Nonsteroidal anti-inflammatory drugs as a targeted therapy for bone marrow failure in Ghosal hematodiaphyseal dysplasia

Abstract

Advances in genomic diagnostics hold promise for improved care of rare hematologic diseases. Here, we describe a novel targeted therapeutic approach for Ghosal hematodiaphyseal dysplasia, an autosomal recessive disease characterized by severe normocytic anemia and bone abnormalities due to loss-of-function mutations in thromboxane A synthase 1 (TBXAS1). TBXAS1 metabolizes prostaglandin H2 (PGH2), a cyclooxygenase (COX) product of arachidonic acid, into thromboxane A2. Loss-of-function mutations in TBXAS result in an increase in PGH2 availability for other PG synthases. The current treatment for Ghosal hematodiaphyseal dysplasia syndrome consists of corticosteroids. We hypothesize that nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit COX-1 and COX-2, could ameliorate the effects of TBXAS1 loss and improve hematologic function by reducing prostaglandin formation. We treated 2 patients with Ghosal hematodiaphyseal dysplasia syndrome, an adult and a child, with standard doses of NSAIDs (aspirin or ibuprofen). Both patients had rapid improvements concerning hematologic parameters and inflammatory markers without adverse events. Mass spectrometry analysis demonstrated that urinary PG metabolites were increased along with proinflammatory lipoxygenase (LOX) products 5-hydroxyeicosatetraenoic acid and leukotriene E4. Our data show that NSAIDs at standard doses surprisingly reduced both COX and LOX products, leading to the resolution of cytopenia, and should be considered for first-line treatment for Ghosal hematodiaphyseal dysplasia syndrome.

Graphical abstract

Figure 1.

AA metabolism and the clinical characteristics of 2 patients with Ghosal hematodiaphyseal dysplasia syndrome. (A) A schematic diagram of the AA metabolism pathway. AA is released from the membrane phospholipids by PLA₂ and is metabolized by COX-1 and −2 enzymes, (green oval) first into the unstable intermediate metabolite PGG₂, which is converted to PGH2. PGH₂ serves as a substrate for several PG synthases (PGDS, PGES, PGIS, blue ovals) that generate the following proinflammatory PG metabolites: PGD₂, PGE₂, and PGI₂. PGH₂ can also be converted to TXA₂ through the action of thromboxane synthase (red oval), the gene which is mutated in Ghosal hematodiaphyseal dysplasia syndrome. In addition to the COX-1/2 enzymes, AA is metabolized by 5-LOX (blue oval) to generate various products of hydroperoxyeicosatetraenoic acid, including 5-HETE and leukotrienes, for example, LTE₄. (B) Bone marrow biopsy sections for patient 1 have aspiration artifact but show an apparent reduction in marrow cellularity out of proportion to peripheral counts. On the left, H&E-stained section at an original magnification ×10 additionally shows thickened trabeculae (black arrow), and on the right, the H&E-stained section at an original magnification ×20 highlights disorganized osteocytes (black arrow). (C) A schematic diagram of thromboxane synthase A 1, encoded by the TBXAS1, showing the locations of the variants in the 2 patients reported in this manuscript (shown in red, above the diagram), and those from 13 sequenced cases previously reported in the literature (shown in blue, below the diagram). Diagram created using Domain Graph (DOG, version 2.0). D (for Case 1) and E (for Case 2), show. H&E, hematoxylin and eosin; 5-LOX, 5-lipooxygenase; PLA_2, phospholipase A₂; TXA₂, thromboxane A_2.

Figure 2.

Mass spectrometry analysis of 24-hour urinary metabolites performed throughout therapy for 2 patients with Ghosal hematodiaphyseal dysplasia syndrome. Measurements of the urinary prostaglandin metabolites PGEM, PGDM, and PGIM are shown in panels A (for patient 1) and B (for patient 2). (C) The urinary metabolite of thromboxane A2 (TXM, 11-dehydrothromboxane B2 [9α,15S-dihydroxy-11-oxothromba-5Z,13E-dien-1-oic acid]). No TXM signal was detected in the patients’ urine samples. Daily productions of TXM in adult and child healthy controls were 504 ± 1 and 107 ± 3 ng/d, respectively. The urinary levels of LTE₄ are shown in panels D for case 1 and E for case 2. The urinary levels of 5-HETE are in panels F for case 1 and G for case 2. In each plot, the bar represents a mean ± standard deviation, for 3 replicate measurements, with statistical analysis indicated by the bar above, performed by one-way ANOVA. Red bars show urinary metabolites that were measured off therapy. Green bars show the metabolite levels on COX1/2 inhibitor therapy. Urinary metabolites for a control subject, age-matched for each patient are shown by the blue bars. (H) The results of eicosanoid metabolite analysis from A-F are summarized in the schematic diagram of AA metabolism, showing the aberrant accumulation of PGDM, PGEM, PGIM, 5-HETE and LTE₄ in Ghosal hematodiaphyseal dysplasia syndrome (upward red arrows). In Ghosal hematodiaphyseal dysplasia syndrome, TBXAS1 is inactive (red line), preventing the conversion of PGH₂ to TXA₂ and downstream conversion to TXB₂ and TXM. (I) Inhibition of COX-1/2 by NSAIDs (yellow box). ∗P < .05, ∗∗P < .01, ∗∗∗P < .001, and ∗∗∗∗P < .0001.

Figure 2.

Mass spectrometry analysis of 24-hour urinary metabolites performed throughout therapy for 2 patients with Ghosal hematodiaphyseal dysplasia syndrome. Measurements of the urinary prostaglandin metabolites PGEM, PGDM, and PGIM are shown in panels A (for patient 1) and B (for patient 2). (C) The urinary metabolite of thromboxane A2 (TXM, 11-dehydrothromboxane B2 [9α,15S-dihydroxy-11-oxothromba-5Z,13E-dien-1-oic acid]). No TXM signal was detected in the patients’ urine samples. Daily productions of TXM in adult and child healthy controls were 504 ± 1 and 107 ± 3 ng/d, respectively. The urinary levels of LTE₄ are shown in panels D for case 1 and E for case 2. The urinary levels of 5-HETE are in panels F for case 1 and G for case 2. In each plot, the bar represents a mean ± standard deviation, for 3 replicate measurements, with statistical analysis indicated by the bar above, performed by one-way ANOVA. Red bars show urinary metabolites that were measured off therapy. Green bars show the metabolite levels on COX1/2 inhibitor therapy. Urinary metabolites for a control subject, age-matched for each patient are shown by the blue bars. (H) The results of eicosanoid metabolite analysis from A-F are summarized in the schematic diagram of AA metabolism, showing the aberrant accumulation of PGDM, PGEM, PGIM, 5-HETE and LTE₄ in Ghosal hematodiaphyseal dysplasia syndrome (upward red arrows). In Ghosal hematodiaphyseal dysplasia syndrome, TBXAS1 is inactive (red line), preventing the conversion of PGH₂ to TXA₂ and downstream conversion to TXB₂ and TXM. (I) Inhibition of COX-1/2 by NSAIDs (yellow box). ∗P < .05, ∗∗P < .01, ∗∗∗P < .001, and ∗∗∗∗P < .0001.