Monitoring of deep lymphocyte phenotypes in the blood and bronchoalveolar lavage fluid of patients with severe malaria-associated acute respiratory distress syndrome

TL;DR

This study tracks immune cell changes in blood and lung fluid of a severe malaria patient with respiratory failure, showing how immune profiles differ and evolve.

Contribution

The study demonstrates the feasibility of multi-compartment immune monitoring in severe malaria-associated respiratory distress.

Findings

Dynamic shifts in T cells and innate lymphoid cells were observed despite persistent lymphopenia.

A type 2 immune profile dominated during the acute phase, with reduced exhausted T cells indicating recovery.

Blood and bronchoalveolar lavage fluid showed significantly different immune profiles.

Abstract

Restoring immune homeostasis after an acute insult is essential for achieving a full recovery from an acute respiratory distress syndrome episode. Immune monitoring tools that are not exclusive to the blood compartment are in great demand to help guide treatment decisions. In this longitudinal study, we report a case of severe malaria-associated acute respiratory distress syndrome supported by venovenous extracorporeal membrane oxygenation. Although there was persistent lymphopenia, we observed dynamic shifts in T cells and rare innate lymphoid cell populations. The type 2 immune profile was preponderant at the acute phase, and decreased exhausted T-cell populations indicated recovery. There were significantly different blood and bronchoalveolar lavage fluid profiles. Multiple-compartment immune monitoring is possible and valuable for precise immune modulation.

Figures

Clinical timepoints and deep immune monitoring during malaria-associated acute respiratory distress syndrome in blood and bronchoalveolar lavage fluid.

Full text

INTRODUCTION

Acute respiratory distress syndrome (ARDS) occurs due to a nonregulated immune response to several acute triggers and damages the lungs.^(1)^ The inability to rapidly restore lung homeostasis contributes to secondary infections, lung fibrosis, and high mortality.^(2)^ Immune monitoring tools, including the personalized use of corticosteroids, checkpoint inhibitors, and anti-cytokine monoclonal antibodies, are in great demand to help guide treatment decisions.^(3)^ Malaria-associated ARDS (MA-ARDS) usually occurs after parasitemia control due to the host immune response.^(4)^ Herein, we report the lymphocyte kinetic response in the peripheral blood and lung compartment in a unique case of MA-ARDS supported with venovenous extracorporeal membrane oxygenation (VV-ECMO) until complete recovery nine months later.

CASE REPORT

A 52-year-old man with no relevant medical history was admitted to a university tertiary hospital intensive care unit (ICU) with a five-day fever due to Plasmodium falciparum and presented with hyperbilirubinemia, acute kidney injury, and noncardiogenic pulmonary edema. After treatment with quinine and doxycycline for 48 hours, parasitemia resolved (Figure 1A). Nevertheless, gas exchange deterioration led to noninvasive ventilation on day 6 and invasive mechanical ventilation on day 10 of symptoms (Timepoint [TP] 1). The patient then developed severe MA-ARDS, which was treated with dexamethasone and later with methylprednisolone due to concomitant organizing pneumonia. His clinical course was complicated by ventilator-associated pneumonia with secondary bacteremia due to Klebsiella pneumoniae and refractory hypoxemia with acidemia requiring VV-ECMO rescue (Avalon Elite® Bi-Caval Dual Lumen Catheter) for 18 days on day 21 after malaria diagnosis. He was discharged home on oxygen therapy and corticosteroids after a hospital stay of 42 days. After nine months, the patient fully recovered, and the steroid treatment was weaned entirely (TP6).

Clinical timepoints and deep immune monitoring during malaria-associated acute respiratory distress syndrome in blood and bronchoalveolar lavage fluid.

Peripheral blood and bronchoalveolar lavage fluid (BALF) samples were longitudinally obtained (Figure 1A) upon clinical request, and high-dimensional spectral flow cytometry tubes with 21 colors were used to subset both T cells and innate lymphoid cells (ILCs).

Lymphopenia was a hallmark until complete recovery at TP6 (Figure 1B). Compared with TP6, timepoint 1 presented a lower number of CD4 (468 versus 1014 cells/µL) and CD8 (467 versus 1332 cells/µL) T cells but an absolute increase in gamma-delta+ (GD) T cells (237 versus 121 cells/µL) and NK cells (107 versus 61 cells/µL). Blood expansion of effector GD+ T-cell populations, particularly clusters 18 and 16, was observed (Figure 1C). Throughout the more severe phase, until TP4, there was a sustained increase in the proportion of a specific population of CD4+ T cells (CCR6+CXCR3+CD69+ cells) in the blood. Interestingly, in the BALF, parallel accumulation of CD4+ T cells expressing high levels of CD69, PD-1 and CXCR3 was observed, suggesting activated resident Th1 cells.

There were significant shifts in the T-cell composition of the BALF between TP1 and TP4 (CD4+ conventional: 63.1 versus 18.9%; GD: 9.6 versus 0.9%; CD8: 13.2 versus 21%; CD4+ regulatory: 2.0 versus 7.8%; Figure 1D). We documented an influx of ILC2s into the lung in the early phase, eventually reflecting the malaria response, followed by an increase in the number of ILC1s.

DISCUSSION

This was the first study to report the detailed immune lymphocyte profile of a patient with MA-ARDS. Our longitudinal findings included data collected between the initiation of mechanical ventilation and complete recovery nine months later. The results provide support for the hypothesis that severe disease is characterized by ILC2 and GD T-cell pulmonary infiltration, and recovery is characterized by decreased exhausted/activated CD4+ and CD8+ T-cells.

In the early phase, gamma delta expansion might contribute to initial lung lesions, which decline early after corticosteroid treatment (from TP2 to TP4). Additionally, the hyperacute phase was characterized by an expansion of CXCR3+ T-cells. Notably, blocking CXCR3 was found associated with decreased organ lesions and mortality in a sepsis model.^(5)^ Later in the disease process, the increase in regulatory T-cells (Tregs) in parallel with a change in the ILC profile might be relevant for lung recovery.^(6)^ Although they represent rare populations, ILCs are fundamental to lung repair, as we have previously documented in patients with severe COVID-19, where recovery was linked with an increase in ILC1s.^(7)^

CONCLUSION

Complex immune monitoring is fundamental for better understanding acute disease phenotypes and trajectories, as well as the response/impact of immune modulator drugs (e.g., corticosteroids or targeted therapies).