Covid-19 in cystic fibrosis patients compared to the general population: Severity and virus-host cell interactions

BACKGROUND

People with cystic fibrosis (pwCF) are considered at risk of developing severe forms of respiratory viral infections. We studied the consequences of COVID-19 and virus-host cell interactions in CF vs. non-CF individuals.

METHODS

We enrolled CF and non-CF individuals, with /without COVID-like symptoms, who underwent nasopharyngeal swab for detection of SARS-CoV-2. Gene expression was evaluated by RNA sequencing on the same nasopharyngeal swabs. Criteria for COVID-19 severity were hospitalization and requirement or increased need of oxygen therapy.

RESULTS

The study included 171 patients (65 pwCF and 106 non-CF individuals). Among them, 10 pwCF (15.4 %) and 43 people without CF (40.6 %) tested positive at RT-PCR. Symptomatic infections were observed in 8 pwCF (with 2 requiring hospitalization) and in 11 individuals without CF (6 requiring hospitalization). Host transcriptomic analysis revealed that genes involved in protein translation, particularly ribosomal components, were downregulated in CF samples irrespective of SARS-CoV-2 status. In SARS-CoV-2 negative individuals, we found a significant difference in genes involved with motile cilia expression and function, which were upregulated in CF samples. Pathway enrichment analysis indicated that interferon signaling in response to SARS-CoV-2 infection was upregulated in both pwCF and non-CF subjects.

CONCLUSIONS

COVID-19 does not seem to be more severe in CF, possibly due to factors intrinsic to this population: the lower expression of ribosomal genes may downregulate the protein translation machinery, thus creating an unfavorable environment for viral replication.

SARS-CoV-2 variants: what have we learnt so far? Commentary

Besides the timely detection of different SARS-CoV-2 variants through surveillance systems, functional and modelling studies are essential to better inform public health response and preparedness. Here, the knowledge available so far on SARS-CoV-2 variants is discussed from different perspectives, in order to highlight the relevance of a multidisciplinary approach in countering the threat posed by this insidious virus.

Multiple sulfatase deficiency is due to hypomorphic mutations of the SUMF1 gene

Sulfatases catalyze the hydrolysis of sulfate ester bonds from a wide variety of substrates and are implicated in several human inherited diseases. Multiple sulfatase deficiency (MSD) is a rare autosomal recessive disorder characterized by the simultaneous deficiency of all known sulfatases. MSD is caused by mutations in the Sulfatase Modifying Factor 1 (SUMF1) gene encoding the alpha-formylglycine generating enzyme (FGE), which is responsible for the post-translational modification of sulfatases. In all MSD patients, residual sulfatase activities are detectable, at variable levels. To correlate the nature of the residual sulfatase activities detected in MSD patients with residual FGE activity, four FGE mutants (i.e. p.S155P, p.R224W, p.R345C, p.R349W) found in homozygosis in MSD patients were analyzed. Using viral-mediated gene delivery, these mutants were over-expressed in mouse embryonic fibroblasts (MEFs) from a recently developed Sumf1 KO mouse line which is completely devoid of all sulfatase activities. The results obtained indicate that mutant SUMF1 cDNAs encode stable SUMF1 proteins which are of the appropriate molecular weight and are properly localized in the endoplasmic reticulum. Expression of these cDNAs in Sumf1-/- MEFs results in partial rescue of sulfatase activities. These data indicate that MSD is due to hypomorphic SUMF1 mutations and suggest that complete loss of SUMF1 function is likely to be lethal in humans.