Cell-Free Immunotherapies-Effective Approaches Against COVID-19

Yiran Liu

Leonard N. Stern School of Business, New York University, U.S.A.

Keywords:

Interferons, IVIg (Intravenous Immunoglobulin), Antibodies, SARS-CoV-2.

Abstract:

In 2019, an infectious coronavirus disease, known as COVID-19, was discovered to be caused by severe acute

respiratory syndrome coronavirus 2 (SARS-CoV-2). The highly contagious nature of the virus led the

scientific community to urgently develop therapeutic approaches for fighting against SARS-CoV-2. The

mechanisms of COVID-19 are lung damage and dysregulated immune response. This article attempted to

systematically review the available literature on cell-free immunotherapeutic strategies against COVID-19,

shedding light on our understanding of COVID-19. Cell-free immunotherapy methods still have room for

improvement, and understanding the immunology of COVID-19 is crucial for developing therapeutic

strategies. As a result, cell-free immunotherapy could be used more appropriately, which may help scientists

to determine the direction of future research.

1 INTRODUCTION

In 2019, the contagious disease COVID-19 rapidly

became a global pandemic and has to this date caused

approximately 260 million infections and 5 million

deaths around the world. SARS-CoV-2 is recognized

as a novel beta coronavirus (β CoV), which is a

single-stranded RNA virus. The mechanisms of

COVID-19 are cytopathological damage of the cell

and dysregulated immune response. Despite the fact

that many people infected with the coronavirus might

experience organ dysfunction (Figure 1), they could

recover without hospitalization. By contrast, the

elderly and immunocompromised are more likely to

develop serious illnesses or face a higher risk of

mortality. Therefore, the highly contagious nature of

SARS-CoV-2 led the scientific community to

urgently develop therapeutic treatments for

combating SARS-CoV-2. Immunotherapies are

effective methods for combating viral infections by

inducing, enhancing, or suppressing the immune

response. Immunotherapies include cell-based

therapies and cell-free therapies. Cell-based therapies

aim to inject a donor's healthy cells into a patient's

body to fight against disease. Cell-free therapies have

advantages in overcoming the risks associated with

cell-based therapies, such as macro thrombosis and

micro thrombosis. Therefore, Cell-free therapies are

safer, cheaper, and more beneficial to humans.

Current cell-free immunotherapies include

corticosteroids, interferons, monoclonal &

polyclonal antibodies, and other cell-free

immunotherapies (Figure 2). This article reviewed

these cell-free immunotherapy techniques against

SARS-CoV-2 and discussed current peer-reviewed

cell-free immunotherapeutic strategies against

COVID-19.

Figure 1: Organ damages caused by the SARS-CoV-2 can

be solved by cell-free immunotherapies: cell-free

immunotherapies might mitigate cardiac, kidney, liver,

nervous system, and lung injury; decrease macro- and

micro-thrombus formation and endothelial inflammation;

and repair lung epithelial and endothelial cells.

476

Liu, Y.

Cell-Free Immunotherapies-Effective Approaches Against COVID-19.

DOI: 10.5220/0012032700003633

In Proceedings of the 4th International Conference on Biotechnology and Biomedicine (ICBB 2022), pages 476-482

ISBN: 978-989-758-637-8

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

Figure 2: Graphical representation of usage percentage of

cell-free immunotherapies for COVID-19, which data were

from surveys in Chinese hospitals.

2 CORTICOSTEROIDS FOR

COVID-19

Patients infected with coronavirus disease have a

severe immune response leading to acute lung injury

and acute respiratory distress syndrome (ARDS)

(Erika, 2021). Among the cell-free drugs that target

the immune system, corticosteroids are usually used

to mitigate inflammation by suppressing the immune

system in severe cases of coronavirus disease

including SARS, MERS and COVID-19.

Corticosteroids are artificial drugs that are known as

steroids, which are naturally produced in the adrenal

cortex of vertebrates. They could be used in the

management and treatment of almost all areas of

medicine.

On the one hand, WHO claimed that systemic

corticosteroids are powerful immunomodulators,

which are generally low-cost, easy to administer and

accessible in healthcare systems pressured by the

COVID-19 global pandemic (WHO, 2020). Some

studies reported signs of beneficial effects of

corticosteroids through evidence comparing systemic

corticosteroid use to usual care in COVID-19. The

recovery trial demonstrated a lower 28-day mortality

in patients who received corticosteroids and were

either receiving oxygen alone or receiving invasive

mechanical ventilation, compared to usual care

(WHO, 2020). It was shown that the superior potency

of corticosteroids against COVID-19, because they

could lower the fatality rate and reduce the need for

receiving invasive mechanical ventilation.

On the other hand, systemic use of corticosteroids

has potential harms, such as hyperglycaemia

(especially in diabetics), hypernatremia,

gastrointestinal bleeding, neuropsychiatric effects,

neuromuscular weakness, superinfection,

immunocompromise, stroke or myocardial infarction

(WHO, 2020). Additionally, there is reason to

suspect that systemic corticosteroids may also delay

viral clearance and increase possibilities of secondary

infections, even though there is no firm data and

conclusion that could be drawn from studies and

research. As a result, this method is not

recommended for all patients, especially those who

have mild/non-severe/moderate symptoms

associated with COVID-19, because the adverse

effects of mass use of corticosteroids may have more

disadvantages than advantages.

On September 2, 2020, the WHO made a strong

recommendation for systemic corticosteroids in

severe and critical COVID-19 based on the moderate

certainty of evidence which showed a reduction in

mortality of 3.4% in patients with COVID-19 who

were critically or severely ill (WHO, 2020). In

addition, WHO made a conditional recommendation

not to use corticosteroids in the treatment of patients

with non-severe COVID-19. The reasons were low

certainty evidence which suggested an increased 28-

day mortality in patients with non-severe COVID-19;

that systemic corticosteroid use has potential harms

(e.g. hyperglycaemia, neuromuscular weakness,

superinfection); that indiscriminate use of the therapy

for COVID-19 may potentially rapidly deplete global

resources, and deprive patients who may benefit from

it most (WHO, 2020). Ultimately, the impact of

systemic corticosteroids in COVID-19 still remains

unknown and controversial, which means that further

investigations and trials on exploring the roles of the

corticosteroid therapy in the management of patients

are necessary. The clinical use of corticosteroids

should be more conscious about inconclusive adverse

events from corticosteroid administration in severe

COVID-19 cases.

3 INTERFERONS

Interferons (IFNs) are proteins generated by a

plethora of cells through the inflammatory response

to viral infections. In a typical scenario, virus-

infected cells release interferons, which kick off

fundamental cellular defense mechanisms in nearby

cells, such as heightening their antiviral defenses.

There are three types of IFNs: alpha, beta and

gamma. IFN-alpha is from leukocytes infected with

the virus, IFN-beta is produced in fibroblasts infected

with the virus, and IFN-gamma is induced by the

stimulation of lymphocytes.

Cell-Free Immunotherapies-Effective Approaches Against COVID-19

477

Type I IFNs have potentially positive effects for

fighting against coronaviruses. Type I IFNs are

famous for their antiviral and immunomodulatory

properties, and they are usually used for limiting the

spread of infectious agents, enhancing antigen

presentation, and triggering the adaptive immune

response. Studies showed the effectiveness of IFNβ

against viral infections compared to IFNα. For

example, a recent study published by Scientific

Reports assigned patients randomly in a 1:1:1 ratio to

IFNβ1a, IFNβ1b, or the control group (Ilad, 2021).

Through comparing IFNβ1a and IFNβ1b against each

other and a control group, IFNβ1a was associated

with a significant difference against the control group

while the IFNβ1b indicated no significant difference

compared with the control group (Ilad, 2021). In

general, mortality was indeed lower in both of the

intervention groups: 20% lower mortality in the

IFNβ1a group, 30% lower mortality in the IFNβ1b

group and 45% lower mortality in the control group

(Ilad, 2021). Also, these three groups did not show

significant differences regarding adverse effects

(Ilad, 2021). Given the limits of this study, further

confirmation in larger studies was required. In

addition, Sheahan et al found potent inhibition of

MERS-CoV with IFNb (Timothy, 2020). Some other

researchers conducted a preliminary study on 22

SARS patients. Comparing patients treated with

corticosteroids alone, this study indicated the

potential effect of interferon alfacon-1 combined

with corticosteroids (Mona, 2004). Therefore, the

studies on different types of viruses inferred that

interferon could be able to be protective in treating

patients with SARS-CoV-2.

However, such research on interferon therapy in

SARS-CoV is far from enough, especially given that

the virus is highly mutable and keeps changing.

Interferon might not contribute beneficial results for

hospitalized patients with COVID-19 (National

Institutes of Health, 2021). Nevertheless, these

findings still had clinical importance. For example,

the combination of interferon and other therapies may

be helpful for patients fighting COVID-19.

4 MONOCLONAL &

POLYCLONAL ANTIBODIES

Through different ways in which antibodies are

created from lymphocytes when an infection occurs,

antibodies are classified into two main types:

monoclonal and polyclonal. Both play important

roles in the humans’ immune system, diagnostic

exams, and treatments. Polyclonal antibodies (pAbs)

are a heterogeneous mixture induced by different B

cell lineages within the human body, whereas

monoclonal antibodies (mAbs) are secreted by

identical B cells which are clones from a single parent

cell. In addition, unlike polyclonal antibodies which

are from live animals, monoclonal antibodies are

produced in vitro environments using tissue-culture

techniques. The main source of protective pAbs is

recovered patients, whose plasma could be given to

patients infected with COVID-19 as a treatment

practice. In contrast, experimental methods usually

produce antiviral murine, humanized mAbs, or their

fragments. In general, when exposed to a pathogen,

the majority of antibodies produced by the humoral

immune system can target certain antigenic

determinants with sufficient affinity if they are

protective, and some antibodies target domains in the

spike protein can yield protection. This is how

antibodies prevent the reproduction of the virus or its

variants. Emergency use of antibody drugs should be

allowed in order to help patients’ immune systems

fight against viruses.

Scientists expected that pAbs and mAbs could be

useful in reducing viral levels, minimizing damage to

the patients’ lungs, preventing COVID-19 early-

stage infections, and allowing non-hospitalized

patients to heal more rapidly (Michael, 2021). This

treatment has long worked better on individuals who

have higher virus levels. However, the role of this

treatment is still controversial. Scientists are still

researching the population of patients who can

benefit the most from this treatment, and the extent

that this treatment is effective.

5 OTHER CELL-FREE

IMMUNOTHERAPIES FOR

COVID-19

Although there still remain ambiguities in the three

main COVID-19 therapies above, several other

approaches have meaningful results. The following

section discussed other possible treatments for

patients with COVID-19.

5.1 Convalescent Plasma Therapy

Convalescent plasma therapy transfers pathogen-

specific antibodies from recovered patients to help

others recover from the same illness. In response to

SARS-CoV-2 infection, convalescent plasma therapy

was useful when helping hospitalized patients to

ICBB 2022 - International Conference on Biotechnology and Biomedicine

478

recover and helping non-hospitalized patients to

prevent disease. Convalescent plasma therapy is

accessible because requirements for this therapy’s

infrastructure and resources are low. This therapy

only requires the donated plasma from disease

survivors and the standard blood collection

infrastructure. Thus, convalescent plasma therapy

could be readily used in low-resource settings around

the world. In addition, convalescent plasma therapy

could be given to hospitalized patients who have a

weakened immune system and are infected with

SARS-CoV-2. Convalescent plasma therapy could

help them to recover from COVID-19 by lessening

the severity and shortening the time of infection.

Recent studies, which have limited numbers of

patients and do not have control groups, tested the

clinical efficacy of convalescent plasma therapy in

fighting against COVID-19. To be more specific, the

study reported the results of the treatment of five

critically ill patients with COVID-19 with

convalescent plasma in China (Shen, 2020). After

receiving convalescent plasma therapy, four patients’

clinical status improved within 12 days, with

improvements such as enhanced PaO2/FiO2 and

decreased viral loads (Shen, 2020). This study

indicated that using convalescent plasma therapy has

potential to fight against COVID-19, but it must be

noted that this study did not have a control group.

Moreover, it is important to note that the passive

immunotherapy with convalescent plasma therapy

has the most effective therapeutic effects when the

viral load is relatively lower. Furthermore, this study

initiated convalescent plasma therapy from ten to

twenty-two days after admission of patients. Studies

received favorable results showing that convalescent

plasma therapy initiated earlier might have higher

efficacies (Shen, 2020). Furthermore, compared with

therapeutic uses, passive immunotherapies with

convalescent plasma therapy have a better efficiency

when used prophylactically. It is indicated that

scientists should put more effort into investigating

convalescent plasma therapy, especially as vaccines

have already become available around the world.

There are still uncertainties regarding the roles of

convalescent plasma therapy because the study by

Shen et al. was a randomized controlled trial.

Meanwhile, the results were based on limited

evidence so far. Thus, the clinical and therapeutic

impacts of plasma efficacy still need to be confirmed

in the future studies and well-designed clinical trials.

5.2 Intravenous Immunoglobulin (IVIg)

IVIg is the use of a mixture of antibodies from donors

that can be given intravenously. These antibodies are

protective proteins produced by the human immune

system in response to the presence of several

pathogens, such as viruses, bacteria, parasites, and

tumor cells. Donors’ antibodies bind directly with the

abnormal host pathogens, stimulating their removal.

Previous studies on SARS indicated that IVIg has

benefits on SARS patients. A study performed by

Wang et al showed that IVIg therapy improved

leukocyte/platelet counts in patients with severe

leukopenia, thrombocytopenia, and elevated levels of

aminotransferase, lactate dehydrogenase, and

creatine kinase (Wang, 2004). In addition, IgM-

enriched IVIg therapy demonstrated benefits in

patients with COVID-19 who were not cured by

corticosteroid therapy. And a multicenter

retrospective cohort study revealed clinical efficacy

of intravenous immunoglobulin therapy in critical

patients with COVID-19 from analyses on more than

three hundred patients (Shao, 2020). This study

showed that high dose IVIg could be helpful in the

prognosis if administered in the early stage of the

disease (Shao, 2020). A research meta-analysis

retrieved four clinical trials and three cohort studies

including 825 hospitalized patients (Xiang, 2021). In

the critical subgroup, IVIg could reduce the mortality

compared with the control group. However, the

severity of COVID-19 was not related to the efficacy

of IVIg. There was no significant difference in the

severe or non-severe subgroups. In a word, IVIg may

be clinically efficient in patients with COVID-19, but

impacts and roles of IVIg therapy in COVID-19

treatments are still uncertain, and further

effectiveness of it needs to be explored.

Adverse effects associated with IVIg are

commonly muscle pain, blood clots, kidney

problems, anaphylactic reactions and hemolytic

anaemia. However, the role of IVIg in infected

patients remains inconclusive because it is difficult to

isolate its benefits as it has been used in combination

with other drugs. In detail, patients with COVID-19

were benefited by mild dose corticosteroid plus IVIg

therapy (20 g/day), even though they did not benefit

from low dose IVIg therapy (10 g/day) (George,

2020). In addition, researchers found that the

combination of IVIg and methylprednisolone could

reduce respiratory morbidity in COVID-19. Further

studies about therapeutic impacts of IVIg still need to

be conducted, because the specific functions and

effectiveness of IVIg still need to be confirmed

through future research.

Cell-Free Immunotherapies-Effective Approaches Against COVID-19

479

6 CONCLUSIONS AND

OUTLOOK

On January 30, 2020, the World Health Organization

declared the COVID-19 outbreak as a Public Health

Emergency of International Concern, and later, as a

pandemic on 11 March 2020. From when SARS-

CoV-2 first emerged, it has spread so swiftly that the

need to find effective COVID-19 therapies became

necessary and urgent. In the evaluation of current

COVID-19 therapies, patients’ safety should be the

main consideration. This paper summarized the most

recent research and studies of cell-free

immunotherapy, showing that this therapeutic

intervention is proven to be useful against SARS-

CoV-2. Despite this therapy’s initial success,

research on it still showed ambiguities and room for

improvement. An overview of the advantages and

disadvantages of these novel potential therapies that

need to be formally tested in future clinical trials are

presented in Table1, and the applicable conditions are

summarized in Figure 3, indicating that among these

methods, monoclonal & polyclonal antibodies are the

most widely applicable, corticosteroids have biggest

most potential, and there are still room for

breakthroughs in interferons in the future.

Moreover, it is vital to note that the virus is

changing. The Delta and Omicron variants appeared

successively in 2021. The Deltacron variants

appeared in 2022. Researchers must adapt their

therapies with the new mutations in mind. Though

there still remain challenges and uncertainty, this

article attempts to provide a systematic overview of

the available literature on cell-free

immunotherapeutic strategies, with the aim to help

scientists who investigate effective controls and

novel treatments for COVID-19. It is significant to

understand the intricacies of the virus-immune

system in order to treat and manage disease properly

in the future.

Table 1: Current cell-free immunotherapies for COVID-19 introductions and their potential beneficial & adverse effects in

COVID-19.

e Introduction Advanta

es Disadvanta

Corticosteroid

Corticosteroids are

artificial drugs that are

known as steroids, which

are naturally produced in

the adrenal cortex of

vertebrates.

Low cost; easy to

administer and

accessible in

healthcare

systems.

Potential harms, such as

hyperglycaemia (especially in

diabetics), hypernatremia,

gastrointestinal bleeding,

neuropsychiatric effects,

neuromuscular weakness,

superinfection/immunocompromise,

stroke or m

ocardial infarction.

Interferons

There are three types of

interferons (IFN): alpha,

beta and gamma. IFN-

alpha is from leukocytes

infected with the virus;

IFN-beta is produced in

fibroblasts infected with

the virus; IFN-gamma is

induced by the stimulation

of lymphocytes.

Limiting the

spread of

infectious agents,

enhancing antigen

presentation, and

triggering the

adaptive immune

response.

Research on interferon therapy in

SARS-CoV is far from enough,

especially given that the virus is

highly mutable and keeps changing.

Interferon might not contribute

beneficial results for hospitalized

patients with COVID-19.

Monoclonal &

Polyclonal

Antibodies

Polyclonal antibodies

(pAbs) are a heterogeneous

mixture induced by

different B cell lineages

within the human body,

whereas monoclonal

antibodies (mAbs) are

secreted by identical B

cells which are clones from

a single parent cell.

Useful in reducing

viral levels,

minimizing

damage to the

patients’ lungs,

preventing

COVID-19 early-

stage infections,

and allowing non-

hospitalized

patients to heal

more rapidly.

The role of this treatment is still

controversial.

ICBB 2022 - International Conference on Biotechnology and Biomedicine

480

Convalescent

Plasma

therapy

Convalescent plasma

therapy transfers pathogen-

specific antibodies from

recovered patients to help

others recover from the

same illness.

Lessening the

severity and

shortening the time

of infection.

There are still uncertainties

regarding the roles of convalescent

plasma therapy.

IVIg

(Intravenous

Immunoglobu

lin)

IVIg is the use of a mixture

of antibodies that can be

given intravenously. IVIg

gives antibodies that the

human body is not making

on its own but can fight

infections.

IVIg may be

clinically efficient

in patients with

COVID-19.

Clinical and laboratory data on

severe acute respiratory syndrome

(SARS) are limited. Adverse effects

associated with IVIg are commonly

muscle pain, blood clots, kidney

problems, anaphylactic reactions

and hemol

tic anaemia.

Figure 3: An overview of the options for cell-free immunotherapies in patients with COVID-19 depending on the stage of the

disease, according to WHO Clinical Progression Score (Frank, 2022). The treatments based on high-quality randomized trials

are presented in dark blue, while the more speculative treatments based on observational or small case-series studies are

presented in light blue.

REFERENCES

Chenguang Shen, Zhaoqin Wang, Fang Zhao, et al. 2020.

Treatment of 5 Critically Ill Patients With COVID-19

With Convalescent Plasma. The Journal of the

American Medical Association, 323 (16): 1582–1589.

Erika Vainieri. Dexamethasone in Hospitalized Patients

with Covid-19. 2021. The New England Journal of

Medicine, 384: 693-704.

Frank L. van de Veerdonk, Evangelos Giamarellos-

Bourboulis, Peter Pickkers, et al. 2022. A guide to

immunotherapy for COVID-19. Nature Medicine, 28:

39–50.

George Sakoulas, Matthew Geriak, Ravina Kullar, et al.

2020. Intravenous Immunoglobulin Plus

Methylprednisolone Mitigate Respiratory Morbidity in

Coronavirus Disease 2019. Critical Care Explorations,

2(11): e0280.

Huai-rong Xiang, Xuan Cheng, Yun Li, Wen-wen Luo, Qi-

zhi Zhang, and Wen-xing Peng. 2021. Efficacy of IVIG

(intravenous immunoglobulin) for coronavirus disease

2019 (COVID-19): A meta-analysis. International

Immunopharmacology, 96: 107732.

Ilad A. Darazam, Mohamad A. Pourhoseingholi，Shervin

Shokouhi, et al. 2021. Role of interferon therapy in

severe COVID-19: the COVIFERON randomized

controlled trial. Scientific Reports, 11(1): 8059.

Jann-Tay Wang, Wang-Huei Sheng, Chi-Tai Fang, et al.

2004. Clinical manifestations, laboratory findings, and

treatment outcomes of SARS patients. Emerging

infectious diseases, 10(5): 818-824.

Mona R Loutfy, Lawrence M Blatt, Katharine A

Siminovitch, et al. 2004. Interferon Alfacon-1 Plus

Cell-Free Immunotherapies-Effective Approaches Against COVID-19

481

Corticosteroids in Severe Acute Respiratory

Syndrome: A Preliminary Study. The Journal of the

American Medical Association, 290(24): 3222-3228.

Michael Moore. 2021. Monoclonal and Polyclonal

antibodies in COVID-19 treatment. Retrieved

September 27, 2021 from https://www.h-h-

c.com/monoclonal-and-polyclonal-antibodies-in-

covid-19-treatment/

National Institutes of Health (NIH). Interferon does not

improve outcomes for hospitalized adults with

COVID-19. 2021. Retrieved October 18, 2021 from

https://www.nih.gov/news-events/news-

releases/interferon-does-not-improve-outcomes-

hospitalized-adults-covid-19

Timothy P Sheahan, Amy C Sims, Sarah R Leist, et al.

2020. Comparative therapeutic efficacy of remdesivir

and combination lopinavir, ritonavir, and interferon

beta against MERS-CoV. Nature Communications,

11(1): 222.

WHO. 2020. Corticosteroids for COVID-19. Retrieved

September 2, 2020 from

https://www.who.int/publications/i/item/WHO-2019-

nCoV-Corticosteroids-2020.1

Ziyun Shao, Yongwen Feng, Li Zhong L, et al. 2020.

Clinical Efficacy of Intravenous Immunoglobulin

Therapy in Critical Patients with COVID-19: A

Multicenter Retrospective Cohort Study. SSRN

Electronic Journal.

http://dx.doi.org/10.2139/ssrn.3576827.

ICBB 2022 - International Conference on Biotechnology and Biomedicine

482