From HIV infection to AIDS: what happens in the immune system
HIV infection is characterised by the selective attack on CD4+ lymphocytes (or T helper lymphocytes), which are essential in coordinating the immune response against viruses, bacteria, fungi and other pathogens. After an initial phase that may be asymptomatic or present with flu-like symptoms, the virus enters a phase of clinical latency during which it continues to replicate silently. This persistent replication leads to a progressive increase in viral load and a continual reduction in the number of CD4+ lymphocytes. Over time, the gradual destruction of these cells significantly compromises the body’s defensive capabilities. In the absence of treatment, the CD4+ count may fall below the critical threshold of 200 cells/µL, a condition that marks progression to acquired immunodeficiency syndrome (AIDS).
Mucosal barriers
The mucosal barriers present in the intestine, the genital area and the ano-rectal region constitute the body’s first line of defence against pathogens and opportunistic micro-organisms that can cause infections. These barriers form a dynamic and complex system, in which epithelial cells, specific antibodies, the microbiota and immune system cells work together. These components perform several key functions:
- They prevent the adhesion and penetration of pathogens into tissues.
- They control inflammation, preventing damage and excessive reactions.
- They activate an appropriate immune response, aimed at neutralising infectious agents.
- They maintain the integrity and health of the mucosal surface, promoting tissue protection and repair.
HIV and its effects on mucosal barriers
HIV infection compromises mucosal barriers, making them more vulnerable to infections, lesions and impaired tissue repair. Essentially, HIV affects the mucosae in several ways:
- It damages the epithelium, making it more fragile and facilitating the penetration of viruses and bacteria.
- It reduces local immune defences due to the loss of CD4+ lymphocytes.
- It causes chronic inflammation, which further damages tissues and slows their regeneration.
- It alters the microbiota, increasing the risk of opportunistic infections.
- It increases mucosal permeability, allowing harmful substances and micro-organisms to cross the barrier more easily.
These effects create an environment conducive not only to infections and ulcers, but also to possible neoplastic transformations, particularly in the presence of co-infections with viruses carrying a high oncogenic risk
The impact of HIV on the ano-rectal tract
In the ano-rectal tract, HIV infection manifests through changes affecting both tissue structure and functional balance. Among the ano-rectal conditions most commonly observed in patients with HIV are:
- Infectious proctitis, often associated with Neisseria gonorrhoeae, Chlamydia trachomatis or Treponema pallidum.
- Persistent irritation with consequent increased sensitivity.
- Functional and inflammatory disorders, including anal pain, itching, bleeding and changes in bowel habit.
- HPV-related lesions, which may present as condylomata or intraepithelial dysplasia of varying degrees.
- Intestinal disturbances such as bloating, diarrhoea or increased mucosal irritability.
- Anal carcinoma.
For these reasons, the ano-rectal tract requires targeted clinical surveillance, including regular proctological examinations and investigations aimed at the early diagnosis of any lesions. Clinical presentation can vary widely, ranging from mild and minimally symptomatic manifestations to more complex conditions, which may sometimes require a multidisciplinary approach to ensure comprehensive and personalised patient management.
The role of proctological surveillance
Prevention and early diagnosis play a fundamental role in the management of ano-rectal conditions in people living with HIV. Proctological surveillance allows for the timely identification of any dysplasia or pre-neoplastic lesions. At the same time, it enables the early recognition and treatment of infections and ulcerative lesions, reducing the risk of complications and progression to chronic conditions. Ongoing monitoring is also useful for tracking over time conditions related to immunosuppression and for appropriately adjusting therapeutic interventions according to the patient’s immune status. In this context, the introduction of dedicated screening programmes, such as high-resolution anoscopy, now represents an essential tool for the prevention of anal carcinoma and for more effective management of ano-rectal health.
