Molecular biomarkers for grass pollen immunotherapy

Table 1 General classification of molecular biomarkers[1-11]

Biomarkers	Definitions, comments
Disease-related genomic and proteomic biomarkers
Disease risk biomarkers	Biomarkers associated with the risk of a disease
Diagnostic biomarkers	Indicators of the presence of a disease in an individual, including molecular diagnosis, early disease detection and screening biomarkers
Disease staging biomarkers	Biomarkers for assessing disease severity
Disease prognostic biomarkers	Indicators of the likely course/outcome of a disease for an individual; originally defined as markers that indicate the likely natural course of a disease in an untreated individual, also used to define the baseline risk that suggest the likely outcome of a disease independent of treatment
Drug-related biomarkers (provide information about a patient’s response to a therapeutic intervention)
Pharmacogenomic biomarkers	Defining a DNA or RNA characteristic that is indicator of a response to a therapeutic intervention, facilitate the combination of therapeutics with diagnostics through pharmacogenetics (the study of genetic influence on drug response) and pharmacogenomics (the study of how genomic variation influences drug response)
Proof-of-mechanism biomarkers	Assess, in clinical trials, whether a drug has impacted its target
Drug activity biomarkers	Track the effect of a therapeutic intervention in accordance with its mechanism of action
Pharmacodynamic biomarkers	Measure the effect of a drug on the disease and determine the most effective dose for the patient, as efficacy biomarkers
Toxicity biomarkers	Determine the underlying susceptibility of a patient for a particular side effect or group of side effects
Surrogate biomarkers	Intended to substitute a clinical endpoint in clinical trials and expected to predict clinical benefit
Integral biomarkers	Used in clinical trials for eligibility, stratification, or treatment assignment
Integrated biomarkers	Intended to be used in clinical trials for hypothesis generation or testing, without impact on the treatment
Predictive biomarkers	Pretreatment or baseline measurements used to predict the patient response to a particular treatment

Table 2 Molecular biomarkers summarized for grass pollen allergy immunotherapy[26,39-44]

Biomarkers	Description, comments
CRD biomarkers used to guide AIT prescription
Serum specific IgE antibodies to rPhl p 1, rPhl p 2, rPhl p 5, rPhl p 6	Molecular specific biomarkers of genuine sensitization to Poaceae grass pollen
Serum specific IgE antibodies to nCyn d 1	Molecular specific biomarkers of genuine sensitization to Chloridoideae grass pollen
Serum specific IgE antibodies to CCDs	Molecular biomarkers of sensitization to CCDs involved in specific IgE assays cross-reactivity
Serum specific IgE antibodies to rPhl p 7	Molecular biomarkers of sensitization to pollen polcalcin panallergens cross-reactive with pollen from most plants
Serum specific IgE antibodies to rPhl p 12	Molecular biomarkers of sensitization to pollen profilin panallergens cross-reactive with pollen, some plant-derived foods and latex
Predictive candidate biomarkers of AIT clinical efficacy
Stabilin-1 (intracellular scavenger receptor), C1Q complement component expression	Intracellular biomarkers of tolerogenic dendritic cells
Coregulatory PD-L1 (B7-H1, CD274) expression	Surface cell biomarker of tolerogenic antigen presenting cells
Peripheral IL-10+Foxp3+ cells proportion among CD25+ CD4+ leukocytes	Regulatory T cell biomarker
Serum allergen-specific IgE to total IgE ratio	Allergen-specific antibodies biomarkers
Serum allergen-specific IgG4, IgG1 and IgA2
Inhibition of CD23-dependent IgE-FAB to B cells, serum specific IgE-BF competing with IgE for allergen binding	Functional biomarkers of serum IgG-associated inhibitory activity
Serum neopterin and kynurenine-tryptophan ratio	Molecular biomarkers of T cell mediated immune activation
Serum sHLA-G	Non-classical MHC class I immune tolerance molecular biomarker
Serum sTRAIL	TRAIL biomarker

CRD: Component-resolved diagnostic; CCDs: Carbohydrate cross-reactive determinants; IgE-FAB: IgE-facilitated allergen binding; IgE-BF: IgE-blocking factor; sHLA-G: Soluble HLA-G; sTRAIL: Soluble tumor necrosis factor-related apoptosis-inducing ligand; AIT: Allergy immunotherapy; PD-L1: Programmed death ligand-1; MHC: Major histocompatibility complex.

Table 3 Grasses (Poaceae family) which are sources of the most allergenic pollen grains[31,32,47]

Subfamily	Tribe	Species (common names)
Pooideae	Poeae	Phleum pratense (Timothy grass, Herd's grass, meadow cat's-tail) Lolium perenne (perennial ryegrass) Dactylis glomerata (orchard grass or cock’s foot grass) Poa pratensis (smooth meadow grass or bluegrass) Anthoxanthum odoratum (sweet vernal grass) Festuca pratensis syn. F. elatior (meadow fescue) Holcus lanatus (velvet grass or Yorkshire fog) Agrostis capillaris syn. A. tenuis or A. vulgaris (bent grass) Arrhenatherum elatius syn. Helictotrichon elatius (tall oat grass) Avena fatua (wild oat) Avena sativa (cultivated oat)
	Triticeae	Hordeum vulgare (barley) Secale cereale (rye) Triticum aestivum ssp. vulgare (cultivated bread wheat)
	Bromeae	Bromus inermis (smooth brome)
Chloridoideae	Cynodonteae	Cynodon dactylon (Bermuda grass, Bahama grass, Devil grass)
Panicoideae	Andropogoneae	Sorghum halepense (Johnson grass)
	Paniceae	Paspalum notatum (Bahia grass)

Table 4 Grass pollen seasons timing and temporal overlap in Europe[32,55-59]

Regions	Grass pollen seasons timing and temporal overlap with other types of pollen
Northern, Western, Central and Eastern Europe	Grass flowering period starts at the beginning of May, finishes at the end of July Some grass plants are in flower even in August, even September (e.g., Poland) Air concentration of grass pollen usually peaks in June; pollination occurs about two-three weeks earlier at sea level and thereafter in the mountain regions
	Birch (Betula spp): Western Europe flowering period starts at the end of March, Central and eastern Europe from early April until May (2-8 wk), Northern Europe from late April to late May Ash tree (Fraxinus spp): In Central and South-Eastern Europe flowering period may partially overlap (April to May) with grass pollen season
	Asteraceae weeds, such as ragweed Ambrosia artemisiifolia var. elatior and mugwort Artemisia vulgaris, pollen season in Central and Eastern Europe may last from July to August-September
	Plantain Plantago spp: Pollen season from May to September in Eastern Europe
Mediterranean regions of Europe	Different grasses are flowering between April and August
	Olive (Olea europaea): Pollen season lasts from April to June, in regions of Greece, Spain, and southern Italy, overlapping grass pollen season
	Plane (Platanus spp): Pollen season partially overlapping with grass season, from April to May, in Southern France or Spain
	Pellitory Parietaria spp: Pollen has a long persistence in the atmosphere in the Mediterranean region, from April to October, even longer (perennial)
	Asteraceae weeds: Pollinate from August to October, similar to Chenopodiaceae/Amaranthaceae pollen from salt-tolerant weeds significant also for semi-arid areas
	Plantain Plantago lanceolata: Pollen season from April to July in Northern Spain
European islands with special climate characteristics	Iceland (cold-temperate oceanic country): Some grass species and sorrel (Rumex spp) flower in June, both with peaks in July; a second peak of grass-pollen is possible in some years in August; pollen season tails off in September; birch pollen season is short, starting in the second part of May until the beginning of June
	Canary Islands (Spanish archipelago with subtropical climate): Long-range transport of Poaceae and Amarantaceae/Chenopodiaceae pollen from southern Iberian Peninsula and Morocco (mixed with Oleaceae tree pollen) and from the African Saharan sector and Sahel

Table 5 Grass pollen seasons timing and temporal overlap in Africa[60-65]

Regions	Grass pollen seasons timing and temporal overlap with other types of pollen
Extremely variable pollen seasons exist due to great differences in plant distribution
Morocco (North Africa)	Mediterranean region: grass pollen season starts in April and has highest air pollen concentration in May and June, overlapping olive pollen season
	Date palm (Phoenix dactylifera) from Arecaceae family is distributed not only in the Mediterranean areas of Morroco, but also Middle East and central Africa
Nigeria (West Africa)	Southwest region: at the end of the dry season, in March, airborne pollen grains of Chenopodiaceae/Amaranthaceae and Poaceae coexist in significant concentrations
South Africa	Grass pollinating season peaks from October to February (longer grass flowering); in subtropical regions, grasses of the subfamily Panicoideae are predominant: Cenchrus clandestinum (kikuyu) and Stenotaphrum secundatum (buffalo grass)
	South African Cupressaceae (cypress) trees start flowering in June, followed by Quercus robur (oak) in late July, Platanus (plane) in September and Olea europaea subsp. africana (olive) in January, and because their pollen season duration lasts three to four months it overlaps the grass pollen season
	Plantago lanceolata (English plantain) and Chenopodiaceae (goosefoot) are most important weeds with pollen seasons in late summer and autumn, overlapping with the grass pollen season

Table 6 Grass pollen seasons timing and temporal overlap in Asia[32,66-84]

Regions	Grass pollen seasons timing and temporal overlap with other types of pollen
Western Asia,	Most Middle East countries: significant grass and weed pollen seasons during April to May and September to October
Middle East	Desert and semi-desert countries: Chenopodiaceae pollen season overlapping with grass pollen season, such as for Cynodon dactylon
	Indigenous trees/shrubs, such as mesquite (Prosopis juliflora) and date palm (Phoenix dactylifera) pollen seasons from March to May, also in Egypt
	Israel: Cupressaceae (cypress family) and Poaceae pollen seasons throughout the year, grasses especially in spring (March-May), cypresses February and April; Olea europaea flowering begins in late March till July-August; Parietaria judaica pollen highly allergenic in northern Israel
	Turkey Mediterranean coastal area (Antalya): grass pollen frequently detected between April-May and October-November and found in the atmosphere in high concentrations during May to July; Pinaceae pollen airborne between March and June; Cupressaceae pollen, in high levels in February, usually present until May; Chenopodiaceae/Amaranthaceae pollen grains found in air during June to October, all overlapping with the grass pollen season
South Asia	Grass pollen season overlaps with seasons of many other anemophilous plants
	Pakistan: paper mulberry (Broussonetia papyrifera, family Moraceae) pollen season from March to April overlaps with the grass pollen season
	India: spring (February-April), autumn (September-October), winter (November-January) pollen seasons include periods of flowering of grasses (Cynodon dactylon, Paspalum distichum, Sorghum vulgare, Poa annua), of weeds Cannabaceae (Cannabis sativa), Asteraceae (Parthenium, Artemisia spp), and Chenopodiaceae (Amaranthus, Chenopodium spp), and of trees (Prosopis juliflora, Cocos and Eucalyptus spp)
East Asia	Beijing and different provinces of the People's Republic of China, such as Guangdong, Yunnan and Hebei: pollen season lasting from August to October is due to weed pollen from different plant families, Chenopodiaceae, Asteraceae (mugwort Artemisia spp), Cannabaceae (hop Humulus spp), but also to grass pollen
	South Korea: grass pollen airborne between end of April and November, especially Korean lawn grass, Timothy grass, Bermuda grass, and orchard grass; Pollen seasons of trees (pine, birch, oak) and weeds (mugwort, ragweed, Japanese hop) overlap with grass pollination period in the first, respectively last part of it
	Japan: pollen season for Japanese cypress/hinoki (Chamaecyparis obtusa) lasts from March to May, while for orchard grass (Dactylis glomerata), in May-June to August, and for weed yomogi Artemisia, from August to October
	Olive pollen from May to June overlaps with orchard grass season in Shodoshima
	Plantago lanceolata pollen dispersed from mid-May to early September, in Sapporo

Table 7 Grass pollen seasons timing and temporal overlap in America[28,85-93]

Regions	Grass pollen seasons timing and temporal overlap with other types of pollen
United States of America and Canada (North America)	Temperate regions: tree pollen predominates in spring, grasses in late spring and early summer, and weeds from summer until fall, with variable overlap periods
	Ragweed (Ambrosia spp) pollen season starts in July and peaks between August and October, warming by latitude being associated with increased length of pollen season in central North America
	Mountain cedar (Juniperus ashei) pollen season, in Oklahoma, Arkansas, central Texas, lasts from December to February, not overlapping with grass pollen period
	Southern Texas, on the western Gulf Coast: airborne grass pollen concentrations have two peaks, one in May (due to cool temperate grass species) and one in September and October (due to temperate and subtropical species), long distance dispersal of grass pollen is possible also out of season
	Subtropical regions, such as Southern California, Florida: grass pollen season dispersed all year overlaps with Cupressaceae trees (December through May), Asteraceae, Chenopodiaceae weeds pollen seasons (usually May through December)
Mexico, Central and South America (Latin America)	Subtropical regions in Mexico: similar to Southern California and Florida
	Mesquite (Prosopis sp) pollen in Northern Mexico and Southwestern United States
	Tropical regions: grass pollen grains airborne throughout the year, overlapping with the pollination periods of trees, such as Anacardiaceae, Cupressaceae, and weeds, such as Amaranthaceae, Asteraceae and Euphorbiaceae spp
	Maule region of Chile: Platanus acerifolia, Olea europaea, Cupressus spp pollen and grass pollen detected in August through November until end of January; Plantago spp, Rumex and Chenopodium spp pollen present from October to April

Table 8 Grass pollen seasons timing and temporal overlap in Australasia[48,94-98]

Regions	Grass pollen seasons timing and temporal overlap with other types of pollen
Australia	Subtropical northern regions (Brisbane, Queensland): grass pollen season, such as for Paspalum notatum, Sorghum halepense and Cynodon dactylon, from summer to autumn months, December to April, overlaps with the pollen season of groundsel bush (Baccharis halimifolia, Asteraceae family)
	Oceanic southern regions (Melbourne, Victoria): temperate grasses pollinate especially in spring, from September to November, overlapping with trees Cupressus and Betula spp pollen season
New Zealand	Temperate grasses form the major component of atmospheric pollen levels during spring and summer (October to February) and Plantago spp pollen season overlap