Page 95 - CSIR-IGIB Annual Report 2020-21
P. 95
Novel Therapeutic Approaches in Cockroach resulted in marked decrease in cellular infiltration
Allergy in lung and is accompanied by reduction in specific
Periplaneta americana is the principal cockroach serum IgE levels (and increase in serum IgG2a).
species predominant in tropical and sub-tropical Th2 cytokines IL-4 and IL-5 were also reduced in
regions worldwide. Identification of allergenic peptide treatment groups (T1 and T3 treated
proteins is crucial for understanding the etiology groups) exhibiting modulation of cytokine milieu
of allergic reactions and is of paramount in vivo. Recombinant cockroach allergens and
importance for developing diagnostic and their peptides conjugated with adjuvants could be
therapeutic strategies. Allergen Immunotherapy is promising candidates to improve the intervention
the only curative approach with long-term of type I allergy.
remission of symptoms. Conjugation of
immunodominant T cell peptides with adjuvants Food allergy and cross-reactive allergen
may be utilized to improve AIT. Flagellin (FlaA, a Food allergy affects 6-8% children and 3-4% adults
TLR-5 ligand) is a potent TLR-5 ligand and was while pollen from trees, grasses and weeds affect
therefore conjugated with major cockroach approximately 40% of allergic individuals. There is
allergen Per a10 and its immunodominant T cell no treatment for food allergy except allergen
epitopes. Fusion constructs were generated using avoidance. Phaseolus vulgaris (red kidney bean)
recombinant DNA technology, expressed in E. coli has been reported as highly cross-reactive allergic
and recombinant proteins were purified using sensitizer in North India. Utilizing in silico
affinity chromatography. approaches, a cysteine protease from P. vulgaris
Immunomodulatory effect of fusion proteins was demonstrating 50% sequence identity with fruits,
assessed using in vitro and in vivo strategies. pollen and mites has been predicted as a major
Studies on bone marrow derived Dendritic cells cross-reactive allergen. Gene sequence for
co-culture with splenic T cells revealed robust cysteine protease was cloned, expressed, and
induction of Th1 and T regulatory cytokines in FlaA purified. Recombinant protein was found to be a
conjugated fusion proteins. In the murine model major allergen by ELISA and immunoblot. Further,
of cockroach allergy, reduced Th2 cytokines and cross-reactivity studies with recombinant protein
cellular infiltration in lungs was observed in groups showed 50% inhibition at 8.4 ng of self-protein.
treated with FlaA-Per a10, FlaA-PT1 and FlaA-PT3 Purified protein has significant cross-reactivity
associated with induction of CD4+Foxp3+ T with dust mite followed by peanut, black gram,
regulatory cells in spleen. Enhanced levels of and fungal allergens with 50% IgE inhibition at 7.2,
erythropoetin and myeloperoxidase was observed 52, 437, 4, 78 and 73 respectively. Further,
in the mice treated with Per a 10 and equimolar recombinant protease was able to activate
mixture of FlaA and Per a 10 as compared to fusion passively sensitized basophils with upregulated
proteins FlaA-Per a 10 and FlaA-PT1, FlaA-PT2 and expression of CD203c activation marker indicating
FlaA-PT3. Our laboratory has also identified a biological activity. We have identified three B- and
Glutathione-S-Transferase allergen Per a5 from P. T-cell epitopes of cysteine protease using
americana. The allergen exhibits up to 65% bioinformatics. Epitopes were chemically
immune reactivity with cockroach hypersensitive synthesized and in vitro validated using sera
sera and demonstrates cross reactivity with fungal samples. B-cell epitopes showed significant IgE-
and mite GSTs. In silico analysis of immune binding whereas T-cell epitopes showed low IgE
epitopes reveal high conservancy among the binding. One of the clinically relevant pollen
predicted epitopes of Per a5 with corresponding source is Prosopis juliflora sharing cross-reactivity
GST allergens in mite, fungal and helminth. with several tree pollen and food. Recently, a
Further, immunotherapeutic potential of Per a5 35kDa vicilin-like protein, also a glycoprotein was
derived T cell epitopes (T1, T2 and T3) was identified from P. juliflora which showed 75% sera
examined in murine model. Peptide treatment reactivity indicating it as a major allergen. The
Annual Report 2020-21 92
