Circulating Levels of Calcitonin Gene-Related Peptide Are Lower in COVID-19 Patients

  1. Laura Ochoa-Callejero
  2. Josune García-Sanmartín
  3. Pablo Villoslada-Blanco
  4. María Íñiguez
  5. Patricia Pérez-Matute
  6. Elisabet Pujadas
  7. Mary E Fowkes
  8. Rachel Brody
  9. José A Oteo
  10. Alfredo Martínez

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Abstract

Background

To better understand the biology of COVID-19, we have explored the behavior of calcitonin gene-related peptide (CGRP), an angiogenic, vasodilating, and immune modulating peptide, in severe acute respiratory syndrome coronavirus 2 positive patients.

Methods

Levels of CGRP in the serum of 57 COVID-19 patients (24 asymptomatic, 23 hospitalized in the general ward, and 10 admitted to the intensive care unit) and healthy donors (n = 24) were measured by enzyme-linked immunosorbent assay (ELISA). In addition, to better understand the physiological consequences of the observed variations, we investigated by immunofluorescence the distribution of receptor activity modifying protein 1 (RAMP1), one of the components of the CGRP receptor, in autopsy lung specimens.

Results

CGRP levels were greatly decreased in COVID-19 patients (P < 0.001) when compared to controls, and there were no significant differences due to disease severity, sex, age, or comorbidities. We found that COVID-19 patients treated with proton pump inhibitors had lower levels of CGRP than other patients not taking this treatment (P = 0.001). RAMP1 immunoreactivity was found in smooth muscle cells of large blood vessels and the bronchial tree and in the airways´ epithelium. In COVID-19 samples, RAMP1 was also found in proliferating type II pneumocytes, a common finding in these patients.

Conclusions

The lower levels of CGRP should negatively impact the respiratory physiology of COVID-19 patients due to vasoconstriction, improper angiogenesis, less epithelial repair, and faulty immune response. Therefore, restoring CGRP levels in these patients may represent a novel therapeutic approach for COVID-19.

Article activity feed

  1. Version published to 10.1210/jendso/bvaa199
  2. ScreenIT

    SciScore for 10.1101/2020.10.01.20205088: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: All procedures were approved by the local review board (Comité de Ética
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Non-specific binding was blocked by exposure to 10% normal donkey serum (Jackson Immunoresearch Laboratories, West Grove, PA) for 1 h, and then tissue sections were incubated with recombinant rabbit monoclonal anti-RAMP1 antibody, clone EPR10867 (ab156575, Abcam), overnight at 4°C.
    normal donkey serum
    suggested: None
    anti-RAMP1
    suggested: (Abcam Cat# ab156575, RRID:AB_2801501)
    The following day, sections were incubated with fluorescent secondary antibody, CF633 donkey anti-rabbit IgG (20125, Biotium, Fremont, CA), for 1 h.
    CF633 donkey anti-rabbit IgG
    suggested: (Biotium Cat# 20125-1, RRID:AB_10853935)
    Software and Algorithms
    SentencesResources
    Statistical analysis: All data were analyzed with GraphPad Prism 8 software and were considered statistically significant when p<0.05.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    A limitation of the study was that the healthy control group had a lower mean age than the COVID-19 group. This was due to the fact that we wanted to use control samples collected before the pandemia to avoid inclusion of potential asymptomatic subjects, and therefore we had no control over their specific characteristics. Levels of CGRP were not affected by either age or sex in our study, so the age difference should not influence the main conclusions of the study. In addition, the age of the control group is the same as our asymptomatic population, and the CGRP differences between them are remarkable. A previous commentary suggested that CGRP antagonists may be helpful in the fight against COVID-19 24 but, to the best of our knowledge, this is the first report on the reduced levels of the peptide in patients. CGRP belongs to a peptide family including also calcitonin, adrenomedullin, and amylin 25. Interestingly, it has been published that the circulating levels of calcitonin 26 and adrenomedullin 27 are elevated in COVID-19 patients, probably as a consequence of widespread inflammation and/or blood vessel damage. No data are available for amylin. That CGRP goes in the opposite direction suggests a very specific regulation for this peptide. The circulating levels of CGRP in patients which received chronic treatment with proton pump inhibitors were lower than in other patients. Although these treatments may slightly confound the final CGRP levels among the COVID-19 patients, ...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2020.10.01.20205088 on medRxiv