Inherently defective immunity typically results in either ineffective host defense, immune regulation, or both. As a category of primary immunodeficiency diseases, those that impair immune regulation can lead to autoimmunity and/or autoinflammation. In this review we focus on one of the most recently discovered primary immunodeficiencies that leads to immune dysregulation: “Copa syndrome”. Copa syndrome is named for the gene mutated in the disease, which encodes the alpha subunit of the coatomer complex-I that, in aggregate, is devoted to transiting molecular cargo from the Golgi complex to the endoplasmic reticulum (ER). Copa syndrome is autosomal dominant with variable expressivity and results from mutations affecting a narrow amino acid stretch in the COPA gene-encoding COPα protein. Patients with these mutations typically develop arthritis and interstitial lung disease with pulmonary hemorrhage representing a striking feature. Immunologically Copa syndrome is associated with autoantibody development, increased Th17 cells and pro-inflammatory cytokine expression including IL-1β and IL-6. Insights have also been gained into the underlying mechanism of Copa syndrome, which include excessive ER stress owing to the impaired return of proteins from the Golgi, and presumably resulting aberrant cellular autophagy. As such it represents a novel cellular disorder of intracellular trafficking associated with a specific clinical presentation and phenotype.

Outcomes in children with proliferate lupus nephritis (PLN) show 9-15% progress to end-stage renal disease (ESRD) at 5 years. Immunosuppression improves outcome, but significant side effects are possible. Clinical and laboratory analyses are poor predictors of class and progression in PLN. We describe 28 patients with systemic lupus erythematosus (SLE), between 1990 and 2005, whose initial biopsy (Bx1) showed PLN and who received nine monthly doses of intravenously administered cyclophosphamide (CYP) (500-750 mg/m(2) up to 1 g to maintain their absolute neutrophil count (ANC) > 3,000). Continued therapy with additional quarterly intravenous (i.v). administration of CYP was dictated by repeat renal biopsy (Bx2). Bx1 was done 1 +/- 1.6 years after diagnosis of SLE. Bx2 showed histological improvement by WHO classification in 20/25 children; 3/25 were unchanged, 1/25 was categorized as new class V, and 1/25 was worse. Four patients (14%) had infectious complications requiring hospitalization (one of these died). Mean follow-up (f/u) after Bx2 was 3.5 +/- 2.3 years. At last follow-up, 26 patients had normal glomerular filtration rate (GFR), with a mean of 126 +/- 42.8 ml/min per 1.73 m(2) body surface area, one non-compliant patient had ESRD, and one had chronic renal failure. At last follow-up, most patients had minimal to no proteinuria. Clinical and biopsy results greatly improved after 9 monthly intravenously administered CYP pulses in most children with class IV PLN. Those who did not improve are at risk for flares and progression of disease. The tailoring of therapies based on findings from a biopsy after induction may improve outcomes.

Inborn errors of immunity that present with concomitant immunodeficiency and auto-inflammation are therapeutically challenging; furthermore, complexity is added when they are caused by mutations in genes that encode for proteins expressed beyond immune cells. The ubiquitin-proteasome system is the main intracellular proteolytic machinery and participates in most cellular processes by degrading ubiquitinated proteins. Mutations in proteasome subunits resulting in proteasome deficiency cause a severe auto-inflammatory disease characterized by chronic auto-inflammation neutrophilic dermatosis and fever, collectively referred to as Proteasome Associated Auto-inflammatory Syndromes (PRAAS). POMP is a chaperone for proteasome assembly and AD mutations in POMP cause a form of PRAAS with prominent immunodeficiency referred to as POMP-related auto-inflammation and immune dysregulation (PRAID) manifesting with recurrent, severe and opportunistic infections in addition to inflammatory features that are characteristic for all PRAAS disorders, most importantly early-onset neutrophilic dermatosis. JAK inhibitors partially control the disease in individuals with PRAAS, however life-threatening, recurrent and opportunistic infections in patients with POMP mutations limit immunosuppressive therapies and prompted consideration of hematopoietic stem cell transplant (HSCT). We describe successful HSCT in two patients with POMP deficiency. Despite POMP being ubiquitously expressed, the immunologic and auto-inflammatory phenotype were both ameliorated through HSCT which suggests that the clinical and immunological features of PRAID are predominantly derived from a proteasome defect in hematopoietic cells. To our knowledge, these are the first patients with a form of PRAAS cured by HSCT, opening new therapeutic possibilities for these diseases.