CGRP measurements in human plasma – a methodological study

Background Calcitonin gene-related peptide plasma levels have frequently been determined as a biomarker for primary headaches. However, published data is often inconsistent resulting from different methods that are not precisely described in most studies. Methods We applied a well-proven enzyme-linked immunosorbent assay to measure calcitonin gene-related peptide concentrations in human blood plasma, we modified parameters of plasma preparation and protein purification and used calcitonin gene-related peptide-free plasma for standard solutions, which are described in detail. Results Calcitonin gene-related peptide levels are stable in plasma with peptidase inhibitors and after deep-freezing. Calcitonin gene-related peptide standard solutions based on synthetic intercellular fluid or pooled plasma with pre-absorbed calcitonin gene-related peptide influenced the measurements but yielded both comprehensible results. In a sample of 56 healthy subjects the calcitonin gene-related peptide plasma levels varied considerably from low (<50 pg/mL) to very high (>500 pg/mL) values. After a 12-hour exposure of these subjects to normobaric hypoxia the individual calcitonin gene-related peptide levels remained stable. Conclusion Buffering with peptidase inhibitors and immediate freezing or processing of plasma samples is essential to achieve reliable measurements. Individuals show considerable differences and partly high calcitonin gene-related peptide plasma levels without detectable pathological reason. Thus plasma measurements are suited particularly to follow calcitonin gene-related peptide levels in longitudinal studies. The use of data for this study was approved by the Ethics Committee of the Medical University of Innsbruck ( https://www.i-med.ac.at/ethikkommission/ ; EK Nr: 1242/2017).

The nasal symbiont Staphylococcus epidermidis shapes the cellular environment to decrease expression of SARS-CoV-2 entry factors in nasal epithelium

Background Emerging evidence indicates that severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) targets the human nasal epithelium via the principal entry factors angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), which are highly expressed in the nasal epithelium. However, little is known about suppressive biologics against SARS-CoV-2 entry factors. Here, we report that the nasal commensal Staphylococcus epidermidis altered the host transcriptional response against SARS-CoV-2 in the nasal epithelium by reducing ACE2 and TMPRSS2 gene expression in concert with an increase in serine-peptidase inhibitors. Results Our data reveal that ACE2 was more abundantly expressed in nasal epithelial (NHNE) cells than bronchial epithelial cells, and inoculation with S. epidermidis reduced ACE2 transcription in NHNE cells. Our data also show that TMPRSS2 mRNA was significantly decreased in NHNE cells and that S. epidermidis colony number in human nasal mucus was inversely correlated with ACE2 and TMPRSS2 gene expression in the nasal mucosa. In addition, levels of the serine-peptidase inhibitors SERPINE1 and SERPINE2 were significantly increased by S. epidermidis, and this accompanied reduction of TMPRSS2 transcription in nasal epithelial cells. Conclusion These results characterize the S. epidermidis-regulated host transcriptional response restricting SARS-CoV-2 entry to the nasal epithelium via downregulation of receptors and host protease for SARS-CoV-2 cellular invasion coupled with SERPINE1 and SERPINE2 induction.

Repositioning of HIV Aspartyl Peptidase Inhibitors for Combating the Neglected Human Pathogen Trypanosoma cruzi

Chagas disease, caused by the flagellate parasite Trypanosoma cruzi, is a wellknown neglected tropical disease. This parasitic illness affects 6-7 million people and can lead to severe myocarditis and/or complications of the digestive tract. The changes in its epidemiology facilitate co-infection with the Human Immunodeficiency Virus (HIV), making even more difficult the diagnosis and prognosis. The parasitic infection is reactivated in T. cruzi/HIV co-infection, with the appearance of unusual manifestations in the chronic phase and the exacerbation of classical clinical signs. The therapeutic arsenal to treat Chagas disease, in all its clinical forms, is restricted basically to two drugs, benznidazole and nifurtimox. Both drugs are extremely toxic and the therapeutic efficacy is still unclear, making the clinical treatment a huge issue to be solved. Therefore, it seems obvious the necessity of new tangible approaches to combat this illness. In this sense, the repositioning of approved drugs appears as an interesting and viable strategy. The discovery of Human Immunodeficiency Virus Aspartyl Peptidase Inhibitors (HIV-PIs) represented a milestone in the treatment of Acquired Immune Deficiency Syndrome (AIDS) and, concomitantly, a marked reduction in both the incidence and prevalence of important bacterial, fungal and parasitic co-infections was clearly observed. Taking all these findings into consideration, the present review summarizes the promising and beneficial data concerning the effects of HIV-PIs on all the evolutionary forms of T. cruzi and in important steps of the parasite’s life cycle, which highlight their possible application as alternative drugs to treat Chagas disease.