Expression and Activation of Complement Protein and Alveolar Damage during Pneumocystis Pneumonia

A Case Report of Purtscher-Like Retinopathy Secondary to Pneumocystis jirovecii Pneumonia in an Immunocompromised Patient

To the best of our knowledge, we present the first case of a young adult male, on long-term immunosuppressive therapy following a live-donor kidney transplant, with Purtscher-like retinopathy (PLR) secondary to Pneumocystis jirovecii pneumonia (PCP). The patient had presented to a routine medical follow-up and complained of a few weeks' history of dyspnoea and tachycardia after minimal exertion followed by acute bilateral blurring of vision. Unfortunately, the patient did not respond to a trial of corticosteroid treatment and subsequently became severely visually impaired. This case report expands the aetiological spectrum behind PLR and helps portray the disease process which, in some cases, leads to severe ischaemic sequelae.

Soluble mediators in anti-fungal immunity

Although soluble mediators of our innate immune system have a substantial impact on invading microbes, their role against fungal pathogens has been underexplored. Constituting the humoral immunity, soluble mediators comprise the complement system, collectins, acute-phase proteins, antibodies and antimicrobial peptides. These components can prevent fungal infection either by directly interacting with invading microbes, leading to their aggregation (microbistatic), destruction (microbicidal) or linking them to cellular immunity. The composition of soluble-mediator varies with human body-fluids, resulting in different antifungal mechanisms. Moreover, cellular immune system deploys both oxidative and non-oxidative mechanisms to destroy extracellular or internalized fungal pathogens; however, cellular immune activation is mainly influenced as well as regulated by soluble mediators. This review outlines the antifungal mechanism employed, directly or indirectly, by soluble mediators, and in response, the evading strategies of the fungal pathogens.

Complement and fungal pathogens: an update

Fungal infections are a serious complication in immunocompromised patients such as human immunodeficiency virus-infected individuals, patients with organ transplantations or with haematological neoplasia. The lethality of opportunistic fungal infection is high despite a growing arsenal of antimycotic drugs, implying the urgent need for supportive immunological therapies to strengthen the current inefficient antimicrobial defences of the immunocompromised host. Therefore, increasing effort has been directed to investigating the interplay between fungi and the host immunity and thus to find starting points for additional therapeutic approaches. In this article, we review the actual state of the art concerning the role of complement in the pathogenesis of fungal infections. Important aspects include the activation of the complement system by the fungal pathogen, the efficiency of the complement-associated antimicrobial functions and the arsenal of immune evasion strategies applied by the fungi. The twin functions of complement as an interactive player of the innate immunity and at the same time as a modulator of the adaptive immunity make this defence weapon a particularly interesting therapeutic candidate to mobilise a more effective immune response and to strengthen in one fell swoop a broad spectrum of different immune reactions. However, we also mention the 'Yin-Yang' nature of the complement system in fungal infections, as growing evidence assigns to complement a contributory part in the pathogenesis of fungus-induced allergic manifestations.