Mass Spectrometry Characterization of Circulating Human Serum Albumin Microheterogeneity in Patients with Alcoholic Hepatitis
Bibliographic info
- Authors: Marina Naldi, Maurizio Baldassarre, Marco Domenicali, Ferdinando Antonino Giannone, Matteo Bossi, Jonathan Montomoli, Thomas Damgaard Sandahl, Emilie Glavind, Hendrik Vilstrup, Paolo Caraceni, Carlo Bertucci
- Journal: Journal of Pharmaceutical and Biomedical Analysis, 2016, vol. 122, pp. 141–147
- Institutions: University of Bologna, Italy; Aarhus University Hospital, Denmark
Key question
What are the HSA structural (PTM) alterations specific to alcoholic hepatitis (AH), and can a faster analytical workflow detect novel isoforms not previously characterized?
Methods
- Sample type: Human plasma from AH patients (n=3 for characterization; larger IEC-based HPLC series)
- Disease group: Alcoholic hepatitis (AH) patients vs controls
- Technique 1 (top-down): LC-MS using monolithic C4 column (shorter: 5×5.3 mm vs conventional 150×2 mm) for faster separation; ESI-MS deconvolution
- Technique 2 (bottom-up): Preparative RP-HPLC purification of HSA → trypsin digestion → nanoLC-nanoESI-MS/MS (DDA); MALDI-TOF for intact mass confirmation
- Coverage: Mascot search results — 56–68% sequence coverage for AH and control samples
Main findings
- AH characterized by elevated oxidative isoforms: increased cysteinylation, oxidation at Cys34, novel additional modifications
- New oxidative products identified not previously reported in CLD context — HSA undergoes more complex oxidative damage in alcoholic hepatitis than in cirrhosis alone
- Monolithic C4 column: reduced analysis time without loss of separation quality — methodological improvement enabling higher throughput
- BU validation of novel PTMs: nanoLC-MS/MS identified site-specific modifications at Cys34 and other residues; MALDI-TOF confirmed intact mass of major isoforms
- AH vs cirrhosis comparison: the oxidative burden in AH differs from stable cirrhosis — AH as a distinct phase requiring specific isoform characterization
- Cross-center collaboration (Bologna + Aarhus): establishes basis for subsequent larger study montomoli-2026-aah
PTMs characterized
| PTM | Residue | Detection | Notes |
|---|---|---|---|
| Cysteinylation (+119 Da) | Cys34 | TD + BU | Dominant; elevated in AH |
| Glycation (+162 Da) | Lys (multiple) | TD | Moderate in AH |
| Oxidation (+16/+32 Da) | Cys34, Met | TD + BU | Elevated in AH |
| Novel oxidative products | Cys34 + other | BU | ⚠️ Novel; not detailed in abstract — see paper figures |
Clinical context
- Disease: Alcoholic hepatitis (acute-on-chronic ALD, not stable cirrhosis)
- Distinction: AH ≠ alcoholic cirrhosis — AH has acute inflammatory/oxidative burst superimposed on chronic disease; HSA PTM profile reflects this
- Implication: AH may require its own isoform reference panel distinct from stable CLD; oxidative damage is more acute and potentially more severe
Limitations
- Small discovery cohort (n=3 AH, n=3 controls for BU analysis)
- Relative quantification only
- Novel PTMs identified but not quantified at population level
- Clinical correlation (survival, severity) not assessed — done later in montomoli-2026-aah
Connections
- HSA — microheterogeneity in AH specifically
- Bottom-up proteomics — key innovation: BU validation of novel PTMs in AH
- Top-down proteomics — faster monolithic column method
- Liver fibrosis — ALD/AH sub-context
- domenicali-2014 — provides the stable cirrhosis baseline; AH findings differ
- naldi-2017-review — comprehensive review that incorporates findings from this paper
- montomoli-2026-aah — 2026 expansion with n=49 AH patients, survival outcomes
My notes
- This paper is significant for identifying AH as a distinct biochemical context for HSA damage — the acute oxidative burst of alcoholic hepatitis produces PTMs not seen in stable CLD.
- The Aarhus group (Montomoli, Sandahl, Vilstrup) is the Danish center collaborating with Bologna on ALD/AH — they are co-authors on montomoli-2026-aah as well.
- The monolithic C4 column improvement is methodologically relevant to our pipeline — faster separation without quality loss is directly applicable to high-throughput clinical deployment.