Interferon alpha treatment of patients with impaired interferon gamma signaling

Abstract

Patients with deficiency in the interferon gamma receptor (IFN-γR) are unable to respond properly to IFN-γ and develop severe infections with nontuberculous mycobacteria (NTM). IFN-γ and IFN-α are known to signal through STAT1 and activate many downstream effector genes in common. Therefore, we added IFN-α for treatment of patients with disseminated mycobacterial disease in an effort to complement their IFN-γ signaling defect. We treated four patients with IFN-γR deficiency with adjunctive IFN-α therapy in addition to best available antimicrobial therapy, with or without IFN-γ, depending on the defect. During IFN-α treatment, ex vivo induction of IFN target genes was detected. In addition, IFN-α driven gene expression in patients' cells and mycobacteria induced cytokine response were observed in vitro. Clinical responses varied in these patients. IFN-α therapy was associated with either improvement or stabilization of disease. In no case was disease exacerbated. In patients with profoundly impaired IFN-γ signaling who have refractory infections, IFN-α may have adjunctive anti-mycobacterial effects.

Figure 1

Patient 1 (a) CT chest showing necrotizing mediastinal lymphadenitis and extensive parenchymal disease due to refractory MAC infection; (b) After 1 year of treatment with IFN-α, cervical, mediastinal and parenchymal disease had resolved completely.

Figure 2

Patient 3 (a) 1. Multidrug resistant disseminated M. bovis BCG infection with intracerebral lesions; 2. A draining head wound; 3 and 4. The lesion progressively healed while on combined IFN-α and IFN-γ therapy; (b) A large right pleural mass before IFN-α which (c) completely resolved on combined IFN-α and IFN-γ treatment; (d) Laboratory paremeters improved following initiation of IFN-α (arrow).

Figure 2

Patient 3 (a) 1. Multidrug resistant disseminated M. bovis BCG infection with intracerebral lesions; 2. A draining head wound; 3 and 4. The lesion progressively healed while on combined IFN-α and IFN-γ therapy; (b) A large right pleural mass before IFN-α which (c) completely resolved on combined IFN-α and IFN-γ treatment; (d) Laboratory paremeters improved following initiation of IFN-α (arrow).

Figure 3. Gene expression in vitro

PBMC from normal donors (Nm) and IFN-γR deficient patients were stimulated with IFN-γ (400 IU/ml) or IFN-α (1,000 IU/ml) for 3 h and assayed for the expression of target genes (a) CXCL9, CXCL10, IRF-1 and (b) MX1, ISG15. *p<0.05 vs. the response observed in healthy controls; (c) Levels of CXCL10 protein were assayed in the 20 h culture supernatants. Results are mean ± SD of five independent experiments.

Figure 3. Gene expression in vitro

PBMC from normal donors (Nm) and IFN-γR deficient patients were stimulated with IFN-γ (400 IU/ml) or IFN-α (1,000 IU/ml) for 3 h and assayed for the expression of target genes (a) CXCL9, CXCL10, IRF-1 and (b) MX1, ISG15. *p<0.05 vs. the response observed in healthy controls; (c) Levels of CXCL10 protein were assayed in the 20 h culture supernatants. Results are mean ± SD of five independent experiments.

Figure 4. Gene expression ex vivo

Gene expression in fresh isolated unstimulated PBMC obtained from IFN-γR deficient patients was assayed before and 20 h after IFN-α injection. Results for each patient represent mean fold induction ± SD of triplicate wells for each condition compared to samples obtained before IFN-α injection.

Figure 5. Gene expression following mycobacterial stimulation

(a) MDM obtained from patients were stimulated with mycobacteria (myc = M. avium, MOI 5) and IFN-α (1,000 IU/ml) added simultaneously to the wells. Supernatant levels (pg/ml) of TNF-α and IL-1β were assayed 20 h after culture stimulation; (b) Gene expression was evaluated in MDM 3 h after stimulation; (c) Alveolar macrophages (AM) obtained from normal donors were plated, stimulated and assayed as above. Results are mean ± SD of three independent experiments. *p<0.05 when compared to cells stimulated with mycobacteria alone.

Figure 5. Gene expression following mycobacterial stimulation

(a) MDM obtained from patients were stimulated with mycobacteria (myc = M. avium, MOI 5) and IFN-α (1,000 IU/ml) added simultaneously to the wells. Supernatant levels (pg/ml) of TNF-α and IL-1β were assayed 20 h after culture stimulation; (b) Gene expression was evaluated in MDM 3 h after stimulation; (c) Alveolar macrophages (AM) obtained from normal donors were plated, stimulated and assayed as above. Results are mean ± SD of three independent experiments. *p<0.05 when compared to cells stimulated with mycobacteria alone.