable Disease Center, and all affiliated quarantine centers managed under the Communicable Disease Centre, Mesaieed Hospital, and Ras Laffan Hospital) between March and June 2020. We excluded patients with factors that contributed to hyponatremia. Three score grades were established to describe the CXR findings. Patients were divided into three groups by the principal researcher according to their serum sodium levels. A radiologist evaluated the CXR findings with the patient and group information obscured. The principal researcher collected the X-ray scores for analysis with the serum sodium levels. We used SPSS for Windows, Version 15.0. (SPSS Inc., Chicago, IL, USA) and STATA Package Version 12.0 (StataCorp, College Station, TX, USA) to analyze the data. A p-value ≤  0.05 was considered significant.

Results: A total of 414 CXR patients with COVID-19 were recruited; 275 patients had hyponatremia and 139 had normal sodium levels and were used as the control group. Patients with normal serum sodium and hyponatremia were classified into three categories based on the CXR findings. Grade 0 (95), Grade 1 (43), and Grade 2 (137) hyponatremic patients were reported. The mean sodium levels were 133.6, 131.3, and 127.2 mmol/L for Grades 0, 1, and 2, respectively (p < 0.001). More than 95% of the patients who developed hyponatremia were >30 years. Moderate and severe hyponatremia was more prevalent in patients with Grade 1 or Grade 2 CXR findings and were >30 years.

Conclusion: Serum sodium levels in COVID-19 patients correlated well with the severity of the CXR findings observed at the early disease stage. Furthermore, simple CXR scores can be used to identify COVID-19 patients at a higher risk of hyponatremia, length of hospital stay, medical care support type, and mortality.

All those exanthematous fevers are not Covid-19

Fever with a rash is a common case scenario that clinicians encounter in their practice. The ubiquity of the presentation is proportional to the magnitude of the physician's dilemma due to its numerous causes. The diagnosis varies from infectious diseases to non-infectious, life threatening diseases including the current COVID-19 pandemic. Here we present a case of a 31-year-old male, who presented to the Emergency Department with fever and rash and was initially diagnosed and managed as a case of COVID-19 which on further evaluation proved to be brucellosis. This is a case of brucellosis with cutaneous manifestations which had been masquerading as COVID-19.

Coronavirus Disease-19-associated Acute Pancreatitis: Report of Three Cases and Review of Case Reports

BACKGROUND: Reports on coronavirus disease 2019 (COVID-19) associated with acute pancreatitis continue to emerge. In this series, we present three cases of acute pancreatitis associated with COVID-19 with no obvious etiology. CASE REPORTS: The first case was a 47-year-old man who presented with severe abdominal periumbilical pain, preceded by fever and dry cough. Based on a positive COVID-19 polymerase chain reaction (PCR) test and elevated serum amylase and lipase >3 times the upper normal limit, the diagnosis of COVID-19 and acute pancreatitis were established. The next case was a 57-year-old man with confirmed COVID-19 who developed severe epigastric pain radiating to the back and was associated with nausea and vomiting. His serum amylase and lipase were elevated >3 times the upper normal limit confirming the diagnosis of acute pancreatitis. The third case was a 31-year-old man who presented to the emergency department with a few hours of severe epigastric pain radiating to the back associated with nausea and vomiting. Two days before his presentation, he had a runny nose and fever. A combination of serum amylase and lipase elevation, >3 times the upper normal limits, and a positive COVID-19 PCR test were obtained concurrently, confirming the diagnosis of COVID-19 associated acute pancreatitis. All patients were admitted to the Mesaieed Hospital COVID-19 facility and received treatment for COVID-19 according to our local guidelines, while acute pancreatitis was treated conservatively. All three patients were discharged in good condition. CONCLUSION: This case series suggests a possible correlation between COVID-19 and acute pancreatitis.

Case Report: Prolonged Viral Shedding in Six COVID-19 Patients

COVID-19 has surfaced as a multi-organ disease predominantly affecting the respiratory system. Detection of the viral RNA through reverse transcriptase–PCR (RT-PCR) from a nasopharyngeal or throat sample is the preferred method of diagnosis. Recent evidence has suggested that COVID-19 patients can shed the SARS-CoV-2 for several weeks. Herein, we report six cases of COVID-19 who had persistently positive SARS-CoV-2 on repeat RT-PCR testing reaching up to 9 weeks. The spectrum of cases described ranges from asymptomatic infection to severe COVID-19 pneumonia. A full understanding of the virus’s transmission dynamics needs further research. Prolonged viral shedding currently has unclear implications on the management and isolation decisions—the role of the cycle threshold (Ct) value in guiding therapeutic decisions is yet to be clarified. More data on the relationship between Ct values and viral cultivation are needed, especially in patients with prolonged viral shedding, to understand the virus’s viability and infectivity.

Proposed Scoring System for Evaluating Clinico-radiological Severity of COVID- 19 using Plain Chest X- ray (CXR) changes (CO X-RADS): Preliminary results

Background:

Plain chest radiograph (CXR), although less sensitive than chest CT, is usually the first-line imaging modality used for patients with symptomatic SARS-CoV-2 infection. The relation between radiological changes in CXR and clinical severity of the disease in symptomatic patients with COVID 19 has not been fully studied and there is no scoring system for the severity of the lung involvement, using the plain CXR.

Aim of the study:

Current COVID-19 radiological literature is dominated by CT and a detailed description CXR appearances in relation to the disease time course is lacking. We propose an easy scoring system (CO X-RADS) to describe the severity of chest involvement in symptomatic COVID 19 patients using CXR and to correlate the radiological changes with the clinical severity of the disease.

Patients and methods:

The clinical manifestations and CXR findings were recorded in 500 symptomatic COVID-19 positive patients who were admitted to Hamad Medical Corporation (HMC) COVID-19 designated facility Center from January to June 2020. The severity and outcome of the disease included: intensive care unit admission, need for oxygen therapy, mechanical ventilation. and mortality rate.

Results:

Most of our symptomatic patients (86.8%) had mild and moderate clinical manifestations. The remaining 13.2% had severe manifestations, including: fever, persistent dry cough, shortness of breath, dyspnea, abdominal and generalized body pains. Based on our radiological scoring system (0 to 10) patients were distributed according to their CXR findings into different categories and according to our suggested (CO X-RADS) severity system into five categories (0 to IV). Patients with mild clinical manifestations showed low scoring in CXR (score 0 up to 4) and they represented 72% of our patients. Patients with moderately severe clinical manifestations showed mainly GGO (scoring 5 and 6) and represented about 14.8% of patients. Patients presented with severe clinical manifestations had obvious lung consolidations at the time of presentation with CXR scoring system ≥ 7 and represented about 13.2% of patients.

Conclusion:

We proposed a simple CXR reporting scoring system (CO X-RADS) to categorize COVID19 patients according to their radiological severity. This radiological score was correlated well with the clinical severity score of patients. We encourage other centers to test this scoring system in correlation with the clinical status of patients. (www.actabiomedica.it)

Clinical Outcome of Eosinophilia in Patients with COVID-19: A Controlled Study

Background:

Eosinophils can be considered as multifunctional leukocytes that contribute to various physiological and pathological processes depending on their location and activation status. There are emerging eosinophil-related considerations concerning COVID-19. Variable eosinophil counts have been reported during COVID-19. Whether these changes are related to the primary disease process or due to immunomodulation induced by the treatment has not yet been elucidated.

Aim of the study:

To describe changes in the differential leukocyte counts including eosinophils, in a cohort of symptomatic patients with confirmed COVID-19 and to correlate these changes, if any, with the severity of the disease.

Patients and methods:

We recorded the clinical data, lab findings, including inflammatory markers and leukocyte and differential count, course of the disease and severity score in 314 confirmed symptomatic cases of COVID-19.

Results:

Laboratory tests revealed that 28.7 % (n =86) had mild eosinophilia (eosinophil count > 500 <1,500/µL). Thirty-four patients (11.3%) had elevated absolute neutrophil count (ANC) (>8,000/µL), and 7 (2.3%) had decreased ANC (< 1,500/µl). Seven patients (2.3%) had lymphopenia (<1,000/µL) and 4 (4.67%) had lymphocytosis (> 4,000/µL). C-reactive protein (CRP) was elevated in 83 patients (27.6%). Chest X-Ray changes included: increased broncho vascular markings (38%), ground-glass opacity (GGO) pneumonitis (19.3%), lobar consolidation (5%), bronchopneumonia (8.3%), nodular opacity (1%), acute respiratory distress syndrome (ARDS) (2.3%), pleural effusion (1.0%) and other atypical findings (6.6%). Patients with eosinophilia had significantly lower CRP, and lower % of GGO, lobar and bronchopneumonia and ARDS in their chest images compared to patients without eosinophilia (p: <0.05). They also had a lower requirement for a hospital stay, ICU admission, mechanical ventilation, and oxygen supplementation versus patients without eosinophilia (p: <0.05). The eosinophils count was correlated negatively with the duration of ICU admission, mechanical ventilation, and oxygen supplementation and with CRP level (r: - 0.34, -0.32, -0.61 and - 0.39, respectively) (p: < 0.01).

Conclusions:

Our study reports a relatively high prevalence of eosinophilia in symptomatic COVID-19 positive patients. Patients with eosinophilia had a lower level of CRP, milder clinical course and better disease outcomes compared to those without eosinophilia. Our findings indicated a protective role of eosinophils in mitigating the severity of inflammatory diseases through an inhibitory mechanism, as evidenced by lower CRP. This protective role of eosinophils needs to be validated by further prospective studies. (www.actabiomedica.it)

Prevalence, clinical manifestations, and biochemical data of type 2 diabetes mellitus versus nondiabetic symptomatic patients with COVID-19: A comparative study

BACKGROUND

There is a scarcity of data regarding the effect of Type 2 diabetes mellitus (T2DM) and associated comorbidities on the clinical presentation and outcome of symptomatic patients with -COVID-19 infection in comparison with non-diabetic patients.

AIM OF THE STUDY

We described and compared the clinical presentation and radiological and hematological data of a cohort of symptomatic COVID19 positive T2DM diabetic patients (n = 59) versus another cohort of non-diabetic symptomatic COVID19 positive patients (n =244) diagnosed at the same time from January 2020 to May 2020. Associated comorbidities were -assessed, and the Charlson Comorbidity Index was calculated. The outcomes including duration of hospitalization, duration of Intensive Care Unit (ICU) stay, duration of mechanical ventilation, and duration of O2 -supplementation were assessed.

RESULTS

Prevalence of T2DM in symptomatic COVID19 positive patients was 59/303 (=19.5%).  Diabetic patients had higher prevalence of hypertension, chronic kidney disease (CKD) and cardiac dysfunction [coronary heart disease (CHD)], and congestive heart failure (CHF). Charlson Comorbidity score was significantly higher in the T2DM patients (2.4± 1.6) versus the non-diabetic -patients (0.28 ± 0.8; p: < 0.001). Clinically and radiologically, T2DM patients had significantly higher percentage of pneumonia, severe pneumonia and ARDS versus the non-diabetic patients. Hematologically, diabetic patients had significantly higher C-reactive protein (CRP), higher absolute neutrophilic count (ANC) and lower counts of lymphocytes and eosinophils compared to non-diabetic patients. They had significantly higher systolic and diastolic blood pressures, longer duration of hospitalization, ICU stay, mechanical ventilation and oxygen therapy. CRP was correlated significantly with the duration of stay in the ICU and the duration for oxygen supplementation (r = 0.37 and 0.42 respectively; p: <0.01).

CONCLUSIONS

T2DM patients showed higher inflammatory response to COVID 19 with higher absolute neutrophilic count (ANC) and CRP with lower lymphocytic and eosinophilic counts. Diabetic patients had more comorbidities and more aggressive course of the disease with higher rate of ICU admission and longer need for hospitalization and oxygen use.

A microfluidic flow analyzer with integrated lensed optical fibers

Rapid optical interrogation of flowing cells or particles is a powerful tool in the field of biomedical diagnostics. Determination of size and composition of fast-flowing cells, with diameters in the range of 2- 15 μ m , often require complex open-space optics and expensive high-speed cameras. In this work, a method to overcome these challenges by using a hydrodynamic flow-based microfluidic platform coupled with on-chip integrated fiber optics is reported. The lab-scale portable device developed uses a combination of on-chip lensed and non-lensed optical fibers for precision illumination. The narrow light beam produced by the lensed fiber ( f = 150 μ m ) enables precise optical analysis with high sensitivity. A planar arrangement of optical fibers at various angles facilitates multi-parametric analysis from a single point of interrogation. As proof of concept, the laboratory-scale portable bench-top prototype is used to measure fluorescence signals from CD4 immunostained cells and human blood samples. The performance of microfluidic flow analyzer is also compared to the conventional Guava® easyCyte 8HT flow cytometer.

A Case of COVID-19 in a Patient with Asymptomatic Hemoglobin D Thalassemia and Glucose-6-Phosphate Dehydrogenase Deficiency

Patient: Gender, 26-year-old

Final Diagnosis: COVID-19

Symptoms: Cough • fever

Medication:—

Clinical Procedure: —

Specialty: Hematology

Congenital paediatric atlantoaxial dislocation: clinico-radiological profile and surgical outcome

INTRODUCTION

Congenital atlantoaxial dislocation (AAD) is the most common bony abnormality affecting the craniovertebral junction. The paediatric population has specific problems like preoperative diagnostic difficulties, precise neurological examination, radiological diagnosis, surgical problems including physical fitness to tolerate surgery (including problems of anaesthesia), technical difficulties in surgery and problems related to immobilization.

MATERIAL AND METHODS

A total of 229 consecutive paediatric (≤18 years) patients of AAD visited our centre from the period of January 1997 to August 2011. Twenty-nine cases were excluded from the study as these cases were diagnosed as CVJ tuberculosis, 31 cases were excluded as they were traumatic and the remaining 169 cases were retrospectively analysed. These patients were operated by a single experienced surgeon (the senior author) at the Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow. The preoperative and the postoperative clinical evaluation of the patient was done by the Kumar and Kalra myelopathic scoring system. The score was recorded in the preoperative period, at the time of discharge, at 3 months follow-up and at 6 months follow-up.

RESULTS

Ninety-four were males and 75 were females. The age range was 4 to 18 years with mean age 9.96±3.78 years. The follow-up ranged from 3 to 120 months with mean follow-up being 39.03±13.38 months. One hundred five cases were of fixed/irreducible AAD, and 64 were cases of mobile/reducible AAD. Majority of these cases presented with features of pyramidal tract involvement, and 108 cases had compromised pulmonary function test. One hundred thirty-seven cases had improved outcome, and 18 cases were in the same grade in the postoperative period with only 14 cases either deteriorated or died.

CONCLUSIONS

Congenital paediatric AAD are a different subset of abnormalities and have a satisfactory outcome. Preoperative evaluation must also include identification of various syndromes associated with paediatric AAD and respiratory reserve. Cormack-Lehane grade can be helpful in selecting borderline cases for postoperative need of tracheostomy. Majority of the cases have a good outcome, and therefore, surgery should be offered even in severe grade.

Intracranial haemorrhage in severe haemophilia: prevalence and outcome in a developing country

Intracranial haemorrhage (ICH) is a common cause of morbidity and mortality in haemophilic patients all over the world. From 1995 to 2004, we have investigated 37 patients with 43 episodes of ICH at our Comprehensive Haemophilia Care Center from a total of 600 registered patients. Diagnosis of ICH in the patients was confirmed by clinical, haematological and computed tomographic imaging data. Three patients died despite replacement therapy while one child who had a ventriculo-atrial shunt for acute hydrocephalus also died before further intervention. One of the four patients who died also had severe aplastic anaemia for 6 years in addition to severe haemophilia. Detailed history obtained from 143 families with haemophilia attending the Genetic Diagnosis Clinic at our Center showed a positive history of cerebral bleed in 39 episodes in 37 patients. Sixteen families gave a history of death in the family of haemophilic patients due to ICH, while in the remaining 21 families, the patients had survived the episode after treatment elsewhere. However, the ICH was not confirmed by image data in these cases. The treatment protocols were also not available in these cases. Conservative factor replacement therapy 100% correction for 3 days followed by 50-60% correction for 7 days) coupled with the epsilon amino caproic acid, the antifibrinolytic agent at least for 30 days led to a mortality (10.8%) similar to that of the western countries and almost no morbidity. Surgery was not required in any of these patients except in one elderly patient with HIV infection on antiretroviral therapy.

Global analysis of differential gene expression after transformation with the v-H-ras oncogene in a murine tumor model

Mouse PB-3c mast cells stably transfected with the v-H-ras oncogene induce tumor formation in vivo when implanted into mice. Such tumor cells are characterized by an autocrine IL-3 loop. DNA microarrays allow simultaneous transcript imaging of several thousand genes and the technique was applied in this tumor model to analyse gene expression following malignant transformation. Using three independent tumor lines derived from the same precursor the expression of about 400 out of 11 000 genes was modulated in each tumor. A subset of only 75 genes (0.68%) is shared and up- or downregulated in all three lines. A significant portion of this gene pool possesses functions related to tumorigenesis such as cell adhesion, signaling or transcriptional regulation. Apart from a number of expressed sequence tags (EST's) we find downregulation of four interferon-inducible genes in the tumor lines. Finally, when we extrapolate our data to the complete mouse genome, we estimate that about 500 genes are differentially expressed in tumor cells compared to the precursor cell PB-3c.

Cyclosporin A promotes translational silencing of autocrine interleukin-3 via ribosome-associated deadenylation

Translation is regulated predominantly by an interplay between cis elements at the 3' and 5' ends of mRNAs and trans-acting proteins. Cyclosporin A (CsA), a calcineurin antagonist and blocker of interleukin-2 (IL-2) transcription in T cells, was found to inhibit translation of IL-3 mRNA in autocrine mast cell tumor lines. The mechanism involved ribosome-associated poly(A) shortening and required an intact AU-rich element in the 3' untranslated region. FK506, another calcineurin inhibitor, shared the effect. The translational inhibition by CsA was specific to oncogenically induced lymphokines IL-3 and IL-4 but not to IL-6, c-jun, and c-myc, which are expressed in the nonmalignant precursor cells. Furthermore, no translational down-regulation of the mRNA was observed in IL-3-transfected precursor cells. These data suggest that translational silencing is associated with the tumor phenotype.

Rapamycin destabilizes interleukin-3 mRNA in autocrine tumor cells by a mechanism requiring an intact 3' untranslated region

We analyzed the effect of rapamycin on autocrine mast cell tumor lines with abnormally stable interleukin-3 (IL-3) transcripts due to a defect in mRNA degradation. Rapamycin inhibited IL-3 mRNA expression specifically, while transcripts of IL-4 and IL-6 were not affected. As indicated by the use of the transcriptional inhibitor actinomycin D or by reporter constructs, inhibition was posttranscriptional and resulted from destabilization of the mRNA. Transcripts from transgenes lacking the AU-rich 3' untranslated region were refractory to drug-induced degradation, suggesting that these 3' sequences contain the target of the rapamycin effect. Rapamycin did not promote IL-3 mRNA degradation in cells of a tumor variant lacking expression of FKBP12, the binding protein of rapamycin. Experiments with wortmannin indicated that rapamycin does not act via p70S6 kinase. FK-506, another ligand of FKBP12 affecting the phosphatase calcineurin, did not antagonize but shared the effect of rapamycin. Our data fit a model whereby both FKBP12 and calcineurin target an unknown regulator of IL-3 mRNA turnover.

Interleukin-3 mRNA stabilization by a trans-acting mechanism in autocrine tumors lacking interleukin-3 gene rearrangements

Tumors obtained from v-Ha-ras-transformed PB-3c cells are characterized by autocrine interleukin-3 (IL3) expression, which occurs either without (class I tumors) or with enhanced transcription (class II tumors). To address possible post-transcriptional mechanisms of IL3 expression, IL3 mRNA stability was examined in both tumor classes. Increased stability of IL3 mRNA was detected in class I tumor lines (t1/2 > 3 h), whereas rapid decay of IL3 transcripts (t1/2 < 0.5 h) was found in class II tumor lines. In both tumor classes, the c-myc and interleukin-6 transcripts were short-lived. Transcripts of a constitutively expressed IL3 reporter gene were stable in class I tumor cells but unstable in class II tumor cells, suggesting that IL3 mRNA stabilization involved a trans-acting mechanism. Rapid decay of IL3 reporter transcripts was observed in untransformed PB-3c as well as in v-Ha-ras expressing precursor cells linking transcript stabilization to the tumor stage. Reporter transcript stabilization in class I tumor cells correlated with increased IL3 production. Deletion of the AU-rich element from the IL3 reporter gene further augmented IL3 mRNA levels as well as IL3 production, suggesting that the stabilizing mechanism in class I tumor cells is not equivalent to AU-rich element deletion.

Cyclosporin A inhibits growth of autocrine tumour cell lines by destabilizing interleukin-3 mRNA

In T cells, cyclosporin A (CsA) exerts its immunosuppressive effect by preventing transcriptional induction of the expression of interleukin(IL)-2. This is achieved by a mechanism that involves binding of a CsA-cyclophilin complex to calcineurin, which in turn inhibits the phosphatase-controlled translocation of transcription factor NFAT to the nucleus. We have previously identified IL-3 as an autocrine oncogenic regulator in tumour cell lines generated by introducing the v-H-ras oncogene into IL-3-dependent mast cells. Here we report that CsA specifically blocks autocrine tumour cell growth. The mechanism involves down-regulation of IL-3 expression by destabilization of the messenger RNA and requires ongoing transcription. Transcripts from exogenous IL-3 genes lacking the (A+U)-rich element (ARE) in the 3' untranslated terminal repeat could not be destabilized, suggesting that at least part of this sequence, which is known to mediate decay of short-lived mRNA, participates in a CsA-sensitive regulatory mechanism.

Suppressible and nonsuppressible autocrine mast cell tumors are distinguished by insertion of an endogenous retroviral element (IAP) into the interleukin 3 gene

After v-H-ras expression, the interleukin 3 (IL-3)-dependent PB-3c mast cells progress in vivo to two different classes of IL-3 autocrine tumors. Class I tumors show a germline configuration of the IL-3 gene and represent more than 90% of tumors analyzed so far. Somatic cell fusion of class I tumor lines with the nontumorigenic parental PB-3c resulted in loss of oncogenic IL-3 expression by a posttranscriptional mechanism with concomitant tumor suppression. Class II tumors arise rarely and contain an insertion in one IL-3 allele. This alteration was linked to enhanced IL-3 gene transcription. For one tumor, the insertion was shown to be an endogenous retroviral element (intracisternal A-particle). Cell hybrids of class II tumors with PB-3c remained IL-3 independent, expressed IL-3, and formed tumors rapidly. These results suggest that the v-H-ras oncogene synergizes with a recessive and a dominant lesion in class I and II tumors, respectively, both of which lead to the autocrine production of IL-3.

Mast cells sensitive to v-H-ras transformation are hyperinducible for interleukin 3 expression and have lost tumor-suppressor activity

Subcloning of interleukin 3 (IL-3)-dependent PB-3c mastocyte cells revealed two populations, of which only one is sensitive to oncogenic transformation by v-H-ras. The corresponding tumors produce IL-3 and grow in vitro in the absence of exogenous IL-3 [Nair, A.P.K., Diamantis, I.D., Conscience, J.F., Kindler, V., Hofer, P. & Moroni, Ch. (1989). Mol. Cell. Biol., 9, 1183-1190]. In the present investigation, IL-3 gene regulation was compared in ras transformable (rT) and ras nontransformable (rNT) lines. We report that upon expression of v-H-ras rT clones but not rNT clones express low levels of IL-3 mRNA as detected by reverse polymerase chain reaction. Treatment with ionomycin, a calcium ionophore, induced high levels of IL-3 expression only in ras-expressing rT clones. Somatic cell fusion between the rNT clone 20 and the IL-3-expressing mastocytoma line V2D1 led to down-regulation of IL-3 expression and to the requirement for exogenous IL-3 for in vitro growth and tumor suppression. In contrast, rT clone 15 lacked tumor-suppressor activity and failed to down-regulate IL-3 expression in somatic hybrids which grew in vitro without added IL-3. Our results indicate that IL-3 gene expression is a critical determinant for the generation of v-H-ras-induced mast cell tumors and show that disturbances in IL-3 gene regulation can be detected already at the premalignant level in v-H-ras transformation-sensitive cells.

Ras oncogenes amplify lymphokine (interleukin 3, granulocyte-macrophage colony-stimulating factor) induction by calcium ionophore

Interleukin 3 (IL-3) expression in PB-3c mastocytes is transiently induced in vitro by treatment with the drug A23187, a calcium ionophore, or constitutively following ras-dependent transformation in vivo. While the mechanism of oncogenically induced IL-3 expression is not clear, A23187-mediated lymphokine mRNA accumulation is primarily the result of calcium-dependent mRNA stabilization. We investigated whether the expression of various ras alleles influenced IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA induction by A23187. It was found that activated forms of ras potentiated ionophore-mediated lymphokine mRNA accumulation. This enhancement involves a post-transcriptional mechanism, as ionophore-induced lymphokine mRNAs are significantly more stable in ras oncogene-expressing lines than in the control line. We propose that one way by which ras genes exert their oncogenic potential is by extending the half-life of short-lived growth factor mRNAs.

Tumor suppression involves down-regulation of interleukin 3 expression in hybrids between autocrine mastocytoma and interleukin 3-dependent parental mast cells

Interleukin 3 (IL-3)-dependent PB-3c mouse mastocytes can be transformed by the v-Ha-ras oncogene to generate autocrine IL-3-producing mastocytomas. Hybrid cell lines were constructed by fusing an IL-3-producing mastocytoma cell line with its IL-3-dependent normal parental cell. Unlike the mastocytoma parent cell line, hybrid cell lines required growth factor for in vitro proliferation, indicating that the IL-3-dependent phenotype is dominant. IL-3 mRNA, expressed at high levels in the tumor cells, appeared down-regulated in the cell hybrids. In contrast, p21v-Ha-ras levels were not reduced in the hybrids. The hybrid lines generated tumors in vivo with drastically prolonged latency times when compared to the tumor parent (10 versus 2 weeks). We propose that down-regulation of IL-3 mRNA production after cell fusion is responsible for the loss of growth autonomy in the hybrids and is likely to play a role in the partial suppression of tumor formation in vivo. Our data are consistent with the hypothesis that a tumor suppressor, present in PB-3c cells, acts as a negative regulator of IL-3 expression.

A v-H-ras-dependent hemopoietic tumor model involving progression from a clonal stage of transformation competence to autocrine interleukin 3 production

Autocrine interleukin 3 (IL-3)-secreting tumors were generated from an IL-3-dependent mouse mast cell line (PB-3c) after introduction of the v-H-ras oncogene. Tumor progression was characterized by four distinct phenotypes. The first corresponded to immortalized mast cells unresponsive to the oncogenic effect of v-H-ras. The second was expressed in a clonable subpopulation of PB-3c cells and was marked by the competence to form v-H-ras-dependent tumors (immortalized transformation competence). The third was a direct effect of v-H-ras expression on all PB-3c cells and was characterized in vitro by a reduced IL-3 requirement. Upon injection of v-H-ras-expressing, transformation-competent cells into mice, the final, fully malignant phenotype developed with a long latency period and was marked in vitro by independence of exogenous IL-3 and by autocrine IL-3 stimulation. Northern (RNA) blot analysis and an RNase A-T1 protection assay showed that IL-3 production was strictly associated with the tumor phenotype. Two of six tumors showed an alteration at the 5' region of the IL-3 gene. We conclude that v-H-ras required complementation by IL-3 gene rearrangement or an alternate event to generate autocrine mastocytomas.