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\begin{document}

\title{Systemic inflammatory response and fast recovery in a pediatric patient
with COVID-19}



\author[1]{Adam Klocperk}%
\author[1]{Zuzana Parackova}%
\author[1]{Jitka Dissou}%
\author[1]{Hana Malcová}%
\author[1]{Petr Pavlíček}%
\author[1]{Tomáš Vymazal}%
\author[2]{Pavla Doležalová}%
\author[1]{Anna Sediva}%
\affil[1]{Motol University Hospital}%
\affil[2]{General University Hospital in Prague}%


\vspace{-1em}



  
  \date{June 15, 2024}


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Adam Klocperk\textsuperscript{1}, M.D., Ph.D., Zuzana
Para\selectlanguage{polish}č\selectlanguage{english}kov\selectlanguage{ngerman}á\textsuperscript{1}, MSc., Jitka Dissou\textsuperscript{2},
M.D., Hana Malcová\textsuperscript{3}, M.D., Ph.D., Petr
Pavlí\selectlanguage{polish}č\selectlanguage{english}ek\textsuperscript{4}, M.D., Tom\selectlanguage{ngerman}á\selectlanguage{polish}š \selectlanguage{english}Vymazal\textsuperscript{4},
M.D., As. Prof., Pavla Dole\selectlanguage{polish}ž\selectlanguage{english}alov\selectlanguage{ngerman}á\textsuperscript{5}, M.D., Prof., Anna
\selectlanguage{polish}Š\selectlanguage{english}ediv\selectlanguage{ngerman}á\textsuperscript{1}, M.D., Prof.

\textsuperscript{1}Department of Immunology,
2\textsuperscript{nd}Faculty of Medicine, Charles University in Prague
and University Hospital in Motol, Prague, Czech Republic

\textsuperscript{2}Emergency Department for Children, University
Hospital in Motol, Prague, Czech Republic

\textsuperscript{3}Department of Children and Adult Rheumatology,
University Hospital in Motol , Prague, Czech Republic

\textsuperscript{4}Department of Anesthesiology and Intensive Care
Medicine, 2nd Faculty of Medicine, Charles University in Prague and
University Hospital in Motol, Prague, Czech Republic

\textsuperscript{5}Centre for Paediatric Rheumatology and
Autoinflammatory Diseases, Department of Paediatrics and Adolescent
Medicine, General University Hospital in Prague and
1\textsuperscript{st} Faculty of Medicine, Charles University in Prague,
Prague, Czech Republic

\section*{Running title}

{\label{running-title}}

Severe course of pediatric COVID-19

\section*{Corresponding author}

{\label{corresponding-author}}

Adam Klocperk, MD, Ph.D. Department of Immunology, 2nd Faculty of
Medicine, Charles University in Prague and University Hospital in Motol
V Uvalu 84 Praha 5 150 06 Czech Republic adam.klocperk@fnmotol.cz Tel:
+420~702~013~154

\section*{Word count}

{\label{word-count}}

1032

\section*{Tables}

{\label{tables}}

0

\section*{Figures}

{\label{figures}}

2

\section*{Conflict of interest
statement}

{\label{conflict-of-interest-statement}}

The authors have declared that no conflict of interest exists.

\section*{Ethical approval}

{\label{ethical-approval}}

This study was carried out in accordance with the recommendations of the
Ethical Committee of the second Faculty of Medicine, Charles University
in Prague and University Hospital in Motol, Czech Republic. The protocol
was approved by the Ethical Committee. All subjects gave written
informed consent in accordance with the Declaration of Helsinki.

\section*{Financial support}

{\label{financial-support}}

The study was funded by grants NV18-05-00162 and NU20-05-00320 issued by
the Czech health research council and Ministry of Health, Czech Republic
and by institutional support issued by the University Hospital in Motol,
Prague, Czech Republic.

\section*{Keywords}

{\label{keywords}}

COVID-19, SARS-CoV-2, children, pediatric, inflammation, systemic
inflammatory response syndrome, hemophagocytic lymphohistiocytosis,
macrophage activation syndrome, corticosteroids

\section*{Main text}

{\label{main-text}}

To the Editor:

The recently emerged SARS-CoV-2 virus causes pneumonia and, in severe
cases, acute respiratory distress syndrome (ARDS) in adults, but its
clinical picture can be markedly different in children, most of whom
undergo only a mild or even asymptomatic course of the
disease\textsuperscript{1--3}. In some cases, however, profound systemic
inflammatory response is triggered, sharing few similarities with the
more commonly seen self-limited respiratory infection.

Here we report a case of an 8-year-old girl who manifested with fever
(\textgreater{}40°C), headache, abdominal pain and vomiting, but no
signs of respiratory involvement with only mildly elevated C-reactive
protein (CRP, 27 mg/l, Fig 1A). Over the next 2 days she developed
diffuse itchy maculo-papular rash (Fig 1B) and watery diarrhea with CRP
of 139 mg/l. At this point, SARS-CoV-2 nasopharyngeal swab polymerase
chain reaction (PCR) was negative. The girl was started on
amoxicillin/clavulanic acid. However, her condition deteriorated with
ongoing high-grade fever, diarrhea and headache necessitating hospital
admission on day 5 from symptom onset. She was febrile and dehydrated
with severe abdominal pain, diarrhea and positive meningeal signs. She
had high inflammatory parameters (CRP 267 mg/l, procalcitonin 70 \selectlanguage{greek}μ\selectlanguage{english}g/l),
elevated D-dimers and urea, creatinine, liver enzymes, troponin and
proNT-BNP. Stool PCR showed only weak positivity for rotavirus and
astrovirus, chest X-ray was largely normal (Fig 1C), spinal tap
suggested mild serous meningoencephalitis. At this point, the
nasopharyngeal swab PCR was still negative, however, anti-SARS-CoV-2 IgG
antibodies were positive, with negative IgM. Due to recurrent episodes
of hypotension and other signs of septic shock the patient was started
on intravenous ceftriaxone and transferred to an intensive care unit.
Abdominal ultrasound suggestive of paralytic ileus with appendicitis and
overall worsening of clinical status resulted in an empirical exchange
of ceftriaxone for piperacillin, tazobactam and metronidazole and
abdominal surgery on day 6 of the disease, which revealed serous
peritonitis but no appendicitis or other pathology. Subsequent serology
showed positive IgA against \emph{Yersinia enterocolica,} but negative
rectal swab culture.

After extubation and discontinuation of analgosedation on day 7, the
patient's consciousness deteriorated towards Glasgow coma scale (GCS) of
7-8 on day 8, despite normal central nervous system magnetic resonance
imaging (MRI) and lack of topical neurological symptoms. Here the
patient developed dry cough for the first time. Even though all tests
including the cerebro-spinal fluid, blood culture, urine, stool and
broncho-alveolar lavage were negative for any microbial pathogens, with
the sole exception of nasopharyngeal swab PCR positivity for SARS-CoV-2,
her CRP and procalcitonin remained very high (199 mg/l and 28,4 \selectlanguage{greek}μ\selectlanguage{english}g/l
respectively). The persistent elevation of inflammatory markers along
with very high soluble IL-2 receptor (6326 IU/ml), ferritin (577 \selectlanguage{greek}μ\selectlanguage{english}g/l)
and history of juvenile idiopathic arthritis (oligoarticular subtype,
currently inactive without therapy) lead to suspicion of viral-induced
macrophage activation syndrome (MAS) / secondary hemophagocytic
lymphohistiocytosis (HLH), which however was not abundant in bone marrow
aspirate and the patient did not fulfill diagnostic criteria for
MAS/HLH\textsuperscript{4}. Heart ultrasonography was repeatedly normal,
making the diagnosis of Kawasaki disease unlikely. The patient was
administered intravenous methylprednisolone (2mg/kg/day in 3 doses), one
dose of 400 mg/kg intravenous immunoglobulins, prophylactic nadroparin
and the piperacillin and tazobactam were discontinued due to apparent
lack of effect in favour of ceftriaxone. This therapy lead to gradual
improvement of clinical symptoms with full recovery of her consciousness
by day 11. Her inflammatory markers, cardiac enzymes, liver and renal
functions normalized apart from the mild hepatopathy most likely related
to the combined antibiotic therapy. The patient was finally discharged
from the hospital in good health on the 15\textsuperscript{th} day after
onset of symptoms.

We observed a spike in markers of inflammation around day 8, coincident
with the worsening of patient's symptoms. Of particular interest in the
context of COVID-19 was the elevation of CRP and PCT, but relatively
``low'' levels of serum IL-6 (cytokine associated with severe course of
the disease and higher mortality in adults\textsuperscript{5}) -- the
patient reached IL-6 of 215 pg/ml (normal range 0-6 pg/ml) at the time
of worst clinical symptoms. For comparison, adult patients admitted to
our hospital with severe course of COVID-19 who required mechanical
ventilation frequently reached IL-6 levels in the thousands. Soluble
IL-2 receptor which is produced by activated mononuclear
cells\textsuperscript{6} was very high, while both monocytes and
lymphocytes were normal on day 8 and increased only slightly between
days 10 and 15 (Fig 2A). On the other hand, neutrophils and eosinophils
peaked on day 8 and decreased sharply thereafter. While the elevation of
neutrophils and lymphopenia are both well-established as negative
prognostic markers of COVID-19 in adults\textsuperscript{7}, the role of
eosinophils remains more elusive, with some reports suggesting they are
decreased in severe cases\textsuperscript{8}. Aside from the waxing and
waning of leukocyte subpopulations, the pivotal role of innate immunity
in defense against SARS-CoV-2 is further supported by the depletion and
gradual recovery of complement (C3 and C4 proteins) during the disease
(Fig 2B).

We additionally show stark changes in neutrophil phenotype during the
course of the disease (Fig 2C). The expression of HLA-DR, previously
described to be decreased in COVID-19\textsuperscript{9}, was low on day
8 and gradually recovered to normal levels. CD10, a marker of neutrophil
maturation associated with immunosuppressive
function\textsuperscript{10}, was markedly decreased during the worst
clinical symptoms, suggesting efflux of young, active neutrophils from
the bone marrow, but together with the inhibitory molecule PD-1L and
CD15, a marker of activation in mature neutrophils, reached supra-normal
expression during recovery as these cells matured. The adhesion molecule
CD62L was low during the time of most fulminant infection, but its
expression recovered and was even elevated on day 19 at recovery.
Together, these data suggest full activation and engagement of
neutrophils during the disease with compensatory contraction of the
response and contra-regulation of neutrophil phenotype during recovery.

In summary, our patient developed systemic inflammatory response to
SARS-CoV-2 infection in absence of other infectious pathogens, which had
some but not all hallmarks of secondary MAS/HLH and which quickly
deteriorated and then resolved with corticosteroids, preventive
anticoagulation and supportive therapy only. This case report
illustrates the variability of clinical presentation of SARS-CoV-2
infection in children, which should be suspected in case of unexplained
inflammatory symptoms even in the absence of signs of respiratory
infection. Immunosuppressive therapy may be helpful for these patients.

Adam Klocperk\textsuperscript{1}, M.D., Ph.D., Zuzana
Para\selectlanguage{polish}č\selectlanguage{english}kov\selectlanguage{ngerman}á\textsuperscript{1}, MSc., Jitka Dissou\textsuperscript{2},
M.D., Hana Malcová\textsuperscript{3}, M.D., Ph.D., Petr
Pavlí\selectlanguage{polish}č\selectlanguage{english}ek\textsuperscript{4}, M.D., Tom\selectlanguage{ngerman}á\selectlanguage{polish}š \selectlanguage{english}Vymazal\textsuperscript{4},
M.D., As. Prof., Pavla Dole\selectlanguage{polish}ž\selectlanguage{english}alov\selectlanguage{ngerman}á\textsuperscript{5}, M.D., Prof., Anna
\selectlanguage{polish}Š\selectlanguage{english}ediv\selectlanguage{ngerman}á\textsuperscript{1}, M.D., Prof.

\textsuperscript{1}Department of Immunology,
2\textsuperscript{nd}Faculty of Medicine, Charles University in Prague
and University Hospital in Motol, Prague, Czech Republic

\textsuperscript{2}Emergency Department for Children, University
Hospital in Motol, Prague, Czech Republic

\textsuperscript{3}Department of Children and Adult Rheumatology,
University Hospital in Motol , Prague, Czech Republic

\textsuperscript{4}Department of Anesthesiology and Intensive Care
Medicine, 2nd Faculty of Medicine, Charles University in Prague and
University Hospital in Motol, Prague, Czech Republic

\textsuperscript{5}Centre for Paediatric Rheumatology and
Autoinflammatory Diseases, Department of Paediatrics and Adolescent
Medicine, General University Hospital in Prague and
1\textsuperscript{st} Faculty of Medicine, Charles University in Prague,
Prague, Czech Republic

\section*{Impact statement}

{\label{impact-statement}}

SARS-CoV-2 infection in children may trigger systemic inflammatory
response without symptoms traditionally associated with COVID-19 in
adults. Its course is characterized by the activation of the innate
immune response and may resolve quickly with supportive therapy and
intravenous corticosteroids.

\section*{References}

{\label{references}}

1. Xu Y, Li X, Zhu B, et al. Characteristics of pediatric SARS-CoV-2
infection and potential evidence for persistent fecal viral
shedding.\emph{Nat Med} . 2020. doi:10.1038/s41591-020-0817-4

2. Brough HA, Kalayci O, Sediva A, et al. Managing childhood allergies
and immunodeficiencies during respiratory virus epidemics -- the 2020
COVID\selectlanguage{english}-19 pandemic. \emph{Pediatr Allergy Immunol} . 2020:0-3.
doi:10.1111/pai.13262

3. Lu X, Zhang L, Du H, et al. SARS-CoV-2 Infection in Children. \emph{N
Engl J Med} . 2020;382(17):1663-1665. doi:10.1056/NEJMc2005073

4. Henderson LA, Cron RQ. Macrophage Activation Syndrome and Secondary
Hemophagocytic Lymphohistiocytosis in Childhood Inflammatory Disorders:
Diagnosis and Management. \emph{Pediatr Drugs} . 2020;22(1):29-44.
doi:10.1007/s40272-019-00367-1

5. Ruan Q, Yang K, Wang W, Jiang L, Song J. Clinical predictors of
mortality due to COVID \selectlanguage{english}- 19 based on an analysis of data of 150 patients
from Wuhan , China. \emph{Intensive Care Med} . 2020.
doi:10.1007/s00134-020-05991-x

6. Nelson DL, Rubin LA, Kurman CC, Fritz ME, Boutin B. An analysis of
the cellular requirements for the production of soluble interleukin-2
receptors in vitro. \emph{J Clin Immunol} . 1986;6(2):114-120.
doi:10.1007/BF00918743

7. Zhang B, Zhou X, Zhu C, et al. Immune phenotyping based on
neutrophil-to-lymphocyte ratio and IgG predicts disease severity and
outcome for patients with COVID-19. \emph{medRxiv} .
2020:2020.03.12.20035048. doi:10.1101/2020.03.12.20035048

8. Qin C, Zhou L, Hu Z, et al. Dysregulation of Immune Response in
Patients With Coronavirus 2019 (COVID-19) in Wuhan, China. \emph{Clin
Infect Dis} . 2020;2019(Xx Xxxx):4-10. doi:10.1093/cid/ciaa248

9. Wilk AJ, Rustagi A, Zhao NQ, et al. A single-cell atlas of the
peripheral immune response to severe COVID-19. \emph{medRxiv} . 2020.
doi:https://doi.org/10.1101/2020.04.17.20069930

10. Marini O, Costa S, Bevilacqua D, et al. Mature CD10+ and immature
CD10\selectlanguage{english}- neutrophils present in G-CSF--treated donors display opposite
effects on T cells. \emph{Blood} . 2017;129(10):1343-1356.
doi:10.1182/blood-2016-04-713206

\section*{Figure legends}

{\label{figure-legends}}

\subsection*{Fig 1}

{\label{fig-1}}

Blood biochemistry and markers of inflammation over the course of the
disease (A). Exanthema on day 12 (B). Chest X-ray on day 6 (C).

\subsection*{Fig 2}

{\label{fig-2}}

Leukocyte subpopulations over the course of the disease (A). Complement
protein C3 and C4 levels over the course of the disease (B). Neutrophil
phenotype on day 8 (fulminant disease), 12 and 19 (recovery) in
comparison to a healthy control (C).\selectlanguage{english}
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\includegraphics[width=0.70\columnwidth]{figures/Fig-2/Fig-2}

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