Psoriasis associated with idiopathic CD4+ T-cell lymphopenia: a regulatory T-cell defect?

Idiopathic CD4 Lymphocytopenia: Current Insights

Idiopathic CD4 lymphocytopenia is a condition characterized by low CD4 counts. It is rare and most of the information about this illness comes from case reports. Presentation is usually in the 4th decade of life with opportunistic infections, autoimmune disease or neoplasia. The pathophysiology of this condition is not well understood. Management revolves around treatment of the presenting condition and close follow-up of these patients. This review presents a narrative summary of the current literature on idiopathic CD4 lymphocytopenia.

Humanized mouse models reveal an immunologic classification of idiopathic CD4 lymphocytopenia subtypes

Idiopathic CD4 lymphocytopenia (ICL) is a clinically heterogeneous immunodeficiency disorder defined by low numbers of circulating CD4+ T cells and increased susceptibility to opportunistic infections. CD8+ T cells, NK, and/or B cells may also be deficient in some patients. To delineate possible pathogenic cellular mechanisms in ICL, we compared immune system development and function in NOD-RAGKO-γcKO (NRG) mice transplanted with hematopoietic stem cells from patients with ICL or healthy controls. CD34+ hematopoietic stem cells from healthy controls and patients with ICL reconstituted NRG mice equally well. In contrast, PBMC transfers into NRG mice identified 2 ICL engraftment phenotypes, reconstituting and nonreconstituting (NR), based on the absence or presence of donor lymphopenia. For patients in the NR group, the distribution of lymphocyte subsets was similar in the peripheral blood of both the patient and the corresponding humanized mice. The NR-ICL group could be further divided into individuals whose CD3+ T cells had defects in proliferation or survival. Thus, ICL cellular pathogenesis might be classified by humanized mouse models into 3 distinct subtypes: (a) T cell extrinsic, (b) T cell intrinsic affecting proliferation, and (c) T cell intrinsic affecting survival. Humanized mouse models of ICL help to delineate etiology and ultimately to guide development of individualized therapeutic strategies.

Antibiotic Exposure, Infection, and the Development of Pediatric Psoriasis: A Nested Case-Control Study

IMPORTANCE

Antibiotics disrupt human microbiota and have been associated with several pediatric autoimmune diseases. Psoriasis activity has been linked to group A streptococcal and viral infections.

OBJECTIVE

To determine whether antibiotic exposure and infections are independently associated with incident psoriasis in children.

DESIGN, SETTING, AND PARTICIPANTS

This nested case-control study used data from the Health Improvement Network database, a population-representative electronic health records database from the United Kingdom, from June 27, 1994, through January 15, 2013. Data were analyzed from September 17, 2014, through August 12, 2015. Children aged 1 to 15 years with newly diagnosed psoriasis (n = 845) were compared with age- and sex-matched controls (n = 8450) randomly chosen at the time of psoriasis diagnosis from general practices with at least one case, excluding children with immunodeficiency, inflammatory bowel disease, and juvenile arthritis.

EXPOSURES

Systemic antibacterial prescriptions and infections of the skin and other sites within 2 years before psoriasis diagnosis.

MAIN OUTCOMES AND MEASURES

Incident psoriasis as determined by validated diagnostic codes. The association of antibiotic exposure and infections with incident psoriasis was determined by conditional logistic regression, adjusting for confounders.

RESULTS

After adjusting for matching, country, socioeconomic deprivation, outpatient visits, and infections within the past 2 years, antibiotic exposure in the last 2 years was weakly associated with incident psoriasis (adjusted odds ratio [aOR], 1.2; 95% CI, 1.0-1.5). The associations for infections of skin (aOR, 1.5; 95% CI, 1.2-1.7) and other sites (aOR, 1.3; 95% CI, 1.1-1.6) were similar. Untreated nonskin infections (aOR, 1.5; 95% CI, 1.3-1.8) but not antibiotic-treated nonskin infections (aOR, 1.1; 95% CI, 0.9-1.4) were associated with psoriasis. Results were similar when using a lifetime exposure window. Different classes of antibiotics and age of first antibiotic exposure were also not associated with psoriasis. The findings did not substantively change when excluding periods of varying length before diagnosis.

CONCLUSIONS AND RELEVANCE

Infections are associated with the development of pediatric psoriasis, but antibiotics do not appear to contribute substantially to that risk.

Genetic, Cellular and Clinical Features of ICF Syndrome: a French National Survey

PURPOSE

Autosomal recessive deficiencies of DNMT3B or ZBTB24 account for two-thirds of cases of immunodeficiency, centromeric instability and facial dysmorphism (ICF syndrome). This primary immunodeficiency (PID) is characterized mainly by an antibody deficiency, facial abnormalities and centromeric instability. We analyzed the national cohort of patients with ICF syndrome with the aim of providing a more detailed description of the phenotype and management of patients with ICF syndrome.

METHODS

Demographic, genetic, immunological, and clinical features were recorded for each patient.

RESULTS

In the French cohort, seven of the nine patients carried DNMT3B mutations, six of which had never been described before. One patient had compound heterozygous ZBTB24 mutations. All patients were found to lack CD19(+)CD27(+) memory B cells. This feature is a major diagnostic criterion for both ICF1 and ICF2. Patients suffered both bacterial and viral infections, and three patients developed bronchiectasis. Autoimmune manifestations (hepatitis, nephritis and thyroiditis) not previously reported in ICF1 patients were also detected in two of our ICF1 patients. The mode of treatment and outcome of the French patients are reported, by genetic defect, and compared with those for 68 previously reported ICF patients. Immunoglobulin (Ig) replacement treatment was administered to all nine French patients. One ICF1 patient presented severe autoimmune manifestations and pancytopenia and underwent allogeneic hematopoietic stem cell transplantation (HSCT), but she died from unknown causes 6 years post-transplant.

CONCLUSION

Autoimmune signs are uncommon in ICF syndrome, but, when present, they affect patient outcome and require immunosuppressive treatment. The long-term outcome of ICF patients has been improved by the combination of IgG replacement and antibiotic prophylaxis.

Severe Pneumocystis jirovecii pneumonia in an idiopathic CD4+ lymphocytopenia patient: case report and review of the literature

INTRODUCTION

When diagnosing Pneumocystis jirovecii pneumonia (PJP), the clinical suspicion must be confirmed by laboratory tests. PJP is rarely described in patients with idiopathic CD4⁺ lymphocytopenia (ICL), a rare T-cell deficiency of unknown origin with persistently low levels of CD4⁺ T-cells (<300 µl^-1 or <20 % of total lymphocytes) but repeated negative human immunodeficiency virus (HIV) tests. We retrospectively analysed a case of an ICL patient with severe PJP associated with multiple opportunistic infections (OIs). We also reviewed the literature since 1986.

CASE PRESENTATION

A laboratory-confirmed case of PJP associated with invasive candidiasis and cytomegalovirus infection was reported in an ICL patient. Despite early treatment, the patient died of respiratory failure under polymicrobial pneumonia. According to the literature, the mortality rate of ICL patients is 10.4 % (33/316). In ICL patients, the risk of OI is 83.2 % (263/316), with viral infections being the most prevalent (58.2 %, 184/316), followed by fungal infections (52.2 %, 165/316) and mycobacterial infections (15.5 %, 49/316). Dysimmunity is reported in 15.5 % (49/316) of ICL patients. Among the fungal infections, cryptococcal infections are the most prevalent (24.1 %, 76/316), followed by candidiasis (15.5 %, 49/316) and PJP (7.9 %, 25/316).

CONCLUSIONS

The high risk of OIs underlines the importance of more vigorous preventative actions in hospitals. The response to therapy and the detection of early relapse of PJP may be monitored by several laboratory tests including quantitative PCR. It is essential to treat the ICL and to follow the guidelines concerning therapy and prophylaxis of OIs as given to HIV patients.