Enhanced production of IGF-I in the lungs of fibroproliferative ARDS patients

The effect of IGF-1 plasma concentration on COVID-19 severity

BACKGROUND

The severity and fatality of Coronavirus disease 2019 (COVID-19) infection are not the same in the infected population. The host immune response and Immune-stimulating factors appear to play a role in COVID-19 infection outcome. insulin-like growth factor-1 (IGF-1) affects the immune system by controlling the endocrine system. Recently, the effect of IGF-1 levels on COVID-19 prognosis has been considered.

OBJECTIVE

To investigate the difference between circulating IGF-1 and inflammatory cytokines concentration among COVID-19 patients, infected patients admitted to the Intensive Care Unit (ICU) (n = 40; 35 ± 5 y) and patients with mild cases of COVID-19 (n = 40; 35 ± 5 y) were screened prior to participation in the study. There was no significant difference between the groups in terms of gender and preexisting inflammatory state. Collected samples were evaluated by ELISA for IGF-1 and IL-6.

RESULTS

The study outcomes included a significant decrease in IGF-1 and an increase in IL-6 serum concentration, as an inflammatory marker, for infected patients admitted to the Intensive Care Unit (ICU) (P ≤ 0.001). Finally, there was a significant increase in the IGF-1 and a decrease in the IL-6 serum concentration of hospitalized patients.

DISCUSSION

it appears that inflammatory cytokines (IL-6) serum concentration in the severe form of corona virus-based infections causes reduced defenses because of suppressed IGF-1.

CONCLUSIONS

Our findings show that lower IGF-1 concentrations are associated with a Severe form of COVID-19 disease. It seems, IGF-1 supplementation or anti-inflammatory treatment rescued the severe form of COVID-19 infection. Further studies are required to determine how to design COVID-19 therapeutic strategies targeting the IGF-1 pathway.

Teprotumumab: Interpreting the Clinical Trials in the Context of Thyroid Eye Disease Pathogenesis and Current Therapies

Teprotumumab, a monoclonal antibody targeted against the insulin-like growth factor 1 (IGF-1) receptor, was recently approved by the United States Food and Drug Administration for the treatment of thyroid eye disease (TED). Phase 1 studies of teprotumumab for the treatment of malignancies demonstrated an acceptable safety profile but limited effectiveness. Basic research implicating the IGF-1 receptor on the CD-34+ orbital fibrocyte in the pathogenesis of TED renewed interest in the drug. Two multicenter, randomized, double-masked, clinical trials (phase 2 and 3) evaluated the efficacy of 8 infusions of teprotumumab every 3 weeks versus placebo in 170 patients with recent-onset active TED, as defined by a clinical activity score (CAS) of at least 4. Teprotumumab was superior to placebo for the primary efficacy end points in both studies: overall responder rate as defined by a reduction of 2 or more CAS points and a reduction of 2 mm or more in proptosis (69% vs. 20%; P < 0.001; phase 2 study) and proptosis responder rate as defined by a reduction of 2 mm or more in proptosis (83% vs. 10%; P < 0.001; phase 3 study). In both studies, treatment with teprotumumab compared with placebo achieved a significant mean reduction of proptosis (-3.0 mm vs. -0.3 mm, phase 2 study; -3.32 mm vs. -0.53 mm, phase 3 study) and CAS (-4.0 vs. -2.5, phase 2 study; -3.7 vs. -2.0, phase 3 study). Teprotumumab also resulted in a greater proportion of patients with a final CAS of 0 or 1, higher diplopia responder rate, and a larger improvement in the Graves' Ophthalmopathy Quality of Life overall score. More than half of patients (62%, phase 2 trial; 56%, phase 3 trial) who were primary end point responders maintained this response at 51 weeks after the last dose of therapy. The most common adverse events reported with teprotumumab included muscle spasms (25%), nausea (17%), alopecia (13%), diarrhea (13%), fatigue (10%), hearing impairment (10%), and hyperglycemia (8%). Teprotumumab is contraindicated for those with inflammatory bowel disease and who are pregnant. Although the current dosing regimen has proven effective for TED, dose-ranging studies including variable concentrations, infusion frequencies, and durations of teprotumumab therapy in the setting of TED have not been performed.

Is there a role for insulin-like growth factor inhibition in the treatment of COVID-19-related adult respiratory distress syndrome?

Adult respiratory distress syndrome (ARDS) is the leading cause of death associated with SARS-CoV-2 infection and COVID-19. IGF-1 has been implicated in ARDS, yet its role in relation to COVID-19-related lung injury has not been investigated. We hypothesize that blockage of the IGF-1 receptor (IGF-1R) mitigates lung injury and decreases the risk of death in patients COVID-19-related ARDS. Patients with fibroproliferative ARDS have been shown to have increased IGF-1 and IGF-1R staining in lung tissue specimens. Rising levels of IGF-1 in bronchioalveolar fluid (BAL) and increased IGF-1 mRNA expression in lung tissues (but declining serum IGF-1 levels) have been found in late stage ARDS compared with early lung injury. Blockage of IGF-1R decreases lung tissue damage and increases survival in bleomycin-induced as well as H1N1 influenza-related lung injury in animal models. Teprotumumab is a monoclonal antibody directed against the IGF-1R that was FDA-approved in 2020 for the treatment of Graves’ orbitopathy. In order to determine if teprotumumab may reduce lung injury and death related to ARDS in the setting of COVID-19, preliminary clinical data is needed. IGF-1 levels in serum and BAL fluid must be measured in patients with COVID-19-related ARDS. Histopathology from lung samples from patients with COVID-19-related ARDS must be examined for increased expression of the IGF-1R. Once these are ascertained, and if the data support IGF-1 involvement, a randomized, placebo-controlled phase 2A trial of teprotumumab therapy in the setting of COVID-19-related ARDS and non-COVID-19-related ARDS designed to generate initial data on short-term efficacy, safety, dosing and administration should be performed.

Novel functional role of GH/IGF-I in neonatal lung myofibroblasts and in rat lung growth after intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a risk factor for neonatal chronic lung disease (CLD) characterized by reduced alveoli and perturbed matrix remodeling. Previously, our group showed an activation of myofibroblasts and matrix remodeling in rat lungs after IUGR. Because growth hormone (GH) and insulin-like growth factor I (IGF-I) regulate development and growth, we queried 1) whether GH/IGF-I signaling is dysregulated in lungs after IUGR and 2) whether GH/IGF-I signaling is linked to neonatal lung myofibroblast function. IUGR was induced in Wistar rats by isocaloric low-protein diet during gestation. Lungs were obtained at embryonic day (E) 21, postnatal day (P) 3, P12, and P23. Murine embryonic fibroblasts (MEF) or primary neonatal myofibroblasts from rat lungs of control (pnF^Co) and IUGR (pnF^IUGR) were used for cell culture studies. In the intrauterine phase (E21), we found a reduction in GH receptor (GH-R), Stat5 signaling and IGF-I expression in lungs after IUGR. In the postnatal phase (P3-P23), catchup growth after IUGR was linked to increased GH mRNA, GH-R protein, activation of proliferative Stat5/Akt signaling, cyclin D1 and PCNA in rat lungs. On P23, a thickening of the alveolar septae was related to increased vimentin and matrix deposition, indicating fibrosis. In cell culture studies, nutrient deprivation blocked GH-R/IGF-IR signaling and proliferation in MEFs; this was reversed by IGF-I. Proliferation and Stat5 activation were increased in pnF^IUGR. IGF-I and GH induced proliferation and migration of pnF^Co; only IGF-I had these effects on pnF^IUGR. Thus, we show a novel mechanism by which the GH/IGF-I axis in lung myofibroblasts could account for structural lung changes after IUGR.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

Repression of Igf1 expression by Ezh2 prevents basal cell differentiation in the developing lung

Epigenetic mechanisms involved in the establishment of lung epithelial cell lineage identities during development are largely unknown. Here, we explored the role of the histone methyltransferase Ezh2 during lung lineage determination. Loss of Ezh2 in the lung epithelium leads to defective lung formation and perinatal mortality. We show that Ezh2 is crucial for airway lineage specification and alveolarization. Using optical projection tomography imaging, we found that branching morphogenesis is affected in Ezh2 conditional knockout mice and the remaining bronchioles are abnormal, lacking terminally differentiated secretory club cells. Remarkably, RNA-seq analysis revealed the upregulation of basal genes in Ezh2-deficient epithelium. Three-dimensional imaging for keratin 5 further showed the unexpected presence of a layer of basal cells from the proximal airways to the distal bronchioles in E16.5 embryos. ChIP-seq analysis indicated the presence of Ezh2-mediated repressive marks on the genomic loci of some but not all basal genes, suggesting an indirect mechanism of action of Ezh2. We found that loss of Ezh2 de-represses insulin-like growth factor 1 (Igf1) expression and that modulation of IGF1 signaling ex vivo in wild-type lungs could induce basal cell differentiation. Altogether, our work reveals an unexpected role for Ezh2 in controlling basal cell fate determination in the embryonic lung endoderm, mediated in part by repression of Igf1 expression.

SUMMARY: The histone methyltransferase Ezh2 inhibits basal cell differentiation in the mouse lung by depositing repressive marks on the promoter region of basal cell genes and by repressing Igf1 expression.