D-Arabinitol: the pathway in the body

D-Arabinitol is part of the pathway “Candida”. This page shows the whole pathway; the station of D-Arabinitol is highlighted.

Where this laboratory value sits: D-Arabinitol — sugar alcohol of the yeast. Candida yeasts form the sugar alcohol D-arabinitol from glucose via the pentose phosphate pathway and release most of it to the outside. It enters the blood and passes via the kidneys into urine; the body itself mainly forms L-arabinitol. Source 10, 12

In brief

Candida albicans is a yeast that lives on the mucous membranes and in the gut of many people. It can switch from round yeast cells to filaments and then forms the peptide candidalysin, to which mucosal and immune cells respond. The immune defence recognises it by its β-glucan.

The pathway step by step

Each station states what the compound does there. Three signs: ↑ supplies — builds up or makes available · ↓ depletes — inhibits, consumes or withholds · ↕ both, depending on amount. Behind it stands what the statement rests on: established physiology, observed in studies, or contested. The signs do not grade; they name the direction.

1. Candida as yeast cell → Hypha · cAMP–PKA pathway Warmth, pH and certain nutrients switch on a programme via the cAMP pathway: the cell grows out into long threads and forms adhesion molecules such as Als3 on its surface. In this form it can invade the mucosa. Source 1, 2↓ depletes The threads attach to mucosal cells with Als3 and push between and into them; at the same time their β-glucan is more strongly masked. Candidalysin forms only in the thread form. observed in studies Source 2, 1, 3
   ⚖ When the balance tips

   too much — If many cells grow as threads, more candidalysin forms, and the mucosa switches on its alarm programme; its messenger substances then attract neutrophils.

   too little — If few threads grow out, Candida stays mostly in the yeast form; in animal models, strains that cannot form threads hardly invade tissue.

   observed in studies · Source 2, 3, 1

2. Hypha → Ece1 protein In the thread form, the fungus reads the ECE1 gene. The resulting protein consists of eight segments lying one after another. It is the precursor of candidalysin. Source 3, 4↑ supplies Ece1 is the precursor protein: only when Kex2 cuts it is the third segment released as candidalysin. In cell culture, only this one of the eight segments damages the membrane. observed in studies Source 3, 4
   ⚖ When the balance tips

   too much — If a lot of Ece1 is made, more precursor for candidalysin is available; how much of it is released depends on cutting by Kex2.

   too little — If no Ece1 is made, no candidalysin forms; in cell culture and animal models such strains still grow as threads but hardly damage the mucosa.

   observed in studies · Source 4, 3

3. Ece1 protein → Candidalysin Kex2 protease The protease Kex2 cuts the protein into pieces. The third segment is candidalysin: a small peptide that inserts itself into cell membranes and makes them permeable. The amount decides whether it only triggers an alarm or damages cells. Source 3, 4↕ both, depending on amount In small amounts candidalysin only triggers the alarm signal in mucosal cells; in larger amounts it makes the membrane permeable: calcium flows in and the cell loses contents. The amount decides which prevails. observed in studies Source 3
   ⚖ When the balance tips

   too much — If a lot of candidalysin builds up at the mucosa, cell membranes become permeable and the cells die; in cell culture the release of the enzyme LDH then rises.

   too little — If little candidalysin is present, the membrane stays intact and the mucosa hardly switches on its alarm programme, even when threads are present.

   observed in studies · Source 3

4. Cell wall β-glucan → Dectin-1 Phagocytes carry Dectin-1, a receptor that binds specifically to β-glucan. Other receptors recognise the mannose chains of the cell wall. This is how the phagocyte engulfs the fungus. Source 5↑ supplies Dectin-1 translates binding to β-glucan into a signal inside the cell: its binding motif is phosphorylated and recruits the kinase Syk. Through this the phagocyte engulfs the fungus and forms messenger substances. observed in studies Source 5
   ⚖ When the balance tips

   too much — If many Dectin-1 receptors are occupied, phagocytes release more messenger substances and form more reactive oxygen species.

   too little — If little signal comes from Dectin-1, phagocytes engulf the fungus less well; in some animal models without Dectin-1, more Candida remains in the tissue.

   observed in studies · Source 5

5. Dectin-1 → Syk and CARD9 Syk kinase · ATP After binding, the kinase Syk switches on the signalling pathway via CARD9. It leads to genes that produce messenger molecules of the immune defence. This sets off the Th17 response. Source 5, 2↑ supplies Syk and CARD9 pass the signal on to the switch NF-κB; through it, genes for messenger substances such as IL-6, IL-23 and IL-1β are read, which set off a Th17 response. observed in studies Source 5, 2
   ⚖ When the balance tips

   too much — If the signal through Syk and CARD9 is strong, more messenger substances form, and more T cells follow the path to the Th17 response.

   too little — If little signal runs through CARD9, the phagocytes form fewer messenger substances; in animal models without CARD9, the Th17 response against Candida hardly gets going.

   observed in studies · Source 5, 2

6. Syk and CARD9 → Messengers The cells release cytokines. These attract further immune cells and steer the T-cell response, among other routes via the interleukin-17 axis. Above all, they summon neutrophils. Source 2, 5↑ supplies The messenger substances attract neutrophils and steer T cells towards the Th17 response; IL-17 prompts mucosal cells to release further attractants and defensive peptides. observed in studies Source 2, 5
   ⚖ When the balance tips

   too much — If many messenger substances are released, many neutrophils move in; their enzymes and oxygen species then also hit the surrounding tissue.

   too little — If few messenger substances are released, few neutrophils arrive and the Th17 response stays weak; in animal models without IL-17 signalling, fungal cells persist longer on the mucosa.

   observed in studies · Source 2, 8

7. Messengers → Neutrophils Neutrophil granulocytes follow the messenger molecules, engulf fungal cells and break them down with enzymes and reactive oxygen species. In the process, myeloperoxidase forms hypochlorite. Source 2, 5↓ depletes Neutrophils break down fungal cells: NADPH oxidase forms superoxide and from it hydrogen peroxide, which myeloperoxidase converts with chloride into hypochlorite. These oxidants kill engulfed fungal cells. observed in studies Source 8
   ⚖ When the balance tips

   too much — If many neutrophils gather, oxidants also reach the surroundings; hypochlorite then alters proteins of the nearby tissue.

   too little — If few neutrophils arrive or their NADPH oxidase works slowly, little hypochlorite forms, and engulfed fungal cells survive longer.

   observed in studies · Source 8

8. Epithelial cell alarm → Neutrophils Neutrophil granulocytes follow the messenger molecules, engulf fungal cells and break them down with enzymes and reactive oxygen species. In the process, myeloperoxidase forms hypochlorite. Source 2, 5↓ depletes Neutrophils break down fungal cells: NADPH oxidase forms superoxide and from it hydrogen peroxide, which myeloperoxidase converts with chloride into hypochlorite. These oxidants kill engulfed fungal cells. observed in studies Source 8
   ⚖ When the balance tips

   too much — If many neutrophils gather, oxidants also reach the surroundings; hypochlorite then alters proteins of the nearby tissue.

   too little — If few neutrophils arrive or their NADPH oxidase works slowly, little hypochlorite forms, and engulfed fungal cells survive longer.

   observed in studies · Source 8

9. Candida as yeast cell → D-Arabinitol Pentose phosphate path Candida yeasts form the sugar alcohol D-arabinitol from glucose via the pentose phosphate pathway and release most of it to the outside. It enters the blood and passes via the kidneys into urine; the body itself mainly forms L-arabinitol. Source 10, 12↑ supplies For the fungus, D-arabinitol is a stress metabolite: under heat and oxidative stress it forms and stores more of it, as it does glycerol under salt stress. No task in the human body is known. observed in studies Source 11, 13
   ⚖ When the balance tips

   too much — If many metabolically active Candida cells are present, more D-arabinitol enters the blood, and its ratio to L-arabinitol in urine shifts. If the kidneys filter more slowly, both forms rise in the blood.

   too little — If few yeasts are active, or if they belong to species that form no D-arabinitol, little of it reaches the urine; what appears there is the small amount found in body fluids even without yeasts.

   observed in studies · Source 12

   Field of research — The ratio of D- to L-arabinitol is studied in research on Candida infections. Source 12

Further stations

• Candida as yeast cell — round, single cells In many people, Candida albicans is present as a yeast cell on mucous membranes and in the gut. In this form the fungus divides by budding. The thread form can grow out of it. Source 2, 1↕ both, depending on amount The yeast cell is the starting form: in it, Candida usually lives on the mucosa without damaging it. Given the right signals, the thread form grows out of it and can invade the mucosa. observed in studies Source 2, 1
  ⚖ When the balance tips

  too much — If the yeast cells multiply strongly, β-glucan is exposed at more budding sites, and more cells are ready to switch to the thread form.

  too little — If there are few yeast cells, few grow out into threads; the mucosa then hardly responds, because its alarm only starts with a larger amount of fungus in thread form.

  observed in studies · Source 2

• Cell wall β-glucan — sugar scaffold of the fungus The fungal cell wall is made of chitin, mannoproteins and β-glucan. At budding sites β-glucan is exposed; in the thread form it is more strongly masked. Exposed β-glucan is recognised more easily. Source 2, 5↑ supplies β-glucan is the fungus's recognition mark: when it is exposed, Dectin-1 binds and switches on the defence. The thread form masks it under mannoproteins and is therefore recognised less strongly. observed in studies Source 2, 5
  ⚖ When the balance tips

  too much — If a lot of β-glucan is exposed, more Dectin-1 receptors bind; phagocytes then engulf the fungal cells more quickly and form more messenger substances.

  too little — If β-glucan is masked under the mannoprotein layer, Dectin-1 recognises the cell less strongly; recognition then relies more on the mannose receptors.

  observed in studies · Source 5, 2

• Epithelial cell alarm — EGFR and MAPK signalling The mucosal cell senses candidalysin at its membrane and switches on the signalling pathway via EGFR and MAP kinases. In response it releases its own messenger molecules. In this way it summons neutrophils. Source 3↑ supplies Through the alarm signal the mucosal cell releases messenger substances such as IL-1α, IL-6 and G-CSF and summons neutrophils. In this way it distinguishes threads that form candidalysin from yeast cells on the surface. observed in studies Source 3, 2
  ⚖ When the balance tips

  too much — If the alarm is triggered strongly and for long, the cells keep releasing messenger substances, and many neutrophils gather in the mucosa.

  too little — If little alarm is triggered, for instance because little candidalysin is present, the mucosa releases hardly any messenger substances and neutrophils are summoned sparsely.

  observed in studies · Source 3, 2

Cofactors in this pathway

• cAMP — Messenger that switches on the filament programme through protein kinase A; with little of it, the yeast form remains Source 1, 2
• Calcium — The Kex2 protease, which cuts candidalysin out of the Ece1 protein, works in a calcium-dependent way; idle without it Source 6, 3
• Zinc — Bound by the secreted fungal protein Pra1 and then retrieved by the fungus; in this way it obtains zinc from the host Source 7
• ATP — Phosphate donor of the kinase Syk, which passes on the signal from Dectin-1; without ATP the signal stalls Source 5
• NADPH — Electron donor of NADPH oxidase, with which neutrophils form reactive oxygen species; superoxide forms from it Source 8
• Iron — Central atom in the haem of myeloperoxidase, an enzyme of neutrophils; without haem it forms no hypochlorite Source 9In the ORY catalogue as a laboratory value: Eisen

Sources

1. Whiteway M, Bachewich C. Morphogenesis in Candida albicans. Annu Rev Microbiol 2007 · PubMed 17506678
2. Gow NA, van de Veerdonk FL, Brown AJ, Netea MG. Candida albicans morphogenesis and host defence: discriminating invasion from colonization. Nat Rev Microbiol 2011 · PubMed 22158429
3. Moyes DL, Wilson D, Richardson JP et al. Candidalysin is a fungal peptide toxin critical for mucosal infection. Nature 2016 · PubMed 27027296
4. Richardson JP, Mogavero S, Moyes DL et al. Processing of Candida albicans Ece1p Is Critical for Candidalysin Maturation and Fungal Virulence. mBio 2018 · PubMed 29362237
5. Drummond RA, Brown GD. The role of Dectin-1 in the host defence against fungal infections. Curr Opin Microbiol 2011 · PubMed 21803640
6. Fuller RS, Brake A, Thorner J. Yeast prohormone processing enzyme (KEX2 gene product) is a Ca2+-dependent serine protease. Proc Natl Acad Sci U S A 1989 · PubMed 2646633
7. Citiulo F, Jacobsen ID, Miramón P et al. Candida albicans scavenges host zinc via Pra1 during endothelial invasion. PLoS Pathog 2012 · PubMed 22761575
8. Klebanoff SJ, Kettle AJ, Rosen H et al. Myeloperoxidase: a front-line defender against phagocytosed microorganisms. J Leukoc Biol 2013 · PubMed 23066164
9. Singh E, Gupta A, Singh P et al. Exploring mammalian heme peroxidases: A comprehensive review on the structure and function of myeloperoxidase, lactoperoxidase, eosinophil peroxidase, thyroid peroxidase and peroxidasin. Arch Biochem Biophys 2024 · PubMed 39278306
10. Wong B, Leeson S, Grindle S et al. D-arabitol metabolism in Candida albicans: construction and analysis of mutants lacking D-arabitol dehydrogenase. J Bacteriol 1995 · PubMed 7768790
11. Kayingo G, Wong B. The MAP kinase Hog1p differentially regulates stress-induced production and accumulation of glycerol and D-arabitol in Candida albicans. Microbiology (Reading) 2005 · PubMed 16151209
12. Christensson B, Sigmundsdottir G, Larsson L. D-arabinitol--a marker for invasive candidiasis. Med Mycol 1999 · PubMed 10647119
13. Sánchez-Fresneda R, Guirao-Abad JP, Argüelles A et al. Specific stress-induced storage of trehalose, glycerol and D-arabitol in response to oxidative and osmotic stress in Candida albicans. Biochem Biophys Res Commun 2013 · PubMed 23261427

Whole pathway: Candida

Related pathways

• ASCA and ANCA — neutrophils
• Clostridioides difficile — neutrophils
• Calprotectin — neutrophils
• Granulocytes in the gut wall — neutrophils

As of 2026-09-16. Draft written by Claude to schema v2; sources checked in PubMed; expert approval pending
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