Therapeutic consideration and treatment of conjunctivitis, food and skin allergies

The allergic disorders present a wide array of manifestations in the humans, demanding unique therapeutic strategies. The previous article shed light on treatment strategies for lethal Anaphylaxis, Allergic Rhinitis & Asthma. The ocular and skin allergies not only compromise the quality of life but also makes the patient self-conscious about appearance. The food allergies, on the other hand, compromise the ability to intake food, associated with hassles of finding alternative supplements. These allergies could also trigger severe allergic reactions such as lethal anaphylaxis. Hence, the present article discusses the therapeutic options available for respective allergic diseases.

Allergic conjunctivitis an ocular allergy

Allergic conjunctivitis is an ocular allergy involving an inflammatory process which is bilateral and self-limiting in nature. It is divisible into seasonal allergic conjunctivitis and perennial allergic conjunctivitis. Furthermore, it also finds a strong association with allergic rhinitis as 90% of the patients suffer at least one episode of allergic conjunctivitis (Berger 2005). The inflammatory reaction results from either IgE mediated immune response or immediate hypersensitivity reaction. Besides these, the allergic reaction can also result from neurogenic mechanisms, adhesion molecules and systemic immune cff. Both seasonal allergic conjunctivitis and perennial allergic conjunctivitis are mast cell-g, type-1 hypersensitive, acute allergic reactions (Sánchez et al., 2011).

The binding of IgE with FcεRI receptors on mast cells causes changes in the cell membrane permeability. This results in the release of inflammatory mediators such as histamine, leukotriene, Carboxypeptidase A, serotonin, prostaglandin, Cathepsin G, Eosinophil, Neutrophil and Platelet-activating factor. It causes a biphasic response: early and late phase. The early phase response involves itching, swelling, redness, tearing, and oedema. Whereas, the late phase involves infiltration of basophils, neutrophils, and eosinophils.

Therapeutic considerations for allergic conjunctivitis

A large number of drugs are available to counter the effect of mediator molecules and bring relief from the allergic reaction. Besides these treatments, allergic conjunctivitis can also benefit from allergen-specific immunotherapy, same as allergic asthma. Immunotherapy is known to improve seasonal allergic conjunctivitis symptoms and medication usage.

A wide range of drugs for allergic conjunctivitis

The available treatment options for allergic conjunctivitis as mentioned by Carr et al. (2016) are as follows:

Topical histamines

Table 1: Drug action for Topical Histamines
Examples: Levocabastine, Emedastine difumarate

Antihistamine-vasoconstrictor combinations

Table 2: Drug action for antihistamine-vasoconstrictors

Examples: Naphazoline-pheniramine, Naphazoline-antazoline

Leukotriene receptor antagonists

Table 3: Drug action for leukotrienes

Examples: Montelukast

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Table 4: Drug action for NSAIDs

Examples: Ketorolac, Nepafenac, Bromfenac

Corticosteroids

Table 5: Drug action for corticosteroids

Examples: Prednisolone, Loteprednol, Difluprednate

Mast cell stabilizers

Table 6: Drug action for Mast cell stabilizers

Examples: Lodoxamide tromethamine, Pemirolast potassium, Nedocromil sodium, Cromolyn sodium

Dual acting agents

Table 7: Drug action for dual acting agents

Examples: Ketotifen, epinastine, Olopatadine

Allergies due to food

Food allergies are hypersensitive reactions, occurring due to specific food substance-related stimuli and resulting from immune mechanisms. In the case of non-immune hypersensitive responses, the phenomenon is termed as non-allergic food hypersensitivity or food intolerance (Olivier, 2013). Below shown is the classification of food allergies as per the immune response.

Table 8: Types of food allergies with respect to immune response (Olivier, 2013)

These allergies develop in two stages, namely, sensitization and elicitation. Sensitization involves the establishment of pathways of reaction to the allergen. On the other hand, elicitation involves the inflammatory immune response during re-exposure to the allergen. The allergic response perpetuation results from the cytokines and chemokines produced by mast cells and basophils (Syed, Kohli, & Nadeau, 2013).

Therapeutic considerations for food allergies

The treatment of food allergy involves the removal of sensitizing agent or the allergen from the system. These allergies can develop from reactions to more than one food,  thus correct diagnosis to detect unsuspecting agents is important. However, there is no particular or standard cure for food allergies. Precautionary measures on the part of patients and dietary elimination of allergens is advised (Olivier, 2013).

Immunotherapy and desensitization mechanisms form the basis of treatment. Immunotherapies can be either food specific or non-food specific. Non-specific therapies do not target a specific allergen and are advantageous in desensitizing the individual to a number of different allergens. Examples include herbal formulations, anti- IgE therapies, use of probiotics, and parasites. Food-specific therapies involve Sublingual immunotherapy, gene therapy, and delivery of bacterial adjuvants with allergens which skew the immune system(Syed, Kohli, & Nadeau, 2013).

Allergic reactions involving Skin

A range of allergic conditions affects skin such as atopic dermatitis, angioedema, contact dermatitis, psoriasis, urticaria and autoimmune blisters. Most of these allergies are chronic, proliferative, and inflammatory in nature, influenced by both genetic and environmental factors. Here we discuss atopic dermatitis and urticaria.

Atopic dermatitis

The skin becomes dry and itchy, and eczematous skin lesions relapse. It is one the common occupational disease, exhibiting heterogeneous pathophysiology. Below shown is the mechanism of atopic dermatitis, which involves the interaction of impaired innate immunity and distorted adaptive immunity. Cytokines are the mediator molecules, resulting in dysfunction of the role of skin as a barrier. Also, filaggrin gene mutations play an important role in atopic dermatitis (Fonacier, Dreskin, & Leung, 2010).

Therapeutic considerations for atopic dermatitis

Atopic dermatitis treatment can follow a combination of emollient, anti-inflammatory, and antimicrobial therapy. The traditional treatments include the application of topical anti-inflammatory agents such as corticosteroids or calcineurin inhibitors. Proactive therapy is yet another approach. It involves the long-term, low-dose anti-inflammatory therapy besides emollient treatment of unaffected skin. Some of the emerging strategies involve subcutaneous immunotherapy and target therapy. Acupuncture treatment has also shown appreciable efficacy (Wollenberg & Feichtner, 2013).

Urticaria

Urticaria is the appearance of pruritic, edematous erythematous lesions of different sizes. These lesions exhibit blanching under pressure. Angioedema, on the other hand, is a form of urticaria exhibiting deeper swelling of the skin. An individual may show either of them or both together. Below shown is the list of causes resulting in Urticaria.

Table 9: Different aetiologies for urticaria (Deacock, 2008)

Therapeutic considerations for urticaria

Urticaria may not always be an outcome of an allergic reaction. The treatment options include administration of second-generation H1 antihistamines such as cetirizine, desloratadine, fexofenadine, leukotriene receptor antagonists such as montelukast or corticosteroids. Corticosteroid treatment is preferred for patients showing refractory urticaria. The topical treatments such as doxepin cream having anti-H1 and H2 activity also provides symptomatic relief (Bernstein et al., 2014). Moreover, the step treatment approach is also preferred for Urticaria as shown below:

Availability of treatment options

The discussion on conjunctivitis and skin allergies show that considerable treatment options are available for both of them. In contrast to this, the broad horizon of causative agents of food allergies makes the design of a standard treatment difficult. However, the treatment of immune reactions resulting from intake of allergic foods uses the standard treatment pertaining to the respective condition.

References

• Bernstein, J. A., Lang, D. M., Khan, D. A., Craig, T., Dreyfus, D., Hsieh, F., … Blessing-Moore, J. (2014). The diagnosis and management of acute and chronic urticaria: 2014 update. Journal of Allergy and Clinical Immunology, 133(5), 1270–1277.
• Carr, W., Schaeffer, J., & Donnenfeld, E. (2016). Treating allergic conjunctivitis: A once-daily medication that provides 24-hour symptom relief. Allergy & Rhinology, 7(2), e107.
• Deacock, S. J. (2008). An approach to the patient with urticaria. Clinical & Experimental Immunology, 153(2), 151–161.
• Fonacier, L. S., Dreskin, S. C., & Leung, D. Y. M. (2010). Allergic skin diseases. J Allergy Clin Immunol, 125(2), 138–149.
• Mishra, G. P., Tamboli, V., Jwala, J., & Mitra, A. K. (2011). Recent patents and emerging therapeutics in the treatment of allergic conjunctivitis. Recent Patents on Inflammation & Allergy Drug Discovery, 5(1), 26–36.
• Olivier, C. E. (2013). Food Allergy. Journal of Allergy & Therapy, 3(4), 1–7.
• Sánchez, M. C., Fernández Parra, B., Matheu, V., Navarro, A., Ibáñez, M. D., Dávila, I., … Valero, A. (2011). Allergic conjunctivitis. J Investig Allergol Clin Immunol, 21(2), 1–19.
• Syed, A., Kohli, A., & Nadeau, K. C. (2013). Food allergy diagnosis and therapy: where are we now? Immunotherapy, 5(9), 931–944.
• Wollenberg, A., & Feichtner, K. (2013). Atopic dermatitis and skin allergies – update and outlook. Wollenberg, A. Feichtner, K., 68(12), 1509–1519.