Chromogranin A and Its Fragments in the Critically Ill: An Expanding Domain of Interest for Better Care

Abstract

Life-threatening diseases challenge immunity with a release of chromogranins. This report focuses on Chromogranin A (CGA) and some of its derived peptides in critically ill patients, with attention paid to their potential to become biomarkers of severity and actors of defense. First, we studied whether circulating CGA may be a biomarker of outcome in non-selected critically ill patients: CGA concentrations were reliably associated with short-term death, systemic inflammation, and multiple organ failure. Additionally, when studying Vasostatin-I, the major N-terminal fragment of CGA, we noted its reliable prognostic value as early as admission if associated with age and lactate. In trauma patients, CGA concentrations heralded the occurrence of care-related infections. This was associated with an in vitro inhibitor impact of Chromofungin on both NF-kappa B- and API-transcriptional activities. Secondly, in life-threatening disease-induced oxidative stress, the multimerization of Vasostatin-I occurs with the loss of its anti-microbial properties ex vivo. In vivo, a 4%-concentration of non-oxidized albumin infusion reversed multimerization with a decrease in care-related infections. Finally, in vitro Catestatin impacted the polymorphonuclear cells-Ca++-dependent, calmodulin-regulated iPLA2 pathway by releasing immunity-related proteins. Furthermore, human Cateslytin, the active domain of Catestatin, helped destroy S. aureus: this prompted the creation of synthetic D-stereoisomer of CGA-derived peptides against superbugs for the protection of implanted devices. In conclusion, CGA consideration in the critically ill is only starting, but it offers interesting perspectives for improved outcomes.

Keywords: Catestatin; Chromofungin; Chromogranin A; Vasostatin-I; albumin; biomaterials; critically ill; outcome; prognosis; superbugs.

Figure 3

Typical Western blotting analyses of plasma samples to evaluate the time-dependent changes in extracellular processed VS-I (top panel), and simultaneous hemodynamic profile (bottom panel) during a human septic shock. Time (Day X) runs over 3 days from admission (Day 1, hour 10:00 pm (H22)) to the end of the third day (Day 3, 02.00 pm (H14) and is represented on the X-axis (top and bottom lines). Plasma samples harvested by 8 h, from admission until Day 3, were immediately centrifugated (4000 rounds/min at 4 °C), and SDS-PAGE electrophoresis followed by electrophoretic blotting with immunological detection of VS-I was performed in standard conditions. The anti-VS-I antibodies were a generous gift of Pr A. Corti, Milan, Italy. Periods of norepinephrine and dobutamine infusion are represented as bold arrows from admission until weaning. Please note that the processing of chromogranin A is notably changing around Day 2 at 2:00 (H14) when the patient’s circulatory status no longer requires the two vasopressors. The global immunoblots are decreasing in intensity, and both small and large molecule multimerization is decaying (top panel). This phenomenon is contemporary to the decrease in doses of vasopressors (norepinephrine and dobutamine) and corresponds to circulatory failure recovery. Altogether, these data explain (i) why dosages of any of these proteins must be performed at a similar time window of the disease if a proper interpretation of their role is to be considered; (ii) that a pharmacological intervention must be scheduled at a moment when it can be efficient. Thus, our data on 4% albumin-impact on multimerization show that such an intervention must start as early as possible after admission, and it has no sense after the 5th day of disease onset [16]. Please remember that the apparent molecular weight (MW) of full-length CGA is around 70–75 kDa, and that of VS-I is approximately 18 kDa, which explains the immunoblotting of multimers on the top panel. Boxes (solid line, dashed line…) focus on processed molecules of interest, tagged with VS-I-antibodies: a careful identification must specify whether some multimers are not just large monomeric, full-length CGA molecules containing the VS-I domain.

Figure 1

Number of annual papers issued in the PubMed database according to the query from 1967 to 2022. Please note that the scale of measurement is ten times larger for the query “Chromogranin” (left vertical axis) than for the query “chromogranin and critical care” (right vertical axis).

Figure 2

Gel filtration HPLC of purified and oxidized VS-I samples to evaluate the impact of different concentrations of therapeutic human serum albumin (HSA) on multimers of VS-I. For the four graphs, the X-axis corresponds to the elution time (expressed in min), which is linearly related to the molecular weight of the components included in the peaks. The Y-axis corresponds to absorbance expressed in milliUnits of absorbance. Whether in vitro or in vivo, the oxidation of VS-I leads to multimerization, as shown on the first chromatogram (upper graph, numbered 1). The monomeric form of the peptide corresponds to peak E, while peaks A-D correspond to VS-I multimers. When adding fresh, non-oxidized therapeutic HSA at a molar albumin/VS-I ratio (R) from 1/10 to 1/10⁵ (as shown on chromatograms 2–4), the release of the monomeric VS-I increases (see changes in the amplitude of peak E). This counterintuitive result explains the possible release of monomers of VS-I with the restoration of its anti-microbial properties [15].