Introduction

You may have heard of psoriasis being a skin condition, but it goes beyond that. It's an auto-immune disease that causes widespread inflammation across the body. As this disease involves misregulation of the immune system, viral infections may trigger the disease and symptom flare-ups. In this article, we’ll explore psoriasis, adenovirus, and the potential role of the virus in exacerbating symptoms.

Psoriasis

Symptoms

Typical symptoms of this disease include:

• A rash that produces raised, flaky skin (plaques) that can be small or large across the body. Common areas include the knees, elbow, and the lower back. This rash often goes away and returns, lasting a few weeks or months
• These plaques often look pink or red, with white or silver colour scales. On darker skin, these patches may appear purple or dark brown, and scales can look grey
• Itchy, burning, and/or soreness of the skin
• Joint pain may also be experienced due to general inflammation. In some cases, the skin-protecting joints can begin to bleed
• Because of chronic inflammation, patients may develop other diseases such as type II diabetes, high blood pressure, obesity, and cardiovascular disease

Different types of psoriasis exist, and you may experience more than one at the same time. 

Types

Plaque psoriasis

This is the most common type in the patients. As the name suggests, it is characterised by the appearance of scaly plaques. Scalp psoriasis is a form of plaque psoriasis affecting the parts of or the entirety of the scalp. Depending on the person, this may be itchy.

Image showing plaque psoriasis on the back and arms of the patient. Source: Wikimedia Commons by The Wednesday Island (of the English Wikipedia)

Plaque psoriasis on the darker skin tone. Source: Wikimedia Commons by MediaJet

Inverse psoriasis

This is typically observed as smooth, inflamed patches in skin folds, such as beneath the breasts, buttocks, and groin. Fungal infections such as thrush are thought to trigger this type of psoriasis. Friction and sweating also seem to worsen this condition.

Pustular psoriasis

This form is quite rare and causes the appearance of blisters containing pus. These can be in small parts of the body, such as the palms of hands and soles of feet, or across the larger sections. The former often results in the blisters peeling off. If the blisters form quickly across a large body area, The patient may require urgent treatment. When these blisters begin to form during disease flare-up, you may experience:

• Weight reduction
• Chills
• Fever
• Tiredness

Psoriatic pustules on the hand. Source: Wikimedia Commons by Roland Tanglao

Nail psoriasis

Psoriasis affects nails on the toes and fingers to dent, as well as become yellow and show an unusual growth. The nails may begin to separate from the nail bed, and in severe cases, can disintegrate entirely.

Psoriasis affects the toenails. Source: Wikimedia Commons by JVO27

Psoriasis affects the fingernail. Source: Wikimedia Commons by Seenms

Erythrodermic psoriasis

This is the rarest form of the disease, characterised by a rash across the body. The rash tends to peel and is associated with a strong itch and burn. This type can last short-term or long-term and often requires urgent treatment. Complications can occur, such as:

• Malnutrition
• Dehydration
• Hypothermia
• Heart failure

Guttate psoriasis

This type is typically seen in children and young adults; and can be triggered by a bacterial infection, such as strep throat. The scaling in this type is often smaller and roughly the size of a water droplet. Guttate psoriasis is often not chronic, but there’s a chance it may progress into plaque psoriasis.

Guttate psoriasis on a child. Source: Wikimedia

What causes psoriasis?

The exact mechanism behind psoriasis is not fully understood. However, people with psoriasis have a much faster turnover rate for their skin cells, typically taking 3-7 days, while for an average person, this requires 21-28 days. As a result, the excess skin cells gather to form the characteristic plaques^{.1, 2} There are also some genetic factors at play, however, it is not unusual for someone to be the first in the family to develop this disease.¹ Different triggers can also cause the condition to begin or worsen. Beyond genetics, excess skin growth is associated with the immune dysregulation in psoriasis.

Immune system

The immune system helps us defend against disease by recognising antigens. Cytokines are the molecules that help coordinate immune responses and are involved in inflammation. In psoriasis, the immune system perceives the body’s skin cells as foreign substances, eliciting a response. Current research suggests that the cytokines TNF (tumour necrosis factor), IL-17 and IL-23 (interleukins) play key roles in the inflammatory reaction of  psoriasis in the following way:²

1. Inflammatory dendritic cells produce TNF, which helps make IL-23^{3, 4}
2. IL-23 can then be used to make IL-17that plays a major role in inflammation.² Typically, this cytokine causes our skin cells to divide, but overproduction increases the number of skin cells
3. A signal is sent to T cells, which produce even more IL-17 and IL-23⁴
4. IL-17 and TNF can also work together to prolong inflammation^{5, 6}

Triggers vary but can include:

• Injuries to the skin.
• Throat infections.⁷
• Medicines containing lithium, antimalarial drugs, and drugs to manage high blood pressure.¹
• Smoking¹
• Excess alcohol consumption
• Cold, dry weather
• Rapidly stopping a course of corticosteroids

Treatment

There is currently no cure for this disease, but different treatments may help alleviate symptoms:

• Topical treatments (applied to the skin) include vitamin D analogues or corticosteroids
• Phototherapy may be used in more severe cases, which involves exposing the skin to UVB rays
• Systemic drugs such as cyclosporine and methotrexate can be used to reduce immune system activity to normal levels. These are typically used in more serious cases

It’s important to seek out treatment, even if you have mild disease, as one form can progress into another. According to Dr. Mehta at the National Heart, Lung, and Blood Institute (NHLBI) in Maryland, treating psoriasis may help prevent the onset of psoriatic arthritis. He has also stated, "People who don’t treat severe disease, for example, are growing coronary plaque at an alarmingly fast rate.”

Adenovirus

This is a common viral infection that causes symptoms similar to the cold and flu. It is easily spread in enclosed environments, such as childcare and healthcare settings.⁸ Cases are common in winter and early spring but can affect people during any time of year. It has an incubation period of 2-14 days, and there are over 49 different types known to cause infection in humans. This disease can impact several parts of the body, but most infections do not show symptoms.⁸ Those with compromised immune systems, such as psoriasis patients, are more likely to develop worse illnesses from the virus. 

Symptoms

• Fever
• Sore throat
• Acute bronchitis
• Pink eye (conjunctivitis)
• Acute gastroenteritis
• In some cases, bladder inflammation and neurologic disease can occur

Transmission

This disease can be spread by:

• Droplets from an infected person coughing and sneezing
• Touching a surface that contains virus particles on it
• Being in close contact with an infected person
• Water in public swimming pools
• Changing nappies for an infected person

Treatment

Over-the-counter medications can typically be used in mild cases of adenovirus infection. Antiviral drugs are used in severe cases, however, they may show adverse side effects.⁸ A vaccine has been used by the United States militarily to treat type 4 and 7 adenoviruses but is not available to the general public.

Link between adenovirus and psoriasis

To our knowledge, there has been no study looking at the effect of adenovirus infection on patients with psoriasis. However, a study in 2016 looked at the safety of the oral adenovirus vaccine provided to US military personnel and found a link between some cases of psoriasis.⁹ However, only adenovirus 4 and 7 were studied, and no causal relationship between the vaccine and psoriasis was found. Factors such as vaccines being taken simultaneously and incomplete medical information for candidates may also affect results.

Other vaccines, such as the flu and COVID-19 vaccines have been associated with worsening psoriasis symptoms.^{10, 11, 12} In latter cases, it’s worth noting that some use adenovirus, which stimulates an immune response, producing TNF and other interleukins.¹³ As a result, this may worsen psoriasis in the existing cases. However, cases of vaccines causing the onset of psoriasis are generally quite low.¹⁴

Viral infections generally lead to increased cytokine levels in the body, like TNF. Because of this, a lot of infections, including strep throat, plague, and thrush, may exacerbate psoriasis.⁷ It’s an autoimmune system and produces inflammatory signals, adenovirus could also contribute to disease flare-ups. However, further research needs to be performed to confirm this.

Prevention of adenovirus

If one is suffering from psoriasis and is concerned that adenovirus may affect him/her, here are some preventive measures that can be taken:

• Practise good personal hygiene such as washing hands regularly, especially if you work in a healthcare or childcare setting
• Never share towels or pillows with someone who has pink eye
• Avoid close contact with people who have flu or cold-like symptoms

Summary

Psoriasis is an autoimmune disease that causes systemic inflammation, often seen as raised, flaky skin plaques. Various triggers, including infections, can exacerbate symptoms. Adenovirus, a common virus causing cold-like symptoms, may likely worsen symptoms by further activating the immune system. However, no direct evidence links adenovirus to increased psoriasis symptoms. Preventive measures, such as good hygiene and avoiding close contact with infected individuals, may be taken to reduce the risk of adenoviral infection.